The Speed is surging...

[Motokag444]

Strange issue... When Im cruising at a constant speed (5th-6th gear) on the highway at low RPM with no acceleration my car is surging intermittently. I still can get full boost and when I let the car idle it is fine. Also when surging my boost gauge is also very sporadic. I have a SURE TIH, Cobb intake, and FORGE recirculation valve. I checked all hoses and clamps leading up to turbo inlet and all are tight. This started to happen about a month after TIH and intake install (might not be related). Is it possible i need to just get an Accessport and tune. It is pretty intermittent and I have no CEL or fault codes in car. I am a bmw mechanic and have never ran into something like this??? Any thoughts, ideas, or experiences would be helpful. Thanks

[littleloogy]

So when you are in 5th and you boost it does not surge?

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[Motokag444]

No not at all, when I intentionally boost the car is fine. It doesnt skip a beat when I intentionally boost in any gear. It is only when cruising that it acts up.

[sidekick]

How many miles? The EGR valve could be stuck open with carbon build-up. EGR would only be active during cruising, so just something to think about.

[Motokag444]

Damn thats a good thought, 88k on the car. I will have to look into that. Would that really have an impact on my boost (boost guage though?) It is pretty frustrating and I have been searching like crazy to get some ideas. Its definitely not a missfire sort of feeling... just more of a surging/lunging that the car does. Im gonna have to pull spark plugs, check EGR and do some simple shit first to see whats going on.

[littleloogy]

Originally Posted by Motokag444 When Im cruising at a constant speed (5th-6th gear) on the highway at low RPM with no acceleration my car is surging intermittently. I still can get full boost and when I let the car idle it is fine. Also when surging my boost gauge is also very sporadic.

You are boosting while cruising at a constant speed? I am confused by this part of your statement.

Originally Posted by Motokag444 No not at all, when I intentionally boost the car is fine. It doesnt skip a beat when I intentionally boost in any gear. It is only when cruising that it acts up.

It was a trick question to try to get you to admit that you boost in higher gears which is a NoNo! The MZR does not like low RPM torque. It is good practice to Never boost in 5th or 6th gear unless you are shifting to 5th from 4th while going WOT.

[Motokag444]

That's why I put "boost gauge" in parenthesis. I guess technically it would be vacuum it's affecting. I honestly didn't know that they don't like boost in higher gears though. Thanks for the heads up.

[Haltech]

Moved to the proper section...

[Big Dog]

Originally Posted by Motokag444 Damn thats a good thought, 88k on the car. I will have to look into that. Would that really have an impact on my boost (boost guage though?) It is pretty frustrating and I have been searching like crazy to get some ideas. Its definitely not a missfire sort of feeling... just more of a surging/lunging that the car does. Im gonna have to pull spark plugs, check EGR and do some simple shit first to see whats going on.

Sounds like someone's car has been neglected and is due for maintenance.

1. Check where your tih and turbo meet. That coupler or hose likes to get lose and after install of a aftermarket tih it has to be retightened.
2. Thoroughly clean the EGR, Throttle body, Intake Manifold, Valves,. Be sure to use a new intake manifold gasket.
3. Replace the PCV valve with a new OEM Mazda one.
4. New NGK factory Plugs - Go stock heat range with your mods and gap between .028-.032
5. Clean MAF Sensor
6. Buy a DashHawk or AP so you can monitor things afterwards.
7. Report back after the above is done.

[Motokag444]

Sounds like a plan, I will try and get everything for next weekend, u recommend the walnut shell blasting that a lot of guys are doing for valve cleaning?

[Kyle Undefined]

Yes, it works really well.

[LordKingston]

Any news?

[Jeff23spl]

are you having turbo surge or another king of surge because it cannot surge out of boost ????

[pzr2874]

Bet you a dorra it's the BCS