1994 Griff 500 fuelling issues
Discussion
Hi TVR fanatics,
As a lifelong fan, I have finally saved enough pennies to "rescue" possibly the roughest Griff (albeit it has an MOT) in the country.
Plenty of cosmetic TLC required, the usual electrics problems etc, but the most pressing thing is the engine. Brain dump of what has happened so far...
When I got the car it was running so rich it was choking itself out - wouldn't idle or drive when warm. It went back to the garage who have cured the problem with various component changes and had the ECU checked and diagnosed as "damp".
Since then the car runs well unless it is on very light throttle. I have read a lot about the dreaded "shunting" but struggling to diagnose that this is in fact what it is, having only had cars on carbs it feels like a lean mix from the seat of the pants.
The engine temperature can also be all over the place. Last night coming back from Southhampton on the motorway it was below 90 on the gauge, but the drive down in the morning nearly had me in the red at times.
Mark T (Blitzracing) has been really helpful in supplying rovergauge and the cable and sitting on the phone trying to get it to work, but with no success - my car doesn't want to speak to Rovergauge for some reason.
I've just had a crypton tune done and ignition was performing well and timed correctly, but now a weak mixture diagnosed. Car idles at 950rpm and cannot be made to drop to 800-850. It also has a suspicious "tremor" when idling or on light throttle cruise. Whilst working on it the pressure cap on the expansion tank blew as temp climbed, despite fans. Technician recommended I dip the coolant to see if there was a head gasket issue, which I will do together with a compression test.
No air leaks identified either by me or the technician.
I would dearly love to get some data out of the ECU but have clearly run out of IT talent. Is there anyone in the Hitchin / Stevenage area who uses Rovergauge that could point out where I'm going wrong?
All advice gratefully received!
Chris
As a lifelong fan, I have finally saved enough pennies to "rescue" possibly the roughest Griff (albeit it has an MOT) in the country.
Plenty of cosmetic TLC required, the usual electrics problems etc, but the most pressing thing is the engine. Brain dump of what has happened so far...
When I got the car it was running so rich it was choking itself out - wouldn't idle or drive when warm. It went back to the garage who have cured the problem with various component changes and had the ECU checked and diagnosed as "damp".
Since then the car runs well unless it is on very light throttle. I have read a lot about the dreaded "shunting" but struggling to diagnose that this is in fact what it is, having only had cars on carbs it feels like a lean mix from the seat of the pants.
The engine temperature can also be all over the place. Last night coming back from Southhampton on the motorway it was below 90 on the gauge, but the drive down in the morning nearly had me in the red at times.
Mark T (Blitzracing) has been really helpful in supplying rovergauge and the cable and sitting on the phone trying to get it to work, but with no success - my car doesn't want to speak to Rovergauge for some reason.
I've just had a crypton tune done and ignition was performing well and timed correctly, but now a weak mixture diagnosed. Car idles at 950rpm and cannot be made to drop to 800-850. It also has a suspicious "tremor" when idling or on light throttle cruise. Whilst working on it the pressure cap on the expansion tank blew as temp climbed, despite fans. Technician recommended I dip the coolant to see if there was a head gasket issue, which I will do together with a compression test.
No air leaks identified either by me or the technician.
I would dearly love to get some data out of the ECU but have clearly run out of IT talent. Is there anyone in the Hitchin / Stevenage area who uses Rovergauge that could point out where I'm going wrong?
All advice gratefully received!
Chris
Presuming your Griff is still on the standard ECU with distributor, the idle speed is adjusted by setting the base idle first with the bypass hose blocked or clamped shut. The screw is next to the plenum mouth on the RHS as you look in from the passenger side. It may be covered by a plastic plug.
Do a search for 'base idle' and you should find plenty of threads. The ECU / stepper motor will then hold the idle speed. Otherwise, you'll need to check the timing setting on the distributor body. At idle, this is with a strobe light and the vacuum advance disconnected (although it has little effect at idle), old school tuning!
Do a search for 'base idle' and you should find plenty of threads. The ECU / stepper motor will then hold the idle speed. Otherwise, you'll need to check the timing setting on the distributor body. At idle, this is with a strobe light and the vacuum advance disconnected (although it has little effect at idle), old school tuning!
Thanks Ian, yes I'd set the timing etc manually up and it was all working as it should do which the Crypton tune confirmed.
Mucked about with the base idle screw in no scientific way - the ECU however just seemed intent on holding it higher than I would like. To be honest the idle a minor annoyance compared to not being able to see the ECU readings to identify the source of the lean running.
What rpm does your car idle at and is it perfectly smooth or does it have a slight tremor? Interestingly I have an MG with a 3.5l V8 and it also has a tremor at idle...
Mucked about with the base idle screw in no scientific way - the ECU however just seemed intent on holding it higher than I would like. To be honest the idle a minor annoyance compared to not being able to see the ECU readings to identify the source of the lean running.
What rpm does your car idle at and is it perfectly smooth or does it have a slight tremor? Interestingly I have an MG with a 3.5l V8 and it also has a tremor at idle...
The ecu is standard Land Rover apart from the map, so to rule out a mildly moist ecu with comms problems maybe try and beg or borrow one from anything with the 14CUX system on it just to test everything else? Just don't put it under too much load as the map will be too lean.
Shunting can be caused by running lean as the cam and induction don't work together very well with emissions control - you can remap the ecu now and as far as I know all it does to sort the shunting is tweak ignition and chuck a load more fuel at it at low-ish engine speeds.
Air flow meter or temp sender can be dodgy afaik but it is a bit hit and miss diagnosing unless you can get rovergauge or ecumate to work.
When I bought mine it had been imported back from Japan and was running really badly - local guys couldn't sort it and possibly made it worse. Best thing I did was get it trailered to Joolz at Kits and Classics in Chesterfield - he sorted the thing literally in minutes. Recommended!
Dash gauge is notoriously unreliable as the sensor position TVR used is right in the cooling airflow so at motorway speeds or in cold weather it'll tell you all sorts - but it's usually reading too low, not too high, which sounds a bit worrying - I think rovergauge will tell you what the ecu sender is seeing once you can get it to talk. If fans kick in and out maybe once every minute or two when it's sat idling that would be a good sign it's not getting too hot.
And congratulations - it'll be worth the effort. Pics!
eta - tremors could be misfire? Plug extenders/leads can fail. New rotors etc can be crap quality which doesn't help. Tickover at about 800ish can be wobbly, 900's smoother.
Shunting can be caused by running lean as the cam and induction don't work together very well with emissions control - you can remap the ecu now and as far as I know all it does to sort the shunting is tweak ignition and chuck a load more fuel at it at low-ish engine speeds.
Air flow meter or temp sender can be dodgy afaik but it is a bit hit and miss diagnosing unless you can get rovergauge or ecumate to work.
When I bought mine it had been imported back from Japan and was running really badly - local guys couldn't sort it and possibly made it worse. Best thing I did was get it trailered to Joolz at Kits and Classics in Chesterfield - he sorted the thing literally in minutes. Recommended!
Dash gauge is notoriously unreliable as the sensor position TVR used is right in the cooling airflow so at motorway speeds or in cold weather it'll tell you all sorts - but it's usually reading too low, not too high, which sounds a bit worrying - I think rovergauge will tell you what the ecu sender is seeing once you can get it to talk. If fans kick in and out maybe once every minute or two when it's sat idling that would be a good sign it's not getting too hot.
And congratulations - it'll be worth the effort. Pics!
eta - tremors could be misfire? Plug extenders/leads can fail. New rotors etc can be crap quality which doesn't help. Tickover at about 800ish can be wobbly, 900's smoother.
Edited by andy43 on Wednesday 28th November 15:26
You'll nail a lot of issues with a rolling road session and a decent operator. Getting it remapped will sort the shunting also.
I recommend larger injectors as at standard they're stretched to the limit.
when i did mine multiple issues turned up inc leaky HT leads, dodgy distributor, poor plugs all playing their part and hard to diagnose individually.
I used Mark Adams who was highly recommended and delivered the goods.
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