car popping and sputering, will not idle or run

[speedracing944]

I just did my cam tower gasket and after I put it back together I took it out for a 10 mile drive. The car drove perfectly and had lots of good power. I drove it home and parked it. That was Friday night. Fast forward to Monday (today). My wife, kids and I were going to go to the Library in the 944 and I tuned the key and there was a big POP! and sputter. There was mist coming from the air intake where it meets the inside fender. My wife noticed I didn't tighten down the hose clamp for the J-boot right after the AFM. I slipped the J-boot back on all the way and tightened the clamp. I tried to start the car again. It would start with a little nursing of the throttle but would stall if I didn't continue to nurse it along by blipping the throttle. we took the van to the library instead.

After I got home this is what I have done

Brought the motor to TDC and verified the cam and flywheel were still in sync. CHECK

replaced the coil CHECK

wiggled the AFM connector CHECK

I now have the AFM off the car and was going to test it according to clarks-garage to see if I blew it up from the initial backfire.

Besides testing the AFM what else do you guys think it could be??



I WANT MY '83 BACK


Speedy

[legion]

Loose distributor? Loose cables to fuel injectors? Sounds like its not firing consistently or in time for some reason. Just a guess.

[speedracing944]

Oh ya I pulled the distributer as well and double checked the rotor and cap. All the spark plug wires are on tight and correct. All the fuel injectors are plugged in and clipped with those little metal clips.

Oh there is no black soot coming from the tail pipe so i think the fuel pressure regulator is good. I pulled the vacuum lines off the regulator and dampener and the was no fuel odor or wetness.


Speedy

[legion]

Something really simple....plugs wired out of order? If it ran before, that seems unlikely.

Maybe a loose DME connection? Bad fuel pump? Loose ground? Short somewhere? I'm at a loss.

[speedracing944]

Plug wires are correct. I made note of the position before I pulled them and reinstalled them correctly. The car ran good Friday night.

I did clean alot of chasis grounds last fall.

I double check the battery post terminals and they are clean and tight.



The only things I touched electronic wise during the cam gasket was..

fuel injector plugs
cap and rotor
spark plug wires on cap and rotor
AFM plug
negative battery terminal
Starter wires so I could pull the starter and install the flywheel lock



Speedy

[legion]

Maybe a shorting injector? I'm at a total loss and am just trying to throw out ideas to get you thinking.

[speedracing944]

you are doing a good job so far. You made me remeber all the things I have tried.

What else??/

Speedy

[onZedge]

A factory trained Porsche mechanic told me not to touch the gas pedal when you go to start these cars otherwise, and under the right conditions, it might backfire and blow off the AFM boot. Since you have the AFM off, look inside and check if the barn door is stuck due to being tweeked by the backfire. It happened to me.

[SolReaver]

Could something have been blown off other than the boot so that you are not getting vacuum?

[924Sman]

Check the hose port/inlet and lines under the j boot for cracks.

Dal

[speedracing944]

The barn door moves smoothly and isn't stuck. I was going to tear it apart and test it according to clarks-garage but I think I will check on the suggested vacuum leaks under the J-boot and elsewhere first.

Thanks guys for the suggestions

Speedy

[speedracing944]

I did a vacuum hose check and everything was where it was suppose to be with no loose fittings. i looked at the J-boot and it looked good too but I couldn't see the underside to well so I will pull it off tonight and inspect it.

Any more ideas?


Speedy

[Icey1174]

Strange that the car ran fine for your quick run and now this.

I wonder about the AFM too. Why did you have it off for a cam gasket? Was there other work you were doing besides the cam gasket?

Check the fuel injectors again for any leaks or if they are "wet" with gas near the top. Did you reuse the old o-rings? Did you use ATF on the o-rings? Those little metal clips on the fuel injectors can be deceiving how they fit. I wonder if you are not getting some kind of a leak around there somewhere. All the wires for the fuel injectors tight?

[blown 944]

I bet there is a vacuum leak you are missing. Check the hoses on the underside of the manifold and the mainfold gasket area.

If it blew the j boot off, chances are it blew something else off as well, causing the exact symptoms you are describing.

Try spraying some ether (starting fluid) around various areas including manifold mating area. its the easiest way to detect a vacuum leak.

[speedracing944]

Originally posted by Icey1174
Strange that the car ran fine for your quick run and now this.

I wonder about the AFM too. Why did you have it off for a cam gasket? Was there other work you were doing besides the cam gasket?

Check the fuel injectors again for any leaks or if they are "wet" with gas near the top. Did you reuse the old o-rings? Did you use ATF on the o-rings? Those little metal clips on the fuel injectors can be deceiving how they fit. I wonder if you are not getting some kind of a leak around there somewhere. All the wires for the fuel injectors tight?

I pull the AFM and air box off everytime I do belts and/or cam gasket. I gets me more working space.

The only work I did was the cam gasket and everything related to accessing this area. Oh ya I replaced a ball joint on the drivers side A-arm as well but I know that wouldn't have anything to do with it

Yes I reused the O-rings. They were only 6 months old, still plyable with no knicks

I used motor oil on the bores in the intake manifold to allow the O-rings to slide in easier.

I did not pull the fuel injectors from the fuel rail. I pulled the whole fuel rail as 1 unit including the injectors. All the clips holding the fuel rails on are in place as they should. All the electrical connectors are in place and the little metal clips are snapped in. There is no leak on or around the fuel rail. Everything is fuel free.

The car ran great after I got it put back together.


It does seam like a vacuum leak with how it is behaving.

[speedracing944]

Originally posted by blown 944
I bet there is a vacuum leak you are missing. Check the hoses on the underside of the manifold and the mainfold gasket area.

If it blew the j boot off, chances are it blew something else off as well, causing the exact symptoms you are describing.

Try spraying some ether (starting fluid) around various areas including manifold mating area. its the easiest way to detect a vacuum leak.

I need to pul the boot off to see the underside more clearly. I just did a quick scan this morning and found nothing.

I saw 2 large vacuum lines under the manifold. It looks like one goes to a crankcase breather and the other one goes to a sensor. I am not sure what the sensor does. I will inspect the area under the manifold more as well.


Could of the backfire traveled to the AFM, hit the barn door and send a shockwave up into the electronics of the AFM maybe screwing up the mechanical components of the AFM? I am thinking bending of the wiper arm or something like that?


Speedy

[924Sman]

Chance of the AFM door is slim as the backfire has to pass the TB butterfly first.
If you do find you need to move the wiper North or South be very careful about it! That brass wiper bends very easily and out of shape leaving one pickup point to not hit. Not a job you want to just bend it and go, it takes some calculated movements to get both sides equally bent. Find a used one that is trash and practice bending it first. Having said that, you may find the PO has already tweeked the wiper PU's and no more room to move. If you see 2 grooves in one black strip, you have a pre adjusted wiper. Look very closely in many angles to see the wiper tracking/wear....2 grooves, may as well get a replacement.
But before anything else rule out the vacuum leak(s), then dig into the AFM. You really need to remove the entire j boot and get a good look, I could not see mine until I turned in upside down.

Dal

[KY944S]

Check the J boot again. Make sure it didn't curl under when you put it back on. You could even slide under the car and look up at the boot to double check (don't ask me how I know).

[onZedge]

I'm with Sid. Vacuum leak.

[EMBPilot]

when my vac line was came unpluged (after it was leaking) from UNDER the jboot my car acted the same exact way yours did.