Chevy & GMC Vans

this is makin me crazy!!

took the van out this morning, after re-torquing the inlet manifold and TBI bolts last night, it definitely ran better, smoother

all was going well until i had to sit at a stop light for a few minutes and there it reared its head again, rough idle, sat there in Drive, waiting, it came from nowhere??

then when i have to drive away, the thing's running like a bag of wrenches....not as bad as before the torque down but rough all the same.

have changed the fuel and air filters, checked last night (in the dark) for electrical shorting on the ignition system

so, whadya think guys?? what is it about the relationship between the engine and tranny, ie, being in gear, under load, that might affect something to produce a rough idle while sitting there??...this is the first vehicle that i have ever had with an auto tranny so im not well versed on the effects of them on eachother....does the TV cable come into this somewhere??

HEEEEEELLLLLLP

Could still be a vacuum leak. EGR valve could be stuck in the open position.

I would change the cap rotor plugs and leads. If the spark is weak that can cause a rough idle with the extra load of being in gear. The other thing would be to check the injectors and see if your getting a good cone shaped spray with no dripping. You can get a TBI rebuild kit for around $30 with all new gaskets and spring for your fuel pressure regulator in the TBI.

My old 89 did the same thing and the rebuild kit helped. If the egr was staying open it should turn your check engine light on. Try driving at 90kph steady throttle if your check engine light comes on then it is usually a bad egr.

THANKS!

cap, rotor, leads and plugs have done very little, all were changed not long ago.....

the injectors do look as if they are producing a good cone shape.

The EGR valve moved easily by hand also.

the TBI rebuild kit sounds like a good procedure to go thru

it def runs better for having the TBI and inlet manifold torqued

regarding the weak spark under load, what is the difference between being under load sitting in D and actually driving/moving??...the latter of the 2 causes no issues??

Have you checked your motor mounts? My motor mounts had deteriorated so badly that the engine side of the mount was resting on the frame causing the engine vibration to be transfered to the frame. At idle it felt like a bad idle when it was actually just vibration. When I changed the mounts everything was smooth again.

motor mounts recently replaced with OEM (the only real option!)