Tamora troubles... engine cutting out when warm

[JockyWilson]

Looking for some advice on the Tamora as me (and two mechanically minded mates) are out of ideas!

Brief history:
12 k service at end of October, driven straight to France (put a few hundred miles on it, no issues)
Second or third drive after that, engine cut out while driving. Managed to restart it and get it home.
On the next attempt a week later, started fine from cold, idled for 10 mins then cut out when put in first gear and tried to pull away.
Called the service garage and was recommended to change the coil pack. This is all detailed in this thread:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...

So, have recently got a replacement coil pack and fitted it. Following the coil pack change, this has happened on 2 cold start attempts:

Started from cold (started first time, no extra throttle required)
Idled fine for 9-10mins
After about 10 minutes, with water temp at 65 deg, oil around 26 deg, the engine briefly struggled and cut out.
It's possible to restart it, but it needs a constant foot on the gas. As soon as you remove the slight pedal pressure, it cuts out.

Troubleshooting since:

Have increased the engine idle - still cuts out when it gets warm.
Have checked all the high temp leads with a multimeter - resistance fine.
Checked all spark plugs - look fine (and new at the service).
Checked resistance across the ECU water temp sensor - measured around 795 then 1118 five minutes later when slightly cooler (so guessing it's doing its job)
Disconnected the ECU water temp sensor and started the car. EFI Fault - Warning Code 4. Engine was still warm when started and needed a foot on the gas to stay running.
Disconnected the fuel hose going into the fuel rail to check for residual fuel pressure straight after the engine died - no fuel came out.
Did the same after having the engine running and turning the ignition off - again no fuel came out of the pipe.

Listened to the fuel pump priming in the boot - seems to be doing its job when the car is turned on.

Have been trying to get the speed 6 diagnostic software running but have failed so far. Can't get hold of a laptop with a sufficiently old enough version of windows to run the software. I have read this thread on it (http://www.pistonheads.com/gassing/topic.asp?h=0&f=152&t=1051057&nmt=)

So, we're thinking it's still looking like a fuel or electrical issue but now out of ideas. Has anyone had these symptoms before?

A mate suggested the throttle pot, but looks like you need to take the bonnet off to properly get at this.

The car's been off the road for two months now as have been fiddling with it when I've had the time. Getting pretty frustrating now though, especially straight after a big service.

All suggestions welcome!

[JockyWilson]

Thanks for the suggestions and thanks for the evoOlli software link Andy, I wasn't aware of it before, looks good! I've got a new crank sensor / fuel relay on the way and the software is downloaded to have a play this weekend. Will update on progress..

[JockyWilson]

That does look like a quality set up, will do just that...
How have you managed to attach it? Guess it might also fit in the glove box if only used for troubleshooting etc

[JockyWilson]

So troubleshooting is ongoing. Got the software working now but haven't changed the crank sensor yet as the parts only recently arrived. Car started fine today but on initial start up the passenger side exhaust seemed to be pumping out much more puff then the driver's side.

Would the data below point more to a faulty throttle pot rather than crank sensor? Will still likely replace the crank sensor next as I have the part, but wondering whether it's looking like the throttle pot is the main culprit. Looks like £115 for the two parts.

Does anyone know how hard the throttle pots are to change? Is it a bonnet off job?

[JockyWilson]

Englishman said:

Before you change anything, do both throttle pot readings change with throttle movement? If so, it'd suggest to me that the throttle balance is way out.

.. both throttle pot readings change with throttle movement yes. On driving, I reset the adaptive maps and things seem fine for 10-20mins then the same issues reappear (engine hesitant then cuts out). I've never balanced the throttle bodies myself, but it's recently back form the full 12k service at a very well known TVR dealer.

[JockyWilson]

K4TRV said:

Deffo take the bonnet off to do any more work etc!!

T

Never taken the bonnet off before... heard it can be tricky to get back in the right alignment. Proving to be quite a learning curve this issue

[JockyWilson]

Thanks I'll try get hold of a syncrometer, in the meantime I have the crank sensor to try and have also got some new HT leads so will change them (although resistance seemed fine when the old ones were checked). The bonnet doesn't seem that tricky then

[JockyWilson]

Englishman said:

Ok, can I suggest another test - you can do this without actually starting the engine. Connect up the computer and turn the ignition on, what do each of the pots show? Then press the accelerator slowly until fully open. They should start about 15%, finish about 94% and progress roughly in step. If you reset the throttles and repeat is there any change?

Thanks for the suggestion... did this test a few days ago with engine off and the throttle readings did both start around 15% and ended on 94% on full travel. Both readings stayed close to each other throughout the pedal travel.
Yesterday the throttle 1 and adaptive 1 readings were much higher than normal, plus had the AFR 123 FAULT message.

[JockyWilson]

Also ref. the cold idling you're right, it's not a regular habit Only during this troubleshooting as it's a bit dodgy to take for a drive (can be ok for a while, then be cruising along in 3rd at 2500rpm for example, foot off the gas and drop the clutch when approaching a junction and the engine cuts out)...