Idle stumble...Help!!!

[Supersix]

Hey whats up...Ive been fighting this idle issue for a while now..
Lets see..well I am using a snap on scanner and ran all data...only spec I found off was the vaccum and map readings...I repl the unit w/ gm 2 bar sensor..My vaccuum on a mech. gauge is -21 about the same on the new sensor..checked ecm,grounds,new delco plugs,accel 9000 wires,delco cap and rotor.Motor top dead center lines up with 0 degree timing mark and timing is set at 0 with tan wire off...no leaks,good charging,Iac is good ..I bumped idle a little up due to shut down when I put it in gear...Cleaned t-body..egr etc...When it sumbles it is for a brief second and stabilizes and
happens again...you also hear puff in the exhaust..Only hapeens at idle..Runs great on throttle...lots of power,100% driveability..Idle sucks..
Really feels like ignition...but where should I check now...Thank you for any advise...Rob

 

[ed hess]

i will save you a lot of posting by telling you to go search the words stall, stalling and ed hess. we wrote a novel about this in the fall of 2002. we never found it there. read all that and when your done doing everyting under the sun possible as i did. the culprite turned out to be the seal between the heads and the lower intake. whe the lower intak bolts came out the lower was lifted off with 1 finger. No tests were able to find it. and when i said we did everyting i mean it. but anyway hoefully after you find the threads you might do better than we did.

The real symptom was the stalling going into gear, what you are seeing now is proably due to that same cause.


hth

ed

 

[Supersix]

All intake gaskets are new Gm gaskets..bolts all have thread sealant...
Dist. gear is new...had delco wires..repl with accels still the same..

 

[SeattleSy#1255]

never mentioned the type of plugs you are using...i'd go with Taylor wires or something other than accel in my opinion...cap/rotor delco probably find, but might want to go brass like conrad...i know that is basic, but somethimes it is that easy.

 

[turbodog]

Also, did you check the park/neutral switch at the shifter? ECM adjusts spark/fuel depending on if in gear or not. Bad or misadjusted switch could cause your symptoms. DM or other OBD tool will tell you if status of that switch.

 

[Supersix]

The plugs are the stock delco CR-42ts...I just went out and got a Conrad cap and rotor part #DR2012G....Let you know how it goes...I will also check the park neutral switch...Thank you for your response..

 

[Supersix]

Update..Checked Park/Neutral switch..OK..Pulled cap and rotor off..Removed ignition module checked all related plugs.cleaned out distributor rust and blow out with air...Reinstalled module with electric grease ..Repl cap and rotor with Conrad unit...Ran truck...SAME CRAP...
any one else have any ideas?

 

[ed hess]

use a meter and ohm your wires. just cuz they are new doesnt mean they are all good.

ed