Intermittent misfire on T350

[NWTony]

OK, me again with electircal gremlins.

The major issue is with the engine intermittently firing on just one bank of cylinders (3 cylinders)and pissing neat petrol out of the exhaust. Up until now I've been blaming the wiring to the injectors - we fiddle with them, splicefrom one wire to another on the same bank and the problem goes away. However we've now replcaed the engine wiring altogether and it's still doing it.

Is it the wiring fromt he ECU to the bulkhead that's causing the issue? We've replcaed the wiring after the bulkhead connector so it isn't that. ECU drivers perhaps? Anyway of knowing for certain what the issue is?

Also and this may or may not be associated, the shift lights keep flashing on and the rev needle is jerky and inconsistent. The dash was recently repaired by Paul Smith and was working fine for a couple of months but has now started playing up again. In addition to the shift light / needle issue the display becomes corrupt, extra characters / word appear from different screens, ie "Fuel 24LWater" is displayed, which is briefely cured by moving away and backonto the screen in question.

Could this be a bad earth, dodgy connection? I've checked all the wires and ribbons to the back of the dash again and all appear fairly secure.

Damn TVR electrics

[shep1001]

NWTony said:

OK, me again with electircal gremlins.

The major issue is with the engine intermittently firing on just one bank of cylinders (3 cylinders)and pissing neat petrol out of the exhaust. Up until now I've been blaming the wiring to the injectors - we fiddle with them, splicefrom one wire to another on the same bank and the problem goes away. However we've now replcaed the engine wiring altogether and it's still doing it.

Is it the wiring fromt he ECU to the bulkhead that's causing the issue? We've replcaed the wiring after the bulkhead connector so it isn't that. ECU drivers perhaps? Anyway of knowing for certain what the issue is?

Also and this may or may not be associated, the shift lights keep flashing on and the rev needle is jerky and inconsistent. The dash was recently repaired by Paul Smith and was working fine for a couple of months but has now started playing up again. In addition to the shift light / needle issue the display becomes corrupt, extra characters / word appear from different screens, ie "Fuel 24LWater" is displayed, which is briefely cured by moving away and backonto the screen in question.

Could this be a bad earth, dodgy connection? I've checked all the wires and ribbons to the back of the dash again and all appear fairly secure.

Damn TVR electrics

My dodgy dash gremlins was down to the ribbon cables breaking down (looked OK visually but had a break in the cable). i had Paul look at the dash and it came back as having no fault. Changed the ribbon cables and it went away. Get a pair of 25pin printer extension cables off flee bay and try those. They cost about £5 each compared to the ridiculous cost of the flat cables like you have as std.

[NWTony]

shep1001 said:

My dodgy dash gremlins was down to the ribbon cables breaking down (looked OK visually but had a break in the cable). i had Paul look at the dash and it came back as having no fault. Changed the ribbon cables and it went away. Get a pair of 25pin printer extension cables off flee bay and try those. They cost about £5 each compared to the ridiculous cost of the flat cables like you have as std.

Thanks once again Shep, I do have a spare pair of printer cables to try so I will try fitting them just in case the ribbons have deteriorated recently. Paul Smith suggests it might be worth checking the PCBs in the ECU to see if they are firmly connected, so I'll give that a go as well.

The misfire was there last night, but absent this morning, making it hard to pin down. I know it's not the engine loom so it may still be the ECU to bulkhead loom but God only knows how you get to that easily - I can feel it, but not see it. Knowing my luck it is the ECU itself, because I clearly haven't spent enough money on the car recently.

[shep1001]

NWTony said:

Thanks once again Shep, I do have a spare pair of printer cables to try so I will try fitting them just in case the ribbons have deteriorated recently. Paul Smith suggests it might be worth checking the PCBs in the ECU to see if they are firmly connected, so I'll give that a go as well.

The misfire was there last night, but absent this morning, making it hard to pin down. I know it's not the engine loom so it may still be the ECU to bulkhead loom but God only knows how you get to that easily - I can feel it, but not see it. Knowing my luck it is the ECU itself, because I clearly haven't spent enough money on the car recently.

Cool they need male/female ends as the connections are different on the dash pod & ECU .

[NWTony]

I got some when the dash first started playing up but they made no difference, I seem to remember it was you who pointed me to the e-bay supplier

It could be that the ribbons have deteriorated or simply been trapped or folded when I reinstalled the ECU and dash and since I have them anyway it's a no cost option to try them out - nothing to lose!

[Targarama]

Str8Six replaced part of my wiring loom - I think from engine to inside the cabin, but might have been to the ECU. My symptoms were slightly rough running (no errors), they recognised the fault and said it is a common problem. Now this may be what you mean by replacing the engine wiring loom, but you might want to ask them for advice.

[NWTony]

I've replace the engine loom, or at least the injectors part of it and that didn't solve the problem, which is unfortunate because the loom from the ECU to the bulkhead looks like it's going to be a bugger to get at. You can feel it but you can't see it

[NWTony]

Just to close out the thread, I replaced the wiring loom from the ECU to the bulkhead and lo and behold, car runs perfectly. Part of me just thinks that I've moved something whilst doing it mind you...

I had visions of having to fork out for a new ECU.

[Targarama]

Great news!