<SOLVED> Stuttering

[daveismissing]

stock reg 233
stock jectors
stock chip

I didn't want to prejudice interpretation by stating anything beforehand.
The pressure seems to follow the rules.
~close to 40 line off.

Drops with vacuum and rises smoothly with throttle. When the stutter  is happening the gauge doesn't seem to vary by more than +/- 1 LB? or less Hard to tell exactly on that small gauge.

I'd guess the problem occurs  still in the vacuum range vs boost?

It was much warmer overnight and the problem went away quickly and less pronounced so not much opportunity for capture, I was solo and didn't see the o2s.

[Steve Wood]

You cannot make an interpretation without knowing the basics

stock injectors...wh o knows what might be going on after all these years with regard to gum, etc.

The SM showed it to be extremely lean yesterday...wh en in closed loop, I would expect something like a continual movement between 300 and the 700s.

Factory chip is aiming for stoch.

Okay, next time look at the blms and see what they are reporting while this is going on.

Assuming you were not under boost during the video, then the fuel pressure was probably about right.

In the mean time...try some logger shirt maintenance.  Crank it up, let it idle, and rattle each injector by holding an extension against the shoulder and tap it rapidly with a hammer...not hard enuf to break the housing of course...do each one-won't clean them, but, it might free up a sticking pintel

go to the home store, paint store, or whatever, buy a gallon of xylene and pour it in the tank with about ten gals of gas....half a tank, whatever

[daveismissing]

Well, I couldn't pronounce xylene so I swapped the injectors ( and ancilliary items).
no change.

[Steve Wood]

so this happens in normal driving, not when in boost?

This happens in both open loop and closed loop?

Your SM showed the car to be very lean.  Once the problem goes away, do the O2s get back into a normal range?

What are your blms showing while this is going on?  What do they show when it goes away under the same driving conditions?

[Turbodave]

H

Can you glean anything from this?
stupid cameras stupid new format stupid operators...

http://youtu.be/T_wiMWe6Ba4

How are your scanmaster IAC and TPS numbers at warm idle?

[daveismissing]

BLMs seem to be 117-119 in the area of interest.
No real change cold to hot.

I want to say it still looks lean but let me confirm again, not really seeing much diff there either hot vs cold.

TPS seems to around 0.8-1.5   when it stutters.
Gotta be in vacuum still, pushing it into boost clears or masks the stutter

Now TT 5.6 installed so I'll look at open/closed loop.

hot park
TPS .38
IAC .19

[Steve Wood]

so, if O2s are still lean like they were, and the blms say they are pulling fuel instead of adding it, then we seem to have a paradox, eh?

[gbsean]

bad spot on the TPS...

[Steve Wood]

will the car miss when you bring the gas up in Park?

[Steve Wood]

Got anyone around that you can borrow an ecm with Powerlogger on it from?  God bless Bob Bailey and Scanmaster/Powerlogger!

[1KWIKSIX]

Got anyone around that you can borrow an ecm with Powerlogger on it from?  God bless Bob Bailey and Scanmaster/Powerlogger!

Hey Dave,
 
Sent you a PM on the above subject.
 
Dave

[daveismissing]

will the car miss when you bring the gas up in Park?

Yes

[Steve Wood]

Just like a treasure hunt...one clue at a time

Let's see,  O2s seem low indicating it needs more fuel, blms are low indicating it is pulling fuel, fuel pressure might be okay-was hard to coordinate it with unknown driving conditions

Fueling is supposed to be easy on these cars.  ECM has a fueling curve that depends upon the maf and the O2 inputs for adjustment.  This can be messed up by unmetered air leaks between the maf and the O2 sensor.  This could be a leak between the maf and the turbo or anywhere else in the system including vacuum lines, plenum seal to intake, etc.  Also, any leaks in the exhaust before the turbo can suck air in.

At this point, we know the stutter goes away when it gets hot, but, we really don't know if the problem goes away, or simply gets covered up to some degree.

Can you tell us if this happens only in open loop operation, or does it happen in closed loop initially as well?

Also, are you running a factory original maf, a rebuilt unit, or a Translator?

What brand and how old O2 sensor?

[ULYCYC]

Wonder if the egr is hanging up?  When it's stumbling at idle pull up on the diaphragm a few times and let it reseat and see if it clears up.

[daveismissing]

I appreciate the responses, bear with me as I try to give accurate answers.

New Denso O2 installed with the injectors.
Rebuilt MAF 3yrs in service, tested/bought thru turbofish.