S10 issue... again

[david-b]

My bros truck is having this problem. 99 or 2000 GMC Sonoma

The thing ran fine for a long time. A while back, it starting "shaking". Seemed like a misfire almost. When looking at the engine, when it did it, the whole motor would shake just really quickly. Like one jerk to the side and then it'd be fine. It would go away after warmed up. It's been doing it more and more. You can feel it while driving. Totally random.

I thought spark plugs since it's been 2 years since those were changed. I replaced them. Still didn't do anything though

Apparently the CEL came on but went off (probably random ECU reset) before he was able to take it in and code was cleared. Any ideas on this one? It seems like a misfire almost, but it's random, jerks the engine just a little, but still has good performance.

[JoeShmoe]

VAC leak?

[wrightz28]

GM truck engines of that era 98-03s? around about, had some intake manifold issues with carbon build up which may be partially clogging a injector There's a TSB for the condition.

[david-b]

Cool. Should I should pull the injectors or run injector cleaner through?

[wrightz28]

You know, it's been a bit since Ive dealt with that particular issue, but I would use a direct feed cleaner (attaches to the fuel rail schraeder valve) and that shoud better the situation, but I believe it was the fuel rail and intake design that since it posed no safety issues, didn't mandate a recall.

---NOTE---
Any time you use one of these type cleaners, pay close attnention to the directions and manufacturer precautions. There is a good chance the O2 sensor(s) can become irreversably fouled warranting either their removel during cleaning or replacement there after.

[david-b]

Can't us just pull the injectors and clean them up? Is the carbon build up on the injectors themselves or the FR and iM that gets the dirt? Kinda confused.

[wrightz28]

It's all internal (rail and manifold), there is now real way of pulling injectors and claining them, i don't care if it's dipping them in Willy Wonka's magic potion or using a toothbrush or whatever other wife's tale method. A direct run cleaner is the only way to truely clean injectors. Plus it only takes but a few minutes to disable the fuel system, and clamp off the return hose, versus a hour or so to remove the entire rail assembly.

[david-b]

Got ya.

Now this direct feed cleaner... is this something at Autozone or something? I wish the truck would throw a CEL again so I can test for sure. Of course the truck can only benefit from a cleaning like that but it would be good if that was the actual problem too.

[wrightz28]

As far as I know, places like Az started carying it over the counter in states that allow it as of a couple of years ago, and run's around $25-30. Like I said previously, be sure to read all the manufacturer notes before hooking up and going to town.

I normally either have new o2 ready to go, or if cost or the o2(s) are already new, I remove them and run a bolt in their place.

On a side note, even tho the CEL isn't on, the PCM should have stored a soft code for te next 50 key cycles.

[david-b]

Originally Posted by wrightz28

As far as I know, places like Az started carying it over the counter in states that allow it as of a couple of years ago, and run's around $25-30. Like I said previously, be sure to read all the manufacturer notes before hooking up and going to town.

I normally either have new o2 ready to go, or if cost or the o2(s) are already new, I remove them and run a bolt in their place.

On a side note, even tho the CEL isn't on, the PCM should have stored a soft code for te next 50 key cycles.

States that allow it? Sounds illegal.

When he took the truck in (I wasn't there) the computer wasn't pulling any codes. The CEL was off when he went and apparently was non-exsistant afterward.

[wrightz28]

Not illegal, but I couldn't see a place like California letting everybody blow pumes of black carbon out there tails at will

Matter of fact, I believe I have seen it here in IL for sale. If not, there are certain GM guys who for a few extra bucks will "hook you up"

[david-b]

Got ya. OK I'll see what I can find and give that a try... probably not this weekend though. I hope that's the problem

[gthompson97]

What's that stuff called?

[vanilla gorilla]

Misfire huh? IDK, spark plug wires?

[wrightz28]

Originally Posted by gthompson97

What's that stuff called?

I use OTC Pro Inject-R Kleen:

http://www.otctools.com/products/detail.php?id=1776

Now, this particular brand is applied in a holding canister that you have to buy sepreately (comes with a free OTC pressure gauge tho )

I had heard that stores were starting to sell a over the counter version that has a hose attached to the dispenser can (like fix-a-flat), but I searched Autozone this morning and didn't come across it.