stock 3400, horrible idle

[bob442]

I got a 01 chevy venture, all stock, it has a really bad idle issue, it pretty much wants to die, but any RPM above 1500 is runs seeminly smooth, heres the fun part. if i pull plug wires 2 or 4 or 3 or 5 the issue doesnt get worse. basically it doesnt even fase the motor. So, i check the plugs, they were replaced 20.km ago by "said" mechanic they test good, little bit of black carbon on them, aside that no indications of running lean. also good spark, so i figure the little module under the coils, swapped the whole pack with mine from my monte, still runs like shit. Ok maybe the injectors are NFG, swap them runs...better, but still like shit, doesnt stall but still farts and shakes like mad. Drop the fuel filter, has a little bit of resistance to(blowing out the fuel with my lips) it was kinda full of brown deposits....but it has a plastic tank. so i'm suspecting fuel contamination, but the fuel lit my fire pit quite well....
So, i have a code to pull still, i'll get a scanner tomorrow, but i'm starting to suspect a crank or cam sensor.... it almost seems like the spark timing is out to lunch. i dont feel that it is much of a fueling issue. the FPR isnt full of fuel. and not lean indication is

given just read the only code it had, p0305, cyl 5 misfire, no shit. at this point, i cant imagine what could cause this issue exactly.

Any thoughts.....

[TGP37]

Hmmm...

Maybe there is a high resistance in the battery supply line. Causing rough operation at idle when the alternator can not handle the load. 1500-1600 rpms is the range most alternators hit full operation. Having symptoms gone past that may indicate the alternator is handling the load past 1500.

The connection to the battery can not sustain the amps needed, voltage drops and the whole system suffers.

Test ground across the block, frame to the batt (-) terminal for resistance above 0.3-0.5 Ohms. 0.0-0.1 Ohms is a good strong connection. Or just use some jumpers from batt (-) to engine block and see if that improves the idle.




by the harmonic balancer is used for idle quality. But the car should run okay with out it, unless maybe the sensor is sending bad data, failing.

I believe the fueling goes batch fire if the cam sensor fails, that shouldn't be a big issue either.

Maybe the MAF sensor is really dirty or the MAP sensor has a cracked nipple (happened to me before). Did you try unplugging the MAF?

Did the TPS sensor get wet? They hate water and a bad signal at 0-5% TPS would make the engine run like crap.

Was the main crank sensor wire altered at all?

Hope this helps

[bob442]

Answer to problem:
stripped out rockers, going to tap out to 10MM or helicoil, and do the LIMG's, as this being a venture, i can only pull the motor ahead so far, and i cant see what i'm doing now. horray for me!

[TGP37]

Sounds like an interesting project. Plan on aftermarket rockers?

Nice finding the problem so quickly.

[bob442]

i spent 3 hours fucking around looking for the problem, so not so quick lol swapping parts, checking ever single thing.
I'm going to have to pull the intakes to see what the hell i'm doing.

[SappySE107]

01 is 10mm already so why are they 8? Oh, and I finally got some flat rates. Did you still want to try more of those lifter springs or are you done with them?

[bob442]

its actually a 03 as per vin, i just guessed the year.
I would like a set of springs. I'm done F'ing around with these. Its no ones fault Ben, i simply got atleast 2 springs that are out of spec, it happens all the time with valve springs, thats why they have shims and press guages to test each one. That OR my good set of lifters had 2 that failed and F'ed up the springs. could be both. All i know is its quiet now with the stock springs and used lifters.