just774

Hey All...

I have a 2003 Mustang GT which is having a major issue with what I can only guess at this time is the ignition system. About 4 months ago, one of the ignition coils went down..... the engine shakes like it's a lawn mower because it is firing unbalanced. The engine put out an code that pointed out the problem and it was easily replaced. Well, something similar is happening again..... but the part failure has been coming on slowly, but came on strong today....

The problem started about a week ago... the engine would loose power at high rpm ranges but would run fine between 1K-3K on the tac........ on longer drives the engine would start to flutter or skip and I still could not put a load on the engine (move the rpm range above 4K) withouta power fall off.

Today the power failure finally came into the low rpm ranges and the engine is shaking massively again...

The only way I could it run enough to get home was to unplug the Mass Airflow Sensor....

Up until that point the engine had not given a check engine light.....it only came on after I unplugged the sensor...

1. Would the computer list a problem code even without a check engine light notification?
2. How common are, what a assume to be an ignition coil failure again??
3. Is there an easy way to identify this problem prior to basic engine failure?...

Thanks for the help..

J

cliffyk

How old are the spark plugs; do you have any sort of custom intake (K&N filter), etc.; any other mods?[/align][/align]

8banger

I had a similar problem a few weeks ago....first started losing power above 4k and then got worse and ran like crap even at idle,,almost didnt make it to the shop...turns out,,fuel pump took a dump....Dang aftermarket walbors!might check fuel pressure,,and the plugs,all tune up related items...FUEL filter....etc.......

just774

Spark plugs are brand new... this week... thought that might be part of it....... I have not done any custom work to the car yet, (intake, etc.)...so no mods yet...

cliffyk

Fuel (as suggested by 8banger) is the next place to look...filter? [/align][/align]Nearly anything in the ignition would throw DTCs.[/align][/align]How many miles on it?[/align]

just774

Fuel filter was replaced about 7K miles ago.... I have 62K on the car...

Brute03

usually when you unplug the mafthe car will die, so that's something i would look into

cliffyk

Making this difficult, huh?[/align][/align]An engine needs three things to run properly, a combustible air/fuel mixture, compression, and a properly timed spark...[/align][/align]The first (fuel mixture) is controlled by the PCM based upon what it is being told by the MAF, IAT sensor, ECT sensor, TPS, O2 sensors, head temp sensors, fuel rail pressure sensor, and tach--and used to control the fuel pump speed and injector duty cycle so as to inject the proper amount of fuel;[/align][/align]The second (compression) is a mechnical function of the ring/piston/cylinder seal, and the timing and sealing of the valves;[/align][/align]The third (ignition) is generated by electronic switches turning the coil primary current on and off (spark happens when it's turned off), as directed by the PCM based upon signals from the crank position sensor, and advanced/delayed response based upon the PCMs evaluation of a lot of the same info used to control the mixture.[/align][/align]So it boils down to which one (or more) of these is acting up...[/align][/align]I want to belive that anything in the electronic sensor or control (PCM) domain would throw a code--modern automotive computers are pretty sophisticated with regard to self-monitoring there inputs and outputs; this leaves fuel and compression.[/align][/align]Intermittent compression problems would have to mean sticking valves, sloppy timing chain(s) (very sloppy) or something else being sporadically rather bad--I'm not buying this right now, but maybe.[/align][/align]This leaves fuel delivery and/or the injectors themselves not behaving--I'd get the fuel pressure checked, maybe look in to the fuel rail pressure sensor (on the driver's side fuel rail).[/align][/align]My "can't sleep, got the Flu" ramblings, FWIW.[/align][/align] [/align][/align]BTW--unplugging the MAF puts the PCM in "limp home" mode where it runs open loop, ignoring many of the inputs mentioned above...[/align]

just774

Thanks for the input guys... I really appreciate it.... I am heading out to check a few things...(among which is the fuel rail pressure and the spark on each cylinder....will also take the car to and Advance Auto, replug in the MAF sensor and then see what error codes I can get.....

I will post what I find after a while...

Thanks again for the time...

thx.

J

Phirantes

Hey man, I had the exact same problem except one of my coils quit firing completly which after 1-2 months finally threw a CEL. I checked the whole fuel system, ie: changing filter, checking pressure, and it all checked out fine. It wasn't untill i took it to a Ford shop till I found out that 1 coil was completly dead and 2 others only worked periodically, which would explain the randomness of the poor running of the car. 3 new coils later my car was running better then it ever had.