Wally

iTrader: (1)

Ive had a mistery issue poping up every so often in my 1996 K2500 big block Vortec suburban. Every once in a while when i go to start the truck up it fires up and runs like its missing on a cylinder. I have changed the cap and rotor. Ohmed out the plug wires and they are all good. New plugs. A recent fuel filter..but i may just put another new one in anyway. The fuel regulator is good (we checked it for Psi leakdown) we recently did a injector cleaning. Now i'm at a wall and cant think on anything else. And this past weekend it happened again and the right side cat started to GLOW RED!!!
My thought was a clogged cat....and since the truck has over 100k miles i can replace without question.....so i gutted it....and still no difference. I have a new set of hi-flo cats on order along with a new muffler. (figure if i'm doing cats it may as well sound good to! )

So any thoughts? Its nothing consistant is the problem....it just happens and goes away wihout cause. Most times it will actup on first start...no matter if warm or cold....then it will run that way for a while....may do it 10min....or last time i restarted the truck 3times doing errands before it went away. Could it be the controll modual under the distributor cap? maybe the crank sensor going bad??? I'm at a loss

sellsman11

Control module. I would've bet on the converter being clogged but you covered that.

stecz20

i know your problem....


































should have bought a ford........lol

Ted G

iTrader: (1)

Check the EGR valve for sticking. If slightly open it will cause a nice misfire. The misfire is what lit the cat up-unburned fuel.

ChrisK

I had something similar happen to me in my camaro.. it was VERY intermitent.. but i did find the issue to be the pickup on the distributor.. I pulled it, changed it and BAM.. problem solved.

Wally

iTrader: (1)

stecz20... ...my Dad used to be a die hard Frod man years ago. And that was because he had a company car that the company paid for all the repairs. SO he never gave it much though when it needed repairs. Then a few years laer he through he would buy my mom a ford Suv.......and then he realized how much was being spent on fixing the thing all the time!!! Got rid of it year and a half later and never looked at another ford since! And i have never liked Fords from my experiences with other friends having them (Knock on wood) none of my GM trucks have ever let me down yet! And thats with me only doig normal maintenance on them Its all personal preferance i know and to be honest if the Fords had a better interior i would have considered one cause i realy like the 250/350 styling.....

sallsman11...that was my next move..i thought i'd throw it out there to see if anyone knew for sure....i hope that cures it!

insptech....we tested it with a tech2 and it was working fine. I eve pulled it and cleaned off the carbon buildup just to be sure.....you think it may be on its way out? maybe the stepper motor is starting to fail??? hmmm.......but then again why would only one of my cats glow red then? This truck has true duals with dual cats tothe muffler then into one exhaust pipe.....and only the passanger cats was red???????

ChrisK...I think that woudl be the control modual in this application and thats what it seems to leaning to the more i think and read reply's

Thanks for the reply's guys....i think i'll order up a control modual during lunch today and swap it out this weekend......should only take about 2hrs with all the brackets and crap covering the distributor back there!!!

Any other ideas or thoughts on the subject?

Outdrive1

I would bet you have a clogged injector, I forget them name of the product but they sell an additive to your gas at auto part stores that will clean your injectors out. If I can remember the name I'll post it later. Those motors are notorious for injector problems. Have you ever had to change any? If you got 9 years with no problems you were pretty lucky. Try running some Chevron with Techroline gas through your tank as well, that stuff works wonders on Gm injectors. You'll know if you run that cleaner through there and the problem goes away, its a cheap and easy trial... If not your only out a couple of bucks but your fuel system will be clean.

Wally

iTrader: (1)

That was my initial thought as well when it first hit. I ended up having a buddy of mine run the GM Top End Cleaner through the injectors. We diconected the fuel pump realy and he hooked up this gizmo of his that hooksup to the fuel rail and feed the injectors directly. So i know they are clean. Thanks for the reply!
I was actually thinking of replacing them with a matched set anyway sometime in the near future because like you said they are old and have some mileag on them

wannabe

Cat glowing red means way too much fuel on that side.

Injector issue possibly. If it starts doing that stop the engine and pull the plugs on that side, if "wet" there you go.

Wannabe

Wally

iTrader: (1)

well i changed the control modual this weekend....so far so good...but like i said it just comes and goes for no reason so i'll just wait and see