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I've never own a car or truck that did this but I've seen plenty....where the car's idle will surge...it will go up then come down, then go up then come down, then go up then come down....I think i've seen it most notably on FWD vehicles for some reason. I recall a co workers 87 Honda CRX did it.
Taking a stab in the dark, my guess would be a vacuum leak where the intake mates up to the head, or maybe an ECM issue...just wondering if anyones ever had this isse on their car and what the cause/remedy was.
I've never own a car or truck that did this but I've seen plenty....where the car's idle will surge...it will go up then come down, then go up then come down, then go up then come down....I think i've seen it most notably on FWD vehicles for some reason. I recall a co workers 87 Honda CRX did it.
Taking a stab in the dark, my guess would be a vacuum leak where the intake mates up to the head, or maybe an ECM issue...just wondering if anyones ever had this isse on their car and what the cause/remedy was.
Unfortunately, it can be any number of issues, or any combination of those issues. Vacuum leak(s) is the most common cause, but there's the occasional malfunctioning idle air control valve.
I've never own a car or truck that did this but I've seen plenty....where the car's idle will surge...it will go up then come down, then go up then come down, then go up then come down....I think i've seen it most notably on FWD vehicles for some reason. I recall a co workers 87 Honda CRX did it.
Taking a stab in the dark, my guess would be a vacuum leak where the intake mates up to the head, or maybe an ECM issue...just wondering if anyones ever had this isse on their car and what the cause/remedy was.
Wow that is a lot of evidence that this problem occurs "most notably on FWD vehicles."
My '87 Trans Am with 350 TPI has done this ever since I bought it. I've replaced all hoses, injectors, TPS, and IAC valve. It still does it, so I just live with it.
My '87 Trans Am with 350 TPI has done this ever since I bought it. I've replaced all hoses, injectors, TPS, and IAC valve. It still does it, so I just live with it.
This may be an oversimplification, but does it have a performance cam in it? Those "lope" at idle.
I am getting now in my 1998 F-150. I think it is a vacuum problem too. I probably won't fix it. So my idle occasionally runs high and wastes a little gas. It will probably cost over $100 to get fixed. Not worth it.
Another thing that happens with bad vacuum is losing the ability to control the climate control source. It will default to the defroster if I am not mistaken. You can't divert the air to the vents or the floor.
Another rant about fords (domestics?): when in the combination vent/floor position, the AC compressor is enabled. I hate that. I wish the AC compressor was an independent switch like it is on Japanese cars.
1. taking stab in the dark - what car is it? Read your post 5 times, can't find it.
2. Fords had major issues with ISCs, idle speed control solenoid.
3. without knowing the car, it's everyone's guess. Just because you had Honda mentioned, older Hondas had coolant heated idle speed valve, air valve, that needed to be taken apart and cleaned.
4. for vacuum leaks, buy can of brake cleaner, stick straw in, and start the engine. Give quick shots of cleaner moving around throttle body and intake. When engine bogs, you got it. Sometimes even red silicone applied to well cleaned gasket on the outside may fix it.
5. On some vehicles, transmission can cause this.
But like I said - everyone's shooting in the dark here.
vacuum leak, build up on crucial parts, Mass air flow is dirty, Throttle body needs cleaning/ re-adaption, tune up.
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