Houston, we MAY no longer have a problem . . . . . . .
Discussion
Electrical / fuel Gremlin update for anyone interested in my troubles over the SCH weekend. Huge thanks to everyone who has pitched in with their thoughts to date (TVR-Git in particular, who provided us with new hope just prior to us leaving on Sunday)
Car is a late S3c and still has the cats in place.
The symptoms:
Sudden but typically very transient lurch, loss of power, followed by poor running, miss-firing, backfiring and general grumpiness. Happening at steady revs, typically motorway cruising. Temporarily resolved by booting the throttle but over time turning into a real lumpy, horrible bag of . . . .
Things tried:
Yellow connector - already been removed by previous owner
Earth straps
Checking most likely connections - pull apart, spray and reconnect a few times
New fuel pump relay
New fuel filter
Connect to code reader (garage) - no error codes except for idle control valve (but idle never a problem)
Clean and check distributor cap contacts/connections etc
Swapped rotor arm
Swapped Throttle pot
Remove shield around disti cap and ignition lead contact extenders
Swapped carbon filter
New coil
Problem persisted through all the above efforts and through SCH, including travelling back to Guildford on Sunday. However, we noticed the problem seemed to be consistently at its worst when cruising at approx 3200 revs. Avoiding this resulted in a much better trip home than the trip up to SCH, but still not right.
Latest update: Having had a rummage around on the net yesterday I found something on a 'Ford Ignition' website re the 'MAP sensor'. Unbelievably, I had a spare one in the boot which came with the car but I had no idea what it was or what it really did until yesterday! Web-talk of it having an impact on 'air/fuel ratio, ignition timing and ERG flow' resulted in a quick swap-out earlier this evening. Having had a little run, I am (very cautiously) optimistic. I could not create the problem at 3200 revs and also the overall performance of the car seemed much smoother, especially driving at and accelerating from low revs, where I have been progressively unhappy of late.
I will let you know how things go at the weekend when I will get chance for a longer run, but could this finally be it!!
Car is a late S3c and still has the cats in place.
The symptoms:
Sudden but typically very transient lurch, loss of power, followed by poor running, miss-firing, backfiring and general grumpiness. Happening at steady revs, typically motorway cruising. Temporarily resolved by booting the throttle but over time turning into a real lumpy, horrible bag of . . . .
Things tried:
Yellow connector - already been removed by previous owner
Earth straps
Checking most likely connections - pull apart, spray and reconnect a few times
New fuel pump relay
New fuel filter
Connect to code reader (garage) - no error codes except for idle control valve (but idle never a problem)
Clean and check distributor cap contacts/connections etc
Swapped rotor arm
Swapped Throttle pot
Remove shield around disti cap and ignition lead contact extenders
Swapped carbon filter
New coil
Problem persisted through all the above efforts and through SCH, including travelling back to Guildford on Sunday. However, we noticed the problem seemed to be consistently at its worst when cruising at approx 3200 revs. Avoiding this resulted in a much better trip home than the trip up to SCH, but still not right.
Latest update: Having had a rummage around on the net yesterday I found something on a 'Ford Ignition' website re the 'MAP sensor'. Unbelievably, I had a spare one in the boot which came with the car but I had no idea what it was or what it really did until yesterday! Web-talk of it having an impact on 'air/fuel ratio, ignition timing and ERG flow' resulted in a quick swap-out earlier this evening. Having had a little run, I am (very cautiously) optimistic. I could not create the problem at 3200 revs and also the overall performance of the car seemed much smoother, especially driving at and accelerating from low revs, where I have been progressively unhappy of late.
I will let you know how things go at the weekend when I will get chance for a longer run, but could this finally be it!!
Norman - yes it's the cat versions only, it's a little black matchbox fixed to the bulkhead behind the distributor. It has a rubber hose to the plenum ( well to a t-piece in another vacuum hose) to measure vacuum. Then it has 2 wires to the ecu.
The ecu uses various signals, including MAP, lambda, throttle pot, etc, to determine fuelling and ignition timing. That's why they don't need air flow meters.
The ecu uses various signals, including MAP, lambda, throttle pot, etc, to determine fuelling and ignition timing. That's why they don't need air flow meters.
I have a similar problem with my Sc3 but have not replaced the black box which could be my problem as I have replaced similar to what you have done. Trying to source one from Ford, quick question when you replaced the leads to the ECU did you dis-connect the battery many thanks for new thread on this.
tvrgit said:
Norman - yes it's the cat versions only, it's a little black matchbox fixed to the bulkhead behind the distributor. It has a rubber hose to the plenum ( well to a t-piece in another vacuum hose) to measure vacuum. Then it has 2 wires to the ecu.
The ecu uses various signals, including MAP, lambda, throttle pot, etc, to determine fuelling and ignition timing. That's why they don't need air flow meters.
Thanks Andrew - theres always something extra to learn - appreciated, thanksThe ecu uses various signals, including MAP, lambda, throttle pot, etc, to determine fuelling and ignition timing. That's why they don't need air flow meters.
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