ive got a 95 jimmy, its vin code w, obd2 with the pcm on the pass shock tower.

just got the truck and last owner said it needed tune up as it was stumbling.

did tune up which consisted of new after market distributor ( made by richporter ), new wires, ngk plugs, fuel filter and oil change. now followed instructions by putting cyl 1 to tdc by using this diagram :

http://i561.photobucket.com/albums/s...inding1TDC.jpg

car runs, but has idle stumble, ive checked the valve in the middle of the intake for fuel leaks, non found. upon scanning found the ignition timing is in the -20, upon test drive it reaches -36*. acceleration is smooth it behaves like a blazer but the negative ignition timing is concerning. ive tried to look for the single wire for timing reset procedures but cant find it under the dash on the passenger side.

any advice?

also i may add that the distributor that the parts vendor sold me is the newer mettalic kind that didnt have the alignment tab, they assured me its the correct one as they used the full vehicle vin to order the parts, could this be an issue?

 

Here are the complete instructions:
EDI Engine Timing

Did you follow them completely? If you did, the #1 cylinder will not be at TDC.

I doubt that the aftermarket distributor is to blame, but did you mark the distributor base precisely where the '6' was on the old base?

 

thanks for that link!

looks like i may have the rotor in the wrong location, i have it pointed at cyl 1 marked on the cap, not at the number 6 on the dist base. but than that should make the rotor in between 2 and 4 on the opposite side, how is it that it still runs?

so if i set tdc using the crank hub marks its not at tdc?

 

Take a look at the traces on the top of the cap. Follow the tower for #1 (between 3 & 5) and it will go over between the towers for 2 & 4. So the '6' in the distributor base actually lines up with pin 1 in the distributor cap. But since the location of the towers on the cap are more conducive to the cylinder locations and not the firing order (1-6-5-4-3-2 btw), GM put a timing indicator in the base of the distributor.

By using the marks on the balancer (provide the outer ring of the balancer has not slipped), the timing will be set properly.

 

Ok thanks a bunch I'll pull it apart and have a look for it. Hopefully the aftermarket distributor has the marks!

 

all right all timed up following the link, rotor is right on the "6" pointer and crank mark lined up to the timing cover, fires right up and runs but ignition timing still bounces from -20 to -25* on the scanner....and another problem started up, fuel is spitting out the schrader valve!

 

The timing is going to move around at idle. That is just the nature of the beast. If it's running properly, then the timing is good to go.

The fuel spraying out the shrader valve means you have somehow either loosened the valve or the valve itself has been damaged. The shrader valve core can be tightened in with a regular tire valve tool so if you have one of those, try that first. I would hazard a guess that the seal materials in the fuel test port shrader valve are different than those used in a typical tire valve... I'm not sure where you would find a new one if you had to.

 

i had a valve stem tool ill look for it, even though its a relatively smooth idle, i thought ignition timing at idle is supposed to be 0*, this one is -20 and more. when i test drive it drops to -36* at times....

weve got tunercats for obd2, i wonder if i should just reflash it...

ok just for ****s and giggles i checked timing on the crank via two different timing guns. crank timing is 20* advance and it corresponds with the scanner, which the pcm retards the timing equal amount to make 0* at idle which its supposed to. so i think everything is fine, now i gotta fix the schrader valve issue along with few other minor things that go along with a used vehicle.

thanks for the input swartlkk, and i hope this thread helps someone in the future.




Edit: ha more crap, this jimmy wants to make a trip to the crusher i think....so take out the schrader valve, found dirt in it keeping it open, must have fallen in during the multiple dist re and re's, anyway upon re installing it fell.....and didnt come out the bottom....the truck ate it....and GM wants 75 bucks and 5-7 days for one....

 

Junkyard maybe?

Your values for timing coincide with my scans that I have from my old '00 Bravada.

 

I'll call around a few tomorrow. I ended up ordering one from the stealership anyways because it takes so long to get one. Hopefully I'll find it tomorrow. It's gotta be hiding back there somewhere...lol