Stuttering when boosting

[goshred005]

yo-

Here is my problem, I just installed my 3in rnr turbo back(no o2 elim). when i floor it, at around 9 psi my car begins to buck and stutter really fast. my car is stock, only some free mods, intake, MBC. what is the problem here? THanks for your time. WTF

 

[andymoraitis]

Check the following:

1. Spark Plugs: NGK BPR6ES
2. Spark Plug Gap: .026-.028
3. Plug Wires: NGK's or Magencore's work well.
4. Catalytic Converter: remove and check for broken or crumbled catalyst
5. Fuel Filter: replace if not done in the last 60K
6. Fuel Pump: test for correct voltage
7. Scan it: Check for any codes
8. Boost leak test: listed last, but do this first.

Keep us posted,

Andy

 

[Ultimatedsm]

What RPM does it buck? Does it buck when boost hits, or just generally around 4000 RPM and up?

 

[goshred005]

it bucks at around 3-3500 and only happens when i boost

 

[sonicnofadz]

Sounds like a boost leak. You are probably getting huge amounts of knock and this "bucking" is the engine pulling back the timing due to "detonation".

 

[goshred005]

if i have -18hg vaccum. does that indicate if i have any leaks. How do i check for leaks because i have never done this before. thanks for your guys help.

 

[andymoraitis]

Vacuum leaks are an entirely different story than boost leaks. Boost leaks will kill performance since the system is accounting for air that it believes is metered that's leaking from the system. This spins the turbine harder, depending on the severity of the leak, makes the motor run rich and kills performance. FYI your vacuum looks OK.

For a guide on how to build a boost leak tester and test, check out:

http://www.vfaq.com under the Intake section.

Hope that helps,

Andy

 

[andymoraitis]

Sounds like a boost leak. You are probably getting huge amounts of knock and this "bucking" is the engine pulling back the timing due to "detonation".

Boost leaks cause a rich condition which in turn wouldn't cause detonation. Detonation and pulled timing are caused by running too lean. Just an FYI.

Andy

 

[Ultimatedsm]

Alright once you tested for boost leaks let us know the results. Next thing I would check is ignition then MAF sensor.

 

[TEAMONEINC]

I had the same exact problem you had it sounds like. I purchased the following:

1. NGK spark plugs
2. Accel Wires
3. Perrin MBC
4. Boost gauge
5. HKS SSBV Recirculation Kit (already had the blow off valve)

I am installing all of this within the next few days and I will let you know what happens, but every "knowledgeable" person on here, recommended the above measures. Good Luck.

 

[goshred005]

the other day i took off my muffler and ran it like that. i noticed that it doesnt stutter with it off. why is that?

 

[andymoraitis]

It's very likely that your catalyitc converter is collapsiing and not allowing for proper exhaust flow. Removing the rear section freed up enough restriction that it could properly run. Remove the catback and pull the cat. If you hold it up to a light source and can't see through it past the honeycombs, then it's shot and needs to be replaced. Any reputable muffler shop can sell you a high flow unit or you can bang out the internals and run the cat empty if you don't have emissions.

Andy

 

[RotaryRyan]

Make sure your TPS is plugged in. Mine came off once and it stutters badly when hitting boost.

 

[TEAMONEINC]

I just installed all of the stuff on my previous post...problem solved. check your plugs and wires.

 

[TJGoSurf]

Are you sure its not wheel hop being mistaken for stuttering? I notice you said the whole car bucks.

 

[RotaryRyan]

Are you sure its not wheel hop being mistaken for stuttering? I notice you said the whole car bucks.

He really shouldn't be losing traction in the middle of a gear with his mods. Plus, it's hard to mistake wheel hop for anything else.

 

[goshred005]

its fixed, i put inside some new spark plugs. ngk bpr6es. thanks for your guys help