weird problem...please take a look

rock4451 · Jul 11, 2009

Okay, I just got my 95 cobra last week, upon getting it home I noticed an exhaust leak at a gas station, no big deal, the x pipe is in the mail now. but i dont think thats related to my problem (help me out?) my car starts and idles fine, but when driving it feels like there's a slight miss in it. when i step on it, it doesn't exactly feel like a miss but just not as strong as it should. i replaced the wires, checked plugs (all look new), changed the oil, replaced the fuel filter, and changed the battery (it was bad anyway). it still feels like a slight miss, and my tach jumps up or down in intervals of about 2 or 300 when i'm cruising at say 60? from what i've read looks like distributor, but any other input is more than welcome.

302GTS · Jul 12, 2009

Check the MAF sensor for dirt and grime, clean it for sure. Spray some carb cleaner on a qtip, and lightly rub the dirt off until the qtips come out clean. Sounds just like a problem I used to have. Car ran great but just didn't pull hard past 3k rpms, and the tach would jump like crazy.

turbogt · Jul 12, 2009

302GTS said:
Check the MAF sensor for dirt and grime, clean it for sure. Spray some carb cleaner on a qtip, and lightly rub the dirt off until the qtips come out clean. Sounds just like a problem I used to have. Car ran great but just didn't pull hard past 3k rpms, and the tach would jump like crazy.

DO NOT TOUCH the filaments in the MAF.. Just buy some mass air sensor cleaner and spray the hell out of it..

Chythar · Jul 12, 2009

I have never had a problem with touching the MAF filaments with a q-tip. As long as you are very gentle, you won't break them.

rock4451 · Jul 12, 2009

okay, great idea, i didnt even think of that, slipped my mind. i'll give it a whirl tomorrow and let ya know how it works. until then, anybody else have other experiences that were similar they could attest a possibility to? any ideas at all would be fantastic

rock4451 · Jul 12, 2009

so far i've ruled out the battery, wires, plugs, could be the coil (mine rattles a bit, its a MSD TFI Blaster coil, it can be wiggled up and down a bit) I am sure it is a spark or ignition prolem, because when it misses a bit, my rpms take a dip of about 2 or 300 for a split second...then come back up...and this can happen nonstop until i step on it. somebody has to have had some similar experience? i havent had a chance to clean the maf yet but thats a possibility, i just dont think it would affect a miss and my tach moving the same time as a miss

rock4451 · Jul 13, 2009

HISSIN50 · Jul 13, 2009

Though the wires are new, check them for spark leak. They might be getting hot and limp and grounding out intermittantly.

Be sure the EGR is functioning properly.

If it misses at idle, run a cylinder balance test (you do that after pulling KOER codes).

Good luck.

rock4451 · Jul 14, 2009

KOER codes? i am not familiar, I had the guy at autozone run his diagnostic OBD II on it, and it came up with no codes, i only did this because i didnt wanna spend the money on it if they did it for free. im not sure how to pull the koer codes...i replaced the coil and it appeared to be running alright, but then about 5 hours later i took it for a drive and there the miss was again...while i was out, my dad gapped the plugs at 52, the guy before me had then gapped at 34. stock calls for 52 but maybe that is too big for my setup for some reason for it to keep constant spark? i am just thinking out loud, please give your input if you're electrical/ignition knowledgeable...

Chythar · Jul 14, 2009

The 5.0 Mustangs are OBDI cars, not OBDII. The connector under the dash does NOT work on our cars. (it does work on the V6, Ford's way of saving money on parts) The scanner hookups for the 5.0 are behind the passenger shock tower.

KOEO - Key On Engine OFF tests. KOER - Key On Engine Running tests. The Autozone scanner can run these tests, then the codes are read. You have to run the KOEO test before running the KOER test. While each test is running, you'll hear things in the car click and turn on & off.

94GTCoupe · Jul 14, 2009

Posted via Mobile Device
and keep clear of the fan while the test are run.

rock4451 · Jul 14, 2009

okay, he did plug the connector in under the dash. you say it's besides the passenger side shock tower, can i use an OBD I on that or do i need a different scanner? thanks

HISSIN50 · Jul 14, 2009

rock4451 said:
okay, he did plug the connector in under the dash. you say it's besides the passenger side shock tower, can i use an OBD I on that or do i need a different scanner? thanks

Yes, use the OBD-I Ford scanner.

desertcox05 · Jul 15, 2009

get a haynes/ chilton manual.
It will help you with the engine codes and there meanings and also how to pull them with a paperclip. Plus loads of other great info unless you like to give your money to the stealership.

rock4451 · Jul 15, 2009

haha no, i have a haynes manual, i'll check it out. thanks

moosetang408w · Jul 24, 2009

My car was doing the same thing but it turned out my battery was shorting internally. It could be a bad ground. Bad gnds do weird things. You changed your battery though so I don't know what to tell you except that both my mustangs did this due to bad grounds. Good luck.

94-302-vert · Jul 27, 2009

My car did that when I got it and the coil was shot. The elctrode on the coil was worn creating a arc to the coil wire...

final5-0 · Jul 27, 2009

If you still got your OEM coil ............

put it back on and see if the prob goes away

Grady

rock4451 · Jul 29, 2009

problem didn't go away...at full throttle, there's no miss, when my foot's off the gas, no miss, but if i am going say 60 and hold it steady at 60 the rpms jump down about 2-300 in intermittent spurts and jump back up to what they should be. i can also hear the car miss at the same time and it feels to vibrate slightly when it misses but as soon as i step on it, or take my foot off completely it doesnt do it anymore. i am completely stumped. changed the coil, got rid of my msd box, cleaned the maf, new IAC (which is unrelated), changed my wires, gapped my plugs at 52. should i check the voltage at the coil? new stock distributor is in the mail to be here today. i am just scratching my head b/c if it was with my valves or compression wouldn't it be constant no matter what? just frustrating as hell

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