I have a error showing for 35 code but the CEL is not lit, it lit briefly when slowing to stop. I do have a hard start and have to pump the throttle to get it running and then a rough idle around 800 cold engine or not. Also starts really easy after the first initial start. Fuel pressure checked out at 45 with a mechanical guage. Originally had a higher idle and I reset the IAC because it would not come down below 2000 even when warm and the IAC hole in the TB was screaming like a stuck pig.. I had been thru the engine prior to this problem checking for vacuum leaks. Tuner pro rt shows a postion of the IAC which varies but starts out in the hundreds and as time and driving went by it finally settles out to 30 at idle. Is this showing an actual position or what should be position? My thoughts are that the IAC should close as the throttle body opens, which could be entirely wrong.
Originally posted by LornesGT: My thoughts are that the IAC should close as the throttle body opens, which could be entirely wrong.
No. IAC is open some so you can't stall the engine when you pull your foot off gas pedal.
IAC DTC cause by vac egr or wiring problems or bad IAC.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Will the computer report the position or expected position?
So if the EGR is open or closed when it should not be this can affect the IAC position? Should I close off the EGR to test a reaction of the IAC? I can remove the IAC and cover the mounting hole and see if the IAC is moving or measure the voltage out of the IAC that is fed back to the ECM, right?
I first went thru the idle reset and cleaning as I mention below, with a warm engine and reset everything. By the way I could not kill the engine no matter how low I set the idle screw. I then drove the car for a while and the same results the idle hunts quite a bit. I know it won't be dead on steady but I got back and got a 35 code. After removing the IAC and cleaning the ports and checking the movement of the IAC in the diagnostic mode. The pintle moves to the closed postion in the diagnostic mode but will not move back open when running and installed. I can see the pintle in the same postion when forcing a low idle with the idle screw. It should move out trying to control the idle due to lack of air, correct? Tuner pro is telling me a 160 position until I start the car and then the position goes to 100 but I see no movement. At least I think I see the pointed end of the pintle thru the intake on the throttle body. There is a small amount of air entering as I can cover the hole and feel a small amount of suction. Doing this doesn't change the idle so i suspect a vacuum leak. The idle doesn't change so checked for vacuum leak and at the EGR with a digital manometer there is a .56 pull on the EGR. One of 2 lines running to the evap canister pull a 42 inches of vacuum and does not change with the speed of the enginge and the other has nothing. I don't understand that. Removing the map vacuum line off the upper intake the idle goes up. I block the EGR but still no change, I have a new RD EGR tube. At first and I am not sure when things change but unplugging the MAP the car would die but now it doesn't. This all started after I pulled the engine changed gaskets and got her running again. I had a high extremely high idle the and found the IAC wide open and I reset it. So I am following this diagnostic chart from the link below and I probed the IAC for each terminal to ground and only show 6 volts at best. This could be that the voltage pulses fast enough that I don't read 12vdc, if that is what it should be. I also check the IAC connector with it removed and only had 13 volts on 2 pins. So I went to the next step and I don't know where ckt423 is so I need help finding that. http://www.fieros.de/en/v6help/code35.html
[This message has been edited by LornesGT (edited 01-03-2015).]
I know you replaced your vacuum tubes with the RD set. I don't know about on the Fiero, but my Impala would run w/o the MAP sensor. Have you tested for vacuum leaks?
No the swap is going to go slower than I would like so I wanted to make sure I could have fun driving the 2.8 for now. Yes RD vacuum lines. I haven't blown smoke if that is what you mean as I don't have anything to generate that much smoke.
When I originally put it back in I had a high idle and I used propane and throttle body clean but never found one. That when I adjusted the IAC, it was whistling there was so much air going thru it. I need a separate one to hook up and see if it adjust.
I will be there!
[This message has been edited by LornesGT (edited 01-04-2015).]
My phone is currently dead dropped and broke the glass and digitizer while trying to fix this problem Saturday. I will call from my home phone if I don't have a replacement by then. I think I pmed my new number already.
So, the new IAC seems to behave the same as the one in the car. Also the same as the one in my car. I think we can safely eliminate that.
So, since you have to open the throttle on cold start, that could be an issue with the cold start injector, which we didn't test. Could this injector cause any issue when the engine is warm?
We found the engine runs more smoothly with the cruise vacuum line unplugged, or when the fans kick on. Noted that the cruise does not work, plugged or unplugged.
Lorne, you were right. That other thing was an IAC for a 2.5L Fiero. Anyway, it was good to see you again.
Thanks for the help! I will trade cars out right, you won't owe me a thing!
I think I will pull the IAC out tomorrow and open it up a little so I have a higher cold idle, then see what happens as the car warms up. Weird that I got a low map error today and IAC error at the same time, never happened before.
If we'd been more motivated, we could've tested the MAP sensor also, but I think the way to go is to troubleshoot the problems in order. The first problem is when starting.
Just now getting around to reading your thread... yup, this is all sounding way too familiar.
I am not having the start-up issues you are having, but other symptoms sound so much alike.
I have been through the EGR system multiple times and have checked, double checked and triple checked the entire system for vacuum issues. Right now, I don't even have a code 32 as I did previously, but idle is still fluctuating between 1350-1550 RPM's. Today I tried the IAC reset procedure out with no change in the idle whatsoever, even after lots of driving/stopping/restarting.
So far here's what my own suspicions are; dirty fuel injectors, bad sensor connector(s), or a quirky ECM.
Right now my engine has 155,000 miles with the original injectors. Remanufactured/rebuilt/flow-matched injectors can be bought for $90... I think they are the next thing to do on my list.
I'll be watching this thread; best of luck. I'm curious what you find out.
[This message has been edited by ITALGT (edited 01-11-2015).]
Bad sensor connectors would make the most sense. All was good before some upgrades. Also, when the fans kick on, much better idle. Almost seems like a vacuum or ground issue.
Oddly, on the computer, it shows lower RPMs. 900, I think, but the tach showed like 1500. Something to think about. My first thought was that the ECM may be confused, but it should see what the computer is showing. Not sure if that's a wiring issue, or a sync issue.
Tshark I guess if we had the right tool to remove the IAC we would have fixed it at your house. I fixed mine, it was the IAC. It would move to the closed postion but would not open back up. Testing before I put the original one in it always moved, I guess I must have broke it. I threw in one that a mechanic friend had laying around (in the full open postion) and I had a cold idle back. I was afraid that it was going to close back down (2000 rpm) to lower the idle but it did with in about 2 minutes, no driving at this point. I had to blip the throttle then it can back down. I am going to try it again after it sets for a while and I know the engine is good and cold. I hooked up the aldl cable and the IAC positions was shown as it should from my google searches. The postion was at 78 and as the idle reduced I could see the IAC position close more. I also did move the throttle screw back out. I know that is not the correct thing to do so I will try the resetting of the IAC and throttle screw this weekend when it warmer especially if trying it later today and the idle doesn't react properly.
