Poor start, cold stumble etc

[rmcdonnell]

Hi,
So, she wouldn't start this cold and wet morning. Had to leave it, came home, and eventually jump started it. Lots and lots of cranking, only fires if accelerator on the floor, is misfiring badly, runs on two or three cylinders, conks out. Fired and started about ten times before it decided to run. Cloud of smoke when started. Or vapour.

During process, I have had a duff fuel regulator before so I tried removing a spark plug cable, no improvement, misfiring worse. Was nightime, bonnet open, no stray sparks when cranking. So don't think it's too much fuel pressure.

Got it running, ran her (quite rough) for 10 mins, took her round the block, to get car warm. During warm up, throttle needed nursing to keep running, not confident with idle. Returned home, stopped her. Restarted no problem 20 minutes later. Looked for stray sparks when idling, sprayed Easy start everywhere- no change in idle, which has small occasional stumble, but no response to starter fluid. So probably not vacuum leak. A lifter is clanking.

Could be intake leak when very cold, of poor injector(s), or duff spark plugs. Will try to change plugs tomorrow. Don't think it's DME relay, as it tries to run, but conks out during process. Could be AFM. Anyway folks, any other ideas on what I can test for?

regards
Russell

[John_AZ]

Rissole,

Due to my superior recall (I looked at your old posts) ,
I found you reside in, quote " it's not even all that cold in sunny Cambridge in the UK ".

From my vast knowledge of the UK and the current weather and flooding conditions, my suggestion would be to check if the last tank of petrol had a bit of water or sludge included.

OK, if the car was operating normally for a period before the problem, there may be moisture in the fuel. When was the last time you changed the fuel filter?

With all the dampness, start to clean all the connections on the AFM and the reference sensor connections on top of the engine.

Clean all the grounds. Put a piece of tape over the TDC bell housing hole!

Clean the negative grounds on top of the bell housing. The battery.

Yes it could be the AFM sticking.

Were there any operating conditions before the current problem?

GL
John_AZ
1988 924S + 1987 924S

[running_cold924]

sounds like plug wires to me, especially when they are wet. use a spray bottle and mist them at night, check for arcing then.

what is easy start?

[rmcdonnell]

Bother, just lost my last reply before posting, much longer and lovely.

Hi John, thanks for the ideas, checking the AFM is a good idea. The battery is knackered (starts from a jump start, eventually). Fuel filter never changed (a stuck bolt means the ensuing carnage might be way worse!). S'pose I'd better have another look. ;-)

I'll get out the DME jumper if she fails to start tomorrow, to rule that out, and clean the plugs at lunchtime, see how they look.

The car always starts first time, on the third crank, waa, waa, vroom, idle, and usually catches and runs without problem. When cold or wet, sometimes she will start, then conk out the first time, (waa, waa, vroom, burble, misfire, stop). She then takes loads of cranking with the accelerator pressed to the carpet. Waa, waa, waa, vwaa, waa, waa, waa, vwaa, waa, vwawavavav, burble, serious misfire, runs on one or two, usually stops, but eventually repeating this scenario ten times, another cylinder kicks in, then the last, then runs rough for a mile or two, then fine

Easy start (running_cold924) is a highly volatile aerosol, used on recalcitrant motorbikes, lawnmowers to kick start the combustion process or just start some wild fireball experience. Fun, fun, fun.

Anyway, thanks for the ideas. I may have grounds for cleaning.
Cheers, Rissole.

[HondaDustR]

Easy start=starting fluid, pretty much ether spray (usually).

Check the DME temp sensor. It's the frontmost one screwed into the block right under the intake J-boot and has a 2 pin plastic connector. The other one is for the instrument cluster guage and doesn't affect the DME. Could also be the AFM, or the air temp sensor built into it. Wiring can break down at any time, so pulling the DME and testing sensors through the main connector is also helpful.

DME Connector 35-pin

What the heck, check everything you can so you know what isn't the problem.

Be aware that the AFM has it's own ground that is actually called AFM return, pin 6. Test between 9and 6 at the AFM connector to measure DME supply and test between 7 and 6 at the DME harness to measure the AFM signal returned to the DME. Measure the same sets of pins again with the measuring locations swapped to see if the wiring is affecting the readings at all. The nice thing is, at least on the AFM and TPS, the pins on the units are numbered the same numbers that correspond to their respective pin numbers in the DME harness. The DME connector comes apart to allow you to access the pins from the back of the pin block while it is plugged into the DME, since the AFM voltages must be tested with everything plugged in and the key turned on.
http://www.the944.com/afm.htm

[John_AZ]

Originally Posted by rmcdonnell

The battery is knackered (starts from a jump start, eventually).

Rissole,

Do not use a bad battery that you have to jump. This will cause the DME computer to get too many amps and you may distroy the computer.

GL
John_AZ

[running_cold924]

ohh, ether....basically what it is over here. use sparingly.

[idontknow]

Originally Posted by rmcdonnell

During process, I have had a duff fuel regulator before so I tried removing a spark plug cable, no improvement, misfiring worse. Was nightime, bonnet open, no stray sparks when cranking. So don't think it's too much fuel pressure.

Could be intake leak when very cold, of poor injector(s), or duff spark plugs. Will try to change plugs tomorrow. Don't think it's DME relay, as it tries to run, but conks out during process. Could be AFM. Anyway folks, any other ideas on what I can test for?

regards
Russell

Try removing a fuel injector connector if you suspect a bad fuel regulator.

From clarks garage:
"Disconnect one fuel injector connector and attempt to start car. If the car starts and runs, where it would not before, then the Fuel Pressure Regulator (FPR) is most likely bad and should be replaced. Bascially when the FPR fails causing the fuel rail pressure to go high, the injectors have too high a differential pressure across them, they draw too much current, and the injector driver shuts down. Disconnecting one injector wire reduces the injector current enough to allow the engine to start. Realize that the car will run very rough as it's running on three cylinders"