Mechanics

ENGINE MISFIRES AND RUNS ROUGH

2001 Ford Escape

Engine Performance problem
2001 Ford Escape 6 cyl Four Wheel Drive Automatic 151000 miles

I have been trying for some time to get my '01 Escape to run smoothly - I have been having problems with poor acceleration, loss of power, rough idle, and rough running for quite a while. My check engine light has been coming on, showing codes in pairs - either misfire in cylinder 1 and 5, 3 and 4, or 2 and 6. Nothing that I do seems to keep it from misfiring.

In my efforts (in part to fix the problem, and also just as a tune-up), I have replaced: Spark Plugs, Upper and lower intake manifold gaskets, Idle Air control, Fuel Filter, Throttle Position Sensor, DFPE sensor, EGR valve, air filter, all 6 COP, fuel injector O rings, battery (which was dead) and the Camshaft Position Sensor.

I checked the MAF (it is a hot wire) - it is spotless, but I tried to clean it as well. No improvement. Cleaned the throttle body just for good measure, but couldn't find any significant blockage or deposits.

I also tried some fuel system cleaner with not much improvement - I took it down to the injectors and swapped a couple of them out to see if the misfire moved with them. It didn't - I still got the same codes. While I was down there, inspected the manifold and gaskets but didn't notice anything out of the ordinary.

I have looked for a vacuum leak, but was unable to find any - as far as I can see the hoses, etc are in good shape. Possible I missed something.

All of this work has resulted in some improvements - i.E. It idles better, accelerates better, has some more power, etc than it did. Still getting the CEL, still feels like it is running rough, still a lot of vibration and still a loss of power, especially just after it shifts up into the next gear on acceleration. Still has poor fuel economy also.

One of the reasons that it has taken me so long to diagnose this is that every time I replaced a part, I disconnected the battery, and for a couple of days it would run better. Then it would start running badly, and the CEL would come back on. I thought I finally had the right solution about a dozen times. Just recently realized that disconnecting the battery was resetting something in the computer. One time I got codes PO302 and PO306, disconnected the battery, reconnected it, and a day later got codes PO301 and PO305 - without doing anything else to the car.

After that, I replaced all 4 O2 sensors (150K, and I don't believe that they have ever been replaced). That was yesterday - took the car for a drive today. CEL has not come on, but when I accelerated the car skipped - almost like something either missed, hesitated, or misfired in the car. It feels better, but still has a hard time accelerating after it shifts up into the next gear - almost like it is shifting too early or something.

I'm afraid that I still haven't fixed the problem, and hoping to get it licked for once and for all. So any answers that might help me do that would be greatly appreciated. I have recently got an computer scan tool (AutoEnginuity)- I can read and monitor the codes and some live data streams if that would be of any use. If there is any other information that would be helpful or testing procedures that you would recommend, please let me know. I know this is a lot of verbiage, but I figure the more information the better.
Avatar
ArchMedic
January 1, 2010.



HELLO ArchMedic

The random misfire DTC indicates multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring.
you did replace what we call the most likely causes of the problem such as such as DFPE sensor, DPEVR(differential pressure EGR vacuum regulator)
Next is to check the camshaft position sensor,it could cause similar problem.then you have a faulty catalytic as a potential candidate. Beside that you have the fuel pressure sensor as a second candidate to cause that problem.

This can help to locate the components
(check your email )


http://www.2carpros.com/forum/automotive_pictures/46384_dpevr_1.jpg




http://www.2carpros.com/forum/automotive_pictures/46384_camshaft_1.jpg


Tiny
Mathiaso
Jan 1, 2010.
I was hoping you could clarify your response. As I mentioned, I have already replaced the camshaft position sensor. I am reluctant to go ahead and replace the catalytic converters, as there are multiple converters and the two just off the engine are both expensive and a royal pain to access.

The fuel rail pressure/temperature sensor however, shouldn't be too big of a problem, but I am unable to find any information about it. None of the usual resources that I check have any info about it. Is this usually a dealer only part? Do you have any further info about the location, or the part number or manufacturer, or where I could find such a thing? Thanks!

Tiny
ArchMedic
Mar 21, 2010.
All codes point to vacuum leak or a weak pump or pcm problem.

If you have a scan tool, look at the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) values. Normal range is plus or minus 8. If the numbers are +10 or higher for STFT and LTFT, the engine is running LEAN. If you rev the engine to 1500 to 2000 rpm and hold it for a minute or so, and the STFT value drops back down to a more normal reading, it confirms the engine has a vacuum leak at idle. If the STFT value does not change much, the lean fuel condition is more likely a fuel delivery
problem (weak fuel pump than a vacuum leak.)
From there we see which way to go.
Do not replace any parts yet.
Get back to me as soon as you find something.

Tiny
Mathiaso
Mar 22, 2010.
Between when I asked the first question and my follow-up I had already replaced both the fuel injectors and the fuel pump (with a used one) - believing it was a weak fuel delivery problem. The following are screen shots from several of the times that the CEL came on.


http://www.2carpros.com/forum/automotive_pictures/169479_2CP1_29DEC09_1.jpg



http://www.2carpros.com/forum/automotive_pictures/169479_2CP2_06MAR10_1.jpg



http://www.2carpros.com/forum/automotive_pictures/169479_2CP3_22MAR10_1.jpg



Hopefully they will help. I did not do the test that you suggested because the first thing that I noticed when I hooked up the scanner was the STFT was below 8 (as in the last capture). I can still try it if necessary, just let me know.

Tiny
ArchMedic
Mar 25, 2010.
Thank you for the screen shots

have the ignition module tested at an automotive repair shop then get back to me.

Tiny
Mathiaso
Mar 26, 2010.
There is no " ignition module" on this vehicle. There is also no distributor - according to the Haynes manual, the ignition system consists of the PCM, Crankshaft sensor, camshaft sensor, spark plugs, COP, and that's pretty much it. It says that " the functions of the ignition control module are incorporated into the PCM.&Quot; And before you ask, yes - I already replaced the Crankshaft sensor.

What else could it be?

Tiny
ArchMedic
Apr 1, 2010.
Have them check the ignition transformer, if the transformer is good ,have the computer tested,if you're sure that the problem is not in the crankshaft wiring, something you may have overlooked.


http://www.2carpros.com/forum/automotive_pictures/46384_0996b43f80240139_1.jpg


sending this diagram to your email.

Tiny
Mathiaso
Apr 1, 2010.
I had almost the same issue. I have a 2001 Escape with 154,000. My vehicle would run really rough and misfire, especially worse when it would rain or snow. I took my vehicle to a mechanic several times and he had no idea what was going on with it. I spent several hundred dollars and the issue was not fixed. He just said you must have bad gas or something. I kept driving on it for some time and one day my EGR valve blew out and my vehicle was inoperable. My catalytic converter was glogged up to the point the pressure blew out the EGR. I took my vehicle to a Ford Dealership and spent $2,000 to have them run the diagnostics on it and fix the problem. I had 2 coil packs that were bad and a few seals needed replaced. The coil pack itself wasn't bad, just the rubber boot, but I didn't realize at that time just the boot could be replaced by itself. It had cracks in it and moisture was leaking in. Several months later I had the same symptoms return and after scanning the check engine light, I found another coil pack had went out. Replaced it with a new one and that fixed my problems. No issues. Just wish I would have spent the 2 grand in the first place.

Tiny
Mjacoby
May 6, 2010.
Mjacoby - Replacing all 6 coil packs was one of the first things that I did.

Mathiaso -

I took my car to a mechanic and asked him to check it out and let me know what he thought was causing the problems described. It continues to sputter, jerk, and hesitate - even popping from the rear when we start it up in the morning. The CEL continues to read Cylinder misfire. The mechanic did a cylinder leak-down test and told me that cylinder's 1, 2 and 6 had a greater than 20% compression loss, and that he believed that the leakage was not just at the valves but also through the piston rings. He suggested a refurbished engine to the tune of $4,000.

Although I have no reason to distrust this mans word, I have a hard time believing it is such a serious problem, when it is so intermittent and I still seem to get a significant improvement in the performance just by unhooking the battery and re-setting the system. Further, I discussed this with a second mechanic and he told me he would hardly ever trust a cylinder leak-down test as they are not reliable at all - but with this many miles on the engine it could definitely be a mechanical failure.

Further research (on this site among others) suggests that it may indeed be the valves as the popping sound is characteristic of bad valves. I am also loosing some anti-freeze (very slowly) - I've had to add more twice over the last 3 months. But no, I haven't had anyone test the ignition transformer yet.

My question would be - is this a likely scenario? Could bad valves/rings/head gasket be causing all the problems that I describe and lead to cylinder misfire? Or is it still more likely that one of the other cause previously mentioned is the culprit? (Fuel rail pressure regulator, catalytic converter, ignition transformer, PCM, etc)

Tiny
ArchMedic
May 21, 2010.
Hello ArchMedic

A loss of 20% compression in cylinder's 1, 2 and 6 could make the engine running 80% on 3 cylinders and 100% on the others 3 cylinders in your 6 cylinder's engine, causing misfire.
When compression is lower in one or more cylinders, then the valves or the rings are suspect.
A wet compression test is useful in deciding whether rings or valves are the problem.
If compression comes up during the wet compression test, then the rings are most likely the problem. Conversely, if compression does not comes up then leaking valves are the likely problem.
A leak-down test is more precise and pinpoint what the problem is.
If air is heard escaping from the exhaust, then you have a leaking exhaust valve.
If air is heard escaping from the intake, then you have a leaking intake valve.
If air escapes and causes bubbles in the radiator, the head gasket or cracked head is the problem.
If air comes from the pcv valve, leaking ring is indicated.
The popping noise you mentioned is coming from the catalytic converter, because of the misfire, unburned fuel enter the exhaust and ignites in the converter.
The most likely is leaky exhaust valve
that has been allowing unburned fuel to enter the exhaust system.
A real cylinder leak-down test must be perform to make sure the problem is only the valves or the rings, because it is expensive repair and there is no room for guessing.

Tiny
Mathiaso
May 22, 2010.
Page 1 of 3