Erratic Idle '01 Job 1 ST 87K miles

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DawnVic M

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Sep 25, 2000
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Sacramento, CA
Hi everyone! My '01 Job 1 ST with 87K miles has started having an erratic higher than normal idle. Normally it drops to 700-800 RPM at idle when the engine is fully warmed up. In the last 2-3 weeks it has started periodically staying at about 1200 RPM at idle when the engine is warm. It feels like when I'm braking I'm fighting the engine acceleration a bit, but not dangerously so (at least so far). As I typically drive in stop and go traffic, I've noticed that sometimes the idle is normal but more and more frequently it's high. And when I get to where I'm going and I put her in Park, she stays high and sometimes revs higher to about 1400 RPM. And sometimes she's normal and drops to 800 RPM or so. It seems to me that it's idling high more often, but maybe it's just that I'm paying closer attention to it now. I just had her serviced a couple months ago at 86K at my very reputable Ford dealer that's been exclusively servicing her the last several years and the inspection was fine. I haven't done anything yet like cleaning the IAC. I would appreciate hearing what you think might be going on and what it will take to fix it. I'm willing to take on easy maintenance-type repairs before going to the dealer. Thanks!
 
Another symptom of leaking intake manifold gaskets is very high idle at cold start - especially in winter.
Click to expand...

No CEL or trouble codes? Job 1 engines have a history of failed intake gaskets. (Post #3)
 
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Aloha Vic, I had the problem with my 02. I sprayed the throttle cable with lubricant, all good now.

'hope this works for you cheep fix.

Ed
 
Vic,

Also with 87k It wouldnt hurt to check the TPS voltage. Make sure it stays below 1vdc at isdle, or with KOEO. If you have an auto ranging vom. Make sure it ranges smoothly KOEO. up scale and down.And re-peaets while hand stroking The TB wot and closed. It should repeat between, .990 vdc and .995 vdc when th TB isclosed. WOT around 4.75vdc. Reference voltage is 5vdc



Some with auto matics like to set them @ .998 vdc tb closed. It can make the ecu more readyffor faster take off,Injectors and spark advance. IMO that is gtting to close to 1vdc. Which is closed loop. As if the engine is accellerating. And can cause irratic idle. I have seen some tps units go bad at that millage, GL.....It is just a varible voltage reostat. If they get to Floating around with tb closed .Especially above 1vdc. The IAC wont settle down and hold steady idle.
 
Thanks everyone for your input, it's really helpful. Something new happened today that I think is related to this problem. It started overheating. It didn't get to red, but it's higher than I've ever experienced in this vehicle. I also haven't had a chance to try any of the fixes since I've been sick for the last several days. Does the overheating either pinpoint a problem or suggest something else has happened?
 
I had an idle issue a month ago. I've cleaned the IAC as best as I could four times. Finally replaced it for $44. Also cleaned the throttle body and MAF sensor. Idles like new.
 
Hi everyone, it turns out the culprit of the RPM issues was a faulty thermostat! Ford replaced the thermostat and the thermostat cover/water outlet connection and it's running like a top again. The service manager said the RPM issues were the result of the engine computer(s) compensating for the failing thermostat.



Again, thanks for all your help and suggestions. We know we can always count on members to pitch in and help us out.:haveabeer:
 

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