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Discussion Starter · #1 ·
I just bought this car, it's a 03 gt with crower stage 2 cams, long tubes, h-pipe, catback, and a jlt ram air intake. Everything else is stock, I'm having basically like a stumble while driving, sometimes it does it under a load other times it does it while at cruise. There's no CEL or anything, I took it to the local stang specialist and he put it on the computer and said it was a bad MAF, I went ahead and had them change the fuel filter and do an inj, tb/intake, and IAC cleaning. I got a new MAF from ford changed that and it didn't fix it, I've checked for vaccum leaks and all that already and found nothing. The guy I got the car from had it tuned but put the headers on after it was tuned, it's running a little rich, if u stand behind it it will get u high. If I let it idle in the garage too long it will burn your eyes. I'm begining to think it's the tune but there's no tuners in my area...anyone else have any idea what else I could check before getting it retuned??
 

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Maybe as a result of it running rich you have fouled plugs as this sounds like an ignitiion problem. Have you pulled them to see what they look like? How does the car idle? Might also consider a bad COP.
 

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yea sounds like spark problem. Most aftermarket tunes disable the misfire monitor so you won't know if the car is missing except by how it feels. Replace the plugs and check the coils to make sure theres no coolant or oil in the boots which can cause the coil to miss. I had a coolant leak from my thermostat hose and coolant was running down the driver side head and pooling up in the spark plug holes causing the cops to short out and car would miss
 

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Discussion Starter · #4 ·
I'm going to pull the plugs today and check those, I'm thinking it's a coil problem too, I thought the shop would be able to tell that when they put it on the computer but I guess not. I don't get how it idles fine but does this under a load, I'm also noticing the gas mileage is starting to suck and the car has no power!!
 

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I'm going to pull the plugs today and check those, I'm thinking it's a coil problem too, I thought the shop would be able to tell that when they put it on the computer but I guess not. I don't get how it idles fine but does this under a load, I'm also noticing the gas mileage is starting to suck and the car has no power!!
I have a similar issue with my car but I have a stock vortech tune tune for my s/c and everything was fine for 20,000 miles. I don't think it's the tune. My mustang buddy suggeted it was a bad MAF but I had no codes present. Maybe u can swap a MAF out of another vehicle for testing purposes.
 

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It definately sounds like your tune........I would get that fixed ASAP....let it go too long and you can wash your piston rings.......if it is really rich...it will drastically effect performance.....drivability....gas milage and keep fouling out your plugs........also check to ensure there is no moisture in your spark plugs and boots....this will cause the car to knock and run like drap too.........get her retuned ASAP!

"ED"
 

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Sounds just like the issue I had.

I had two dead cylinders that would fire sometimes and would cause the car to "stutter" when cruising around. The car also smelled like a gas can from all the unburnt fuel.

Check your plugs definitely.. I bet one or two will be black..

Riley
 

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Discussion Starter · #8 ·
I pulled the plugs today and they looked fine, it had NGK tr6's in it and they were gapped at .037. I was thinking that was more for a supercharged motor??? I put new plugs and gapped them to factory specs and it didn't help, it did clean up the smoke though. It doesn't seem to be running as rich now. I'm thinking I'm going to change the IAC tomorrow and if that doesn't fix anything I'm going to get it retuned.
 

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Discussion Starter · #9 ·
The CEL came on today and I got a P1311 code which says bank 1 is lean. I called the guy I got the car from and he said it had that before, he cleared it and it didn't come back. Now I'm starting to think it's a vaccum leak or a bad O2 sensor since it's only on one bank. I'm going to log the longft and the shortft some today, is there anything else I need to log that can help me figure this out??
 

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Discussion Starter · #10 ·
I did some data logging today after I drove around and warmed the car up, this is what I got:

LONGFT1= 1-2%
LONGFT2= 15-16%

SHORTFT1= -3-0%
SHORTFT2= -1-3%

BARO= 26.6 HZ

MAF= .80V

I know the baro is way off, this was the reason the first tech told me to change the MAF. It's on it's 2nd new MAF now and it still has the problem, is it ok to drive it around with the MAF disconnected to see if that clears it up?
 

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my car won't run with the MAF disconnected at all. A buddy's car that had some problems and disconnected his MAF got about 8 codes, everything from random misfire to bank 1 and bank 2 lean. I cleaned the MAF for him, reset the codes and everything went away, and hasn't come back.

The studdering while cruising sounds exactly like the problem I had with my car. Turns out that I had 4 weak COPs. The plugs looked fine, no visible problems at all. Took it to a friend that is a Ford service tech, and they have a machine that they load test the coils, and I had 4 weak, but still firing enough to keep the CEL from coming on. I was a little suspicious, but was out of options, so I replaced the 4 that showed weak, and the care has ran perfectly since then.

That doesn't explain the strange Baro reading though.
 

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I just bought this car, it's a 03 gt with crower stage 2 cams, long tubes, h-pipe, catback, and a jlt ram air intake. Everything else is stock, I'm having basically like a stumble while driving, sometimes it does it under a load other times it does it while at cruise. There's no CEL or anything, I took it to the local stang specialist and he put it on the computer and said it was a bad MAF, I went ahead and had them change the fuel filter and do an inj, tb/intake, and IAC cleaning. I got a new MAF from ford changed that and it didn't fix it, I've checked for vaccum leaks and all that already and found nothing. The guy I got the car from had it tuned but put the headers on after it was tuned, it's running a little rich, if u stand behind it it will get u high. If I let it idle in the garage too long it will burn your eyes. I'm begining to think it's the tune but there's no tuners in my area...anyone else have any idea what else I could check before getting it retuned??
Sounds like an erratic Maf signal due to direct air flow hitting the filter. I had a similar problem till I blocked off the air and it went away.
 

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Discussion Starter · #13 ·
The Baro reading at sea level should be about 155-160hz, mine is crazy low no matter what the car is doing, it doesn't change from idle or while the car is under a load. Is there a baro sensor on this car? I know the older cars had a baro/map sensor but I can't find anything like that on this one. I was thinking it's a COP myself but this baro thing has me baffled.
 
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