If I cant cure this misfire will have to sell

[SlowRider]

... and the way finances are at the moment, it wont be another TVR.

Need some help! Have a 1999 4 litre Chim. All well until suddenly started misfiring about 6 weeks ago. Since then had new coil, rotor arm, cap, leads, elbows, plugs and air filter.

Paul at TMS spent 7 hours on the car, said everything checked ok, but its an intermittent fault and he couldnt find anything wrong.

Sometimes it runs fine. But sometimes when idling the revs drop to 700. Thereafter it runs poorly for anything from a few minutes up to a few hours. Idling is then too fast, up to 1700. When accelerating it spits and misfires up to 3,400 rpm, although over 3,400 it runs well. If I manage to stop the revs dropping to 700 in the first place its fine.

Anyone any ideas? Not sure what to do next other than just wait and hope it either gets better or becomes permanant. Either that or trade it in, but I really dont want to.

Thanks
Jeremy

[Podie]

Take it you've cleaned the stepper motor?

[malloryn]

Does it depend on the engine temp?
i.e. does it do it when warming up or only when its warmed up. Just thinking it could be a fuel problem related to close loop operation ( eg lambda sensors).

[GreenV8S]

I assume it didn't go wrong while it was at TMS or surely they would have fixed it. If they have been changing ignition components speculatively I hope they haven't charged you for bits they changed that were OK after all. I would expect a competant mechanic to track the problem down as a matter of course once they've got the car showing the problem. For instance Mark at Tower View has tracked down many and varied faults on the V8S over the years he's looked after it fo me, including some very bizarre symptoms due to a faulty ECU earth. If TMS are struggling you could do worse than get Mark to take a look at it.

[icb]

Had a similar problem with my 4.5 and both C. neil and TVR Power tried to sort it but fault never came on when they had it. Eventually took it to Mark Adams. Luckily the fault occurred when there and was traced to a faulty pin on ECU. He will sort it for you if nobody else can.

[SlowRider]

malloryn said:

Does it depend on the engine temp? i.e. does it do it when warming up or only when its warmed up. Just thinking it could be a fuel problem related to close loop operation ( eg lambda sensors).

YEs, it seems to. Much more a problem when starting from warm.

[pvapour]

SlowRider said:

... and the way finances are at the moment, it wont be another TVR. Need some help! Have a 1999 4 litre Chim. All well until suddenly started misfiring about 6 weeks ago. Since then had new coil, rotor arm, cap, leads, elbows, plugs and air filter. Paul at TMS spent 7 hours on the car, said everything checked ok, but its an intermittent fault and he couldnt find anything wrong. Sometimes it runs fine. But sometimes when idling the revs drop to 700. Thereafter it runs poorly for anything from a few minutes up to a few hours. Idling is then too fast, up to 1700. When accelerating it spits and misfires up to 3,400 rpm, although over 3,400 it runs well. If I manage to stop the revs dropping to 700 in the first place its fine. Anyone any ideas? Not sure what to do next other than just wait and hope it either gets better or becomes permanant. Either that or trade it in, but I really dont want to. Thanks Jeremy

Nooooo! dont sell just because of one person not being able to fix it! you love this car when it's running fine, don't you?

well get it sorted by someone who knows what they're doing, before being hasty, you'd have to fix it to sell anyway.

Have a look at the actual Distributor (not the cap)itself and the electrics inside, make sure everything is screwed into place and tight and all wires and pipes are connected, I had this on my early 4.0
5 years ago, had exactly the same symptoms, I did exactly the same procedure of replacing and then found this part to fault, it's worth a look.

You'll only regret selling in this frame of mind.

Hope you fix it ok.

Nik

[M@H]

Lambda sensors ok..? They seems to be a popular area for concern at the moment..?

I concur with everyone else here.. get the car sorted out by Mark Adams or similar, then get the grin back.... also, I too am concerned by the replace parts by default approach.. this is often the most expensive way of "finding" and fixing the fault.

Cheers
Matt.

[SlowRider]

M@H said:

. also, I too am concerned by the replace parts by default approach.. this is often the most expensive way of "finding" and fixing the fault. Cheers Matt.

It was only Offord, not TMS, that used this method (and charged heavily)

[sagalout]

lambda sensors can go faulty on an on/off basis.
Is there anyway of "shorting it out" to by pass the damn thing to see if it's causing the problem??
Icanfixthingsmechanicalbutelectricalstuffiswizardry.

[apache]

Lambda sensors can check out ok but still be at fault (according to Mark A) get them swapped out for a diagnostic check.

[SlowRider]

Just wondering .....

is it possible to drive the car with an ECU fault reader plugged in? I might then be able to see what, if any, fault its showing when the thing starts messing about?

[TT Tim]

Excuse my ignorance but most ECUs store the fault codes so that you don't need to do exactly what you just said, is this not the case with the TVR varient? Usually a light will flash so that you can read the 'code'.

I know that the TVR ECU is a Land Rover derivative, do LR not offer or use a diagnostics tool? I have a 300zx of 1990 vintage and Nissan use a tool called a Consult to check all sensor/sender readings does a similar thing not exist for LR V8?

Tim

[andy43]

There is a Land Rover diagnostics tool that'll plug straight into the loom by the battery - any TVR dealer/specialist should have one, costs £100ish and it'll store any fault codes that have occurred (eg dodgy lambda LHS) from whenever the ECU was last powered down/rebooted. The bible has a codes list I think. Don't think you're supposed to drive the car with the reader plugged in though. Could be an earth, could be an intermittent break in a wire to/from the ECU, could be anything, best thing to do is above - get it to a specialist V8/Lucas guru. And if a dealers fleeced you for parts and fitting failing to cure the fault, give them the car back and say you want a refund and the old bits put back on thankyou very much.

[malloryn]

If an error code is detected then shouldn't the MIL light on the dash board light up.

[k4trv]

Some of your problems may be answered in this link:
http://ourworld.compuserve.com/homepages/Peter_Beech/TVR/injprob.htm#ECUFault<span style=

Cheers

Trev