Low rev stalling

[MarkB45]

Hi
I have a1997 Chim 500 with Taraka performance upgrades

Car had been suffering intermittent low rev stalling & sticky tickover (very occasionally sticks about 1500rpm while out driving)

Recently I’ve replaced the
Ignition amplifier module,
Stepper motor,
Distributor cap,
Rotor arm,
Coil

Also reset the ECU (unplug/plug-in)

All the above have made improvements but still have the issue albeit intermittently,

I know it has been very hot weather when I’m out (mid 20s to low 30s) and very hot under bonnet but as it restarts on the key immediately after stalling and drives fine when on the gas

TBH I’m baffled and don’t know if it is fuel, air or spark related

Any ideas?

I’m in West Sussex and wonder if anybody can recommend a good V8 specialist, was at Mole Valley for a very short period but didn’t suffer issue when with them as I’d recently fitted all the parts & they reset ECU prior to test drive, and this is when I saw the best improvement


Thanks
Mark

[blitzracing]

The things that hold the idle high are sticky stepper (replaced), air leak around the plenum,, throttle pot reading high or random speed input to the ECU from the speedo calibration unit.

Idle issues- anything that makes the idle drop faster than the ECU is programmed to cope with. ie:

Ignition Misfire, Rich mixture - possibly AFM failure when hot, or wrong temperature reading to the ECU . Over lean mixture like an air leak.

You really need diagnostics to look at the sensors, guesswork is not the best option as there are so many variables

[MarkB45]

Blitzracing

Thanks for comprehensive response, does seem I’m well out of my depth

I think I’ll get it back to SportMotive as that is where I bought it earlier in the year, and they do seem very knowledgeable with TVRs so with undoubtedly find the cause

[O mage]

It would be worth cleaning the hot wire in the afm easy to do just be delicate with it.

[MarkB45]

Thanks
Is the AFM hot wire in PIN5, as below
Red/black - ground...........Pin2
Blue/green - afm signal.....Pin3
Brown/orange - 12v...........Pin5
Blue/red - CO Trim............Pin6

[O mage]

That's the supply yes but the hot bit is in the air flow inside the casing, Take it off remove both end housings and you will see it. before you do that have a look at the mesh at the front if its dirty then yes the whole thing needs cleaning and check the air ducting to filter for damage if that's the case.

[lancepar]

MarkB45,

YHM

[SILICONEKID 357HP]

Is the throttle cable and linkage ok .

Mine get sticky on hot days .

[LLantrisant]

also had problems with low rev stalling....and finally all improved (idle, starting, general performance, emissions) when channging the timing-chain (as it had quite of lot of slag) and it further improved when i cleaned the injection system by using an intake-cleaner spray.

i did not follow all the usual advises changing parts....as its quite strange why in a tvr common-parts working well in a rover should fail so often.

this said: have you ever driven the car for longer journeys frequently? or just the ususal sunday-morning pub or car meeting visit locally? those cars need to be driven...short distance drives can built-up deposits here and there, which have similar effects on your engine as described.

[MarkB45]

Thanks to all those that replied
After fitting the new parts (original thread) the only other thing I’ve done is cleaned the injectors and taken her for a proper drive
I’ve also stopped doing the short drives in local villages

As a result she is driving well now
I hoping that is all that was needed

[QBee]

Blitzracing is far more of an expert than I am.

One other thought comes to my mind - what spark plugs are you using and in what condition are they?
The standard ones are NGK B7ECS if I remember correctly. When I used them they fouled far too readily.

My car has been on NGK BPR6EIX for a long time now and it runs a lot better. These are iridium, so you change them a lot less often.
Any 6 rated plug will be better for the car than the specified 7s, which I think are too cold for the car. My TVR expert agrees and now fits 6 rated plugs, not 7s.

Just one word of warning - there are a lot of fake NGK plugs out there, so buy from a reputable source, not the cheapest on Ebay from China.