I just got the time to put in the needed throw-out bearing and got everything back together. When I start it up, it run ok for about 15 seconds and then starts idle hunting until it dies. It is also running rich. Finally I unplugged one of the sensors and it cleared a lot of it up but I am unsure which sensor it is. I had thought it was a intake air temp sensor but I cant find one online that looks like this. Im not even sure if its for a 3800 or 2.8. Its plugged into the intake boot just before the TB. As you see in the pic, I was using an ohm meter just to see what pin the tan'ish wire was running to but it seems I was getting a connection through most of the wires, atleast on the blue side. I didn't try the clear.
Thank you for any help on this. I just really want it drivable.
Thanks for the reply, I thought that was what it was but I am still unsure if this one is from the 2.8 or the 3800. Will either one work? Im trying to figure out if it is bad or the wrong one causing the problem. Could also be in the wiring I guess, hope not.
Thanks Dan, Maybe I will just lengthen the 2 wires tomorrow and run them to the canister as it still has the sensor in it. Hope that solves it.
Thanks to both of you.
Steve
[This message has been edited by JumpStart (edited 11-03-2013).]
The Older Fiero sensor has a metal threaded body, the new ones have a plastic body that press fits into the rubber intake hose. The calibration is the same as far as I know.
I do have a small scanner but it is limited. It's an Actron Auto Scanner OBD II Code Reader and runs around $130 now.
When I first scanned it, it did have the 102 code along with the ones that needed to be removed ( 98 GP stock) So I replaced the MAF? ( square one on top of TB) and still had the 102 code. Even though its possible that both the old and new MAF were bad, Its doubtful.
I got a programed ECM from Ryan and all codes are now gone except for the 102. I did try to check for power and ground going to it and it seemed to be ok but I only have a real cheapy volt/ohm meter but if need be I can get a better one.
Ryan also said he thought there might be a vacuum leak so I blocked off the intake with a piece of paper and it did die but not as quickly as I think it should have. I did find a small leak where a vacuum tube was a bit too big ( at the 3 way on top of the charger) and I need to address that today also.
So, all together it seems my problems could be with the MAF, IAT, Vacuum leak or in the wiring.
Thanks and let me know what you think Phonedawgz.
Steve
[This message has been edited by JumpStart (edited 11-04-2013).]
The sensor is nothing more than a thermistor (resistor that has a predictible change in resistance over temperature). You can measure the resistance of the part to get an idea if it's good or bad. Off the top of my head, someone correct me if I'm off, at room temp it should be around 4.7K ohms. If it's bad, it will either be open (infinite resistance) or shorted (zero resistance).
If you measure the voltage in circuit across the wires, the voltage will be around 2.5V at room temp. If it is 0 or 5V, something is wrong.
Well, I just tried using the sensor in the Fiero air can and had the same idle hunting issues. Also noticed that with the IAT unplugged, it would only run smoother a little longer then would start idle hunting really bad until it would die. Seems to me to be something wrong in the wiring.
Well lets start by looking at a number of things. What are you getting for the MAP sensor scan when the engine is idling? How about the IAC, CTS and MAF?
Sorry for the delay. Been busy lately. I don't think my scanner displays these things but I will check again. The only code I am getting though is 102 for the MAF sensor and it is new.
Ok. I have been working on the brakes and think I have finally got them fixed. I still have the miss when cold though. I bought a fuel pressure gauge to test it and found when I turn the key on, The pressure starts dropping as soon as the pump turns off. I then unplugged the injectors and removed the fuel rails. Turned the key on and found no leaks from the injectors unless they need to be plugged in to test this. The only place I can see loosing pressure is from the fuel regulator or around the fuel pump. I tried to remove the regulator but after removing the ring clip, I couldn't pull it out of the rail. Something was mentioned about something that could leak at the fuel pump but I don't remember what it was.
Any ideas? Thanks for any help EDIT: I remember reading about pinching off the fuel line to narrow down where the leak might be.(in tank) Which is the fuel and return? (Im using stock fuel rails)
Steve
[This message has been edited by JumpStart (edited 12-14-2013).]
Thanks Bob, I'm thinking if I pinch off both lines and it still leaks, it could only be the regulator. I will do some more testing this afternoon and post what I find.
Ok. I checked the fuel pressure again and it was at around 40psi when the pump stops and drops quickly after that. I then pinched the return fuel line closed and it would get to around 60psi and drop VERY slowly. I tried starting it with the return line closed and it did the same thing as before, ran fine for about 5 seconds and then tried to stall idle hunting. The fuel pressure with the return line closed and running came up to between 70 and 75psi and dropped to 60psi when it quit running but also dropped VERY slowly like 2psi a minute. When I released the return line, it would drop immediately to 40psi and drop quickly at about 1psi a second.
Ryan also asked about a vacuum leak but I have not been able to find one as of yet.
If I get it running down the street within the first 5 seconds, it will settle out and does run and idle better until it cools down after shutting it off.
New IAC valve tonight and no difference. I guess I'm going to try to see if the scanner I have displays anything useful although I will have no idea what I am looking at. I don't think it does much more than codes which all I have got was the P0102 and I have a new MAF sensor and still get that code.
Edit:
Not sure what it means...
Steve
[This message has been edited by JumpStart (edited 12-16-2013).]
Make sure you let it warm up fully. At least on mine, the IAC will hunt until the coolant reaches temp. Then it takes a few minutes for the learn mode to complete. After that it purrs like a kitten.
Check the wiring on your MAF sensor. Are there any splices in any of the three wires to the MAF. If so the need to be soldered splices. Pull the pin for the yellow MAF wire at the PCM connector and then try in on a pin individually. It needs to fit snugly. Pull the pins from the MAF sensor connector and make sure they individually fit snugly. While the yellow wire is the signal wire any of the three pins being loose can cause trouble. Finally make sure your power AND GROUND are clean. If you put multiple wires on a ground lug, and those wires include devices that are switching on and off they could cause a voltage spike on your ground lug that could cause this MAF error. For that reason it is good to have all the sensor grounds (Black/White) wires on a ground lug that is separate from the other relay/power grounds.
----- While this pic was taken while the system is still running in open loop mode it looks like it ran long enough for the PCM to get into closed loop mode and for the PCM to learn that the engine was running rich. The long term fuel trim is at -16% so that means the PCM was seeing the engine running rich (as opposed to the PCM thinking the engine was running lean and thus increasing the fuel).
Look for fuel in the vacuum line between the fuel pressure regulator and the engine. There should be none. If none in your vacuum lines pull your injectors hot wire the fuel pump and see if you have a leaking injector.
[This message has been edited by phonedawgz (edited 12-17-2013).]
Thanks phonedawgs, I did unplug and remove the fuel rail and with the key on, I saw no leaks from any injectors. I just ran it down the street so it would warm up and run better without dying. I pulled the vacuum line from the fuel regulator and it never started leaking either. After it was warm, I put the scanner on it again. Maybe something else will show up.
I know this scanner does not do Case learn. Is there any way around this or would I need to take it somewhere?
Not too long ago I had to get a new computer and had no access to my older files. I went through tons of emails to finds Ryan's and for a case learn, he says you have to ground out clear 16 and 18 ( wire together?) to make the ECM think the trans is in PARK and have no connections to blue 68 and clear 56. Then you need to hook up the brake switch to blue 30, all for the case learn procedure. Other than looking through emails for this before I just googled how to do a case learn which didn't mention this because mine is a 5spd manual.
I am next going to disconnect the MAF wires from the ECM and just use 3 lone wires from the MAF sensor to eliminate a wiring problem between the MAF and ECM with a separate ground.
I can also wire up the connections for the case learn but do I have to have a scanner that can program a case learn?
Just to Thank everyone and let you know, I did find the problem. Now I feel like an idiot. I checked for a ground on the MAF and didnt get anything even though I thought I had before so I tore the harness apart all the way back into the cabin. There was the MAF ground wire loose and wrapped around another ground. I took a guess and checked the O2 ground and that was it. I soldered the 02 and MAF grounds together and bolted it down, It fired right up and idled fine with no hesitation using the throttle. Thanks again everyone and thanks phonedawgs for leading me back to the wiring.
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