Hi everyone, I need some help again, I’ve got a Mk2 escort running a cosworth turbo engine, the engine has developed a running problem, obviously I realise it’s near on impossible to diagnose with a couple of questions but I’ll ask anyway, basically its started to idle higher than normal and when you try to give it a rev it splutters and has a very severe flat spot and the engine dies, it’s still running on all 4 and I’ve replaced the iscv with the one from my Sierra 2wd and it’s still the same, there doesn’t seem to be an air leak and all pipes and wires are still connected, so before I start changing everything, has anyone got any ideas?
Thanks in advance

 

Is it on the original fuel pressure regulator? If so check it's in working order. They can fail with age.

 

Yes it is still the original fuel regulator, definitely worth investigating
I’ll check it Monday,
thank you

 

I had a defective temperature sensor once. It was giving around 2.5 volts (around 20 degrees) even when the engine was fully warm.
The effect is a raise in idle (the ecu thinks the engine it is still in warmup) and more fuel (warmup enrichment, "choke" if you will).

I would have the exhaust gasses analyzed with a 4-gas tester.
Then I would measure the signal from the coolant and inlet temperature sensors, as well as the map sensor.

 

Definitely worth checking, similar symptoms, thanks buddy

 

First things first, does the idle change with the ISCV disconnected, if not then it's an air leak.

I don't believe it's FPR, this would not change the idle and usually results in rough running.

From the symptoms you describe, it sounds like TPS may be at fault, do you have early management (i.e. L1 or L6) or L8 (4x4)?

Martin

 

Hi Martin, I’ll double check tomorrow but I think the idle speed lowered when it’s disconnected, the management is just the standard L6, I’ve got a different throttle body with a tps still fitted which I’m gonna change tomorrow because when I tried to remove the iscv one of the screw heads snapped, i saw the engine it came off and it was running fine, admittedly it was about a year ago, I realise that the tps will probably need resetting but will hopefully give me an idea whether the old one is at fault,
someone said it could be the phase sensor but not sure that would cause the severe flat spot,
many thanks
John

 

Yes, that's expected and so means it is being operated in a manor to cause the high idle.

The TPS contains a switch (you should have a PF01) at idle it's open circuit, which is what the ECU looks for to activate the idle strategies. A bad calibration will cause the problems you describe, you can simply unplug it and see if it improves the idle.

Martin

 

Yes it is a PF01, I’ll try your suggestions tomorrow and see how it goes,
thanks again and I’ll post what happens,

 

You was spot on with your diagnosis, the different tps made all the difference, runs spot on now, really happy again, thank you so much for taking the time to help me, it’s very much appreciated, kind regards
john.

 

A bg Thanks to everyone for all of your suggestions, all sorted now. ��

 

No worries, there isn't much I haven't seen and done on these, over the years.

Martin