Engine stuttering...please help

[bigschoen]

OK...

This problem has been going on for a while. My car, while pressing on the accelerator, will take off and just start to stutter, like it's choking, it will continue to accelerate, but slowly and choppy, choking all along.

The car dealership orginally replaced spark plug cables, which helped for 2 weeks, untill it did it again. They re-replaced the spark plug cables again.

Eventually, the problem came back. They told me I had oil in the plug wells - so they replaced all the gaskets and the spark plugs. In that same time I put in a new fuel filter and replaced both of the oxygen sensors.....

Now a couple months after all that work, I have the problem back - same as before. The dealership had my car for 8 months within the last year or so and I had to bring it back for the above problem and another problem every week cause they could not fix it properly. If it were the above stuff, I imagine the problem would not have come back like it did.

Can anyone give me some ideas on what this is so I can go back and yell at them? I am fed up - have spent tons of money and I feel frankly, embarrassed to even go back to that place - but I don't want to pay for anymore work somewhere else. I am considering sending a letter to Ford - main customer service (will that even do anything?? I don't want to get the main guy at the dealership here in trouble, he had been pretty cool about doing all this reworked stuff (unfortunately they can't fix it...)

Please give me some help if possible. Much thanks in advance!!

adam in Ohio
...and fuming....

 

[ret]

Does your check engine light come on at all? Have you checked the cpu codes to see what it says is wrong (Ford "should" have done this, but ya never know)? You can get a cheap ($30) code reader from advance auto parts or you can make a jumper for about 10 cents worth of stuff (of course you'll have to buy $5-$10 worth of it) that will make the check engine light flash out the error codes for you.

you can find instructions for doing so here:
http://www.corral.net/tech/maintenance/eecivtest.html

Technically, these are for a mustang with an eec-iv ignition, but the ignition is the same, so the same instructions apply to our cars.

 

[bigschoen]

Yes, there was a Check Engine light reading - which was that I believe fuel mixture was running rich - it was for a Oxygen Sensor. They replaced both of them... After all the stuff they fixed, the car ran great - but here I am again, two months later and it's running like crap....

any other ideas??

adam in ohio

ret:
Does your check engine light come on at all? Have you checked the cpu codes to see what it says is wrong (Ford "should" have done this, but ya never know)? You can get a cheap ($30) code reader from advance auto parts or you can make a jumper for about 10 cents worth of stuff (of course you'll have to buy $5-$10 worth of it) that will make the check engine light flash out the error codes for you.

you can find instructions for doing so here:
http://www.corral.net/tech/maintenance/eecivtest.html

Technically, these are for a mustang with an eec-iv ignition, but the ignition is the same, so the same instructions apply to our cars.

 

[luigisho]

Computer codes would be helpful if you have any present. Did you have the wires and plugs changed after the oil in the plug wells issue? This could take a bit to diagnose. Are there any shoclubs or other sho owners in your area? I ask because it is often easier to swap parts before you buy them to see if they make a difference. I would say for starters since it's cheap try cleaning the maf,act, and iac sensors and replace the fuel filter. How about checking the fuel pressure? Anything else been replaced? Cam sensor?

 

[bigschoen]

Here is what was replaced:

CPS
Plug Wires
...then everything ran fine.
....then problem came back.

Plug Wires again
...everything fine.
....the problem came back.

Then they replaced..
1. Both Oxygen Sensors
2. Fuel Filter
3. All gaskets
4. Spark Plugs

Car ran great until two days ago (they fixed the stuff above about 2 months ago...) I am at wits end...

I don't have tools, time or space to look into this myself now unfortunately - and frankly, the dealership should have this fixed by now...it's pretty absurd if you ask me...8 months!!!!

What else could this be? Everytime they replaced the plug wires it ran great - but for only a couple of weeks.

OH - and I have been losing oil. I don't know if I am burning it...I am not leaking it on stand still (could be front/rear main seal???) I lose oil about a quart- 2 quarts a week maybe and I don't even drive much.) The dealership told me this leak was due to the gaskets - and that the oil was leaking into the plug wells - but I still have the oil leak. I asked them about the front main seal and they said no - but I am not convinced. They are so sick of me down there, when they did that last round of repairs (about $1,000 worth of work for $75) he basically told me he didn't want to see me again... I am nervous to bring the car back
cause I think they want to roll it off a cliff...

any more help or suggestions...I am dying here...

adam in ohio

luigisho:
Computer codes would be helpful if you have any present. Did you have the wires and plugs changed after the oil in the plug wells issue? This could take a bit to diagnose. Are there any shoclubs or other sho owners in your area? I ask because it is often easier to swap parts before you buy them to see if they make a difference. I would say for starters since it's cheap try cleaning the maf,act, and iac sensors and replace the fuel filter. How about checking the fuel pressure? Anything else been replaced? Cam sensor?

 

[sdpatt]

The misfire situation you describe sounds like a secondary ignition fault: plugs or wires. The curious thing is that the problem actually goes away for awhile before returning. They must be touching the source of the problem. I would need to inspect the plugs, the insulators on the plugs and the plug wires. Check for black arc trails down the outside of the white insulator on the plugs. It only takes one.

I'll bet the oil in the plug wells was the original problem and the fact tat they changed the wires and the plugs helped until the oil shoerted the wires again. If they reinstalled the old plug wires after there was oil in the plug wells, that could also cause a ground path. The oil must be cleaned out of the plug boots before they are reinstalled.

There is another possibility and that is the DIS module ground path is intermittent. Check the ground strap on the top screw of the back, passenger side intake manifold bracket. Even remove and replace the 15mm brass nut that holds this ground strap on (and also the wiring harness bracket). Also check the tightness of the two 12mm bolts, one on the front and one on the back bracket that holds the intake crossover tube to the intake plenums. Also check the tightness of the four 5.5mm (7/32") screws that secure the DIS module to the crossover tube. Check the tightness and integrity (corrosion) of the connectors to the front and rear plugs on the DIS module.

 

[bigschoen]

Sdpatt...

sorry for the novice question - what are "black arc trails" on the plug wires? I looked at the wires and they have black spiral lines going throughout the clear plastic. I thought that was how it was supposed to look - can you describe a bit more?

Another thing to note - don't know if this has anything to do with it. At idle (especially right when I turn the car on for the first time of the day, there is a moaning sound every 20 seconds - almost sounds like the car is moving with the parking brake still engaged - but it's not that. Sounds like it coming from the trunk (is that the fuel pump???) Could that have anything to do with the misfiring??

thanks again
adam in ohio

sdpatt:
The misfire situation you describe sounds like a secondary ignition fault: plugs or wires. The curious thing is that the problem actually goes away for awhile before returning. They must be touching the source of the problem. I would need to inspect the plugs, the insulators on the plugs and the plug wires. Check for black arc trails down the outside of the white insulator on the plugs. It only takes one.

I'll bet the oil in the plug wells was the original problem and the fact tat they changed the wires and the plugs helped until the oil shoerted the wires again. If they reinstalled the old plug wires after there was oil in the plug wells, that could also cause a ground path. The oil must be cleaned out of the plug boots before they are reinstalled.

There is another possibility and that is the DIS module ground path is intermittent. Check the ground strap on the top screw of the back, passenger side intake manifold bracket. Even remove and replace the 15mm brass nut that holds this ground strap on (and also the wiring harness bracket). Also check the tightness of the two 12mm bolts, one on the front and one on the back bracket that holds the intake crossover tube to the intake plenums. Also check the tightness of the four 5.5mm (7/32") screws that secure the DIS module to the crossover tube. Check the tightness and integrity (corrosion) of the connectors to the front and rear plugs on the DIS module.

 

[luigisho]

Adam, that's why I asked what was done. I agree that the timing is a little odd. From what you have listed my best guess is that the oil damaged the wires (which happens often) which weren't replaced AFTER the seal replacement. I would suggest that you check all the plug wells again for oil to be sure. Then replace the plugs (check the gap)and wires (get them from Torrie at fordpartsnetwork). The sound from the trunk could indeed be significant. Improper fuel system operation can cause significant problems. You need to check into both fuel and ignition areas.

<small>[ April 02, 2002, 09:13 PM: Message edited by: luigisho ]</small>

 

[sdpatt]

What I said was, "Check for black arc trails down the outside of the white insulator on the plugs." The high voltage spark will find the easiest path to ground. Sometimes that is not through the seemingly small gap in the spark plug inside the cylinder even if it is gapped to the specified .042"-.046" range. Larger than stock gaps only compound the problem. The fuel/air mixture in the cylinder serves to insulate the gap. If there has been some contamination of the interior of the spark plug boot (oil, water, etc.), the spark may find it easier to travel from the top metal tip of the plug, down the white insulator to the metal base. When this happens repeatedly, the arcs leave a black "arc trail" of oxidized rubber and contamination on the insulator. I have one in the picture below that was causing a progressively worse misfire at throttle tip-in at highway cruising speeds.

Overheated plug due to continuous pinging. Plug only had about 5,000 miles on it. Internal insulator looked clean and white, browning on exterior insulator and that black arc trail.

Close-up of the arc trail.

bigschoen, the rumble you hear from the fuel tank is the return fuel that has turned to vapor and is bubbling up through the fuel. This is usually due to the wear of the fuel return line check valve that allows the pressure in the return line to fall below the temperature of vaporization of the volatile gasoline. This is usually more of a problem after a hot restart. It can cause a stumbilng idle until the rumbling stops. See the related topic in this section about the fuel pumps in today's active topics. http://www.shoforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=17;t=001478

Scott

<small>[ April 03, 2002, 10:12 AM: Message edited by: sdpatt ]</small>