Engine/Transmission (1994 - 1998) HELP! Light Throttle Stumble

[vssman]

I've developed a stumble or miss when I'm on the throttle lightly. It will clear up if I step on it. It is really noticeable with the TC locked around 1800 rpm and somewhat noticeable at lower speeds (TC unlocked) and lower RPM's. So far I've replaced my rubber fuel lines, fuel filter, and pre-heater gasket thinking the I possibly had a little air being drawn into the fuel. (I can see a few bubbles right when I crack the injector lines but it will clear up in a few seconds). I also re-installed my 180 injectors and it actually seemed to make the stumble at lower RPM's more noticeable. Boost, EGT's, oil & coolant level are all good. About 2 months ago I did have my timing bumped from stock to 15. 5°. I'm thinking (hopeing) that it may have slipped. The TC seems to hold good in lockup so I don't think it's starting to separate. Any ideas?? HELP...





TIA



Paul

 

[ToolManTimTaylor]

Paul I forgot to ask you the other nite how old that pump is. I was thinking a DV issue.

 

[vssman]

The pump is the original one. Hmmmm, DV's? I know the DV was removed when the timing was advanced. I'll see if I can get the socket to remove it and make sure it's clean - not to mention put a new washer in.

 

[SWendell]

I have the same stumble. It appeared after I installed a set of 300 injectors. I have been thinking it was due to poorly adjusted GSK springs (I neglected to measure the factory spring position when I put in a 3 GSK... . well I did use my thumbnail to measure, but. . ) anyway it ran fine with stock injectors... . I figured the bigger injectors made any maladjustment more apparent. I have since adjusted the springs individually, a 1/4 turn at a time... . from barely on the stud, to 4-5 full turns tighter... . still has the stumble, just at different rpms. Its fairly annoying and I am wearing out the AFC threads by tearing it down so often.



Im sure none of this helps you, but at least your not alone

 

[vssman]

It looks like I might have corrected (or masked) the problem. I removed and cleaned #1 DV just in case some goober was left in it when the timing was adjusted. While it was out, I decided to verify the timing... 11°???? Either it slipped or it was retarded instead of advanced. So I bumped it up to 16°-ish. Sounds a lot quieter - never sounded like that before - and "normal driving" pre-boost smoke is now just a haze. Also checking the timing is a PIA without the barring tool. Not to mention having to pull the radiator so that I could get an IMPACT wrench on the nut because it was so darn tight. :--)