I replaced my idle air control but still have sputtering and air sucking sound, but no check engine light. I tried connecting jumper wires to both the old and new iac and neither one moves. I don't want keep spending money on iacs. My question is could the ecm have caused the iac to burn out? The ecm does seem to be working otherwise. Does anybody know how the wiring works? How much voltage should I get from which wires, and when (ignition on, running). I have voltage from 2 of the 4 wires with the ignition on, wires disconnected. The only explanation I could find on the internet is for a newer car I think, and it says 2 of the wires control the iac and 2 of the wires send a signal back to the ecm, so I think it's odd that I'm getting voltage from more than 1 with it disconnected.
Update: I have full continuity between all 4 wires with ignition on and some continuity, but not much with ignition off. That sure don't seem right. Thoughts?
I read your post and you should have posted your 1st question in the 1st gen forum as we are probably better able to answer the issue.I am just wiped out from being outdoors all day and tired! Let me revisit the problem later when not just flat wiped out.I have some ideas already to suggest but keeping this short due to the reasons said.OK Ron
I apologize for the very belated response.It is late and I am tired.I could suggest something that I think really will not change the problem but I will.I need to check my factory shop manual for a true solution.However if you want try unhooking the negative battery cable for 1 minute and then reconnect.Turn the key ON but wait 1 minute then crank the car.This should set the IAC with the ecm in theory to the new part.I am just tossing a idea and I do know my way around these cars.I would also suggest unhooking the vacuum line to the EGR valve prior to any of the above.If the egr diaphragm is leaking (any) air this can cause the car to idle erratic but while unhooked (if this is a problem) it should smooth out.Let me check my information before I suggest a legit idea.I am not saying these ideas are not the real problem but,I like to research the books a touch and relate that with my knowledge.I doubt your ecm is the problem really!
I checked for vacuum leaks and tried every method suggested for resetting the iac. Also replaced the coolant temp sensor, tps, and entire distributor. The odd thing is when it warms up and the oxygen sensor starts working, instead of giving me a lean code like it should, it just seems to be adjusting the timing and fuel so it runs pretty good but idles very fast. I don't have a tach, but it is way to fast. When I adjust the timing I can trigger a code for the oxygen sensor, so that as well as the ecm seem to be working.
Should I have a code 35 for the iac, or do only newer cars do that? I read something about a short in the 5 volt reference signal causing incorrect readings from the sensors. It says the most common cause is the air conditioner. I took the fuse out, disconnected some wires from the air conditioner, but not sure if I got the right ones. Do you know anything about this?
To technically reset the IAC you have to drive the car at 30mph for the pintal to seat for the actual adjustment.Being you replaced the Tps (this if were faulty) would very all over the place idle and checking with a multimeter with just the key On would prove that.I am very dialed in tonight and thinking hard!!! If removing the egr vacuum line made no difference that is a good sign that part is not failing.On your car you have two items that can contribute to idle issues.1 is a Air temperature sensor in the air cleaner housing itself with 2 vacuum lines that feed to that.This component controls the idle based on the engine temperature.This Part is NOT cheap but can wreak havoc with a annoying problem on idle hot or cold.My 2nd choice is your map sensor on the firewall.I has a 3 way plug on recall and 1 vacuum line going to it.I cannot write a novel on how to check it but can link a site that will walk you thru the steps and it is accurate to determine if this part is failing.The Map sensor can totally screw with the idle 100%.I will do a follow up and maybe link the said air temp sender to save you the headache trying to find it as I have done this already years ago.I had to replace my map sensor due to ide and or voltage issues years back and a low cost fix and easy!Let me get my information together Monday on the parts and the website you can check out to do diagnostic with EASE! using a multimeter and some jumper wires in minutes to determine if any components are bad.Ok R
Read this and follow his steps and see if this fixes your problem!!! Just trying to make this easier and less costly.I will post up the website that will allow you to use a simple multimeter to do diagnostics as a (GOOD) reference regardless for our 1st gen rides.
Check out volume 3 1999 for the Map sensor.I had a busy day and if I am incorrect on the choice let me Know.This webpage walks thru how to check and diagnosis sensors with ease using a a multimeter.I may revisit this later as I am just tired after working on a car all afternoon in the heat.
A couple weeks ago I noticed the blue wire to the ac clutch was worn through and rubbing on the alternator bracket. I just cut it off because the ac hasn't worked in years and I read about an ac short possibly causing my problems. Now I figured out that wire is the ground for the power steering pressure switch. I grounded the p/s switch to the firewall. It still won't run right. I also just discovered the ac/heater fan won't work. Does the ac clutch have to be hooked up?
Ok, forget what I said about the ac/heater fan not working, I forgot that I had removed the fuse. I have now come full circle back where I started. The very first thing I replaced was the temp sensor because the car has run better in cold weather for a couple years now. I now have a GM repair manual, and I checked all of the voltages at the ecm. They are all good except the coolant sensor should be .7 volts and I'm getting 5 volts, just like I thought, the ecm thinks it's really cold. I tested the sensor even though it is brand new. The connectors look good. I checked resistance on the wires from the sensor to the ecm, and also resistance from those wires to all the other wires in that bundle. Everything checks out. The yellow wire goes straight from the sensor to the ecm. The black wire also grounds the tps and goes to some electronic gizmo in the distributor. That gizmo did not come with my new distributor. I don't know what it is or how to test it. I did put an ohm meter on it, it does have some resistance. At this point my only options appear to be either tearing apart that whole wiring harness looking for a short (which looks like a royal pain in the but) or cutting those 2 wires and splicing in new ones. Any suggestions?