Car hesitating... Checked TPS its fine... ???

OneStiffGT · May 31, 2006

2 days ago, my car was only hesitating while I was in X gear and gave it more then half throttle... Today driving back home from work, it started to get worst and worst, now it is not even running properly at idle, the idle doesn't fluctuate but it sounds like tehre is a missfire, and it hesitates when I want to rev it up, or even try to drive it.

I checked my tps, the readings were all good. What else could this be? I searched and tried to read some of the stuff, some people say could be COP's?

Mike97gt · May 31, 2006

most likely a bad plug and or COP..

TPS's rarely go bad on fords and even then it's not a very important sensor and will not cause the conditions you have.

You can start by replacing the plugs and then if you still have a misfire I would suggest having the COP tested.. it's hard to islolate what cylinder is doing it without a good scantool. for problems like this I use power balance on WDS to isolate the cylinder, then injector flow test to make sure the injectors are ok

OneStiffGT · May 31, 2006

To add to this problem... Before it even started doing it when I went WOT, it always misfired sometimes when I bliped the throttle before down shifting etc...

Mike97gt · May 31, 2006

OneStiffGT said:
To add to this problem... Before it even started doing it when I went WOT, it always misfired sometimes when I bliped the throttle before down shifting etc...

this is very common on modular fords, they tend to misfire easier than some of the older ford motors. misfires tend to be very noticable in high load low rpm situations like going uphill in a high gear at low rpm's

OneStiffGT · May 31, 2006

svttech76 said:
this is very common on modular fords, they tend to misfire easier than some of the older ford motors. misfires tend to be very noticable in high load low rpm situations like going uphill in a high gear at low rpm's

Ok thanks Its my first domestic v8, and I am learning more and more as it goes

:SNSign:

04GT · May 31, 2006

I had a similar problem that turned out to be the fuel pump, but I would check the cheap stuff first...plugs, MAF, etc.

OneStiffGT · May 31, 2006

I check the fuel pump by the fuel pressure right?

- What should the plugs be gapped to? My car is a 1999 GT.
- I also heard something in the lines of, I need "full thread" plugs, if not it is highly likely that I will blow out a spark plug and would need to helicoil or retap the head, is this correct? After doing some research on stangnet, I picked up 8 TR55GP plugs, but never got around installing them.
- What should I torque the plugs to? (11lbs????)
- I got a 3pt. steeda strut brace does that need to be taken off in order to change the plugs?

Thanks!

04GT · May 31, 2006

If I was you, I'd pick up a Haynes manual for your car. It's got answers to all the questions about changing plugs.

A speed shop diagnosed my fuel pump by hooking up some kind of pressure gauge at the rail with the car strapped on a dyno. This was after I gave up trying to fix the diagnose myself.

Mike97gt · May 31, 2006

yeah low fuel presure can cause misfiring, but usually when the pump is producing low presure you will not be able to even get to redline when you gun it in gear, it will fall flat on it's face and stop reving.

eblack99 · May 31, 2006

I have a 99 GT had the same problem and engine light would come on, took it to autozone for diagnostics had a missfire so i replaced the bad plug, i also replaced my fuel filter.

COMPSYSTEMS · Jun 1, 2006

First of all, do you have a K&N filter? Try cleaning the mass air sensor first. Is the check engine light on? If it is go to autozone and barrow the code scanner. If no check engine light but you still have a misfire clean any and all of the sensors you can and reset the computer. If the problem continues then start the car and run it in the rpm range where it misfires most and turn off the key without it getting back to idle. Then pull the spart plugs right after. The wet plugs are not getting spark and could be bad coils.

Mel96GT · Jun 1, 2006

Check your plug wires. I had a faulty one on #4 and it did what you described. These wires seem to be somewhat sensitive but it often won't show on diagnostic trouble codes.

OneStiffGT · Jun 1, 2006

I wish we had an autozone in Canada, because no one pulls codes for free. And no plug wires because it is COP.

I will look into cleaning the MAF, and will change plugs today, we had a sever thunderstorm warning here for 2 days, so couldn't get much done.

OneStiffGT · Jun 1, 2006

I think the problem is solved.

Instead of putting in my NGK G-power plugs, I went and bought the full thread Motorcraft plugs. I got a code reader from a friend, code was P0307, misfire on cylinder #7. Changed the plugs, the 7th coil had a bit of water in it, cleaned the water off of it. Did the other bank as well, the car is running much much better. Throttle response seems to be much sharper (or it is just my head).

Here are some pictures.

Cylinder #7 Spark Plug

Same spark plug again

Drivers side bank, plugs and coils. Whats the brown stuff on the coils?

Thanks for everyone who replied to help. Special thanks to SVTTECH76, after seeing him reply to all troubleshooting posts, I decided I should reply back to the thread with a follow up, and even get some pictures for future refference.

Now I gotta shower, eat and have a good night sleep!

Mustanggt108 · Jun 1, 2006

That is one nasty looking Spark plug . Try to change them a bit more often...just a friendly advice. And in case you need to pull codes for FREE next time , and since you also dont have an AutoZone in Canada ...Get a hand held tuner.They work great and help in many many ways , Plus you get some more power

Mike97gt · Jun 2, 2006

OneStiffGT said:
I think the problem is solved.

Instead of putting in my NGK G-power plugs, I went and bought the full thread Motorcraft plugs. I got a code reader from a friend, code was P0307, misfire on cylinder #7. Changed the plugs, the 7th coil had a bit of water in it, cleaned the water off of it. Did the other bank as well, the car is running much much better. Throttle response seems to be much sharper (or it is just my head).

Thanks for everyone who replied to help. Special thanks to SVTTECH76, after seeing him reply to all troubleshooting posts, I decided I should reply back to the thread with a follow up, and even get some pictures for future refference.

Now I gotta shower, eat and have a good night sleep!

Thanks for coming back with the results.. it really helps when somebody can search the thread and see what the fix was.

there sure is a lot of crud on those plugs and coil boots

Are you the original owner of this car? one possibility is the intake cracked at somepoint. When this happens a lot of times coolant makes it's way into the plug wells. when the new intake was installed some colant residue was left behind. and after awile you end up with what you have there.

OneStiffGT · Jun 2, 2006

I have just bought the car, had 60k miles at the time, now its at 62k miles.

Is it bad to put those coils back in?

I am going to change my fuel filter and pcv valve this weekend or next weekend. Is there any other things I shouldd do?

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