So for anyone who's been keeping track, I've been having a minor nightmare with starting my car after replacing the head gasket, belts, waterpump and clutch. '86 944T.

To recap, after the car was all back together it wouldn't start.

Checked the usual suspects
- ref sensors (align, adj, replace, etc)
- Flywheel (pins in the right place and depth)
- DME (swapped relays, swapped DME's)

We bypassed the factory alarm (which hasn' t been used the entire three years I've owned the car) and lo and behold it started. It still starts now even though we're not bypassing the alarm. So that's odd but I'll take the bit of progress.

The problem now is that it runs rough.

The car starts without fail every time now. It's definitely running on
the rich side, but we haven't really run the car till warm/hot yet, so
that might be a by-product of being cold. All 4 cylinders are firing.
It backfires through the tailpipe at anything over 2.5k or so, and runs
rough. Oddly enough, when driving it, it hesitates and stumbles on
acceleration, but decelerates in gear *perfectly*. The cam and valve
timing have been checked ad nauseum and are correct. We had some weird
resistance across the distributor rotor, so a new cap and rotor are
going on tomorrow. Plug wires ohm out fine(we repaired a faulty #2
wire). It feels/acts/sounds like incorrect ignition timing on a normal
car, but since there is no way of adjusting that on this car, I am a bit
stumped.

The problem is 100% electrical in nature. The DME relay/DME/Fuel
Pump/Coil have all checked out. Ref and speed sensors as well. Excess
Fuel pressure and/or stuck injector could be an issue and are on the
"to-do" list.

Any ideas? This car has been down now for over a month. It's simply killing me.

 

I would try putting a timing light on each plug wire, and then the coil wire, and make sure you're getting nice, even, rhythmic spark on each cylinder.

Then I would look at the air flow meter. Your car kinda sounds like what happens if you run a 944 engine with the AFM unhooked. It starts and runs badly, and can kinda limp home. So make sure the flapper door is moving freely (no mechanical binding or sticking) and the resistance on the pins (see FR Wilk site for values) is right, and that the air temp sensor in there is also working.

Is the backfiring at 2500rpm occuring when driving (under load) or just pressing the gas pedal with the car in neutral (no load)?

When coasting down in gear (high vacuum and engine rpm above idle), the injectors are supposed to shut off. So it seems like this is happening and the injectors aren't leaking in any significant way (no popping on coast-down).

Bryan

 

If you need a stock FPR, call me. I have one you can use...

 

This sounds a whole lot more like a vacuum leak to me. For troubleshooting purposes, have you tried putting a vacuum gauge on it? Just a thought, but you might want to check to see if the lid on the AFM is sealing tightly and that the AFM is working properly. It would pressurize on acceleration, which would reveal itself as a vacuum leak and cause the problems you describe; on deceleration, it would "suck", solving the vacuum problem and thus operate properly.

Good luck, as I want to hear your thoughts on the Lindsey exhaust system!

Best regards,

(EDIT: Or you can do what Bryan said... that will teach me to not read through all the posts in a thread... sheesh...)

 

I'll check into that, Bryan.

Thanks for the offer, Simpson. I might take you up on it depending on how things go.

 

is the rotor indexed correctly, does it piont at #1 terminal on the dist cap when the eng. is at TDC? Can you turn the rotor independant of the camshaft, even a little? Was there a shield around the ref. sensor, is it still there? A couple of years ago I had a car where the sensor was picking up electrical noise and driving the ecu nuts, the timing was all over the place. Someone had cut the bell housing to allow its removal without removing the sensors first. If the rotor can move, check the bolt holding the cam gear in place. All I can think of at the moment, good luck.

 

Either a hole in the intake system after the AFM or a crap coil.

If it is the coil it will die soon enough with no spark.

If intake system, try spraying starter fluid/propane around the intake and see if the idle smooths out.

 

You and me both, Scott!

It's sounding like a lot of people think it's a vacuum leak. I'll look into it, for sure.

 

Update.

Definitely something electrical. We're back to not starting. Anyone have good links for tracing the harness?

 

Does your oil reek of gas? Check it out, as I heard too much gas in your cylinders (due to leaky injectors, bad FPR, etc.) will cause a no start condition AND make your car run rough.

Does Mike have a fuel rail pressure gauge that fits our cars? Jumper the DME (30 and 87b, I think) at the fusebox and see what the static fuel pressure is, to test the FPR.

 

Oil smells of oil. No gas.

Just bypassed the alarm. No change.

 

is it flooded out, check the plugs, also check your ground connections on the battery and elsewhere.

 

Grounds checked out.

Checked the plugs and not flooded.

 

Check intercooler pipes make sure everything is tight and free of leaks. Everytime I blow my pipes it runs like this. Tries to run but back fires etc.etc.

Good luck.

 

I know you checked the lines...but take a look at two things

1)the temp sensor on the block near the throttle body and make sure it's plugged in

2)the vacuum hoses to the throttle body are connected...especially that bugger underneath it.