help please - 1992 tempo

[tempo42]

Trying to fix my friends "go to school car" - 1972 Ford Tempo - 4 cylindar. It won't idle well and stalls often - runs strong at speed. "Feels" like it is flooding at idle. I got into it late - others have worked on it - including a mechanic. And I'm an amature - though a logical one - ha. It apparently is a fairly recent problem - after she bought it and drove it awhile.

The first thing I need help on is the firing order. One of her friends changed the plugs, distributor cap and wires. I'm suspicous. I've researched this and other sites and been to the library - finding several versions of the correct plug-to-distributor hook-up. Can someone describe (to a novice) how to wire it correctly as a starting point?

I'm trying not to spend unnecessary money or time on it, so thought I'd retrace what others have done. Can you help? Thanks a ton.

Bob

[dxrflyboy]

The idle problem may be a faulty Idle Air Control Valve (IAC or IACV). It's bolted to the back side of the throttle body next to the EGR valve. You will need a scan tool so you can monitor the duty cycle the PCM is commanding the IAC. If the duty cycle percentage is high, chances are the IAC isn't operating properly and the PCM is commanding excess on time to compensate.

The firing order is 1-3-4-2. Most distributor caps have a "1" molded into them by the #1 terminal. I'll have to check where the #1 wire is on mine in case you don't have the "1" molded into the cap. GBTY on that.

[tempo42]

Originally Posted by dxrflyboy

The idle problem may be a faulty Idle Air Control Valve (IAC or IACV). It's bolted to the back side of the throttle body next to the EGR valve. You will need a scan tool so you can monitor the duty cycle the PCM is commanding the IAC. If the duty cycle percentage is high, chances are the IAC isn't operating properly and the PCM is commanding excess on time to compensate.

The firing order is 1-3-4-2. Most distributor caps have a "1" molded into them by the #1 terminal. I'll have to check where the #1 wire is on mine in case you don't have the "1" molded into the cap. GBTY on that.

Thanks for the reply - it helps, and I appreciate it. I took the little beast to a reliable mechanic. He confirmed the firing order (just as you said. Darn - not the problem.) He advised that the number one cylinder was firing, but not contributing to much (disconnecting the plug didn't make it idle any rougher than it already was). His opinion was a bad injector, or an internal problem. His advice was not to spend any money on the car - he joked that once he put a wrench on it, there would be $100 bills flying all over the place - ha.

On the chanch the injector could be be cleaned, I ran a tank of gas thru it with an injector cleaning additive. It helped somewhat. The car doesn't stall anymore, but is still rough as a cob unless you slip it into neutral. It helps that it's past air conditioner time.

I've tryed to spy the IAC, but feel dumber than a door nail because I don't really see it. I had read a little on how the car works, and the IAC seems complicated enough that it sounds like a good culprit. I don't know what a scan tool is and it's dissapointing that no mechanic has mentioned the IAC or whether it is working properly. Have you any idea what it costs just to replace it rather than test it?

Thanks again -

[dxrflyboy]

The IAC may be a little hard to see because there is a plastic shield over the throttle body where the throttle cable attaches - you may have to remove that before you can see it. It is held on by two small bolts. If you pull it off, you will see two holes in the throttle body. The IAC has two openings on it with a solenoid controlled valve that opens and closes to control the amount of bypass air to regulate the idle speed. Since running fuel injector cleaner helped the idle a bit, it is probably worthwhile to do a professional fuel injector cleaning. I've seen it work wonders on vehicles that were running like crap. I would pursue this before doing anything with the IAC. As far as cost goes, give your local parts store a call for a price. Also, run a compression test on cylinder #1 to check for a burned valve or leaking rings before spending too much money on an IAC or fuel injector cleaning. It doesn't make any sense to chase external problems if your engine has major internal problems that aren't worth fixing.