moalaska

Ok i parked my turbo to reinforce my tranny mount and grease my cv axles. Went to start it and no start. I did have issue with it the other day where it was missing on 1 or 2 cylinders when warming up. Shut it down restarted and it was fine. This was maybe 20 degree weather. Now its about 15 and won't start at all. Fuel pressure good. 12v to ignition coil. Tach bounce check. New sensors anyway but reseated connectors to be sure. New temp sensor but tried a new spare. Pulled spark plugs they are wet. Wiped them and grounded them to check for spark. Spark but sometimes seems weak. Pulled cap checked to see if rotor screw backed out. Swapped in spare coil. Sometimes it will fire once but then nothing. So either a weak spark issue or im thinking injectors sticking and flooding. Msd blaster coil fairly new. Dist cap rotor and plugs new. New fuel filter check valve 54# injectors adj regulator. All vacuum lines replaced new. Old vitesse maf. I had resoldered the dme as well but not ruling that out. Any ideas what to check next? It was running right before I parked it sat for 2 days while i was working on the back of it.

mel_t_vin

Suspect a bad coil and/or degraded wires.

V2Rocket

do you have any way to warm the car up at all (to 32+ degrees?)
old cars don't like to start in the very cold.
when you crank it does it just crank or does it sound like it wants to catch but never does?
how old is DME temp sensor?

moalaska

moalaska

Yes the cold definately will make any car harder to start. I drove my 924s all winter last year and it always started and did fine even in below 0 temperatures. And i barely replaced anything on that car. The turbo has the same sensors electronics ignition etc so only reason it is having problem is because something is out of spec or failing. Its not that cold where it shouldn't start. Unless a sensor isn't functioning correctly. Unless the vitesse maf doesn't like cold but it started fine at 20 degrees f. It was missing though for a bit that's why im thinking injectors sticking, injector driver or only other thing i could think of is a bad spark plug but it sounded like it was missing on 2 cylinders but once warm when i restarted it it ran fine.

moalaska

My spark plug boots have numbers 928.609.105.03. Is this correct or from a 928? Says 3k ohms is this correct resistance for these boots?

mel_t_vin

Correct...same boot used on both the 2v 928 and 2v 944.

Have you swapped out the DME relay...or tried to bypass it?

moalaska

yes. I have solid state relay with pump prime and also have jumpered it to diagnose fuel and spark. It seems my plugs are fouled im going to get show good ones and plug them in. I had new plugs nkgs i think. Last thing i did was start car for a few seconds and shut it down, with all the extra enrichment being cold it left lots of gas on the plugs because i didn't let it warm up and my fuel pressure was a little high just never adjusted it. With cold weather i think it was enough to foul the plugs ill know soon. Does anyone have any afr numbers what they get on a super cold start. Im pretty sure mid 9s is really really really rich i expect super rich starting in Alaska but i think that's a little too much.

Raceboy

If it fires occasionally then the plugs are fouled. Reason is either: spark plugs are too cold rationg or tune is off and it floods the plugs when temperature is cold.

I live at the same latitue as southern Alaska, even though we have a bit milder winters I am way too familiar with this issue and it calls for a retune!

Tom M'Guinn

Always worth checking the timing belt on a sputtering engine. You might try pulling the dme temp sensor connector and putting a 1k or 2k resistor in across the connector leads. If you don't have access to resistors, a hair dryer on the back of the sensor for a good 5 -10 minutes might help. And of course, starter fluid usually works great to get a motor starting in the cold, assuming that's all it is...

moalaska

ok yes plugs were fouled. Put some ngk split grove plugs in and fired right up. So just have to figure why its running rich and why afrs are all over. If I set my regulator at 3 bar everything seems good when i first start it. Once it gets warm the fuel pressure seems to drop im thinking its just because its warm and maybe i need to set it when its warm. Bit if i set it at 3 bar warm my afr is like 11at which is super rich. On throttle it acts lean like it wants to backfire. Almost like the throttle idle switch is stuck. I tested continuity at throttle sensor and switch seems to be working.

Raceboy

If you set it to 3 bar during running you will have higher pressure. It needs to be 3bar with fuel pump running but engine NOT running because vacuum reference lowers the FPR spring pressure and thus gives lower reading.
Note that FPR set pressure (for example 3bar) is meant to be the difference between manifold pressure and fuel, not atmospheric pressure (meaning when at 1 bar boost the fuel pressure is 4bar but still 3bar against manifold pressure).

On throttle it acts real rich and backfires, it reads lean because of unburned fuel (that still has oxygen in it that is read by sensor).

Cold engine draws less vacuum and that's why you get different reading. So please set your fuel pressure to 3bar with engine NOT running (but fuel pump running).