Here with another question about my Bronco. Its a 1989 with the 5.8 engine. It has all the sudden started idling at over 2000rpm when cold and will speed to 2700ish when warm. It will go down the road at 25 with no gas. I replaced the Idle air control valve since that has caused all my idle problems with my 88 f150. It did not fix it. Any ideas? Haven't had a chance to hook the OBD I scanner to it yet.
Ford 5.8 Idling at 2k + rpm
- Thread starter nwjones18
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Check for gasket leaking vacuum at the intake manifold.
What he said, sounds like a vacuum leak somehwhere. Check all the vacuum lines, all the gaskets on the intake system, and make sure the throttle is closing all the way.
As already mentioned check for vacuum leaks, and that the throttle body closing properly. Check for codes, a PITA for that model year. Then check the TPS, that can cause a high idle if its bad. HTH
A few things to note on these trucks that cause fast/erratic idles:
1. Bad TPS
2. Bad IAC
3. Vacuum Leaks
4. Bad EGR Position Sensor
5. Bad EGR DPFE Sensor
What I'd advise is to scan it, get the codes and move forward from there.
Regarding the IAC and EGR Position Sensor, my truck did not like the BWD/Standard brand at all. I had to use Wells/Duralast on these, so either it's Motorcraft or Wells/Duralast, depending on your budget if either one of these are bad.
1. Bad TPS
2. Bad IAC
3. Vacuum Leaks
4. Bad EGR Position Sensor
5. Bad EGR DPFE Sensor
What I'd advise is to scan it, get the codes and move forward from there.
Regarding the IAC and EGR Position Sensor, my truck did not like the BWD/Standard brand at all. I had to use Wells/Duralast on these, so either it's Motorcraft or Wells/Duralast, depending on your budget if either one of these are bad.
the last duralast cap I saw looked like lesser quality than the wells. and wells was decent for the price.
I've run Standard for 25 years, never have had an issue with any of their parts.
I've run Standard for 25 years, never have had an issue with any of their parts.
Originally Posted By: nwjones18
Here with another question about my Bronco. Its a 1989 with the 5.8 engine. It has all the sudden started idling at over 2000rpm when cold and will speed to 2700ish when warm. It will go down the road at 25 with no gas. I replaced the Idle air control valve since that has caused all my idle problems with my 88 f150. It did not fix it. Any ideas? Haven't had a chance to hook the OBD I scanner to it yet.
Did you reset the computer after you put on the new idle air valve? Ive seen a few times when you put a new one on it does not fix the problem , then disconnect the negative cable for a hour and the computer resets and the problem is fixed.
Here with another question about my Bronco. Its a 1989 with the 5.8 engine. It has all the sudden started idling at over 2000rpm when cold and will speed to 2700ish when warm. It will go down the road at 25 with no gas. I replaced the Idle air control valve since that has caused all my idle problems with my 88 f150. It did not fix it. Any ideas? Haven't had a chance to hook the OBD I scanner to it yet.
Did you reset the computer after you put on the new idle air valve? Ive seen a few times when you put a new one on it does not fix the problem , then disconnect the negative cable for a hour and the computer resets and the problem is fixed.
Ditto above. Unplug IAC and see if idle changes. If it does......
Unplug TP sensor, reset PCM, see if idle stabilizes. If the TP shows off idle, PCM commands IAC to open 100%.
Also, if you haven't, make sure the throttle body is not obstructed and the throttle is returning to it's hard stop screw.
Do not adjust the idle stop screw......ever.
I also had one with a shorted IAC driver in the PCM that held the IAC wide open. Rare, but like I said, it happened.
Unplug TP sensor, reset PCM, see if idle stabilizes. If the TP shows off idle, PCM commands IAC to open 100%.
Also, if you haven't, make sure the throttle body is not obstructed and the throttle is returning to it's hard stop screw.
Do not adjust the idle stop screw......ever.
I also had one with a shorted IAC driver in the PCM that held the IAC wide open. Rare, but like I said, it happened.
Clean the throttle body bore and plate really nice.
Still high? Check for vacuum leaks and intake leaks - this can be time consuming, but you can't cheat.
Still high? Check for vacuum leaks and intake leaks - this can be time consuming, but you can't cheat.
Originally Posted By: punisher
Ditto above. Unplug IAC and see if idle changes. If it does......
Unplug TP sensor, reset PCM, see if idle stabilizes. If the TP shows off idle, PCM commands IAC to open 100%.
Also, if you haven't, make sure the throttle body is not obstructed and the throttle is returning to it's hard stop screw.
Do not adjust the idle stop screw......ever.
I also had one with a shorted IAC driver in the PCM that held the IAC wide open. Rare, but like I said, it happened.
Thanks! I did disconnect the battery and let the computer reset, but i didn't realize that The TPS would cause the IAC to open. I will check that then pursue vacuum leaks.
Ditto above. Unplug IAC and see if idle changes. If it does......
Unplug TP sensor, reset PCM, see if idle stabilizes. If the TP shows off idle, PCM commands IAC to open 100%.
Also, if you haven't, make sure the throttle body is not obstructed and the throttle is returning to it's hard stop screw.
Do not adjust the idle stop screw......ever.
I also had one with a shorted IAC driver in the PCM that held the IAC wide open. Rare, but like I said, it happened.
Thanks! I did disconnect the battery and let the computer reset, but i didn't realize that The TPS would cause the IAC to open. I will check that then pursue vacuum leaks.
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Likely TPS. My Mustang did the same thing when mine went bad.
Just wanted to update. Checked the voltage on the TPS and it was out of spec. I replaced it with a BWD unit from AAP and that fixed the problem.
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Originally Posted By: nwjones18
Just wanted to update. Checked the voltage on the TPS and it was out of spec. I replaced it with a BWD unit from AAP and that fixed the problem.
Called it
Just wanted to update. Checked the voltage on the TPS and it was out of spec. I replaced it with a BWD unit from AAP and that fixed the problem.
Called it
Overkill-
You called it, but it is #4 or #5 on the normal list of things that cause this problem.
You called it, but it is #4 or #5 on the normal list of things that cause this problem.
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Originally Posted By: mechtech2
Overkill-
You called it, but it is #4 or #5 on the normal list of things that cause this problem.
Strange, it is the only thing that has ever caused this issue for me on EEC-IV era Ford's (outside a massive vacuum leak). So are you speaking in general or about this particular setup?
To clarify: My suggestion was based on my experience with this particular era of Ford vehicles, and having had this issue in the past (close to 3,000RPM idle, not just a slightly elevated idle). It was not based on any "A's and B's of troubleshooting" checklist that may apply to this scenario in any sort of general sense.
So while one may not normally immediately go to the TPS for a high idle (I default to vacuum leak usually, but I'm just a shade tree) for this era of Ford, I'll always check the TPS because it is easy to do, and has been a problem spot for me in the past, so it is just "one of those things".
Sorry if I violated some "code of orders" or the like regarding the high idle troubleshooting procedure®
Overkill-
You called it, but it is #4 or #5 on the normal list of things that cause this problem.
Strange, it is the only thing that has ever caused this issue for me on EEC-IV era Ford's (outside a massive vacuum leak). So are you speaking in general or about this particular setup?
To clarify: My suggestion was based on my experience with this particular era of Ford vehicles, and having had this issue in the past (close to 3,000RPM idle, not just a slightly elevated idle). It was not based on any "A's and B's of troubleshooting" checklist that may apply to this scenario in any sort of general sense.
So while one may not normally immediately go to the TPS for a high idle (I default to vacuum leak usually, but I'm just a shade tree) for this era of Ford, I'll always check the TPS because it is easy to do, and has been a problem spot for me in the past, so it is just "one of those things".
Sorry if I violated some "code of orders" or the like regarding the high idle troubleshooting procedure®
^I had a lady with a 1999(IIRC?) 5.4L Expedition that had an intermittent CEL, it turned out to be a vacuum hose which had a hole in it.
It saved her money and me the time of replacing an 02 sensor(which is hard to get at on that thing per cat driver side!)...
The thing is, I didn't notice the higher idle and made me realize the need to check that on vehicles with louder engines that perhaps may make a vacuum leak not sound easily distinct.
It saved her money and me the time of replacing an 02 sensor(which is hard to get at on that thing per cat driver side!)...
The thing is, I didn't notice the higher idle and made me realize the need to check that on vehicles with louder engines that perhaps may make a vacuum leak not sound easily distinct.
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