Troubleshooting!?
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Troubleshooting!?
Hello!,
Just found this site and it looks great. I have read through a lot of the forums, but didn't see the trouble I am having, so here goes.
My 98 Ex has developed a couple a problems I think are related, but I am not sure where to start. When I start up, everything seems fine. The engine idles at approx 600-700 rpm and my temp gauge is right in the middle, where it has always been. Sometimes I can drive several miles and never see a problem.
But, sometimes I will notice when stopping that my engine idle speed will climb to 1200-1300 RPM and my temp gauge shows hot...not in the "danger zone", but around the 3/4 mark. I have checked the coolant and radiator and all appears ok, but since I always see these two conditions together, I am beginning to wonder....
About 1 month ago, my IAC valve started acting up, motor would run but not idle, but I took it off and cleaned it out and and have had no further trouble... I think.
Could this be something to do with the IAC, or where should I start?
Many thanks in advance.
Odie
Just found this site and it looks great. I have read through a lot of the forums, but didn't see the trouble I am having, so here goes.
My 98 Ex has developed a couple a problems I think are related, but I am not sure where to start. When I start up, everything seems fine. The engine idles at approx 600-700 rpm and my temp gauge is right in the middle, where it has always been. Sometimes I can drive several miles and never see a problem.
But, sometimes I will notice when stopping that my engine idle speed will climb to 1200-1300 RPM and my temp gauge shows hot...not in the "danger zone", but around the 3/4 mark. I have checked the coolant and radiator and all appears ok, but since I always see these two conditions together, I am beginning to wonder....
About 1 month ago, my IAC valve started acting up, motor would run but not idle, but I took it off and cleaned it out and and have had no further trouble... I think.
Could this be something to do with the IAC, or where should I start?
Many thanks in advance.
Odie
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Joined: Aug 2003
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Is it a 4.0? I'd first off replace the temp sending unit as it's only about 12 bucks at the most - a brass looking thing on top of thermostat housing. Only one wire attached to it. I would do this to make sure the temp guage is accurate. They have a tendency to wear out... but when they wear I think they actually go to lower, not higher values so I'm not sure if this applies to you or not. The other one on there with 2 wires is the EEC temp sensor. You could replace that as well if you want. It's probably a good idea anyways.
The next thought I have is that the engine may not actually be going to 12-1300 rpm. It might not be the actual idle speed increasing but the noise of the fan kicking in. Do you have a tach to verify that it's actually idling faster?
So - to recap... replace your temp sending unit to the dash first so that you have a good reading on your gauge then you can go from there.
The next thought I have is that the engine may not actually be going to 12-1300 rpm. It might not be the actual idle speed increasing but the noise of the fan kicking in. Do you have a tach to verify that it's actually idling faster?
So - to recap... replace your temp sending unit to the dash first so that you have a good reading on your gauge then you can go from there.
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Sorry about that. Yes it is a 4.0 SOHC. I do have a tach and that is what it is showing. I am getting my voltmeter out tonight and will be checking all the sensors I can. WIll check on the two you mentioned. Thanks
WIll report back in the AM
Odie
WIll report back in the AM
Odie
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Just an update.
Last night I drained/flushed the radiator, and everything looked very clear, not like a vehicle with 100K on the clock. Problem still exists. I also learned that O'Rielys (sp?) will "loan" you a diagnostic computer for free (you just put up a $200 deposit, totally refundable upon return).
I went home and try as I may, I could not get it to work. Followed all the instructions, configured the unit, and everytime I tried to scan the codes, the unit just sat there and said "initializing". Tried eveything the manual said, but no go.
I did do some tests on the IAC. When the idle jumps up to 1300, I can disconnect the wires from the IAC and the motor still dies... like it should. I measured the resistance accross the IAC and it falls within the "good" range, even while hot.
My next step is that I work with a guy who's good friend owns a garage, and he is going to hook me up to thje machine and see what happens, and hopefully I can figure out where to go from there.
More when I know it!
James
Last night I drained/flushed the radiator, and everything looked very clear, not like a vehicle with 100K on the clock. Problem still exists. I also learned that O'Rielys (sp?) will "loan" you a diagnostic computer for free (you just put up a $200 deposit, totally refundable upon return).
I went home and try as I may, I could not get it to work. Followed all the instructions, configured the unit, and everytime I tried to scan the codes, the unit just sat there and said "initializing". Tried eveything the manual said, but no go.
I did do some tests on the IAC. When the idle jumps up to 1300, I can disconnect the wires from the IAC and the motor still dies... like it should. I measured the resistance accross the IAC and it falls within the "good" range, even while hot.
My next step is that I work with a guy who's good friend owns a garage, and he is going to hook me up to thje machine and see what happens, and hopefully I can figure out where to go from there.
More when I know it!
James
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Joined: Dec 2001
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From: UT
I don't know for sure how strongly it's related, but in many cases, high idle can be caused by high engine temperatures. The PCM sees that the engine is uncomfortably hot, and increases the idle speed to try to cool the engine off. You might try to get a calibrated temperature gauge on there (If you get the scantool to work, it should allow you to monitor the ECT sensor's output, which is calibrated) to see how hot the engine is running.
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appears that the thermostat is not completely opening, staying partially restricted. I had to put one in my daughter's 1999 OHV about a month ago. If the engine gets too hot, the "check gauge" light will come on, which is what hers did. Her thermostat was completely stuck because when I took it out and put in a pan of boiling water, it would not open at all. Yours may be opening some and not getting to the point where the "check gauge" light comes on. You can monitor the engine temperature with an OBD II scanner to see what the temperature is. It should run around 180-190 degrees. There is a thermostat on the market called "Fail-Safe" that will lock into the fully open position should the engine get hotter than it should. They may be harder to find and are more expensive. I just used an OEM replacement from NAPA that cost about 6 bucks. The OHV engine had an o-ring gasket to seal the housing. No scraping, easy to change. Takes less than 30 minutes. I would fix the heating problem first and then see if the idling problem goes away. Nothing ventured, nothing gained.
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Any chance that the fan clutch is worn out?
A bad fan clutch will cause you to overheat while driving, but not at idle. It doesn't explain the idle problem, but may be worth a look.
A bad fan clutch will cause you to overheat while driving, but not at idle. It doesn't explain the idle problem, but may be worth a look.
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Everyone,
Thanks for all the help. You guys had it right on the nose. Thermostat. Put in on a working scanner and and it showed the temps way up there. Put a new one in and, no further trouble. We had even noticed that we were getting rough shifts, but now, smooth as ever. I guess the engine was trying to race during the gear transitions.
One other thing I wonder though is when on the scanner, it showed that NONE of my oxygen senors were repotrting anything. I have not had it back on a scanner since the repair, but could that have been due to the high temps, or is something else shot? The thing runs as well as ever right now.
Thanks again
Odie
Thanks for all the help. You guys had it right on the nose. Thermostat. Put in on a working scanner and and it showed the temps way up there. Put a new one in and, no further trouble. We had even noticed that we were getting rough shifts, but now, smooth as ever. I guess the engine was trying to race during the gear transitions.
One other thing I wonder though is when on the scanner, it showed that NONE of my oxygen senors were repotrting anything. I have not had it back on a scanner since the repair, but could that have been due to the high temps, or is something else shot? The thing runs as well as ever right now.
Thanks again
Odie
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