Idk what to do

[ChrisAU]

Well I finally got around to picking my truck up today, and it the same old song. They set the timing perfectly, and it runs down the road awesome. But at idle, it has a random miss and stumble, and it stalled on me at a red light on the way home today.

I put some red bottle heet in it tonight and filled it up (about 15 gallons) with Shell 93. I then drove it around town a little bit, and it still stumbled and missed the same but never stalled. Idk.

I'm taking it on a 75 mile trip tomorrow, please pray that I don't have to involve a tow truck!

So far, its has new: plugs, plug wires, rotor, cap, distributor, IAC valve, ICM, just did the intake manifold gaskets, no vacuum leaks present, new fuel line o-rings, new fuel filter, fresh oil change, new EGR valve solenoid....ughhhh.

I'm going to order AC Delco wires tomorrow and throw them on next week, I'm worried my cheap wires may be the culprit.

However, if one wire, or one plug was bad, how would that cause it to stumble bad enough to stall??? Can that even happen? HELP!

 

[ndians68]

fuel pump???

 

[DRAGGIN95]

I have seen a bad plug wire do some strange thing's you never know, I don't remeber if I have asked this before or not, but have you ever rebuilt your throttle body, if not you should it really help's restore a good running truck, not to mention that there is no other way to change the small filter's that are located on the sides of the injector's other than to rebuild it. I can purchase a rebuild kit for around $40 locally, and it take a couple of hours to do.

 

[ChrisAU]

I haven't rebuilt the throttle body, but it was clean enough to suggest to me that it had been done not long ago. I'm gonna trade the shop again Monday for my Tahoe back and ask them to run a fuel pressure test, to watch it at idle to see if the fuel pressure changes when it starts stumbling. If the fuel pressure is good, I'll order wires. If that doesn't fix it, I'll throw some Bosch +4 plugs in there, I know the AC Delcos are sufficient but I ran the +4's in my '92 RCSB with great results, plus no gap to worry about.

I think we will have it by then, remember this started after I did a basic tune-up with new plugs, wires, cap, and rotor. Now the cap and rotor are a different set, same problem.

From there I'm gonna go TPS, then EGR valve. After that, what else is there?

 

[DRAGGIN95]

Sierra's truck on this forum actually had the small piece of rubber line inside his tank right above the fuel pump get soft and it sprang a leak and was loosing fuel pressure right inside the tank, but the pump was still good, anyway that's something you might check also.

 

[Tempted]

Don't use platinum plugs. For some reason our motors hate them. The best plug for a gen 1 is a copper Autolite or Delco plug. And of all the parts you replaced, did you ever change your CTS? Coil?

 

[dirtridinz71]

I wouldnt waste my money on the bosch plug, as the delcos are new and will do just fine for it. Also you can unhook the vacum line from the EGR valve, that will rule that out, when mine went bad it would just surge just over idle, never quit. Also check your map sensor (and hoses) that can cause a very poor and rough idle and make it quit. Assuming the SES light does work and not lit up?

 

[Swims350]

egr itself. if it's stuck open pulling the vac may not make a difference. see if you can get under the pod of it and raise up on the rubber inside while its running. if that doesn't change the idle it's bad, if it does change the idle then it's working.

 

[ChrisAU]

Tempted, both CTS's have been replaced. I forgot to mention those.

Dirtridin, it runs the same with the EGR hose hooked or unhooked. The SES light works (it comes on with every other light when it stalls haha), but it does not ever come on while driving.

Swims, I'll have to try that with the EGR valve I guess.

 

[ChrisAU]

And ignition coil may be the step after plug wires if everyone thinks my AC-Delcos I put in are good (I made sure they are all tight and I know I gapped them all properly).