Griff 500 - Running issue/cutting out when up to temp

[HarryC-G]

Hi,
Having some pretty severe trouble with my '94 Griff 500 - only when it's reached operating temperatures. Hoping someone can give me a steer please on where to start my diagnosis...

Symptoms:
Ony when it starts to reach temperature (80c over over water temp) the problems start. The car doesn't overheat - temp never goes above indicated 90c on guage and never has. Recored rad, new fan switch and thermostat put a stop to that. Suddenly though, the car will start losing power, revs fall away to 0 and the car dies. It will start again to limp home but almost undriveable. It shunts and bucks really hard to the point of having to coast and feather the clutch in and out. Also smells rich. May then die again on the way home. As soon as it's cooled all the way down, it's then fine, until it gets hot again. I'm pretty sure it's directly related to heat - it happens like clockwork as soon as it's up to temp.

What's been replaced?
- Dizzy cap, rotor arm, HT leads, spark plugs, fuel filter and fuel pump all changed in 2021 - only 10k miles ago when it had rough running when hot issues with previous owner. Can't say if it was exactly the same symptoms I have now or not. Carbon sheaths were also fitted over plugs then to try and protect them from the heat.
- I've just changed the ignition coil this morning in the hope it would be the easiest/most accessible answer - afraid not. Same happened after test drive.
- Last year I had a non-start issue due to corroded fuel pump terminals into ECU. Replaced those and also terminals into main ECU relay.


I've read we're looking at all sorts from fuel vapour locking and ignition modules? Any ideas where I should start please, given the parts that have already been replaced? Much appreciated guys.

[Zeb74]

I had this kind of issue few years ago, this was due to ignition plug extenders. Are they still in place?
Could also be an air leak happening when the engine is hot.

[HarryC-G]

Thanks Zeb. I don’t have any extenders on the plugs and the HT leads are only 3yrs and not many miles old. Air leak is an interesting thought. Do you know if there are any common areas for that? Rubber pipe from MAF sensor to intake manifold is again pretty new and no obvious holes.

[Sardonicus]

Substitute the ign module for a known good unit first, what you describe is how they fail just like off the source vehicle Austin Rover/Ford , fuel smell is unburnt fuel because thats what it is, id look no further until you've investigated this item

[HarryC-G]

The little chap on the side of the dizzy, yes? 3 pin on one side and 2 pin on the other.

I can't help but notice a Rover Metro module is almost a quarter of the price on eBay and looks identical... Maybe I try one of those as well, in the name of science and penny pinching for the TVR community!

[Sardonicus]

HarryC-G said:

The little chap on the side of the dizzy, yes? 3 pin on one side and 2 pin on the other.

I can't help but notice a Rover Metro module is almost a quarter of the price on eBay and looks identical... Maybe I try one of those as well, in the name of science and penny pinching for the TVR community!

Metro ? Its the same part but get new old stock Lucas not the current generic junk thats being sold in a green box it will have an embossed logo too like this the real deal anything else is junk, dont mess around they dont come up often nowadays and you'd want one in the spares kit regardless https://www.ebay.co.uk/itm/133318230946?fits=Car+M...

Edited by Sardonicus on Tuesday 13th August 21:16

[Belle427]

Id go for a ste electrical component too which usually breaks down under the heat, check all your connections to the coil etc are all tight too.

[blaze_away]

As a first step the advice on thoroughly sorting any ignition issues is well worth doing.
1 specific odd ball with our Chims/Griffs is the possibility of mixing up the engine wiring and plugging the engine temp connection into the water temp sensor and vice versa, so check that out as its simple fix.

Next you'd be well advised to get RoverGauge which is software for looking at what the ECU is upto. The ECU controls all fueling and is incredibly useful at pinpointing any inputs/outputs problems. Over the past few years I have been helping many people sort out bad running by analysing RoverGauge logfiles for them. If you do get RoverGauge I will help you.

[lancepar]

blaze_away said:

As a first step the advice on thoroughly sorting any ignition issues is well worth doing.
1 specific odd ball with our Chims/Griffs is the possibility of mixing up the engine wiring and plugging the engine temp connection into the water temp sensor and vice versa, so check that out as its simple fix.

Next you'd be well advised to get RoverGauge which is software for looking at what the ECU is upto. The ECU controls all fueling and is incredibly useful at pinpointing any inputs/outputs problems. Over the past few years I have been helping many people sort out bad running by analysing RoverGauge logfiles for them. If you do get RoverGauge I will help you.

HarryC-G,
Why not put your region/country on your profile? Then maybe someone close can help with a RG and supply logfiles as suggested by Frank above.


Regards Frank from Lance.

[HarryC-G]

Sardonicus said:

Substitute the ign module for a known good unit first, what you describe is how they fail just like off the source vehicle Austin Rover/Ford , fuel smell is unburnt fuel because thats what it is, id look no further until you've investigated this item

Thanks for the help here. New module arrived yesterday and was fitted within 5 minutes. Runs like a dream now. It also helped some of the low end driveability that I’d put down to my sports cam with a few miles on running lumpy at low RPM. 👍🏻 👌🏻

[BEARDYB0Y]

Interestingly I'm suffering from the same issue on my Speed 6 Tamora.

Mine only really rears its head starting up again after a particularly short journey. One where the car hasnt had time to warm up fully (for example, when fueling the car on the way out). Last year it would run rough at idle but an off and on again would sort things out, now its progressed to cutting out while driving.

If its just a short journey thing then I can work around it but ideally I'd like to use the car for more normal car things.

[Sardonicus]

HarryC-G said:

Sardonicus said:

Substitute the ign module for a known good unit first, what you describe is how they fail just like off the source vehicle Austin Rover/Ford , fuel smell is unburnt fuel because thats what it is, id look no further until you've investigated this item

Thanks for the help here. New module arrived yesterday and was fitted within 5 minutes. Runs like a dream now. It also helped some of the low end driveability that I’d put down to my sports cam with a few miles on running lumpy at low RPM. ???? ????

Good job hope you went for a NOS Lucas unit and applied the heat transfer paste that will last you well for many many years unlike the alternative crap

[Belle427]

Very simple beasts that rely on quality components to run well but sounds like your sorted now.