TVR Chimaera cutting out at speed

[Wouter_W]

Hi,

After a long overhaul due to a rotten chassis my Chimaera is back on the road. She does seem to have created an issue with cutting out at speed. Bumps are not a problem, it seems to happen randomly. The engine seems to stop for an instance shuddering the car (and giving me shivers). It has also cut out once for a longer time and while rolling I managed to rock the engine by a gear change and it came back to life, preventing a hard-shoulder stop.
What could it be? Coolant temperature sensor? Worn ignition coil? Mass inertia problem?

Cheers,
Wouter

[Sardonicus]

Have you checked both sets of bunched ground cables are clean and secure? n/s rear cylinder head and o/s front engine block next to oil pressure switch

[Wouter_W]

Hi Sardonicus,

Those are secure in place. In my enthousiasm I have even connected another one onto the starter motor.

Cheers,

Wouter

[Barreti]

Does it do this only when the engine is hot?
And is it a complete cut out or a quick stutter?
How long has it been doing it?

[Wouter_W]

Hi,

It is a quick stutter while cruising. And it has cut down twice, once able to recover with a gearchange and the other time on the side of a b-road after some fiddling and a reset of the ecu. It has started a few weeks ago on a trip to Germany. On the way back the roadspeed sensor has come loose. Poly bushes and hardly maintained Autobahn are, even at decent speeds, a bad combo.

Thanks for the advice both :-)

Cheers,
Wouter

[67Fox]

HT lead loose or broken?

[ClassiChimi]

Nobody ever mentions the wiring to the coil, I'd re built my front end last year and whilst cruising upto Qbee's castle,,,, hahah, my car twice just stopped! Once it hit a bump I was on my way again, then total loss of engine,,,
Connections looked good but a quick fiddle and mines never done it since,,
Worth a check. I crimped the two connectors a tad and Bobs your uncle, I hope it could be as simple as that.

[Sardonicus]

ClassiChimi said:

Nobody ever mentions the wiring to the coil, I'd re built my front end last year and whilst cruising upto Qbee's castle,,,, hahah, my car twice just stopped! Once it hit a bump I was on my way again, then total loss of engine,,,
Connections looked good but a quick fiddle and mines never done it since,,
Worth a check. I crimped the two connectors a tad and Bobs your uncle, I hope it could be as simple as that.

Well considering its like a doctor without a patient for me I might as well go piss in the wind .................... its on my shoes too but yes good call

[FlipFlopGriff]

Check the obvious first (everything is connected and tight, no obvious wires loose or chafed) but could be ignition amp.
FFG

[ClassiChimi]

Sardonicus said:

ell considering its like a doctor without a patient for me I might as well go piss in the wind .................... its on my shoes too but yes good call

There's a lot of happy patients out there from most of your posts Simon,,,,
Mucho respecto mate

[Barreti]

Check the usual suspects such as ignition leads etc but my bet is its the ignition amp.
You have exactly the same symptoms as I had when mine was failing.
The time you spend fiddling and resetting the ECU gives it time to cool down and it works OK again until it gets hot.

Unclip the wires to it and check if you have a 2 wire or 3 wire version and get the correct replacement as there are 2 and 3 wire versions in use.
http://www.powersperformance.co.uk/store/search/ig...

The 3 wire version is Lucas part DAB118 (or INTERMOTOR 15410). Lucas part DAB127 should also work because that is a kit which includes a bracket etc. though you may have to change the wires.

Also get some heat transfer paste like this stuff.
http://www.maplin.co.uk/p/coolermaster-ic-essentia...

Should be less than £50 all told.

Edited by Barreti on Thursday 25th June 15:29

[HardMiles]

I’ve just had the car running and it would appear the stepper motor returned on first run. I didn’t hear it return to it’s position on subsequent times turning it off, should it always return, or only when fully cold? Is this my issue? Jumpy at low revs and dies when cruising and warm? Is it staying stuck open? All earths seem good, MAF works fine and fuel seems fine (although haven’t checked pressure, it has no issues delivering at flat chat). Any advice appreciated!

[ianwayne]

If it were to stay stuck out, yes you'd have not enough air. The engine should still have base idle at about 600 rpm when warm if this is the case.

Every time you turn the engine off (hot or cold), the stepper motor should motor back, you'll hear it clicking. It gives the ECU a position to start from because it has no feedback loop telling it how far out the stepper motor plunger actually is. It sends pulses to close or open it and keeps trying if the idle speed is still wrong.

Cutting out is serious Is the alternator putting out enough voltage? The 100A charging fuse may also be cracked or broken, meaning the ECU and all electrics are struggling on battery power alone.

Edited by ianwayne on Thursday 25th October 11:31

[TV8]

HardMiles said:

I’ve just had the car running and it would appear the stepper motor returned on first run. I didn’t hear it return to it’s position on subsequent times turning it off, should it always return, or only when fully cold? Is this my issue? Jumpy at low revs and dies when cruising and warm? Is it staying stuck open? All earths seem good, MAF works fine and fuel seems fine (although haven’t checked pressure, it has no issues delivering at flat chat). Any advice appreciated!

I had some poor running issues on my old car and the stepped didn’t reset correctly. Turned out it was the AFM. I am near Bromley and have a bag of known good bits and pieces if you want to borrow them and try a bit of trial and error?

[HardMiles]

TV8 said:

HardMiles said:

I’ve just had the car running and it would appear the stepper motor returned on first run. I didn’t hear it return to it’s position on subsequent times turning it off, should it always return, or only when fully cold? Is this my issue? Jumpy at low revs and dies when cruising and warm? Is it staying stuck open? All earths seem good, MAF works fine and fuel seems fine (although haven’t checked pressure, it has no issues delivering at flat chat). Any advice appreciated!

I had some poor running issues on my old car and the stepped didn’t reset correctly. Turned out it was the AFM. I am near Bromley and have a bag of known good bits and pieces if you want to borrow them and try a bit of trial and error?

Cheers dude, I’ve checked a load of stuff, Earth is strong, MAF is new, coolant temp sender new, not a fuelling issue, no vacuum leaks, think it has to be a pissy sensor somewhere! What bits have you got & most likely yes please! My number is 07834228821 (Miles) if you can drop me a line (as I’m crap at internets)!! I have it booked in with TVR Sussex as I’ve exhausted my car knowledge and want it diagnosed, but any bits to test in advance would be great. Cheers bud!

[Penelope Stopit]

Although the starter motor should show up a bad engine earth by either not operating or by cranking slower than it should, sometimes bad earths come and go
Where you mention that the earth checked out ok (here or in the other topic that you've been posting to), did you check the engine earth while operating the starter motor?

If your answer is no to the above

The earth can only be checked under starter motor load and the volt-drop measured should not be above 0.75 volts between the battery negative and the starter body

Be careful that you don't lose fingers in moving engine parts when cranking and testing, have someone crank the engine for you

[BIG DUNC]

There is also an earth strap going to the chassis bolt in way of the centre consol. From memory, this goes directly to the battery so would be a good one to check if you haven’t already.

Edited to add, next time it does stops by side of road you need to confirm whether or not fuel pump primes. Also, is it more prone to cutting out in wet weather?

Edited by BIG DUNC on Thursday 25th October 20:20

[HardMiles]

BIG DUNC said:

There is also an earth strap going to the chassis bolt in way of the centre consol. From memory, this goes directly to the battery so would be a good one to check if you haven’t already.

Edited to add, next time it does stops by side of road you need to confirm whether or not fuel pump primes. Also, is it more prone to cutting out in wet weather?

Edited by BIG DUNC on Thursday 25th October 20:20

Thanks again guys.

Weather makes no odds it would seem as its not out in the wet. Fuel pump primes mint each time, fuel / pressure isn't the issue I don't think as when it does decide to die or start dying, a swift prod of the loud pedal sorts it out and it isn't hesitant to rev, which it would be if it was the FPR for example.

I genuinely believe it is either earthing / wiring / lambdas or a stty little sensor / relay somewhere. I'll get it diagnosed and come back with my findings, not having the Rovergauge set-up means I'm best to hand it to an expert. Next time mind you I'll have it and be armed!

[TV8]

HardMiles said:

Cheers dude, I’ve checked a load of stuff, Earth is strong, MAF is new, coolant temp sender new, not a fuelling issue, no vacuum leaks, think it has to be a pissy sensor somewhere! What bits have you got & most likely yes please! My number is 07834228821 (Miles) if you can drop me a line (as I’m crap at internets)!! I have it booked in with TVR Sussex as I’ve exhausted my car knowledge and want it diagnosed, but any bits to test in advance would be great. Cheers bud!

Hi Miles, I am away at the moment, back Saturday night and will call you Sunday if that works with you?

[ChimpOnGas]

HardMiles said:

Thanks again guys.

Weather makes no odds it would seem as its not out in the wet. Fuel pump primes mint each time, fuel / pressure isn't the issue I don't think as when it does decide to die or start dying, a swift prod of the loud pedal sorts it out and it isn't hesitant to rev, which it would be if it was the FPR for example.

I genuinely believe it is either earthing / wiring / lambdas or a stty little sensor / relay somewhere. I'll get it diagnosed and come back with my findings, not having the Rovergauge set-up means I'm best to hand it to an expert. Next time mind you I'll have it and be armed!

Don't dismiss the immobiliser, keep in mind the immobiliser is a switching circuit for two circuits:

1. The starter solenoid (not your issue)

2. The ECU (possibly your issue)

A monetary loss off +12v to the ECU will give your cutting out symptom, an intermittent issue with the Meta relay buried inside the immobiliser and responsible for the ECU circuit will definitely cause cutting out

If you PM me I can help you locate the output wire from your immobiliser to the ECU, once found you can temporarily connect a sidelight bulb holder and bulb to that circuit, place the bulb rig in your natural line of sight when driving and it'll tell you if you're momentarily losing +12v to the ECU when the engine cuts out.

I should now be 100% clear in saying I am in no way encouraging you to make an assumption this is your issue, all I'm doing is providing another circuit to check and encouraging you to study the entire system responsible for providing fuel & spark.

But it is worth making you aware the relays inside the Meta immobiliser system are a known point of failure, mostly it's the one than controls the starter circuit that gives out first and for reasons extensively covered elsewhere on these pages, but it's also not uncommon for the Meta relay that controls the ECU to give trouble too.

The bulb trick is something I was taught years ago and is extremely useful when diagnosing difficult to trace intermittent electrical issues, it's a simple and effective method that can be used to prove/disprove a fault theory on any circuit, for example if you find the immobiliser is not your issue I recommend applying the same method to the +12v supply to your coil, the main ECU relay hanging in the footwell and the fuel pump relay also hanging in the footwell but fitted in the blue relay holder.

Keep in mind in a situation like yours if your engine has spark and fuel it will run, so.....

1. If your bulb rig between the immobiliser and ECU flashes when the engine temporarily cuts out..... the engine will get no fuel and so will be the reason for the cut out!

2. If your bulb rig on the ignition coil flashes when the engine temporarily cuts out.... the engine will get no spark and so will be the reason for the cut out!

3. If your bulb rig on the main ECU relay flashes when the engine temporarily cuts out..... the engine will get no fuel and so will be the reason for the cut out!

4. If your bulb rig on the fuel pump relay flashes when the engine temporarily cuts out..... the engine will get no fuel and so will be the reason for the cut out!

5. If your bulb rig on the fuel pump itself flashes when the engine temporarily cuts out..... the engine will get no fuel and so will be the reason for the cut out!

Test the above five circuits/components using the simple bulb rig in the order I have presented them, make sure your bulb rig earth is a known good one to eliminate any false alarms, obviously the battery is your most reliable earth. Your issue will be a lack of spark or fuel for sure so logically a very systematic check of the +12v supply to anything that provides fuel or spark is where to focus your attention, of course an earthing issue is just as likely as a +12v supply issue so earths should be checked with your bulb rig too.

Like I say.... "If both fuel and spark are present the engine will run"... take either away, for even just a split second, and you'll have cutting out issues for sure

Happy testing, as with all electrical issues it's simply a case of following a series of logical tests in a very disciplined and methodical fashion. Follow this methodology/mindset and avoid making assumptions at all costs, like this eventually you'll find you simply can't help but find the fault!