Internet Diagnosis: 1993 Ford Escort

[JOD]

A friend of mine just picked up a 1993 Escort LX wagon for cheap. It's the 1.9 engine, 5 spd MT; cool little car.

While taking it in for emissions testing, it flunked the hydrocarbon @ idle, just barely. All of the other emissions test were passed easily.

He was experiencing some slight drivability issues: the car would hesitate occasionally, and at idle it would dip down to about 400-500 briefly then go back up to 750 or so.

My suggestions were as follows:

-change the oil (dirty), add 1 qt MMO for a cleaning

-change PCV valve/hoses

-pull MAF sensor and clean it

-clean throttle body bore/plate, and connections on TPS

I had one other suggestion (which I initially guessed was the cause). He hasn't done that yet, but I don't want to color anyone's guesses! He also mentioned that a lot of the vacuum hoses looked rough, so he replaced most of them. He has a fuel filter on order.

The driveability issues are pretty much gone--but the car still has the idle issue and it still flunked emissions.

He's at a point where he can pay $150.00 to a local shop, and if it still doesn't pass he can register the car. Any last-minute thoughts/suggestions on where the problem may lie?

 

[Kruse]

Cleaning the iac valve might help the jumping idle.

 

[Kestas]

Tough call. It could be that the catalytic converter is used up. Or the injectors are dirty and unbalanced.

 

[jmac]

also, car that old, look at plugs, wires, coil, rotor and cap.

 

[PandaBear]

new O2 sensor, new plugs, maybe wires coil rotor cap.

Do it right instead of having someone pass you illegally, barely failing should be easy to fix.

 

[JOD]

Thanks for the responses--all good suggestions so far. Yeah, I forgot to mention he has some plugs on the way. It's a distributor-less ignition, though.

My off-the-cuff guess was a faulty MAF sensor.

EDIT: I should mention this whole experience has given me a new-found respect for OBD-II. This car is OBD-I and it's not throwing any codes.

 

[Kruse]

Originally Posted By: JOD

EDIT: I should mention this whole experience has given me a new-found respect for OBD-II. This car is OBD-I and it's not throwing any codes.


I'm with you 100% on that. My own '93 OBDI Aerostar was throwing about a half a dozen codes a year ago. I replaced the MAF and it was fixed. However, none of the codes pointed to the MAF at all. Some of the codes were car-only codes.

 

[The_Jeff]

Is this one of the ones with the long plastic flexy hose between MAF and TB? Might have a crack/leak in the metered part.

A fresh oil change soaks up HC BTW. New plugs are a given.

 

[mechtech2]

High HC is usually related to misfires.
New spark plugs and wires are the first things to check/replace.
Sure, everything should be correct and perfect, but this is #1.
Vacuuum leaks are critical - lines and manifolding - esp the PCV system.

 

[brianl703]

Originally Posted By: JOD

My off-the-cuff guess was a faulty MAF sensor.

EDIT: I should mention this whole experience has given me a new-found respect for OBD-II. This car is OBD-I and it's not throwing any codes.


If you had a scantool that supports Ford DLC, you could look at the BARO reading which should be about 158Hz. If it's way off, the MAF is bad.

There are also two self-tests that you could run on the car. You need only a jumper wire to make them run--the key on engine off test, and the key on engine on test.

I have had the self-tests throw codes when there were no codes in memory..

 

[wander2039]

How old's the timing belt? Timing belts can stretch and throw timing off in a very small amount.. but with a dirty engine a small amount maybe just enough.

 

[mechtech2]

Do you guys mean the MAP sensor [not MAF}?

 

[JOD]

Originally Posted By: mechtech2
Do you guys mean the MAP sensor [not MAF}?


I was thinking MAF sensor. Truth be told I didn't realize until you mentioned it that this car has both a MAP and a MAF.

Could he just check the MAP with a multimeter?

 

[brianl703]

'93 Escort has only a MAF sensor. The BARO reading is calculated from the MAF sensor. Bad MAF sensor gives incorrect BARO reading.

I'm not sure how EEC gets a BARO reading from the MAF, but I know that it does and I also know that a strange BARO reading points to a MAF problem.

Older EECs have a separate BARO sensor. These also had 2-digit codes. I believe all of the EEC-Vs and the EEC-IVs that output 3-digit codes do not have separate BARO sensor, only a MAF.

 

[jigen]

My old Galant had this exact problem -- it was the MAF sensor.

 

[JOD]

Well, here's the sorta final verdict:

He replaced the plugs, cleaned the wire connects, and the car is running much more smoothly-but it still has the slight idle blip. He also (on the recommendation of a mechanic friend) ran the tank to about 2 gallons, put in 3 bottles of HEET (I'm guessing it's alcohol based?) and then took the emissions test. It passed with w/flying colors. Co2 @ idle was (he thinks)260ppm before, 220 is passing and it was at 120ppm after the plugs and with the alcohol in the tank.

I'd be curious to know if the plugs alone would have changed things, but he flunked the emissions enough times that he was paying for the test, and didn't want to take any chances.

If it were my car, the idle blip would bother me enough to fix it--probably--but other than that it's running perfectly. My money's really on the MAF sensor for the idle issue.

He also got 35mpg on the last tank, pre-plugs! Not bad.

Here's a picture of the plugs, most likely original and 16 years old (sorry for the lousy pic):

 

[Kruse]

Originally Posted By: JOD
Here's a picture of the plugs, most likely original and 16 years old


Those gaps are pretty wide.

 

[demarpaint]

I can tell you that idle blip or surge can drive you nuts. I'm going thru it right now. New cap, plugs, wires, rotor, IAC, TPS, MAP sensor, and a spacer plate under the IAC. Still have the idle blip until I touch the gas then it's OK. I had a mechanic friend check it for codes, nothing. It runs like a champ when it is not surging, no vacuum leaks either. Many of the older Fords have this problem. Mine is a 4.9L, and it is common with the V8's as well as the 4 cyl engines. EGR is a year old, along with many of the sensors. I recall another member had similar issues with an older F series PU.

Try a high pressure FI cleaning, it might help.Be sure there are no vacuum leaks and the EGR is good.

 

[RocketUSA]

Glad you got it to pass. I've got a 1994 LX sedan with 260K on it, and it's been a real champ. Bought it brand new. I'll ponder the idling issue and if anything comes to mind I'll repost about it. I had the ignition control module go out once and it ran like [censored]. It's about $40 for a new one.

 

[demarpaint]

I replaced the ICM, they had an issue with them which resulted in a class action lawsuit, it made no difference in my case.