87 duke 5 speed, still idling at 1200-1400, can not locate any vacuum leaks, replaced O2 sensor, coolant temp sensor, manifold air temp sensor, even swapped out entire throttle body from 88 duke. Pulled plugs, black, tailpipes, even rear bumper above pipes sooty black. Any sugestions? You guys usually talk me thru these, so lets not break the streak. Thanks again!!
------------------ Wanted one for years, now I have 3, what do I do now? Buy another, got 4 now. And another, 5 now
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02:54 AM
PFF
System Bot
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
IAC is clean and functioning, it set O2 sensor lean code a couple times but swappe out 3 different of those, code went away, but no change in symptoms. This car is another junkyard rescue, new battery cables, maybe I need to check main power feed to ECM? May try that today. Thanks again
I had a high idle even without any vacuum leaks. It turned out that the power lead to the ECM was cut at some point and the wire that replaced it was not only a smaller gauge than the original, it was also badly corroded. After I got that fixed it worked perfectly.
In my case the ECM didnt have enough power to drive the IAC so it was always open too far.
I should know the answer to this but, how do I determine "main" power lead to ECM, the only manual I have is Haynes and it doesn't cover 87 2.5. btw from the earlier post thermostat is new, tested and working.
------------------ Wanted one for years, now I have 3, what do I do now? Buy another, got 4 now. And another, 5 now
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08:58 AM
jimbolaya Member
Posts: 10652 From: Virginia Beach, Virginia Registered: Feb 2007
I will be following this closely also. I still have a high idle and I have changed all those sensors and vacuum hoses also. I am interestewd in learning about the power feed to the ECM. I haven't heard this theory before and a lot of my wiring looks like crap. I'm, sure stuff has been sliced together and probably rewired with wrong guage wire.
Have you swapped the Map yet? I'd imagine if it were reading a too much air it would throw extra fuel at the engine and that could increase idle as well as make for a sooty exhaust. The maps are the same from all fiero's(pretty much every 80's gm car with one for that matter) so I'd grab another and try it.
Tried 3 different MAP sensors, no change, leaning towards ECM power, I too have a lot of crappy looking wiring including some splices with, tape wire ,nuts, ect. I know one purple wire I think to alternator has a questionable splice, think I'll go look for some wire!
------------------ Wanted one for years, now I have 3, what do I do now? Buy another, got 4 now. And another, 5 now
New clue? went out started going over wiring, thought I'd crank 'er up and monitor since its cooler than it has been. Car had not been cranked in about a week to ten days, guess what, battery (new in oct) DEAD! 1.4 volts at terminals, key out of ignition and no previous charging or battery issues, related to other issues? Charging battery now, won't get much more done today, work this afternoon. I'll try to get in one more post before leaving if anything turns up. Gotta luv these little cars
------------------ Wanted one for years, now I have 3, what do I do now? Buy another, got 4 now. And another, 5 now
I recently had a similar issue. Check the headlights first. My battery was dead aftera week idle and when I ran a series check to see if the electrical system was pulling any power it showed normal on the meter so I thought it was fine. Later I checked again and found that if I left the meter hooked up for a long time, like 30 seconds+, there was an intermittent 12volt spike. The limit switch on the headlight was going bad and pulling power about every 30seconds for about a 3 second interval. It was so slight that I did not hear any headlight motor noise to clue me in. I took a couple of days to find the problem. Let us know what you find. -B
------------------ D: "We'll just give it the smoke test." B: "What's the Smoke test?" D: "Turn it on...and see if it smokes" ---The above is from an actual Fiero repair conversation. Names have been omitted to protect the ignorant.
Here is a link to a bunch of ECM pinouts. The '87 Duke is not listed but the '86 and '88 are there. Both show W10 and W15 (W = white connector) through a fusable link direct to the battery. http://home.att.net/~subzero350/
[This message has been edited by Hudini (edited 11-16-2007).]
