down on power

[calvinhutt]

I have been a little concerned about the running of my 500 (40K miles) lately, so I cleaned the stepper motor, had the plugs and leads changed. Still seems to pop and bang too much during engine braking. There is a noticable lack of power until just under 4000 revs when it kicks in with what feels like full steam ahead......

Before I had any of the above done, I assumed it may be a lamda sensor, but my mechanic said "probably not", so I went with his advice.

I would guess that it is runnig a bit rich - spluttering a bit of soot out the exhausts when stationary, a bit uneven at idle occasionally.

Is it a lamda sensor, or just in need of a good tune-up? Or is it likely to be something else? I have checked on the web, there seems to be no easy way to test lamda sensors? Hope it aint too expensive, still paying off debts built up since redundancy over Christmas...

Any ideas folks???

[Ballistic Banana]

Would reseting the EMU/ECU as if the unit has seen something is faulty or breaking down then it may have adjusted and made things worse.
This be a short time fix maybe, as the unit will do the same eventually, but this would prove it is prehaps a sensor of some sort.

Hope that helped.

BB

[apache]

check your dizzy. It could also be because it's started to 'eat' the precats

[Ballistic Banana]

apache said: check your dizzy. It could also be because it's started to 'eat' the precats

Saves having them taken out then

BB

[GreenV8S]

As I understand it, the ECU is only supposed to run closed loop using the lambda sensors up to 3500 rpm or so, above that it runs open loop. In the past when mine has had lambda sensor faults, it has been very badly behaved at low rpm but then springs back to life above about 3500 rpm.

[shpub]

Engine braking is a sure fire way to loosing your no claims bonus at best and writing your car off! Don't do it. Brakes are for stopping, gears are for going. Searchhe archive for explanations and it is covered in the bible. Big risk of locking the rear whgeels and doing an involuntary handbrake turn.

[Painey]

I've been shown the effects of engine braking on the track as it caused me to spin at rather high speeds and was very scary. Don Palmer demonstrated to me how easy it was to lock the wheels up so after that heel and toeing is the way forward.

[calvinhutt]

Thanks for the advice...

BTW - I am not talking about tyre-smoking red-line engine braking, more sort of 'taking my foot off the accelerator' as you would when driving safely at very legal speeds on public roads. I guess I really meant to say over-run......

Assuming that it is one or both of the lambda sensors, how easy / cheap are they to buy / fit? Would I be better going to a TVR place so they could plug in my ECU and do a full diagnosis?

[Ballistic Banana]

shpub said: Engine braking is a sure fire way to loosing your no claims bonus at best and writing your car off! Don't do it. Brakes are for stopping, gears are for going. Searchhe archive for explanations and it is covered in the bible. Big risk of locking the rear whgeels and doing an involuntary handbrake turn.

To an even more extreme( rev wise) this is why you never see high performance Bikes engine breaking, as... well you certainly would be flying ... literally, very dangerous

BB

[shpub]

Lambda sensors are around £130 each but your problem could be almost anything or even a combination and you can quickly spend thousands replacing the system by stealth. If it ain't obvious call in the professionals.

PS Lifting off the throttle is fine and not engine braking.

[calvinhutt]

OK, further to previous post, I collected the car from a local 'prestige/classic car' specialist, who were looking into the problem for me. I have not used the car in the last 6 weeks due to work and holiday, etc. I collected the car from the garage on Saturday, being told that all was well, and that they had cleaned various parts. It was immediately obvious to me that the problem was not sorted - lack of power, rough idle, etc. Shock horror, five miles later the car completely died on me. Neither the RAC or the same garage have been able to start the car since.

Spark is OK, fuel getting through OK. Even after many minutes of turning the engine over, the plugs were completely dry.

Can anyone help? From what I have read, it could be either ECU (but spark and fuel are OK, so is it?) or camshaft (the fact that is has gone from running normally to this state in perhaps less than 500 miles rules this out???).

Must say I am losing patience with the plastic rat after 4 enjoyable years and 40K miles of TVR ownership!

Calvin

[Mark.S]

Had a number of problems manifest over the past few weeks. Luckily booked a slot with Mark Adams at short notice (on the rolling road at Power Engineering, Uxbridge).

All faults spotted within an hour and rectified in another. Hopefully back again next week (if theres a slot free) for an upgrade or two and further tune.

Worth considering if your current specialist is struggling?

[gerjo]

I would have your TVR dealer put it on the computer first for a full diagnostic

if that doesn't help, go to Mark Adams for a full tune up

[griffmad]

Your symptoms sound very similar to the ones I had been experiencing .... down on power, and pinking under the lowest of loads at low rpm, and popping and banging on over-run.

Went through the whole electrical route but ended up being a worn cam that was deteriorating rapidly.

Not wishing to throw a spanner in the works but might be worth considering

Cheers

Rich

[GreenV8S]

Plugs completely dry is at odds with your suggestion that the fuel is OK. If you are cranking the engine over, it isn't firing and you *haven't* flooded it, surely that says there is little/no fuel getting in there. Is the fuel pump working? Usual suspects: wiring, fuse, relay, inertial cut off.

[simpo one]

'Must say I am losing patience with the plastic rat after 4 enjoyable years and 40K miles of TVR ownership!'

Hang in there Calvin, it's not the car's fault but the monkeys who didn't know how to fix it properly. 'Prestige and classic car' can mean BMW318 and Capri. Take it to a TVR expert like they say and best of luck!

[BogBeast]

griffmad said:

Your symptoms sound very similar to the ones I had been experiencing .... down on power, and pinking under the lowest of loads at low rpm, and popping and banging on over-run. Went through the whole electrical route but ended up being a worn cam that was deteriorating rapidly.

Mine had very similar symptons, whilst not the cam (as I had worried) but worn timing chain...

[calvinhutt]

thanks for the help everyone..... haven't completely given up yet. Had a worrying call from the garage this morning - they said that the compression was only 80-90psi. I haven't confirmed the figures in the bible yet, but this sounds a bit low???

Calvin

[GreenV8S]

calvinhutt said:

thanks for the help everyone..... haven't completely given up yet. Had a worrying call from the garage this morning - they said that the compression was only 80-90psi. I haven't confirmed the figures in the bible yet, but this sounds a bit low??? Calvin

Sounds very low - mine is about 150-170 psi.

[2 sheds]

calvinhutt said:

thanks for the help everyone..... haven't completely given up yet. Had a worrying call from the garage this morning - they said that the compression was only 80-90psi. I haven't confirmed the figures in the bible yet, but this sounds a bit low??? Calvin

125 is regarded as low !
Tim