My brother's 99 GT....

He went somewhere and as he was getting there the car wouldn't accelerate much. When he went to leave now, it won't start.
I'm going out there tonight in about 4 hrs to take a look at it. Any ideas?
All I know so far is the belts OK, fuel rail had pressure, and there may have been some ticking sound from around the coil packs.


=====UPDATE========
*Fuel pressure is good ~55psi and stays high.
*All 3 coil packs have good spark, although I thought one of them was kinda weak at first.
*Fuses all good, swapped ignition relays.
*Took apart and cleaned ignition module and coil packs, even though spark seems OK.
*PCM has been replaced.
*Spraying starting fluid into the TB (around the MAF) does absolutely nothing. Not even sputtering!
*Oil does not appear to contain coolant.
*Starter cranks strongly.
*Valves are moving (so timing chain should be OK)

=====UPDATE 2 ======
*Swapped ignition module (under coil packs).
*Swapped coils.
*Theres some pressure at the exhaust tips.
*Tested continuity between injector wires and PCM connector. One of them (center front) does not conduct. I uplugged that injector on my running GP and it runs, just a bit rough, so that shouldn't cause the issue at hand (might have damaged it when unplugging to test).

Since spark and fuel is there, and spraying starting fluid did NOTHING, this is really confusing!

if ya figure it out, let me know. sounds a little like my problem.

what does it do when you try to start it?

x2, is it cranking and just not turning over, or does nothing happen at all when the key is turned? could be a bad CPS, could be the coil packs, could be cam/crank sensors wiring harness

Sounds like a clogged cat.

>>>> Update in original post.


The start just cranks it. No sign of anything combusting. When the gas is floored, you can hear a faint putt from the exhaust, but engine starting RPM does not change or fluctuate like a barely-starting engine would.


Interesting idea. Would that really happen so suddenly, though? And shouldn't it still sputter?

X's2 on the cat. my buddies GTP had the exact same problem. then i cut off the cat and welded in a straight pipe and put an O2 sim in the harness and bam car started right up and runs like a champ

perfect excuse for a 3"DP and U-bend delete

Second update in original post.

Dunno about the cat. It was running great up until the minute before parking the car at its death site. Also, we can feel light pressure from the exhaust tips while trying to start it.

Dunno about CPS either. Never had a tach problem, and usually the CPS gives early warning signs, and when it is bad, will at least fire a little.

I just can't believe spark is working, yet spraying starting fluid into the engine doesn't even cause it to pop or anything!

Are valves moving? Never heard of a standard GP breaking a timing chain though.

Yes, listed in the first update.

The chain can't possibly skip links/teeth can it?? They're moving though.

It can, but you'd still be getting it to fire, it would just sound rough and backfire, etc.

If it wasn't such a PITA to unbolt the downpipe, you could just do that and try starting it.

Thats what I figured [about the valvetrain].

I might have him pull the DP tomorow. Possibly also drop the oil pan to take a look around in the ol engine.

I tested all the wires from the injectors to the PCM connector.

I made a LED circuit to connect to the injector wires to check for that, am about to try it out.
Also going to bring home an oscilloscope tomorow to test crank and cam sensors.

Any other ideas?? Even rediculous one?

I don't believe you can drop the oil pan in our cars without removing the cradle or pulling the motor. That's why I changed the gasket when my motor was out.

UPDATE:
Pulled all the plugs. SOAKED.
Put new spark plugs in and it ran for over 5 minutes then started to run rough. Then swapped the original computer back in. Not sure if that had an effect, but it started up again and started running even worse then stalled out and would not start back up. Pulled out the new plugs, and they're SOAKED.

The injectors seem to always be getting ~8 volts, and 13 volts when they're supposed to figure. I thought this might have been normal until now, it seems theres an electrical problem keeping them open and flooding the engine fast. I'm going to run the tests on my car's injectors now and see if thats the case or not.

Problem fixed. Details late. Gotta get up early.

Aw, I wanted to know now! :p

Sorry for the long delay fellas.
It ended up being the famous warmed intake manifold leaking coolant into all the cylinders. Except it happened extremely quickly which made this the last thing we thought about.

Basically for almost the whole week I diagnosed the living heck out of the car. Literally tried everything you could think of. My car came in handy since I could swap lots of stuff.

I built a 6-LED circuit that I connected to the injector connectors to test that they were getting the proper signal. After figuring the engine was being flooded, I went further and hooked my oscilloscope to the injectors so I could accurately measure their pulse width. All that checked out fine.
I hooked the scope up to the crank (CPS) and cam sensor wires to get a visual indication of their health. I did this on MY car too, and my cars signal seemed to be much cleaner. So I stopped at good ol Ed's to pick up crank and cam sensors. Spent some nice time changing the CPS (dang crank pulley) and cam sensors and still didn't help.
Unbolted the manifolds and noticed that before the engine dies (we can get it to run if we let it sit for hours and clean the plugs), coolant spews out the exhaust. Bingo.

So we changed the lower intake gaskets and upper intake manifold +gaskets. Works great now.
It didnt seem like the regular case because it wasn't burning coolant before the problem occured. This kind of thing rarely happens suddently, and when it does happen, its just your engine burning coolant and you can fix it or let it get worse. This just killed the running engine.

Thats about all I can remember. Lots o fun. Lost a few more sockets and wrenches in the famous black hole in the bumper.

LOL! You knock, that magnetic tool ZZP has on their site, the bendy one, I managed to get 4-5 wrenchs/sockets out of it.

Seriously, invest in a bendy manget, it pays for itself.

I have one. And random other grabby tools. I can't get the sockets out of the time warm continuum wormhole thyristor envelope.