Intermittent rough Idle below 1500 RPM HELP!

[tyoneon]

Here's the deal. My 1999 S-10 decided to start idleing really rough, bouncing between 500 and about 1300 RPMs, sometimes stalling altogether. I consulted the "local experts" at Schucks, "sounds like the 'pre-cat O2 sensor to me!'" Me:"ah, OK." No MIL, should have known better! It did appear to fix things immediately, but returned to it's former state within hours. Consulted another "expert", "change the fuel filter." Done. Problem fixed for exactly 24hrs. Same thing all over. Yet another "expert" check all vacuum lines with the "suck and tongue" method. They all held, including the fuel pressure regulator. Fuel pump seems to be running fine. When I get above 1500 RPMs the truck runs "normal". When it's idle is really bad, I let it sit for an hour, and it runs like nothing is wrong! Within 2 hours, it starts up again. PLEASE HELP S-10 Gurus.
Thanks in advance.

[dmbrisket 51]

when was the last tuneup? spark plugs, wires, cap, roter pcv

[tyoneon]

Originally Posted by dmbrisket 51

when was the last tuneup? spark plugs, wires, cap, roter pcv

Plugs and wires within the last year. Is there a cap and rotor on an electronic ignition? What is a PCV?
Thanks!

[kenyonja2007]

I had about the same problem. I had error codes for the throttle position sensor and exhaust recirculation circuit. I fixed the TPS, and the problem remained a little. Then I found a broken vacuum hose to the EGR, and thats solved my problem. Check the function of the EGR, and/or the vacuum lines and solenoid attached to it.

[dmbrisket 51]

Originally Posted by tyoneon

Plugs and wires within the last year. Is there a cap and rotor on an electronic ignition? What is a PCV?
Thanks!

the ignition is electronic, but unless your in a 4 banger, you have a dizzy in the back of the moter (where chevy puts them all) if you are in a 4, look at your crank angle sencor, that could be throwing you for a loop, and pcv is positive crancase valve, its a little silver thing, hooked up to a vacume line on the drivers side, just about uner your air intake, when out, it almost looks like a cig. ligher, they wear out after 10k or so and most people dont bother to change them, go to the dealer for it, they are only a few bucks, and are one item i reccomend from dealer only

[tyoneon]

Originally Posted by tyoneon

Here's the deal. My 1999 S-10 decided to start idleing really rough, bouncing between 500 and about 1300 RPMs, sometimes stalling altogether. I consulted the "local experts" at Schucks, "sounds like the 'pre-cat O2 sensor to me!'" Me:"ah, OK." No MIL, should have known better! It did appear to fix things immediately, but returned to it's former state within hours. Consulted another "expert", "change the fuel filter." Done. Problem fixed for exactly 24hrs. Same thing all over. Yet another "expert" check all vacuum lines with the "suck and tongue" method. They all held, including the fuel pressure regulator. Fuel pump seems to be running fine. When I get above 1500 RPMs the truck runs "normal". When it's idle is really bad, I let it sit for an hour, and it runs like nothing is wrong! Within 2 hours, it starts up again. PLEASE HELP S-10 Gurus.
Thanks in advance.

My bad... Yes I am running the 2.2 liter/ the almighty Vortec 2200, it is mostly stock except an Air-Raid Intimidator intake, a Gibson 2 1/2" Cat-Back Exhaust, and a Venom Module. Everything has been been running
perfect for about 10 months. I have top notch wires and semi-new plugs. It will go toe to toe with any 4.3, "above 1500 RPMs LOL". I ran all day today without a single idle incident, but alas tomorrow is a new day! Intermittent is the only way to describe this damn problem! If it occurred everytime, at least it would push me to seek professional help.
Don't get me wrong, I love this website, and your guy's input is priceless. I kinda feel like someone has shared my pain, empathizes, and really cares.**sniff**, **sniff**, I love you Man!

[getonmylevel]

I have the same problem with my 2001 4.3. The service engine light came on and it said it was running lean on the left side so i put fuel injector cleaner in it and the light went off and it idels better.

[rlith]

The 1st thing I would do is remove the venom module... Then check plugs and wires, then all vac lines.

[noyler]

I have the same problem with my 03 S-10 i took ur advice about the PCV but couldnt find it do have any picutures to help. thanks

[tyoneon]

Hey Noyler! I did eventually solve my problem! I had added a "Venom" module to my rig and it seems to tear the ass out of MAP sensors. I replaced my sensor and all is well. Theonly catch is... power comes with a cost! Roughly $82.00 a year. That is all the MAP sensors can seem to take. I am going to upgrade my "chip" to see if this improves. I will keep you appraised.