little help here :)

Hey guys. I just got done replacing the pcm in my cousins truck. We switched from a 99 to an 01 pcm on his 99 silverado. The injectors and all the tables to go along with the injectors were matched from the 99 file. Now heres the problem. Its got a really rough idle and seems like it wants to die all the time. The fuel trims on bank two are maxxed, the bank 1 looks great. Also the injector pulse width is twice the amount on bank two as it is on one. Does this seem like an injector is either clogged or no longer working. Could it be a coil pack? For a short time we were getting the misfire code on bank two. Also could clogged cat be the problem, i know his cats are getting clogged by the sound of his exhaust. I see a bit of black smoke when he takes off from an idle also. Any help would be appreciated.

Chris

Chris,

Did the issues start after the pcm swap?

well they were more noticeable, but we swapped the old pcm back in and its the same crap. He's going to get his cats chopped off anyways monday so we will go from there i guess. Do you have any experience with this.

Chris

I'll bet if you check your fueling witha wideband you will find out that its extremely rich on both banks...and this will cause all of your idle issues

definately replace your o2 sensor on the side that the trims are maxed out...

and if you dont own a wideband..go to anylocal dyno shop..and just ask to see if you can put the wideband in your pipes while idleingand see what its doing...
I'd be willing to bet its rich as hell...

fueling is teh #1 cause of poor idle
if spark timing is all good..and spark can be a long way from where it should eb and still idle correctly
..but if A/F is off..it will idle like crap

I was just trying to determine if it was mechanical. Check the basics plugs, wires, coil, fuel pressure/leak down. Could be simple as worn plugs bad wires not firing dumping fuel burning up your cats. I would go ahead and replace the 02 on that side as well..

Plugs and wires were recently changed. We are going to swap out the fuel filter and he is cutting out the cats cause we can tell by the sound of the exhaust they are clogged. Would forcing the truck in open loop and disabling trims be a tell if the oxygen sensor is bad? Cause we wouldnt be using the sensors there.

Chris

I'm telling you..put a wideband on it...
I just fixed 3 different cars here in kc that had bad idle issues..all 3 were too rich at idle....

I think you nailed it Scott, I havent put a wideband on it, but I forced it into open loop and it runs like a dream. Looks like its time for new oxygen sensors!

Chris