Intake Valve Cleaning using valve overlap and DI injection window shift

[Vansquish]

I should preface this by saying that I've got enough of an idea about how to do this that I could get into some pretty serious trouble, and I know that there are others who are better equipped to work on this. I'm hoping, therefore, that some of you will chime in.

I've been thinking for some time about the fact that I've got 114k on my car and the valves have never been cleaned (this will be happening on Saturday, I'll take pictures). I don't relish the idea of having to repeatedly remove the IM and clean the valves, and I don't want to remove my EGR (I like fuel economy and lower emissions). That leaves us with Meth/Eth injection (not a great plan, given the additional system complexity and need to refill -- I'm lazy), or figuring out a way to have the valves cleaned by gasoline, as happens in PI engines.

So I dug around a little bit, and lo and behold, there's a Patent on the issue.

Patent US6178944 - Valve cleaning method for direct injection spark ignition engine - Google Patents

Now, keep in mind, the patent is expired, due to failure to pay maintenance fees (this means that Ford didn't end up commercializing the technology, as they would've wanted to enforce it and keep it active and valid for the full 20 year term, otherwise). So there was probably some issue with the idea. My guess is that they were blowing up intake manifolds or frying intake valves.

That said, Porsche has a couple of European Patent Publications on the same subject:

Patent EP1884637A2 - Method for cleaning the combustion chamber and the intake tract of a ... - Google Patents

Patent DE102012213241A1 - Erkennung einer Verkokung im Einlasstrakt eines Verbrennungsmotors Detection ... - Google Patents

So here's my thinking. If we can come up with away of playing with the VVT so as to have a small bit of overlap where the intake valve is open during the appropriate injection/ignition phase (say, at low rpm/load) then we could have means of de-coking our intake valves without damaging anything, and without the need to walnut/B12-blast the valves on a semi-regular basis.

Consider the gauntlet thrown down. I'll send whoever can figure it out successfully some tasty local libations.

@Lex; @rfinkle2; @Justin@Freektune; @phate; @ms3blackmica; @Enki; @dale_gribble; @superskaterxes; @TiGraySpeed6; @Boost_creep;

If I'm forgetting anyone, I sincerely apologize, and I'll be happy to tag you, and extend the deal to you too!

[rfinkle2]

I think that your idea is good, but that I feel more comfortable removing the deposits while being sure they aren't pushed into the cylinders.

From the valves I've seen meth or eth injection has little to no effect on deposit accumulation.

There is a Mazda recommended fluid called zoom juice, which I believe to be much like BG's fuel system cleaner, but I would rather pull the deposits out than push them through / burn them...

That is just my opinion.. I could be concerned for no reason.

[Vansquish]

Originally Posted by rfinkle2 I think that your idea is good, but that I feel more comfortable removing the deposits while being sure they aren't pushed into the cylinders. From the valves I've seen meth or eth injection has little to no effect on deposit accumulation. There is a Mazda recommended fluid called zoom juice, which I believe to be much like BG's fuel system cleaner, but I would rather pull the deposits out than push them through / burn them... That is just my opinion.. I could be concerned for no reason.

I agree with you on principle. What I'm really thinking is that if the map was designed in this way to begin with, when the car rolled off the production line, there would be no coking. Basically, I think what the goal *should* be is to have clean valves, then keep them that way for the lifespan of the car, without having to open anything up.

[TiGraySpeed6]

I've wondered about this myself, and it has been discussed a few times in the past with no positive take away.

My take has always been that if it was that easy to do then it would have been part of the OEM map to begin with.

Or Nishan would have done it because he's smart & stuff.

[Vansquish]

I agree.

My suspicion is that there's something we don't really know about that could result (cavitation/destructive pneumatic hammering/etc.). It still seems like this must be possible, especially given Porsche's recent interest in the topic.

[5LOWMS6]

I like where this is going.

I agree with @rfinkle2;, it's better to remove the deposit rather than burn it, especially when you have that many miles on the engine. But to prevent more build up this could work if you don't have an OCC or if you don't want to delete EGR.

I ended up having to pull my IM while installing the catch can, and I made the mistake of not being prepared to tackle the shit that was cooked nicely on those valves. I instead ended up scraping the most crap I could and proceeded to put my IM back on in hopes of someone figuring out an easier way to clean them.

I'm also interested to see the difference in power that you'll get after cleaning your valves OP.

my car had only 90k KMS and they were that bad.

[Agent_Orange]

Originally Posted by Vansquish think what the goal *should* be is to have clean valves, then keep them that way for the lifespan of the car, without having to open anything up.

Seems like an unrealistic goal. As Rob stated above, even DI cars that are spraying meth/eth will still see accumulation. That's largely due to the geometry of the engine, angle/location of the injectors in relation to the valves etc., and the fact there isn't a constant fuel wash over the valves. Forced induction exacerbates the issue further.

Even in factory PI engines, accumulation will be evident given enough miles. It is heavily influenced by factors such as fuel quality and additives, EGR system, oil type & quality, operating temperatures, and residence time.

Anyone who knows their way around an MZR can probably have the IM pulled within 20 minutes. Then depending on the tools used and experience, have the valves media blasted in another hour or so. Also as Mr. Finkle stated, I'd rather see that shit come out than go in. It's not like your doing it every weekend either. Even at 30k intervals, you'll end up doing it 4 or 5 times over the average life of a speed.

[Vansquish]

I'll take some logs on the way to the valve cleaning (if I remember), and do some on the way back (if I remember) to see if there's a noticeable difference on the same map. I've been having some issues with WGDC control of late, however, so they'll probably not be up to the 289/335 in my sig, especially given that it's going to also be in the 70s.

Originally Posted by Agent_Orange Seems like an unrealistic goal. As Rob stated above, even DI cars that are spraying meth/eth will still see accumulation. That's largely due to the geometry of the engine, angle/location of the injectors in relation to the valves etc., and the fact there isn't a constant fuel wash over the valves. Forced induction exacerbates the issue further. Even in factory PI engines, accumulation will be evident given enough miles. It is heavily influenced by factors such as fuel quality and additives, EGR system, oil type & quality, operating temperatures, and residence time. Anyone who knows their way around an MZR can probably have the IM pulled within 20 minutes. Then depending on the tools used and experience, have the valves media blasted in another hour or so. Also as Mr. Finkle stated, I'd rather see that shit come out than go in. It's not like your doing it every weekend either. Even at 30k intervals, you'll end up doing it 4 or 5 times over the average life of a speed.

Thanks for the insight! I know a fair bit about engines in relative terms, but as I noted above, not enough specifically about this engine to keep me out of trouble. You may well be right, but it still strikes me as an interesting idea, even if it only extends the interval between necessary valve-cleaning jobs.

That said, I hadn't really considered the specific geometry of our engines, so it's certainly possible that my suggestion is an impossibility on this platform. The real goal for this thread is to get minds with more knowledge than my own thinking about this as a potential (partial) solution to a long-standing problem in this community.

I also understand the point about not wanting that shit falling into the combustion chamber. I'm with you on that. My thinking is that if we clean our valves (by walnut blasting/B12/whatever), then if we have some minor tune revision with a bit of overlap, a la what the patent publications are suggesting, then we might be able to keep them from coking up for a significantly longer period of time.

[Jeff23spl]

overlap to clean valves...

if i understand, you mean that intake valves remains open during explosion cycle?

First to do that it would mean it stay open during compression cycle instead of closing and it will touch the piston at TDC and even if this wouldn't happen, with intake open, there won't be compression so there won't be any explosion just gaz going back to IM.
Trying to open them sooner at exaust cycle won't be of any much benefit ? Won't it just put more bad stud and heat to them ?

I think their is no real good option but i have seen W/M and good oil/gaz keeping mine in good shape. I never really burned oil with a bad turbo yet or because of a non working OCC or PCV so this may have helped a lot. I Just have EGR returns and PCV returns to the IM and valves.
If we keep it open

[Vansquish]

Originally Posted by Jeff23spl overlap to clean valves... if i understand, you mean that intake valves remains open during explosion cycle? First to do that it would mean it stay open during compression cycle instead of closing and it will touch the piston at TDC and even if this wouldn't happen, with intake open, there won't be compression so there won't be any explosion just gaz going back to IM. Trying to open them sooner at exaust cycle won't be of any much benefit ? Won't it just put more bad stud and heat to them ? I think their is no real good option but i have seen W/M and good oil/gaz keeping mine in good shape. I never really burned oil with a bad turbo yet or because of a non working OCC or PCV so this may have helped a lot. I Just have EGR returns and PCV returns to the IM and valves. If we keep it open

I understand where you're coming from, but you clearly misinterpreted what I was suggesting. The valves wouldn't be fully open, so there shouldn't be any interference between the valves and the piston. Furthermore, you've misinterpreted the portion of the cycle during which the intake valves would remain open in the first place.

In a 4-stroke, there are: Intake, compression, ignition, and exhaust strokes. Under normal circumstances, the intake valves shut as the compression stroke begins. What I'm suggesting is that the valves could remain open for the first fraction of the compression stroke, and that the injectors dump a little bit of fuel into the chamber at that moment too.

The gasoline *might* then wash over the valves, only to be blown back into the combustion chamber during the next intake stroke.

In any case, there's no chance that the valves would be open and interfere with the pistons.

[Jeff23spl]

humm i see, you don't want to burn the deposit, just wash them with some gaz during a kind of wasted and/or missfire stroke.

We need to keep in mind it is the same cam for each cylinder so if you shift later the intake cylcle to overlap intake valve opening with compression cycle, all cylinder will do it at least once and maybe more. (I don't know how much time the VVT take to adjust VS a 4-5000 rpm speed )

This could work only when the engine is out of boost because the positive pressure will prevent any fuel to go back.

What would work beter could be a mixed dizi and PI injection like the Subaru BRZ...I tough first that it was something weird but after all, it may make sense to have both...If you had a way to just switch from dizi to pi sometime during cruizing, it may be easier to achieve. Just add few injector and a controling circuit like a megaskirt and a way to disable dizi injector for few seconds ?

[dooderek]

just want to point out, even with an occ and meth about a d09's worth, i still built carbon. you would have to spray meth all the time (idle etc. like p.i.) to get it to do a decent job at removing carbon.

and tire pressure

[Chimmike]

sorry to step in off-topic, but what is this myth about EGR helping mpg? That shit is ENTIRELY for emissions purposes, not mpg. New skyactiv=no EGR. Several vehicles have no EGR system.

[HawkeyeGeoff]

Originally Posted by gingermike sorry to step in off-topic, but what is this myth about EGR helping mpg? That shit is ENTIRELY for emissions purposes, not mpg. New skyactiv=no EGR. Several vehicles have no EGR system.

I feel like I saw a healthy drop in MPG after I blocked off my EGR...I could be wrong though.

[Vansquish]

Originally Posted by HawkeyeGeoff I feel like I saw a healthy drop in MPG after I blocked off my EGR...I could be wrong though.

It's early yet but I disabled my EGR yesterday (unplugged it), and thus far, it looks like my fuel economy is dropping off a little bit. Of course, there are some other factors to consider too, as I just did my intake valve cleaning, and put a different tune on the car.

Updates to follow . . .

Originally Posted by gingermike sorry to step in off-topic, but what is this myth about EGR helping mpg? That shit is ENTIRELY for emissions purposes, not mpg. New skyactiv=no EGR. Several vehicles have no EGR system.

On our vehicles, since the ECU logic is designed to take the EGR into account, it does have an impact on fuel economy. Thus far, it looks like mine is dropping off after I disabled the EGR.

[pwdunmore]

Originally Posted by gingermike sorry to step in off-topic, but what is this myth about EGR helping mpg? That shit is ENTIRELY for emissions purposes, not mpg. New skyactiv=no EGR. Several vehicles have no EGR system.

Deleting the EGR will decrease fuel economy. The exhaust gases are inert gases that take the place of oxygen, therefore reducing the need for gasoline to hit desired AFR.

My L/100kms were at 11 with my EGR deleted and are now 9 since I have reconnected it.

EGR systems are not "seen" on newer vehicles as they are not needed because it is integrated into the exhaust valve timing or something of that sort. But then again, I have been wrong once before

[Chimmike]

so by using the intert gases to "replace" oxygen, and using less fuel, you're actually not creating as much power, which is like slapping a small motor in a big vehicle. Less power=needs to work harder to accelerate and maintain speed=uses more fuel in the long run.

[Vansquish]

Originally Posted by gingermike so by using the intert gases to "replace" oxygen, and using less fuel, you're actually not creating as much power, which is like slapping a small motor in a big vehicle. Less power=needs to work harder to accelerate and maintain speed=uses more fuel in the long run.

I think you've got some misconceptions about when the EGR system comes into play. The solenoid only opens the valve and allows exhaust gas into the combustion chamber to "replace" oxygen during low-load, low-rev, cruising conditions. It's not the sort of thing that comes into play at WOT, where the valve remains shut.

This is why if/when you unplug/remove the EGR system, you start seeing P0401/0403 and you see your AFRs at idle jump significantly. The volume of inert gas injected by the EGR system at low load/revs means that there's less O2 in the system, and less fuel is needed. Once the system is disabled, the same volume of air-gases enters the combustion chamber, and the same is true of the quantity of fuel. However, the air-gases are now much more O2-laden, meaning that the downstream O2 sensors begin to see a much leaner-looking burn.

All-in-all, this means that the car ends up more knock-prone, has higher EGTs (at low load/revs).

As we know, our ECUs are set up to be AFR/knock-resistance-fanatics. As soon as our AFRs start reading too high, and the car starts to knock, the ECU commands more fuel into the mixture, and of course, this means worse fuel economy.

Furthermore, the amount of power needed to maintain a steady cruising speed is relatively low (on the order of 20-60hp at 75mph, depending on drag coefficient), so I'm not sure how much water the "needs more power to maintain speed" argument holds. Of course, the more understressed the engine is, the less likely it is to burn fuel, so you're right in that respect.

[TiGraySpeed6]

When I got it, still 100% stock, my car got 19 MPG city(ish) driving. Exactly what the window sticker said it should.

Now, 6 years later, my EGR has been deleted for years, with a different engine, different turbo, different & much more aggressive tune, /and/ running an e30 blend, yet I still get 19 MPG.

Just for grins, it's worth noting that I was also getting spot on 19 mpg on my last engine, at 74,000 miles, same basic tune, turbo & fuel blend & of course, no EGR.

[Vansquish]

Originally Posted by TiGraySpeed6 When I got it, still 100% stock, my car got 19 MPG city(ish) driving. Exactly what the window sticker said it should. Now, 6 years later, my EGR has been deleted for years, with a different engine, different turbo, different & much more aggressive tune, /and/ running an e30 blend, yet I still get 19 MPG. Just for grins, it's worth noting that I was also getting spot on 19 mpg on my last engine, at 74,000 miles, same basic tune, turbo & fuel blend & of course, no EGR.

This isn't entirely surprising. As we all know, a tune makes a huuuge difference in fuel economy on this platform. I saw my highway mileage jump from a maximum of 27.5mpg stock to ~32mpg and have averaged low 20mpg numbers in the city since I tuned my car.

The E30 mixture will obviously decrease your fuel economy, but you've probably just made up the difference between it and the stock, super rich, tune by having your car properly tuned.

[Jeff23spl]

Originally Posted by gingermike so by using the intert gases to "replace" oxygen, and using less fuel, you're actually not creating as much power, which is like slapping a small motor in a big vehicle. Less power=needs to work harder to accelerate and maintain speed=uses more fuel in the long run.

I disagree for newer car because regardless of the motor in a vehicule, the energy to move it will depend of it's weight and resistance to roll+ aerodynamics.

So regardless of a 150 hp engine doing 100 or a 250hp doing 100 hp i believe the V8 moving 8 pistons will use more fuel to make the same energy than a 4 as long as all of them are doing it with a good AFR in the same pressure conditions.
When we compare a Turbo vs non turbo, i don't know but if it is so bad, company would still use V8 instead or replacing them with L4T or V6T

Add human nature to that, if you have a more powerfull vehicule, you will use that added power each time you go from a stop to have more fun especially is you are the type of person that drive a speed.

The larger factor for fuel economy is your right foot and the use of the car

[Vansquish]

Originally Posted by Jeff23spl I disagree for newer car because regardless of the motor in a vehicule, the energy to move it will depend of it's weight and resistance to roll+ aerodynamics. So regardless of a 150 hp engine doing 100 or a 250hp doing 100 hp i believe the V8 moving 8 pistons will use more fuel to make the same energy than a 4 as long as all of them are doing it with a good AFR in the same pressure conditions. When we compare a Turbo vs non turbo, i don't know but if it is so bad, company would still use V8 instead or replacing them with L4T or V6T Add human nature to that, if you have a more powerfull vehicule, you will use that added power each time you go from a stop to have more fun especially is you are the type of person that drive a speed. The larger factor for fuel economy is your right foot and the use of the car

It is not always the case that more pistons means more gasoline. What we have to keep in mind here is the fact what we're talking about cruising conditions. Under these conditions, that is, low load and low revs, generally speaking, fewer cylinders and less displacement means better fuel economy.

If, however, if we were talking about accelerating up to speed in a somewhat aggressive manner more displacement and more cylinders could likely do the job more efficiently than a small displacement engine. If you want to see a practical demonstration of this, look up the Top Gear Toyota Prius vs BMW M3 race around the TG test track.

[Jeff23spl]

Originally Posted by Vansquish It is not always the case that more pistons means more gasoline. What we have to keep in mind here is the fact what we're talking about cruising conditions. Under these conditions, that is, low load and low revs, generally speaking, fewer cylinders and less displacement means better fuel economy. If, however, if we were talking about accelerating up to speed in a somewhat aggressive manner more displacement and more cylinders could likely do the job more efficiently than a small displacement engine. If you want to see a practical demonstration of this, look up the Top Gear Toyota Prius vs BMW M3 race around the TG test track.

interesting but again they say it right, it depend on how you drive more than the car.
If we reffer again to physic laws, the prius very low handling needs to brakes more than the m3 to handle curves and this require more energy to get back to speed than the m3. The m3 just have to slow down a little and turn way faster keeping it's inertia .
This is exactly like this kid that always wot to reach the next red light first, when everyone elses adjust their pace to the lights synchronisation and just go thru. Instead of braking and going wot to brake again...Each time you brakes, it's like if you had a hole in your gaz tank and you spill some of it. We have to brakes for sure but the less you do, the better will be you fuel economy. (And btw the less iddle you do too)

[TiGraySpeed6]

Originally Posted by Vansquish This isn't entirely surprising. As we all know, a tune makes a huuuge difference in fuel economy on this platform. I saw my highway mileage jump from a maximum of 27.5mpg stock to ~32mpg and have averaged low 20mpg numbers in the city since I tuned my car. The E30 mixture will obviously decrease your fuel economy, but you've probably just made up the difference between it and the stock, super rich, tune by having your car properly tuned.

certainly a decent clean tune balances, even improves, things, but really the take away there was that the EGR delete didn't negatively effect my mileage as it's trended across two engines and other configuration changes, and many years.

[Vansquish]

Originally Posted by Jeff23spl interesting but again they say it right, it depend on how you drive more than the car. If we reffer again to physic laws, the prius very low handling needs to brakes more than the m3 to handle curves and this require more energy to get back to speed than the m3. The m3 just have to slow down a little and turn way faster keeping it's inertia . This is exactly like this kid that always wot to reach the next red light first, when everyone elses adjust their pace to the lights synchronisation and just go thru. Instead of braking and going wot to brake again...Each time you brakes, it's like if you had a hole in your gaz tank and you spill some of it. We have to brakes for sure but the less you do, the better will be you fuel economy. (And btw the less iddle you do too)

You're right, and you're still missing part of the point as well.

I understand the laws of physics quite well. I have a degree in the subject, after all. In your post you conflate momentum and inertia, and you don't seem to understand that during the braking process (if you're in-gear, rather than in neutral/clutch-in), then your MS3/MS6 is compression braking and is basically fuel-starving the engine (hence the 29.3AFR fuel trims).

Furthermore, if you were to take a Prius and an M3 to the drag strip, make the Prius go all out, and make the M3 keep the exact pace of the Prius, I would be willing to bet that the Prius burns more gasoline than the M3.

I want you to stop this though, as you're derailing the thread, and I responded in a pretty complete form to gingermike above (I've copied the contents of my earlier explanation and put them below):

"I think you've got some misconceptions about when the EGR system comes into play. The solenoid only opens the valve and allows exhaust gas into the combustion chamber to "replace" oxygen during low-load, low-rev, cruising conditions. It's not the sort of thing that comes into play at WOT, where the valve remains shut.

This is why if/when you unplug/remove the EGR system, you start seeing P0401/0403 and you see your AFRs at idle jump significantly. The volume of inert gas injected by the EGR system at low load/revs means that there's less O2 in the system, and less fuel is needed. Once the system is disabled, the same volume of air-gases enters the combustion chamber, and the same is true of the quantity of fuel. However, the air-gases are now much more O2-laden, meaning that the downstream O2 sensors begin to see a much leaner-looking burn.

All-in-all, this means that the car ends up more knock-prone, has higher EGTs (at low load/revs).

As we know, our ECUs are set up to be AFR/knock-resistance-fanatics. As soon as our AFRs start reading too high, and the car starts to knock, the ECU commands more fuel into the mixture, and of course, this means worse fuel economy.

Furthermore, the amount of power needed to maintain a steady cruising speed is relatively low (on the order of 20-60hp at 75mph, depending on drag coefficient), so I'm not sure how much water the "needs more power to maintain speed" argument holds. Of course, the more understressed the engine is, the less likely it is to burn fuel, so you're right in that respect."

[Vansquish]

Originally Posted by TiGraySpeed6 certainly a decent clean tune balances, even improves, things, but really the take away there was that the EGR delete didn't negatively effect my mileage as it's trended across two engines and other configuration changes, and many years.

I understand what you're saying, but since you're talking about different engines and different sets of mods, I don't see how your argument really stands up, as you've changed a massive number of variables and keep seeing the same result.

Under some circumstances, I would be happy to accept your explanation, but as it stands, the only thing that the 19mpg average would appear to prove is that you're getting 19mpg in the city. You don't really have a controlled experiment is all that I'm trying to say.

You started out stock: 19mpg

You had a tune, E30, no EGR, and 74k: 19mpg

You have a new engine, different turbo, E30, no EGR: 19mpg

If you had started out stock, then went E30 and took baseline fuel economy numbers, then removed the EGR system, then took more fuel economy numbers, then you'd have a stronger argument. The same is true of the new engine/turbo/etc.. For all I know, you could well be right, but the data doesn't necessarily show that. That's all I'm getting at.

[Agent_Orange]

Tangents incoming!

[TiGraySpeed6]

Remember I'm spanning 6 years...

This isn't just an overnight thing- These results have trended true across all the variations and versions. Which is the point- you can't really change something (EGR Delete for example) and then drive it a few days & declare that your mileage has changed.

running a bunch of logs as you tune then wondering why your mileage is so bad....

[Vansquish]

Originally Posted by TiGraySpeed6 Remember I'm spanning 6 years... This isn't just an overnight thing- These results have trended true across all the variations and versions. Which is the point- you can't really change something (EGR Delete for example) and then drive it a few days & declare that your mileage has changed. running a bunch of logs as you tune then wondering why your mileage is so bad....

Perhaps the pertinent question is: how has your highway fuel economy changed (if at all). The reason that I ask is that my understanding of the way the EGR system works in our cars is as I stated earlier. That is, it only pumps exhaust fumes into the intake tract during low load/low rev portions of the drive. So it's feasible that it may not have much of an impact on city driving, but once you're at a steady-state cruise, the numbers begin to fall off more, as the EGR system comes into play.

I'm just spit-balling, of course . . .

[TiGraySpeed6]

Ya know, I really can't say. It's only been on a few trips over the years, from Tally to Orlando or Gainesville, and it's always been in the 32-34 mile range, but I never had a chance to track the long cruise mileage while it still had the EGR in place.

If it helps, the daily commute is ~20 miles and 10 of that is 2 lane country road. Alas that can & will vary, some trips a simple 60-65 mph cruise, other times a more entertaining trip passing folks and driving like a hoon. So, best data point I've got is the mixed "city-ish" driving.

Anyway, the intended point was to let things trend rather than make a change and then a hundred miles later declare that the mileage has suffered because of it.

[jm211]

Ok, the egr make make a 1-2 mpg negative MAX. Who gives a hoot? 16-25 miles over a tank. Which is 1 gallon of gas $4 or so. Thats worst case.

[Vansquish]

Originally Posted by jm211 Ok, the egr make make a 1-2 mpg negative MAX. Who gives a hoot? 16-25 miles over a tank. Which is 1 gallon of gas $4 or so. Thats worst case.

As it happens, I do. I like the fact that this car is capable of surprisingly good fuel economy, while still being a bit of a beast. With the amount of long-distance drives that I do, that could add up to around $4.00/week. Given that, I'm looking at around $200/year in excess gas (not to mention the increased EGTs having a potential impact on the integrity of my catalysts, rings, etc. over the long haul). I don't know about you, but I'd rather have that extra $200/year for mods/maintenance/autocross.

[Cheapspeed]

Originally Posted by Vansquish As it happens, I do. I like the fact that this car is capable of surprisingly good fuel economy, while still being a bit of a beast. With the amount of long-distance drives that I do, that could add up to around $4.00/week. Given that, I'm looking at around $200/year in excess gas (not to mention the increased EGTs having a potential impact on the integrity of my catalysts, rings, etc. over the long haul). I don't know about you, but I'd rather have that extra $200/year for mods/maintenance/autocross.

During the winter that'd be an extra $20 a week for me. So an extra $100 a month in gas would bring me up to $500 from $400.

Now that it's summer it'd probably be about an extra $16.

Would rather have the money for mods. I'll leave my EGR on too.



Because commuter car.

[5LOWMS6]

So were you able to get a before/after datalog OP?

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