Topic

I have an intermittent problem With my 97' MGF Mk1.
On hot days (and I mean Aussie hot days not what most of you Poms would call hot) my car will sometimes just cut out. this usually happens after the car has been parked for a sort while, then when I go to take off from the first traffic light it coughs and splutters then dies.
If I open the boot for a few mins to let the heat out it will then start Ok and be no further trouble.
The engine bay fan appears to start and stop as it's supposed to in fact I've added 2 small extraction fans to the engine fan circuit, they're mounted to the engine cover grill and they do pump out quite a bit of hot air from the engine bay. But the problem still persists in spite of them.
As I understand it the diagnostic system is bloody near useless on MEMS 1.9 ECUs and as this problem is intermittent every time I go near the car with a multimeter the car behaves itself and works perfectly.
I do have a bloody huge Bosch Diagnostic Engine Analiser in the shed but it's going to be a pain in the bum to try and simulate the conditions in the shed.
So I'm hopeful that someone here might have a clue as what the cause might be, although I realise as most of you wouldn't get the weather conditions that seem necessary for the problem to occur, your unlikely to have had the same problem happen to you.

BTW, I didn't fit the extraction fans to try and solve the cutting out problem, I fitted them because of how hot it gets in the engine bay in our climate, I'm worried that all the wiring insulation, hoses and electrics wont last as long as they other wise would in a more hospitable environment.
The fans I used came from an agricultural quad bike with a water cooled engine.
They look a lot like computer fans but they're water resistant.

Coober I drove mine in that stinking heat we had after Xmas. No problems. Someone on here may have some ideas. Dave

sounds to me you have a fuel pump problem
something is expanding in the heat

I think it's more of an ignition problem as I forgot to mention that it will happily rev in neutral but put it under load and it suffers.

I'm thinking hose connections to the inlet manifold/throttle body. Worth checking especially the little hose to the ecu.

Cheers, I'll check those, but I can't help feeling it's something electrical.
Like something electronic breaking down in the heat, a sensor, ECU or even something the interfaces with the ECU like the imobiliser etc.
Like the heat soak from recently running combined with the hot weather causing a problem that goes away once it's had a chance to cool a little.
The worry is that one day it will stay broken, probably a long way from my workshop!

when you say cut out does it shut off really quick or falter then stop?

Falter and stop describes it.
Sometimes it'll start again straight away but as soon as you put it in gear it falters and stops again but if you let it cool for a few minutes then restart it's fine and other times it won't restart until it's cooled for a few minutes then it's OK.

Hmmm its a one of many
Fuel, either filter, pump, relay behind the ECU or the fuel shut off relay
Ignition not plugs or leads as that would be a multiple fail of parts but Coil packs or distributor
wiring/ECU could be the boot wiring shorting out to earth or the ECU wiring
it could be the ecu temp sensor tripping it on to choke but I wouldn't have thought it would stop it running

I guess its just try a few and see

I suspect that I'm going to have to move a couple of trailers the TR7 and a heap of other stuff outta the way so as I can get it up to the Bosch diagnostic machine and try to get it hot enough to fail whilst I go over everything time and time again until I find it.

Maybe this will help?
Don't move the TR7, it probably needs a rest. Maybe you could try one of these gadgets hooked to your phone or laptop on the go. They are cheap! I have ordered one ,it hasn't turned up yet so not sure how it all works??

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=360604575939&ssPageName=ADME:L:OU:AU:3160

That unit highlighted will only work on mems3 versions of our cars, so unless you have at least a MK2 F, it won't work.
Only mems3 is OBD2 compliant.