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'97 XLT Idle Problem

Techrep64

New Member
Joined
September 10, 2005
Messages
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City, State
Clarksville, TN
Year, Model & Trim Level
'97 XLT
I've got an idling problem I'm hoping someone can help me with. During start up the idle runs around 600-800 like it always has. Once you drive it and it warms up, the idle runs to around 1300-1400. After this, once you initially put it in park, it jumps up to around 2000, and then idles back down to 13-1400. I've checked the throttle body and a sensor and it seems to be working properly. Short of sending it to the shop, anyone have any suggestions? Also, just recent, the A/C has started to stop blowing cold air, but kicks back on soon after. Don't know if they are interelated or not. Thanks for the help
 



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Try cleaning your IAC and see if that helps.. Do a search on cleaning the IAC. Moving to Under the Hood & Driveline. The 911 Forum is for situations where your truck is currently stranded.
 






IAC would be my first choice also. You could also have a LARGE vacuum leak, but you'd probably hear it. it would have to be the Brake Booster hose or something. And that wouldnt explain why it doesnt idle high when it's cold, so..

IAC.

Do you have a Check Engine Light?
 






I think MazdaGreg is probably right. I had a massive vacuum leak on mine when I bought mine and I found it by accident. The brake booster hose plugs into a rubber plug hole in the brake booster. Pull the rubber hole gasket off. If the rubber is comprosed or ripped up the slot it will give intermittant vacuum leakage.
 






You SURE the Throttle Position Sensor is ok? Put a voltmeter on it and move it by hand and watch for any jumps or spikes. Might do a search for TPS... lotsa good info on em.

If memory serves me right, idle is around .5 or .6 v and full throttle will be 4. to 4.5.... should be real smooth. (Someone can check me on this though)
 






Well, after my last post I got to wondering why I knew that info, and searched through my binders... I had a graph somewhere I thought.... sure enough, I found it, kinda ratty.... but taken off a recording oscilloscope:

15286DSCN6054-med.jpg


I'd encourage you to check this out first. I think it is a high probabality fix.
 






I've checked the TPS, resistance and voltage. They came out good. Now I did this while it was cold, not after it starts acting up. I'll check the IAC and see what that tells me. Thanks for advice.
 






I don't have a check engine light, or even flicker. If I plug in a scanner, any chance it would pick something up? I've asked one of the auto parts stores and they tell me "no". Just curious as to what you guys may have run into with this.
 






I have had a similar problem, and it was the TPS. With all due respect IMHO this is not a vacuum leak problem, and it is doubtful in my mind that the IAC can produce these symptoms, but hey, I've been wrong before. When you checked the TPS, was the change in voltage smooth? TPS failures rarely throw codes, and when they do the codes are odd ones related to other engine systems usually...in other words my money is on the TPS, still.
 






And sorry, yes a scanner should show you in some fashion the TPS situation, like percent throttle etc.
 






What is your temp gauge reading when it is idling high? Have you noticed any change in tranny shifting? If the computer senses an overheat situation, it will bump up the idle. Will also cause the tranny to delay shift to rev higher.
 






You may be onto something, in that I believe an overheat also cuts out the AC... somethign else he reports.
 






Driving it today I noticed that the temp seemed a bit high, which about that time the A/C would kick off. Once it starts to idle high it does shift differently, almost like it's running through the gears faster. Once the A/C kicks off the temp goes back down, and the A/C kicks back on.
I checked the IAC and TPS today, both rang out good, both Ohms and voltage. The TPS was real smooth on the voltage reading up to 4.7Vdc. I made sure to run it smooth to make sure there was no hiccup.
By the way, I appreciate the help thus far.
 






Ok... I'm satisfied now it isn't the TPS. Woulda fit. But I wasn't so I owe you a beer... TPLYNCH may have hit on the answer. (Either way an insightful observation he made) Either you ARE actually running hot (thermostat) or the computer thinks you are (sender)... solve those problems and see if your Explorer's condition improves.
 






Finally got around to it, and replaced the thermostat. Fixed. Temp gauge reads normal, A/C works great, idle is perfect. Thanks for the help.
 






And a tip of the hat to TPLYNCH for a good call on this one!
 






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