Hi, I have searched around the 500 posts the past couple days to figure this out but seems like i dont have a lot of the symptoms that alot of others have.

Ok, so I have a surging/hunting for idle about 4 min after start up. Starts up fine at about 1200 rpms, then drops down to about 900 rpms, but surges from 450 and 900 rpms. Putting it in gear doesn't really change the surging, just lowers rpms a little. The car is completely stock except the addition of an afermarket temp gauge.Things i have done include:

• changed egr valve
• replaced all vacuum lines
• full ignition tune up (dizzy, rotor, cap, wires,plugs and coil
• rebuilt throttle body w/new base gasket
• R&R intake, cleaned it up as well
• redid base timing and base idle
• changed pcv valve
• new TPS and IAC with calibration
• new air filter
• new map sensor
• new egr solenoid
• new coolant temp sensor

Any help is greatly welcomed. Haven't been able to drive the car since I bought it.

 

Check the fuel pressure, a new pump and fuel filter is possibly required.

Note that by replacing all of those sensors, could have gotten a bad one...

RBob.

 

1. WHAT VEHICLE???

2. Why were all those parts replaced? Was there any diagnosis done that showed those parts were defective? Did replacing those parts fix some other problem?

 

Just got the problem fixed today. Found out that the O2 sensor wire that ran into the harness was grounding out against the back of the cylinder head. The car is a 1991 camaro rs 305 tbi. The parts that are listed were replaced for 2 reasons, 1 being that the car was severely neglected by previous owner and a lot of stuff was beat up. 2 being I don't have a nice fancy scan tool to show me realtime data logging on a domestic vehicle that's OBDI. They were also changed in reference to the idle problem and lean condition that I was having. Obviously sensors like map sensor, coolant temp sensor, IAC, idle problems can arise with a bad TPS. Just the only troubleshooting I can do in my garage is mostly trial and error, asking questions etc. I have a decent knowledge base and that's why I went through it myself. I don't trust garages because my family and myself have gotten screwed over. The car has 249,000 miles on it. Things are bound to go bad. Plus doesn't help that I live in California so its hard to legally repair a vehicle without making an illegal modification or failing the strict smog laws.

 

Yeah, it's way cheaper and faster to throw random parts at a problem than to actually diagnose it.


Glad you found the O2 wire--and that it seems to be running well again.