GN sputtering at low RPM

[8AV8]

I just installed this combo. The car is spooling up very slow and when I give it just a little throttle it starts sputtering. Once boost and RPM get up a bit it does better but its really a pig thru first gear. I changed o2 and my plugs and everything looks OK with them. My friend said my chip could be a lot of my problem. Suggested turbotweak...Any suggestions on where to start fixing this sputtering?

 

[8AV8]

Is this a dumb question? Come on guys ,sunday is almost gone ...wont have ime to work on it till next weekend.I wish I had taken shop in high school.

 

[tyrod]

Sounds a lot like a vacuum leak issue. Give some readings off of your scan tool. A bad MAF will cause similar symptoms as well. With the car idling tap on the maf with the plastic end of a screw driver and see if the car stumbles is one way the other is the idle reading of the maf which I have forgotten.

 

[8AV8]

AF readings

My AF reading was 07 at idle. How many in. of vacuum should I read at idle?

 

[Fuelie600]

What do you have your fuel pressure ( line off ) set at. Should be @ 42lbs with that combo. Brian

 

[8AV8]

38 to 42 psi

I've tried from 38 to 42 psi [line off] and still get the same sputter. The car almost acts fat, thats why I went down to 38, My o2s were getting very lean there though, so I went back up to 40

 

[WIKEDV6]

I just installed this combo. The car is spooling up very slow and when I give it just a little throttle it starts sputtering. Once boost and RPM get up a bit it does better but its really a pig thru first gear. I changed o2 and my plugs and everything looks OK with them. My friend said my chip could be a lot of my problem. Suggested turbotweak...Any suggestions on where to start fixing this sputtering?

What are the things did you actually change? Did you change the Injectors and the chip? or just the Injectors? What brand O2 did you put back in?

Prasad

 

[8AV8]

what changes?

I changed inj. and chip[stock chip wouldn't have worked]...Bosch o2...the car was basically stock I did all the upgrades at once, turbo,inj,DP,exhaust,chip,etc. All that stuff at once is making it hard to troubleshoot.

 

[WIKEDV6]

The Bosch o2's are crap, They will give you problems, for some reason our turbo buicks don't like them. I will put an AC delco or Denzo in there. I don't think that is your problem because you had the issue before that anyway right? Did you put the ground wire back on the head nice and tight, the one that goes with the turbo bracket? If the o2 was changed after the problem started, I would check the mass airflow sensor or the chip being your culpret.

HTH

Prasad

 

[sr71gn]

have you checked turbo wheel for play and freeness

 

[g_wilson]

It's kind of a long shot but I did the same thing, replace O2, plugs, fuel pump, pressure regulator, chip and a few other things over the winter and then chased a similar issue for a while. Cracked spark plug was my issue.

Never again, one change at a time.........

 

[8AV8]

sputtering

ground wire is on good. I'll check MAF tonight if I get off work in time and get back with you. I have a chip from turbotweak on the way.MY AF is 07 at idle ,isn't that right where it should be ? What should I look for at WOT? What about at midrange where this is happening?

 

[WIKEDV6]

Also double check all the IC/ turbo hoses make sure they are tight.

Prasad

 

[chris2316]

back to basics check fuel pressure w.o.t ,check plugs, compression etc! grounds

 

[urhstry]

Your MAF value is fine, 255 is the WOT number you want. It really sounds like a vacuum leak. Did you check the headers for cracks? Is the crossover pipe leaking?

 

[8AV8]

vacuum leaks?

I know I dont have any exhaust leaks...how many in. of vacuum should I be reading? I have a pro comp boost gauge[no vac] but Ihave access to a vac gauge...what should it read? This might be a dumb question but I don't know. Is this best way to determine if I have a vac leak or should I just look around and see what I can find?

 

[VandaLL]

i am trying to trouble shoot a similar situation on my t-type.. one thing i still need to do is adjust the cam sensor to see if that helps bc i read somewhere that with an aftermarket cam the timing (or injection?) may be affected and slightly off, resulting in the engine cutting out at low RPMs. mine always stutters right off idle (prob about 1000-1500), but it goes strong above that.

 

[sr71gn]

module and coil--both put on new together solved mine

 

[8AV8]

what kind of module and coil did you use, GM , after market? My car has been stock until recently, what did you use?

 

[8AV8]

fat

GOSH! I changed ms TPS idle from .46to .42 and wow, the car smoothed out almost totally. Would backing down to .40 or even .38 be alright?