96 Escort 1.9 Idle issues

[Rockhousehootie]

At cold start, car almost will not run (low idle), after warm up, car ran fine and then all of a sudden will not idle below 2000 rpms. Replaced IAC twice, with used (had one lying around) and then with new, same result. Scanned with scanner, and said to replace PCM. Bought used PCM, installed and same result. Scanned again, said bad IAC!!!!!! Scanner says TPS is within voltage. Volt reading at IAC is 7.2 volts at idle? New plugs, wires, coil pack. Checked and checked and triple checked vacuum connections, plugged and unplugged. Cleaned and then clean and swapped throttle body,as well as mass air meter. We are a brake/chassis shop, my daughters car, and alldata, as well as MANY friends in the biz are befuddled! Aside from placing part, after part, I am at a loss!!!!!
ANY HELP WOULD BE APPRECIATED!!!!!!!! Joe.

[Davescort97]

Did you replace the PCV valve? Also, the elbow that connects it to the intake has been known to be cracked. Also, check the vacuum line going to the brake booster. If the car dies or has an rpm change when stepping on the brake the diapragm could be leaking on the booster.

[Arnoldtheskier]

Pcv,elbow,booster diaphragm, as mentioned.

I would go back a bit.

Put the old pcm.,iac, back in.
I would be looking around at the wiring. Do a wiggle test..with the car off/running. While scanning. lol..lots of stuff has shown up during this!

Fuel pressure and volume test.

Failing the above. I had an idle issue that I could not fix. I had to make an idle speed adapter with a bracket. Fixed that problem and drove the car for a year or two..even through E test. Never did find the problem. You can do this with another throttle body.

Run it through an etest,eg gas test. That can often nail down where the problem is by the eg gas readings. Ideally..some pro's start the car cold

My guess is that it is in the fuel rail/injectors. And affected the cold start set up.

A bad fuel line/filter can bring grief.

Some of the newer "real time" scanners are pretty cheap now. As well as being very powerful and sophisticated..lol Drive the thing and they hold a ton of info that can be upoaded too! Read the codes,record them,clear the codes,have at it. I never said to watch it while driving to see when it occurred.

[Rockhousehootie]

Originally Posted by Davescort97

Did you replace the PCV valve? Also, the elbow that connects it to the intake has been known to be cracked. Also, check the vacuum line going to the brake booster. If the car dies or has an rpm change when stepping on the brake the diapragm could be leaking on the booster.

Originally Posted by Arnoldtheskier

Pcv,elbow,booster diaphragm, as mentioned.

I would go back a bit.

Put the old pcm.,iac, back in.
I would be looking around at the wiring. Do a wiggle test..with the car off/running. While scanning. lol..lots of stuff has shown up during this!

Fuel pressure and volume test.

Failing the above. I had an idle issue that I could not fix. I had to make an idle speed adapter with a bracket. Fixed that problem and drove the car for a year or two..even through E test. Never did find the problem. You can do this with another throttle body.

Run it through an etest,eg gas test. That can often nail down where the problem is by the eg gas readings. Ideally..some pro's start the car cold

My guess is that it is in the fuel rail/injectors. And affected the cold start set up.

A bad fuel line/filter can bring grief.

Some of the newer "real time" scanners are pretty cheap now. As well as being very powerful and sophisticated..lol Drive the thing and they hold a ton of info that can be upoaded too! Read the codes,record them,clear the codes,have at it. I never said to watch it while driving to see when it occurred.

O.K. First of all thanx for the replys!!!!!
I have put the old PCM and IAC back in as well as 3 new IAC's. The new PCM was used. When diagnosing with the Snap-On scanner, as well as All Data.com, no matter what combination of old and new parts we use, the results are always a bad PCM! The problem with this diagnoses is with the original IAC, we can jiggle the the Harness for the IAC and get a 12.2 volt result and a normal idle! We can not duplicate this with 2 new IACs (7.2 volts)(all data says needs 12.2v at idle, the lower the voltage the higher the idle) and or the IAC off of my other 93 Escort. I can install the 2 new IACs on the 93, and the result is good. The 93 IAC installed on the 96 is the same as the new ones, 2500-3000 rpm's!!!!!! I guess I would be interested in how to do the "Idle Adapter"! Thanks for all of the help!!!!!
P.S. We still have volt issues.... could this be a bad PCM?

[mightymoose_22]

How does the car run if you pluig all the vacuum ports on top of the intake manifold?

[Arnoldtheskier]

Originally Posted by Rockhousehootie

O.K. First of all thanx for the replys!!!!!
I have put the old PCM and IAC back in as well as 3 new IAC's. The new PCM was used. When diagnosing with the Snap-On scanner, as well as All Data.com, no matter what combination of old and new parts we use, the results are always a bad PCM! The problem with this diagnoses is with the original IAC, we can jiggle the the Harness for the IAC and get a 12.2 volt result and a normal idle! We can not duplicate this with 2 new IACs (7.2 volts)(all data says needs 12.2v at idle, the lower the voltage the higher the idle) and or the IAC off of my other 93 Escort. I can install the 2 new IACs on the 93, and the result is good. The 93 IAC installed on the 96 is the same as the new ones, 2500-3000 rpm's!!!!!! I guess I would be interested in how to do the "Idle Adapter"! Thanks for all of the help!!!!!
P.S. We still have volt issues.... could this be a bad PCM?

You still have a bad pcm code. Seems that was what you had first. Then you changed the pcm with a used one and still had a bad pcm code. I think you gotta iron out the bad pcm/code first. Whether actually in the pcm..or perhaps in the wiring harness to/near it. Would a bad pcm show/cause volt issues. I don't actually know. I would say probably.

As I have posted before a few times..I listen to this pretty fantastic car show!!!!

Last week..if you can believe this..a guy calls in..gets/has problems..lol..pcm code. Changes the pcm..pcm code comes back. The host says SURE. I have seen this. HUNH??..On that model.. ( I can't remember)..they get water leaks..and guess right where they leak??

Idle speed. Get another identical t.body from the bone. The idle speed screw is there..threaded into it(t.body)..adjustable..ONLY FROM THE FACTORY!!..(my 93 was anyway)original t.body. Use the bone t.body. The screw is factory adjusted..and then sealed with some sort of glue. Loosen this screw from the glue..and have at it. Or..if you can't break the glue bond..break it off and re-drill and re-tap. On mine the idle was too low so I just made an angle bracket that bolted to the t.body(I just pulled one of the bolts out..and bolted my bracket right there. ). Drilled,tapped it so the new idle screw could contact the t.body right near the old idle speed screw.

Why was my idle so low? I dunno..probably.. a bad injector. I never actually did a cyl bal test to find if it was one particular cyl. I checked and quadruple checked everything else about fifty times lol.Figured the new idle bracket was cheaper and much quicker/easier than pulling the rail and an injector. lol..I never ever thought it would pass emmissions.

Get a bone t.body to play with.

First fix the pcm code.