Hmm - still have the stuttering problem, w/second MAF

Reply Subscribe

Thread Tools

Search this Thread

Jun 6, 2007 | 05:50 AM

GorTT

Thread Starter

AudiWorld Super User

Joined: Mar 2003

Posts: 10,195

Likes: 1

Hmm - still have the stuttering problem, w/second MAF

the break point is a few hundred rpms (about 200) higher, but that might be due to engine or ambient temps. About the same on the g/s too - maxed out at 113 +/-

The other MAF I dropped in (a nearly 5 year old OEM MAF) was running fine to the best of my knowledge when I pulled it, but I guess it's not an impossible coincidence.

Any other places I should look that might be causing this - small vacuum leak, fueling, etc? I'll probably go for another MAF anyway just to be sure, but...<ul><li><a href="https://forums.audiworld.com/tt/threads/440884.phtml#1649993">logs post below</a></li></ul>

Jun 6, 2007 | 07:44 AM

RoberTT-WWCD

AudiWorld Super User

Joined: Mar 2000

Posts: 8,091

Likes: 1

Other things to check Will...>>

Leaking in IC hose connections. When I installed my APR, I had a lower hose that was loose and it wouldn't make any boost.

Also, check the N75 hose below
<img src="http://images112.fotki.com/v590/photos/5/58883/297210/DSCN0433-vi.jpg">
it's the hose on top with the 90 defgree bend. they sometimes crack on the under side.

Jun 6, 2007 | 07:49 AM

GorTT

Thread Starter

AudiWorld Super User

Joined: Mar 2003

Posts: 10,195

Likes: 1

ok - if a small leak might cause it, then I know a few places to check!

Jun 6, 2007 | 08:37 AM

TTschwing

AudiWorld Uber User

Joined: Dec 2000

Posts: 53,281

Likes: 2

Boost is definitely an issue, but I think something electrical is causing the loss..

Looked at the logs again Will, and the N75 is shutting everything down at 3K rpms...Boost drops to nothing. Looks like limp mode from the logs. This appears to be sensor induced and not a leak issue. The N75 would keep the duty cycle up if it was a leak in an attempt to meet command boost. The MAF could cause this, so could a temp sensor. I'm, surprised you didn't mention the lack of boost, and sorry I missed it. I was focusing on the MAF issue..

Jun 6, 2007 | 08:49 AM

GorTT

Thread Starter

AudiWorld Super User

Joined: Mar 2003

Posts: 10,195

Likes: 1

Hope you had a nice evening! ;-) Temp sensor, huh? >

when I looked at the engine module this am, there were no codes - no overboost, not even a misfire; I'll check again at lunch for anything since. Me sorry too - I just thought the boost drop was inherent with the stutter, and I thought I'd seen it hit 21 since the symptoms started, so I just wasn't paying attention. Just because I'm curious - and given what little I know - I can't fathom how a temp sensor causes this at a specific rpm. Is there an engine sensor that might be the culprit, or is this the infamous green sensor - which I've had for awhile.

Jun 6, 2007 | 09:00 AM

TTschwing

AudiWorld Uber User

Joined: Dec 2000

Posts: 53,281

Likes: 2

If a bad sensor..>>

Sends info to the ECU that is out of range with the parameters it feels comfortable with based on demand/request, then various failsafes will come into play. The N249 can spill boost by opening the DV, the N75 can do the same by defaulting to wide open and spilling the Wastegate air signal to the tip..