Poor starting then cutting out.
- Thread starter Frenchy
- Start date
Jon, thanks for the reply for the primary resistance i assume i check across + ve and -ne where do i check the secondary coil output and earth and what should i expect with regards to readings ? Luckily i can strip the coil unit from my running car should i have to, should the injector driver be the problem where is it driven from ?
I also have the luxury of a spare ECU which was going to be the next move.
Just as well that i love these cars or it could be parked beside a local river [
]
I also have the luxury of a spare ECU which was going to be the next move.
Just as well that i love these cars or it could be parked beside a local river [
]
Indi9xx
New member
A failing fuel pressure reg can make the car run rich, make the fuel pump sound like an F1 car, black smoke, and can over tax the injectors and cause injector driver overheating in some cases.
If you have any of the above issues, it could be the fpr, but if you just have the injector driver overheating issue then it is normally either down to a bad injector or a tired ecu/dry joint
If you have any of the above issues, it could be the fpr, but if you just have the injector driver overheating issue then it is normally either down to a bad injector or a tired ecu/dry joint
Cheers Jon,
I have been in my garage today sorting my tool drawers out as everything is just chucked in there and i spend ages looking for specific sockets etc, looks quite proffesional now []
Took the coil of the 86 turbo and have measured the coil resistances and will go to my other garage (Mothers House) and check the readings on the 88 Turbo coil and if necessary swap over.
I tried the DME relay from the 88 car in the 86 car and it fired up fine and ran okay so DME proven.
The car is taking up to 10 minutes to start then finally catches and runs fine or 2 minutes or so then cuts out, i do not think it is the temp sensor for the ECU as it is still not warmed up thouroughly to cut back the fueling.
Will try the coil then on to the ECU, I will get there and have it sorted though no rush as they both are in "hibernation" at the moment.
I have been in my garage today sorting my tool drawers out as everything is just chucked in there and i spend ages looking for specific sockets etc, looks quite proffesional now [
]Took the coil of the 86 turbo and have measured the coil resistances and will go to my other garage (Mothers House) and check the readings on the 88 Turbo coil and if necessary swap over.
I tried the DME relay from the 88 car in the 86 car and it fired up fine and ran okay so DME proven.
The car is taking up to 10 minutes to start then finally catches and runs fine or 2 minutes or so then cuts out, i do not think it is the temp sensor for the ECU as it is still not warmed up thouroughly to cut back the fueling.
Will try the coil then on to the ECU, I will get there and have it sorted though no rush as they both are in "hibernation" at the moment.
George Elliott
New member
2 Cars for testing, thats really helpful with 944's...[][][]
Jon, given the symptoms and storage circumstances, i'd be suggesting Frenchy looks at the AFM.
My guess is the signal voltage off the wiper may be out of spec.That confuses the life out of the ECU......?
and it runs badly.
Its hard to buzz out on ohms as its a variable reading once the car is drawing air through it, and what it reads when stopped is meaningless.
I have known the connector to corrode slightly at the AFM unit with similar results
Good to see the tacho bounce []
Good luck with it
George
944t
][][]Jon, given the symptoms and storage circumstances, i'd be suggesting Frenchy looks at the AFM.
My guess is the signal voltage off the wiper may be out of spec.That confuses the life out of the ECU......?
and it runs badly.
Its hard to buzz out on ohms as its a variable reading once the car is drawing air through it, and what it reads when stopped is meaningless.
I have known the connector to corrode slightly at the AFM unit with similar results
Good to see the tacho bounce [
]Good luck with it
George
944t
Indi9xx
New member
Airflow meter should be ignored during cranking, using pre set figures in the eprom for load (which the airflow meter usually provides), once the cranking signal to the DME drops out, then it should start to pay attention to the airflow meter.
During cranking, the DME will only look to the speed sensor, reference sensor and coolant temperature sensor.
If it was starting up and then instantly dying as soon as you let off the key, or acting oddly once you let off of the key, then I would say airflow meter.
During cranking, the DME will only look to the speed sensor, reference sensor and coolant temperature sensor.
If it was starting up and then instantly dying as soon as you let off the key, or acting oddly once you let off of the key, then I would say airflow meter.
Indi9xx
New member
It being a pain to start in the first place would suggest another problem than airflow meter.
The symptoms of being a pain to start, and then cutting out after a couple of mins, sounds like either the plugs are fouling/flooding (due to overfueling or poor spark energy) or something is overheating due to age or its operating parameters, such as fuel pump, coil or injector line drivers.
Fuel pump usually overheats and stops working due to high fuel pressure or age of the fuel pump.
Injector drivers in the DME normally overheat due to either a bad injectors, bad harness or a weak injector driver stage.
Coil usually overheats due to age (dried out)
Plugs normall foul up due to...
Overfueling (due to high fuel pressure, the DME engine temperature sensor, etc)
Poor ignition energy (due to poor coil, king lead, plug leads, rotor arm or distributor)
Poor starting can usually be any of the above.
However... A vacuum leak, such as a blown off hose, cracked/split intake hose etc, can cause poor starting, and once the engine has run for a while, built up a little heat, and the DME starts dialing down the fueling multiplyer from the coolant temperature sender, can then cut out due to the unmetered air causing an overly lean condition..
The symptoms of being a pain to start, and then cutting out after a couple of mins, sounds like either the plugs are fouling/flooding (due to overfueling or poor spark energy) or something is overheating due to age or its operating parameters, such as fuel pump, coil or injector line drivers.
Fuel pump usually overheats and stops working due to high fuel pressure or age of the fuel pump.
Injector drivers in the DME normally overheat due to either a bad injectors, bad harness or a weak injector driver stage.
Coil usually overheats due to age (dried out)
Plugs normall foul up due to...
Overfueling (due to high fuel pressure, the DME engine temperature sensor, etc)
Poor ignition energy (due to poor coil, king lead, plug leads, rotor arm or distributor)
Poor starting can usually be any of the above.
However... A vacuum leak, such as a blown off hose, cracked/split intake hose etc, can cause poor starting, and once the engine has run for a while, built up a little heat, and the DME starts dialing down the fueling multiplyer from the coolant temperature sender, can then cut out due to the unmetered air causing an overly lean condition..
George Elliott
New member
Thanks Jon
Hope you get it sorted Frenchy
George
944t
Hope you get it sorted Frenchy
George
944t
Cheers Chaps,
I have not been back to the car yet, the garage is very dry so i suspect that corrosion is not an issue on contacts etc i am suspecting the coil or king lead as when i checked for a spark with a spre plug i had a spark but not the strongest when i come to think about it.
As prevously posted i will get back own to it when time allows as there is no panic, but getting it fired up and a round around the block to execise components will be good.
A couple of my good mates also run turbo's so plenty of comparisons on components along with my other car to donate to achieve the desired result []
I have not been back to the car yet, the garage is very dry so i suspect that corrosion is not an issue on contacts etc i am suspecting the coil or king lead as when i checked for a spark with a spre plug i had a spark but not the strongest when i come to think about it.
As prevously posted i will get back own to it when time allows as there is no panic, but getting it fired up and a round around the block to execise components will be good.
A couple of my good mates also run turbo's so plenty of comparisons on components along with my other car to donate to achieve the desired result [
]
Had a couple of hours on the car today, checked Dizzy and leads and swapped the plugs over all okay, bar the previous plugs where wet and sooty (overfuel) cranked........... over nothing !
Swapped ignition relays x 2 from a bag of spares.................nothing !
Swapped the ECU then put jump leads on the car as the battery was getting tired, the car eventually caught then ran, left it running for a couple of minutes and it would stutter then clear, went to give the car some throttle via the throttle body and it then stopped and would not start again.
Suspect AFM is okay as Jon has said AFM signal ignored on cranking so it would start but it doesn't, i noticed that the fuel pressure gauge fitted to the end of the fuel rail was still showing some pressure since last visit this usually drops to zero after a couple of hours ?
The throttle position switch still has a small audible click.
Comments welcomed as i am starting to get fed up and run out of ideas. [X(]
Swapped ignition relays x 2 from a bag of spares.................nothing !
Swapped the ECU then put jump leads on the car as the battery was getting tired, the car eventually caught then ran, left it running for a couple of minutes and it would stutter then clear, went to give the car some throttle via the throttle body and it then stopped and would not start again.
Suspect AFM is okay as Jon has said AFM signal ignored on cranking so it would start but it doesn't, i noticed that the fuel pressure gauge fitted to the end of the fuel rail was still showing some pressure since last visit this usually drops to zero after a couple of hours ?
The throttle position switch still has a small audible click.
Comments welcomed as i am starting to get fed up and run out of ideas. [X(]
George Elliott
New member
[8|][8|][8|][8|]
I hear all the theory about cranking and AFM signals.....but my reading of your fault is that the car starts OK, but the instant it looks for an AFM signal after cranking, it aint getting a proper one, and its mucking up the fuelling and wont run properly on a cold engine....but you may be sick listening to me so I will get off my soapbox and shut up....[][][]
The residual fuel pressure is maintained by the non return valve at the fuel tank in the fuel feed line, and the FPR must be holding the fuel from returning to the tank on the return line...? thus maintaining rail pressure....that sound possible Frenchy? Otherwise the fuel would be free to drain to tank over time under gravity
George
944t
I hear all the theory about cranking and AFM signals.....but my reading of your fault is that the car starts OK, but the instant it looks for an AFM signal after cranking, it aint getting a proper one, and its mucking up the fuelling and wont run properly on a cold engine....but you may be sick listening to me so I will get off my soapbox and shut up....[
][][]The residual fuel pressure is maintained by the non return valve at the fuel tank in the fuel feed line, and the FPR must be holding the fuel from returning to the tank on the return line...? thus maintaining rail pressure....that sound possible Frenchy? Otherwise the fuel would be free to drain to tank over time under gravity
George
944t
Hear you George, please chip in it is apprecaited, regards AFM car can take a lot of cranking over to start as Jon said when cranking AFM signal is ignored so it would start then fail once running but this is not the case.
When running it revs as it should and then seems fine, after a couple of minutes though and some throttle it dies and refuses to start again ?
Suspecting fuelling FPR which will be changed this weekend or fuel pump, i have my eye on an upgrded Sytec jobbie []
Or possibly a wiring fault in the fuse box area, i need to get the passenger seat out along with the glovebox to get in amongst it, the car has had the odd aftermarket alarm system fitted through it's life so a good sort out when in there will do no harm.
I will keep you posted, forgotten what it's like to drive []
When running it revs as it should and then seems fine, after a couple of minutes though and some throttle it dies and refuses to start again ?
Suspecting fuelling FPR which will be changed this weekend or fuel pump, i have my eye on an upgrded Sytec jobbie [
]Or possibly a wiring fault in the fuse box area, i need to get the passenger seat out along with the glovebox to get in amongst it, the car has had the odd aftermarket alarm system fitted through it's life so a good sort out when in there will do no harm.
I will keep you posted, forgotten what it's like to drive [
]
Fred Hindle
New member
I have experienced similar problems (but with bike engines). First thing to do is make sure the battery is fully charged and holds a charge. If you get another fully charged battery connect it to the fully charged one on the car. Crank it over and hopefully it will start. Leave the two batteries connected for the time being. The car may have to be gently revved to get the alternator to give sufficient power. If the car runs and gets warmed up then disconnect the additional battery. Allow the car to tick over but at a slightly higher rate (1500rpm instead of 1000rpm. When you switch off the engine put the car's battery back on charge so it is full for when you start it again (suggest starting it after a couple of hours - engine should be cold by then).
Basically the cranking of the starter takes so much out of the battery it is unable to maintain the running of the engine when it does start.
Cheers,
Basically the cranking of the starter takes so much out of the battery it is unable to maintain the running of the engine when it does start.
Cheers,
George Elliott
New member
If that does not work Frenchy, what about.......
(I am assuming you have fuel at the rail.....but have not tested the injector spray pattern)
Theory ---- gummed up fuel injectors from poor quality fuel sitting in them while parked up.
If you did something dangerous like take the car outside, remove the fuel rail with injectors remaining attached, place the rail in a large clear polythene bag, and have someone turn the engine while you observe the injector spray pattern....? while holding the powder extinguisher.
Cable tie the hoses as they enter the bag.
I am not serious of course[8|]
Its an odd problem.
George
944t
(I am assuming you have fuel at the rail.....but have not tested the injector spray pattern)
Theory ---- gummed up fuel injectors from poor quality fuel sitting in them while parked up.
If you did something dangerous like take the car outside, remove the fuel rail with injectors remaining attached, place the rail in a large clear polythene bag, and have someone turn the engine while you observe the injector spray pattern....? while holding the powder extinguisher.
Cable tie the hoses as they enter the bag.
I am not serious of course[8|]
Its an odd problem.
George
944t
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