Hard Misfire

[Mullet Bullet]

No kidding on the pan gasket, I can understand a stumble or bad idle but not a miss like this.

I'm more leaning to spark or fuel but it's almost like the primary/secondary ignition is dropping off. Because with fuel it would fall at a certain rpm under a certain load but this will happen with no load at any rpm, almost like it's blowing out the spark.

I just need a few hours to do some real testing.

[Mullet Bullet]

well shit, i just tried a crank sensor and coil off a buddies early car and nothing. its like once the temp started to dive here for the winter the car won't run because now it won't start what so ever since the car is covered with frost.

so now i really need to start thinking what controls fuel/spark depending on temp. ive got a spare DME that im going to swap in. i can smell raw fuel after cranking it a few times so i need to figure out if its not getting spark.

[Mullet Bullet]

getting fuel and spark so it seems. tried a different DME as well and i can hear/feel the fuel pump running while cranking.

im really at a loss.

[Mullet Bullet]

replaced the crank sensor with a brand new one from blunt. still will not start.

[jlevie]

You need to get this car to a shop that can run smoke test. All of your problems are best explained by intake leaks. Other possibilities exist, but until intake leaks can be ruled out it is pointless to peruse those.

[Mullet Bullet]

there is not a intake leak. there is NO vacuum leak WHAT so ever. i have a smoke machine, have ran a smoke test, NO LEAKS.

even with a vacuum leak the car would run, it might run like crap but it would at least kick over. my car doesn't do that. it just cranks, no bang or vroom.

[jlevie]

Just for my piece of mind...

You did plug the exhaust and use an adapter where the AFM would be for the smoke test. And you did hold at least 2psi of smoke pressure for at least five minutes, right?

If the test was done that way, then I'll agree that there are no intake leaks.

[Mullet Bullet]

Throttle body was taped ove as well as exhaust. No leaks out ether. It's not a vacuum leak.

[Mullet Bullet]

pulled the main ground off the frame and oil pan, looks fine, no corrosion what so ever so i cleaned the contact points on the cable pan, and frame. put the cable back on with some dielectric grease on it.

cranks strong, kind hickups a few times like its trying to start but nothing. plugs are dripping with fuel. cap and rotor look ok. pulled the vacuum ling to the FPR and its dry.

just doesn't make any sense why it ran flawlessly 2 weeks ago. parked it and now it won't even start.

[ScHpAnKy]

your coil sounds bad, that or the rubber cap for it is seriously loose. Your CPS/cam sensor didn't come undone, right?

[Mullet Bullet]

swapped coils from a known running M20 car, no luck. CPS is brand new and perfectly connected.

[jlevie]

Throttle body was taped ove as well as exhaust. No leaks out ether. It's not a vacuum leak.

Fair enough. Do you hold at least 2psi of smoke pressure for at least 5 minutes? It can take that long for smoke to work into and fill the crank case, which can have leaks. The best test is to push smoke in via an adapter that replaces the AFM as that tests the entire system as it it during normal operation.

If you have spark and fuel a failure to start will be a serious upset of the A/F ratio, an engine that is out of time, or a valve problem.

What is the rail fuel pressure?

Using a noid light does each injector pulse normally when cranking?

Have you verified cam timing (and checked for broken rockers)?
Given the recent history, I rather doubt this is a rocker problem, but that should be checked.

Is it possible that the plug wires are wrong?

[Mullet Bullet]

Fair enough. Do you hold at least 2psi of smoke pressure for at least 5 minutes? It can take that long for smoke to work into and fill the crank case, which can have leaks. The best test is to push smoke in via an adapter that replaces the AFM as that tests the entire system as it it during normal operation.

If you have spark and fuel a failure to start will be a serious upset of the A/F ratio, an engine that is out of time, or a valve problem.

What is the rail fuel pressure? i need to go get a fuel pressure tester, i currently do not know the rail pressure

Using a noid light does each injector pulse normally when cranking?i don't have noid lights, going to borrow some from a friend or just make one myself

Have you verified cam timing (and checked for broken rockers)?
Given the recent history, I rather doubt this is a rocker problem, but that should be checked. i have pulled the valve cover and everything is perfect, valve adjustment was done about 1300 miles ago and has been perfect

Is it possible that the plug wires are wrong?i wish it was something that simple, ive already checked and they are right on. again this all started after the car sat for 2 weeks. it ran perfectly when i parked it 2 weeks ago

[jlevie]

Check the rail pressure and the injector firing. If the rail pressure is too high (or too low) or the injectors are on all the time, the engine could wind up flooded.

[Keith M]

Possibly moisture somewhere? C191 or one of the relays? Assume your weather has been the same as it is down here, ie cool and foggy, it is a possibility.