intermittent high idle

[backerm]

I've got a 1988 ford ranger, 2.3L, 4x4. It idles up to 1800 on some days and other days it is normal around 700-800. Its lacking alot of power too on some days and other its normal. Checked vaccum and fuel pressure. Anyone have any ideas?

[damnthemachines]

Anymore details? I'm assuming it's EFI. Check your idle air control (if that's on EFI, I'm not sure, I think it's only for carbs.)

[DonSor]

Need more details. Is there a pattern when these phenomena happen? For example, when it loses power "some days", is it all day, every other day, how about speed, acceleration, any other symptom that could lead to solution. How qbout the Check Engine Light? Is it on? Any code detected?

[backerm]

It is just random some days hot some cold. Mornings and night. It is EFI. I haven't checked codes yet. check engine light is not lit. But it has been running good for years. Why all of a sudden? Anyone else having a similar problem? Yes I looked at the IAC, throttle butterfly. It was about 800 this morning, and this afternoon it was idling at 2k rpm.

[backerm1]

It stoped doing it for 2 months and then started again. I found out that when I turn the ignition off and then back on the idle drops down to normal. This thing is really irritaiting.

[DonSor]

You got an OBDI system which does not reveal all possible engine problems. I suggest you take it in for a diagnostics to pinpoint the problem. It'll cost about ninety bucks. I had this done on a 91 Mitsubishi because it was surging at low wpeeds. Diagnostics indicated a "lazy" O2 sensor and a malfunctioning EGR temperature sensor. Replaced both items and that solved the problem.

[backerm1]

yeah the o2 has been bypassed for years and the EGR works ok. Some of the turbo mustang guys have had this problem too, but no one seems to know anything about it.

[DonSor]

For your info, both O2 sensors are critical in maintaining the correct fuel air ratio. Too lean or too rich signal will cause the PCM to compensate up to a point and send out the appropriate code via CEL.

[backerm1]

well i decided to wire the O2 sensor back up. There is only one, on this truck. It still has the high idle problem. But I can pass my emissions test now