EFi Maesto cuts out - Fast Check says loads of faults

[Nick RS]

On my last trip out my 1985 MG Meastro EFi cut out for what seemed like no obvious reason. I'll describe the sympton.

There was a slight hesitancy and then it felt like the throttle cable had snapped. The car kept going but it wasn't possible to accelerate or maintain any sort of speed. I came down the gears and when I stopped and put the car in neutral it died. It would start a couple of times and die again on any touch of the accelerator. Then, after about a minute it would start fine and it would be possible to drive off as normal. It did this four times in about 30 miles so I've banished the car to the garage until I can fix it.

I've got a fuel injection Fast Check so I connected it up. Faults for throttle pot, air flow meter and coolant. I thought it wise to put these right before moving on to anything else.

Throttle Potentiometer. Adjusted it to get the two LEDs showing using the Fast Check harness direct to the battery; however only one LED shows from the harness in the footwell. I've checked all the continuity, open circuits and earths as suggested in Fast Check and they are all fine, but I'm not sure what to do with that now - any ideas?

Air Flow Meter. Similar to above, all the continuity and circuit tests were OK so all pointed to a faulty meter. I've now tried three different ones and Fast Check still records a fault, so again, not sure about that.

Coolant. All circuit testing OK so I have ordered a replacement sensor anyway as the temp gauge has a mind of its own, usually shows 25% across the gauge with occasional 5 second surges into the red zone which triggers Nicolette to say "Warning High Engine Temperature" (digi-dash)

I am beginning to wonder if my fuel injection Fast Check isn't right but I would welcome any thoughts out there as to next steps. I haven't driven the car yet but will do so after I've fitted the new coolant sensor. It does however start fine and run.


Nick

[Jeff Turbo]

First thing. Are you using the fast check correctly as it's highly unusual for all things to be faulty?. Possible coil fault, crank sensor could be dirty, faulty earth lead, have you also checked the fuel filter?

[Juanmacandel]

what is Fast Check?

[Jeff Turbo]

what is Fast Check?

As per picture below

[Jeff Turbo]

This is one fast check unit

[Nick RS]

Thanks Jeff,
Coil OK, I checked the connections to the crank sensor and the plug connector was oily and dirty inside so I gave that a good clean. I'll check the car over for good or bad earths tomorrow and hopefully fit the new coolant sensor if it arrives. After that I'll put everything back together and see how the car goes on the road. I am sure I'm using the Fast Check correctly but may well put it to one side for now.
Is there a test for the fuel filter or should I just replace it?

thanks again - Nick

[Jeff Turbo]

No, you just change the filter nick .

[Nick RS]

Since the most recent post I have changed the coolant sensor, adjusted the throttle pot and put on a different airflow meter. I've also cleaned up the relevant electrical connectors. Then I cleared a load of sludge from the pipes leading from the oil filler, as as well as a new filler cap. The result? The car runs as well if not better than at any time in my ownership. I took it on a longish test run, fully warmed up and found a fast road to see what it was accelerating hard to 70mph* as well as pottering about at lower speeds and in traffic. No spluttering or cutting out so a definite improvement over last week.

I still don't know what was wrong with it so I am going to get it booked in with a professional to set it up properly for the road. I have no CO analyser so can't set the mixture screw. Being an early EFi mine has an adjustable idle screw as well and I suspect that both have been fiddled with in the past; the car always gives a low CO reading at MOT time. There are also a few other jobs needing doing so I may as well get it all done at once.

Nick

[Jeff Turbo]

Excellent , well done and enjoy