Hey, this will be a bit long... Sorry.

I have a 2000 gt (bought new!) with 260+k miles, stock except for rust , intake manifold with aluminum x-over and jegs exhaust. I brought it to Watkins glen for a de event this weekend and likely killed it...I don't wan't to throw a ton of money at it in diagnostics, so I'd like to get your thoughts if I am missing anything.

Problem #1
Over the course of the weekend the engine lost power. During a 25 minute run, it would run a lap or two fairly normal, then start to lose power...eventually it would not be able to redline and would start to miss under load. Most sessions, I had to either baby to or come in early. Water temp was ok, which I confirmed with a scanner after a run(211 I think).

I pulled injectors and found 1 with a crack, which I replaced...changed fuel filter, sprayed a bottle of sea foam. Still had the motor issue...I then had a mechanic scan it with a snap on scanner and it found no issue. I pulled the coil packs and the one next to the thermostat was filled with coolant. I replaced it and pulled out all the coolant. I put a paper towel there and went out for a run to see if I had a leak, but the issue persisted...and there was no coolant on towel or in the spark plug hole.

On my 3 hr car ride home, the car had lots of trouble going up hills... Lack of power and misfires( no code)

Issue #2: when getting off gas in moderate rpm range, there is a vibration/sound that seems to be coming from the motor...it's felt in the ***, not the steering wheel.

Issue #3: last run of day, the transmission would not stay in 4tg gear. This continued to occur sporadically on the drive home.


So...here's what I am thinking to look at:
Compression/leak down test
Open up valve covers and inspect, potentially inspect valve springs
Will check motor motor mounts( for 4th gear issue, although I suspect it is a bearing in transmission)
Pull plugs and inspect( they aren't too old)
I suppose it could be something in the fuel tank...although I might just call it fatal before I pull it.


If it's dead, it led a long wonderful life, and went out in a blaze of glory...hoping I get lucky and can repair for not too much $$, loved driving on a track!


Thanks for the help,
Rob

 

sounds like a catalytic convertor might have let lose possibly. Compression test is a great starting point.

 

Yep pull out front 02 and put in a pressure gauge to see if a cat is plugged up. They will run like **** with a plugged cat. If that's all good compression check is a good place to start. Could be a bent valve or something. Let us know what you find!

 

interesting, hadn't thought of that...I guess I just figured a bad Cat would throw a code, but maybe not. I have definitely had misfires, but haven't thrown that code either.

What sort of pressure should it be at? I imagine there is some normal back pressure there from mufflers and cat. What setup do you use to test...I can check when I start wokring on it, but is the thread pattern the same as the plugs (would be convenient if it is!)

 

what engine do you have??? I have a 4.6L in my 1999 pickup that had a lot of the same traits that you are explaining. It would "mis-fire" or "pop", whichever way you want to look at it, under load. It usually happened at low RPM, especially going up hills prior to it downshifting. In my case, I replaced both my coil packs, plugs and wires. No issues since. It also did not throw any codes.

 

you took a 260,000 mile mustang to a track?

 

It a 4.6l SOHC, it has 8 coil packs... They've all been replaced at some point, I didn't notice any boots in bad shape and when I've had the issue with coil packs in the past, it wasn't related to temperature. But certainly could be a suspect.

 

HELL YES! I bought it new, and was more than happy to have its last miles be at Watkins Glen!

 

that is nice, I hope for you (and it) that it's not dead, and if it is, like you said, at least it died in a blaze of glory.

 

Ford's are bad about not even throwing misfire codes. Generally we have to watch the mode 6 counts and see which one has the highest and start there. This is the gauge we use. Screws right into the o2 hole. Not for sure what normal pressure is but it's not much. Basically if the gauge really reads high it's plugged. Check other side cat to confirm one is higher than the other. Had a truck one time so plugged doing sane symptoms you have that made the gauge spin around three full times and it shouldn't even go around once lol
Or since you really have nothing to lose just cut the cats off and see if it runs better or borrow an o/r pipe and throw it on and see what happens

 

Ok... Small update (I have kids so it takes me a while to do anything). I removed all the coil packs and plugs.

The number 5 plug, which was the one filled with coolant, looks a bit black. Still scratching my head about the coolant, since I drove it about 200 miles after clearing it out at the track, both on track and highway, and haven't seen more fluid in there.

I'll try to figure out to put a picture on here... Not seeing how typing on my phone.

 

But messed up plug would explain a misfire with no code

 

step by step:

 

it's out of order for some reason...

 

Is the coolant dripping from a hose above the #5? Or would that be an internal problem inside the block?

 

Do you have a coolant leak from a hose above the #5? Or is it more of an internal problem inside the block?

 

I was using browser... Not app.. That's why I couldn't figure it out.


Anyhow the top one is #5, all the others look like the bottom.. #5 is right next to thermostat, but as I said.... No more evidence of a leak... Weird. Guess I need to change the plugs and run around at redline again 😃

 

Head scratcher haha

 

Yeah... I imagine it's from the thermostat housing, it right there next to #5...But stuff like that doesn't typically 'self-heal' .

 

If it's any consolation, I did end up passing this cayman... With only 7 cylinders and no 4th gear...