i need to fix a mazda/ford

[numbnuts240]

now that my stint at the power plant has come to an end, i can devote some attention to figuring out the problem on my old man's truck. it's a 1994 mazda b3000, ford 3.0l sohc v6, 5-speed, 4wd, no cruise.

he has tried to describe to me what's going on, but discerning little facts as he hasn't been toying around with cars since the 70's. fresh tune-up done a couple months back, although to problem persisted even before.

so i had a chance to drive it and see for myself what was going on. if you attempt to shift too quickly, the engine will race up to around 3k rpm. i stabbed the gas pedal, racing it up even more, and it returned to normal idle speed. i've also been able to achieve it by braking to a stop, or putting a load on it by shifting to 3rd or 4th (if i came out of 1st gear when it raced up i'd put it in 3rd, and likewise, if i came out of 2nd, i dropped it in 4th). he says it'll do it sometimes while it's still in gear, but it didn't happen to me. check engine light randomly comes on, but i did not notice if it's triggered when the motor is getting itself all worked up. iirc, he went ahead and tried the tps, but i don't remember for sure.

[sx moneypit]

Mornin' Tito!Sounds like he's got a screwed up TPS.If you shut the engine off and restart it , does the idle return to normal?
Another possibility is a bad IAC valve, or the base idle is not adjusted correctly.

[Dattebayo]

Does that thing have a cylinder head temp sensor?

[numbnuts240]

Mornin' Tito!Sounds like he's got a screwed up TPS.If you shut the engine off and restart it , does the idle return to normal?
Another possibility is a bad IAC valve, or the base idle is not adjusted correctly.

shutting the engine off and restarting it will stop the crazy idle. and now that you mention base idle, i did note to him that the truck is idling around 1k and that he should back it off.

Does that thing have a <a href="http://shop.ebay.com/i.html?_nkw=cylinder+head" rel="nofollow" title="Link added by VigLink" class="vglnk">cylinder head</a> temp sensor?

couldn't tell you off the top of my head.

[sx moneypit]

It has two coolant sensors,one for the gauge and one for the computer.
Is the coolant level OK?

[Kompresshun]

It's the idle air control valve. I had the same issue with my old Ranger a few times and it had the same engine and a manual transmission. They get gummed up with carbon build up and it causes the throttle to stick at times. You may be able to get by with just cleaning it well with some throttle body cleaner. That's what I usually did, but with it being a lot older, you may have to replace it this time.

If its anything else, I'd be highly surprised from my experience. I'd say the only other thing would be the TPS, but I've never seen a TPS do that on a Ranger.

<--- Has had 3 Rangers in the past 10 years

[IanS]

It's the idle air control valve. I had the same issue with my old Ranger a few times and it had the same engine and a manual transmission. They get gummed up with carbon build up and it causes the throttle to stick at times. You may be able to get by with just cleaning it well with some throttle body cleaner. That's what I usually did, but with it being a lot older, you may have to replace it this time.

If its anything else, I'd be highly surprised from my experience. I'd say the only other thing would be the TPS, but I've never seen a TPS do that on a Ranger.

<--- Has had 3 Rangers in the past 10 years

sounds like IAC to me too.

I have never seen a TPS cause this sort of issue, on anything.

[numbnuts240]

i'm headed over to his house now, so i'll spray the iac with some tb cleaner and see if it reduces or eliminates the issue. if so i'm going to have him order a new one. thanks for the help guys, i'll report back later.