Predator causing a misfire?

vipergt · Jul 6, 2005

My car has been running crappy with the predator tune lately. During datalogging it shows a misfire. If I go back to factory tune all is well. Anyone no why this may be happening?

Seraphitia102 · Jul 6, 2005

Are you using 91 octane premium gas?

vipergt · Jul 6, 2005

Well 92 Octane. I dont hear detonation. Sometimes if I'm on it feels like the AC comes on, but its off and fans are off so I know its not the compressor kicking on. Then sometimes if I go wot it will accelerate, but a boggy acceleration. The auto dont kick down. Just a bunch of wierd stuff. None of this happens with factory tune. Just got CAI and catback.

Rev Maynard · Jul 6, 2005

How do the plugs look? Too much timing maybe?

Maybe a fuel filter?
Any CEL's popped on stock tune?

03gtmustang · Jul 6, 2005

Sell that pos and get an xcalibrator.

Dragstr05 · Jul 6, 2005

Misfires can be intermittent, and it COULD be coincidence that when you removed the tune, the issue stopped. Just take 10 mins or so, and get a 7mm (I'm pretter sure its a 7), an extension and ratchet, and pull each coil and check for cracks, unless the predator tells you which cylinder is misfiring. It only takes about 10 mins, and you can take the extra time to check the plugs too if you want. If the plugs and coils check out OK, then I would say you have a problem with the tune, or something related to the tune.

At my shop, I have never seen any 4.6/5.4 with a misfire that wasnt caused by a coil or a plug. Given, these are stock cars, but 99% of the time, its just a bad coil.

03gtmustang · Jul 6, 2005

What shop do you work at?

Dragstr05 · Jul 6, 2005

Malloy Lincoln Mercury, Woodbridge VA. I work with one of the lead tech's there as a helper, have been there since January. The only reason I say that the misfire can be intermittent is sometimes a customer will bring their car in and say there is a loss of power (or other symptoms), the check engine light is on, or both. Whenever the ticket for the car is handed to me and I go get it, the ONLY thing I may notice is the CEL is on. Other than that the car may drive fine, but sure enough after scanning for codes there is a misfire. The scanner notes which cylinder is misfiring, and the first step (on a modular, coil on plug design - most misfires are on these) is to pull the coil out, check for cracks. If the coil looks ok, check the plug.

vipergt · Jul 6, 2005

Thanks I'll check it out. Its not throwing a code. Just on the datalogging it says it misfiring. The one accronym and I cant remember it but it stands for #drive cylinders at time of misfire.I dont know what this means really. Maybe the cylinder misfiring? If thats the case its all the cylinders because it will display #1 then may display #4,etc. Maybe I just got some bad gas. I just put a magnaflow catback on, But I dont see how a catback can cause a misfire. Clueless.

03gtmustang · Jul 6, 2005

Bring the car to advanced auto and scan for codes, see if the same stuff comes up.

vipergt · Jul 8, 2005

Well I dont know what happened but the stang just woke up from the flu I guess. Damn thing is running like a raped ape now. Its an auto and will darn near get away from you 1-2 shift and its chirping 2-3. Its probably fixin to blow.The only thing I did was put in a bottle a fi cleaner and half a tank later here we are.

Azarello · Jul 8, 2005

Dragstr05 said:
Misfires can be intermittent, and it COULD be coincidence that when you removed the tune, the issue stopped. Just take 10 mins or so, and get a 7mm (I'm pretter sure its a 7), an extension and ratchet, and pull each coil and check for cracks, unless the predator tells you which cylinder is misfiring. It only takes about 10 mins, and you can take the extra time to check the plugs too if you want. If the plugs and coils check out OK, then I would say you have a problem with the tune, or something related to the tune.

At my shop, I have never seen any 4.6/5.4 with a misfire that wasnt caused by a coil or a plug. Given, these are stock cars, but 99% of the time, its just a bad coil.

Hey, my car misfires, I check the plugs and I think they looked cool, but then again I don't really know what I'm looking for. Question, what signs to look for with plug damage and how and where are the coils and are they difficult to take out? Sorry I'm a novice trying to save a few bucks.

Dragstr05 · Jul 8, 2005

The plugs I cant really tell you if they are bad, only that in a tuning sense or in a modified car, if you pull a plug out and its white, then you are running lean.

The coils are on top of the engine just under and to the side of the fuel rail. There are 4 on each side, 1 for each cylinder. If you took the plugs out, then you took the coils out, because the coil is what sits on top of the plug. Hence the coil-on-plug ignition...there is no distributor. And how do you know you are misfiring? Did you have it scanned for codes? If it is misfiring, it will turn the check engine light on. If that is the case, have it scanned for codes. The scanner may or may not say which cylinder is misfiring...the ford scanner does. If it is infact misfiring, the cheapest route if you arent sure is to just replace the plug. Its just a few bucks. If a plug doesnt fix it, check the coil for cracks (if you didnt already). If it has cracks, replace it. It will probably run you $70 bucks or so. I have seen them as high as $140 on a navigator. Try the plug first.

The thing with coils is that any one can go bad at any time. Thats why misfires are common on the coil-on-plug design. You just replace them as they go bad.

Azarello · Jul 9, 2005

Dragstr05 said:
The plugs I cant really tell you if they are bad, only that in a tuning sense or in a modified car, if you pull a plug out and its white, then you are running lean.

The coils are on top of the engine just under and to the side of the fuel rail. There are 4 on each side, 1 for each cylinder. If you took the plugs out, then you took the coils out, because the coil is what sits on top of the plug. Hence the coil-on-plug ignition...there is no distributor. And how do you know you are misfiring? Did you have it scanned for codes? If it is misfiring, it will turn the check engine light on. If that is the case, have it scanned for codes. The scanner may or may not say which cylinder is misfiring...the ford scanner does. If it is infact misfiring, the cheapest route if you arent sure is to just replace the plug. Its just a few bucks. If a plug doesnt fix it, check the coil for cracks (if you didnt already). If it has cracks, replace it. It will probably run you $70 bucks or so. I have seen them as high as $140 on a navigator. Try the plug first.

The thing with coils is that any one can go bad at any time. Thats why misfires are common on the coil-on-plug design. You just replace them as they go bad.

Thanks for your input...Actually my check engine does not come on, the ford dealer said that my car engine feels like it misses while he was driving it (I'm not sure if that is the same as miss fire ir not). I ask them to eloborate but he claims I had to bring it in to get checked, and I was like F that! I'll do some research and ask guys like you questions about what it could be. It's a 96gt with 94k, I was thinking it might need a full tune up just cause I brought about a 6 months ago and have not had a full one yet. I don't really feel a mis fire or engine miss but it concerns what ford says (even know I suspect that they might be trying to charge me up, I hope they don't work like that). what other possiblities could a engine miss be and is it the same as a miss fire? :

Azarello · Jul 9, 2005

Seraphitia102 said:
Are you using 91 octane premium gas?

Is that you in the picture?

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