Took the engine apart, now it won't idle

[Desaevious]

Alright so I had an air leak from bad gaskets on my intake manifold, so I took the manifold off and replaced the gaskets. Then I went back and installed everything in reverse order correctly. Everything is back together but I'm looking at these three issues:

1) The car will crank find and the car will start to idle, then putter out. If I keep cranking it and pushing down on the gas the car will run, but with a terrible idle that bounces under 1k until I release the gas or key and it dies out.
2) The o-ring on the fuel regulator...I replaced it because where it connects to the rail was leaking gas. I replaced the o-ring and I'm still having the leak...but when I remove the regulator this new o-ring pops due to pressure and gas squirts out like its supposed to (the old one wouldn't) yet I don't see why it would be leaking gas.
3) While having the key cranking the ignition and the gas pushed down, I can hear a gasping coming from the engine itself. Now it doesn't appear to be coming from the intake manifold (I put in the new gaskets, double checked that I had them in, triple checked them for sanity) and then torqued the manifold on. But I don't know where that is coming from...

I'm seriously on the verge of going nuts over this. And with my math final on Monday I'm going up the walls. So R3V, if you could kindly provide me with some answers I'd be obliged...and if you have any questions to furthur diagnose the problems I'll be able to be post again after work at 10ish tonight. And I'm sure the answers are somewhere in this thread but I'll go mad just searching for the right one...thanks guys.

[jlevie]

I'll bet that you still have intake leaks. But there may be other problems as well. If the replacement FPR o-ring is an OE part (not a generic replacement), I have to wonder if the FPR is leaking or is bad and causing excessive rail pressure. The fuel system tests in the Bentley will tell if the FPR is working correctly.

A smoke test will tell if and where intake leaks may be.

[Rascal2pt0]

Definitely check for vacuum leaks first these cars will not run without vacuum. To the point where opening the file fill while running will stall the car. At least mine.

On the o-ring make sure that the surfaces are clean and try a bit of oil to make sure it seals. Make sure the new ring is also viton compound. Gas will eat a rubber one.

[Desaevious]

The FPR o-ring was fine, it was the fuel line leading into the bottom of the FPR that was slowly leaking and making it look like it. That was fixed by me cutting a little off the hose and now there is a good seal.

So what I'm looking at? Stumbling idle at under 1k rpm and when I drive it the car moves forward, stumbles, moves forward, and stumbles again. Sometimes the idle will cut out. I think I still have a vacuum issue but here's what I know so far:

Sources of vacuum leaks are the intake manifold gaskets (replaced), the breather hose from the valve cover to the manifold (replaced), a hose that goes to the bottom of the throttle body, the TB/mani gasket, the brake booster hose, and the ICV hose. I tried using carb cleaner at those places when on and it didn't kick up...leaving me to think that's because the idle itself sucks.

I am still thinking vacuum...but there wouldn't be any chance this is due to jumped timing (not sure how I could've done that) would it?

[jlevie]

The complete list of possible intake leaks on an M20 engine is:

Intake boot
Throttle body gasket
ICV hoses & connections
Brake booster, hoses, and connections
Crank case breather hose
Evaporative control hoses, valve, and expansion tank
Fuel pressure regulator & hose
Injector seals
Valve cover gaskets & bungs
Oil filler cap
Dip stick o-rings
Oil return tube o-rings

While leaks in some of those can be found by inspection or by spraying carb
cleaner on suspect areas, not finding leaks that way doesn't eliminate the
possibility. Only a smoke test of the intake will really work.

[Desaevious]

Wow, you are the master who posted that exact thing on bf.c in a thread I found about half an hour after making my above post. I found a lot of good info there but with a very small post count on there I wasn't abount to PM you.

Question though, the type of tube that is cut up and used throughout the brake booster hoses, is that just a generic tube I can buy at a local parts store? I also noticed the one coming off the brake booster was a formed tube and I'm wondering if I need that exact part as well. Thanks.

[Desaevious]

Alright I replaced EVERYTHING bolded. What are the ones I didn't bold?

The complete list of possible intake leaks on an M20 engine is:

Intake boot
Throttle body gasket
ICV hoses & connections
Brake booster, hoses, and connections
Crank case breather hose
Evaporative control hoses, valve, and expansion tank
Fuel pressure regulator & hose
Injector seals
Valve cover gaskets & bungs (bungs? what are bungs?"
Oil filler cap
Dip stick o-rings
Oil return tube o-rings

While leaks in some of those can be found by inspection or by spraying carb
cleaner on suspect areas, not finding leaks that way doesn't eliminate the
possibility. Only a smoke test of the intake will really work.

This is KILLING ME. I thought I got it all today and now I'm still hearing that occassional gasp coming from somewhere in the engine bay. Although for that gasp I'm starting to think it is from the coolant that I never filled and bled because I wanted to get the car to at least stay on first. So maybe this isn't even a vacuum issue? Is there an electronics related problem that could do this?

[Desaevious]

Also I cleaned up the ICV with carb cleaner and the vane inside it still "vibrates." Meaning the ICV still works?

[Desaevious]

Alright so here's where I'm at now. The idle is FINE. Perfectly fine, no more vacuum leaks. The idle holds at 1k.

Now whenever I try to drive the car or use the throttle manually the car will at first rev properly and then seconds later it will have a rough reving process, but when I let go of the gas or the throttle it goes back to a normal idle. And then I can turn my engine off and I can go back minutes later and have it rev normally until seconds later when it starts to act strange.

For example, when I drive the car now it will speed up to 20mph up my hill no problem and then seconds later the tach will be jumping all over the the car would surge forward, stop, and surge forward again until I limp it home.

I swapped out the ICV, AFM, and the ignition coil with a friend's whose works just for shits. My injectors haven't been cleaned (didn't think to) and when I took them off the fuel rail I put on new o-rings that are properly seated...I'm not leaking gas from anywhere.

Anybody?

[u3b3rg33k]

Plug wires? Re-seat them all and see if it goes away. The coil wire is particularly important.

[jlevie]

For example, when I drive the car now it will speed up to 20mph up my hill no problem and then seconds later the tach will be jumping all over the the car would surge forward, stop, and surge forward again until I limp it home.

If this car has a manual transmission and you see the tach taking a big drop when the engine misbehaves, the cause is likely to be a flaky CPS or something that is interrupting power to the DME. The latter could be a flaky main relay, bad fusible link, or poor connection in or between the ignition switch and the coil/START input to the DME.

Another possibility would be a weak fuel pump, clogged fuel filter, or bad FPR.

[Desaevious]

The car in question is an auto. It isn't a bad main relay or fuel relay because I also swapped those for good ones in a friend's car and the ignition isn't an issue now.

With those out of the way, the weak fuel pump, clogged fuel filter, or bad FPR seem like they could be them. Granted the car is an automatic I think that would rule out your first possibilities.

[Desaevious]

Plug wires? Re-seat them all and see if it goes away. The coil wire is particularly important.

Yeah, I did that...the coil wire and plug wires and pushed in good and proper.

If this car has a manual transmission and you see the tach taking a big drop when the engine misbehaves, the cause is likely to be a flaky CPS or something that is interrupting power to the DME. The latter could be a flaky main relay, bad fusible link, or poor connection in or between the ignition switch and the coil/START input to the DME.

Another possibility would be a weak fuel pump, clogged fuel filter, or bad FPR.

The car in question is an auto. It isn't a bad main relay or fuel relay because I also swapped those for good ones in a friend's car and the ignition isn't an issue now.

With those out of the way, the weak fuel pump, clogged fuel filter, or bad FPR seem like they could be them. Granted the car is an automatic I think that would rule out your first possibilities.

[u3b3rg33k]

You mentioned not having cleaned your injectors. I highly doubt that would be the problem. Only thing that changed (as far as I can tell) when I had mine done is they no longer leak down, so it starts on the first try instead of 2 or 3. I'm sure they're in better shape now spray pattern wise, but that was the most noticeable effect.

[Desaevious]

Yeah I doubt that they are the injectors as well. The injectors are getting proper voltage and are nice and sealed in there so I'd venture its something else...but what that "else" is is beyond me. Therefore I am at R3V's mercy.