Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Starting and running issue1991 Plus 4 M16 engine

If the spay patterns all look the same then the basic injector function is looking good the only other check on that is a timed volume delivery.

I’m not sure this engine has a carbon canister unless you can point me in the right direction for it. I have changed all the vac hose and can feel pressure at the ecu, so I don’t think it that. I could possibly blow an air line from where the ecu is (no on to the ecu) to check it’s clear…

I think this is where I’m headed. Even if it’s not that we don’t plan to sell the car.

I have been thinking it is surely more likely a device, but I have replaces lots of sensors now. Another on I need to check is if there is a switch on the throttle, but I think it’s just the position sensor and that checked out ok. :-(

In case anyone is looking at this in the future we eventually resolved the issue with a new wiring loom! So not entirely sure where the issue was but it was an electrical fault.

thanks for letting us know Ben, very impressed by the comprehensive list of checks you did.

Fairly sure there has been a resent post on similar issue and it turned out to be the ECU. He sent it off for repair and assessment and it came back fixed for a very good price!

Hopefully someone will respond with that info.

Hi, I had same problems with my 1991 +4M16 engine ,at the end t was the idling air stepper motor sitting on top of the throttle, put it out placed in a standard and spray some WD40 on top for several days, put it in again and idling again at 750-800Rpm. Best regards, Bart Bonnaerens/Belgium

Hi Ben,
I am glad that you found the answer: my own guess was that it was electrical due to me experiencing a not entirely dissimilar problem years ago with an M16 Plus4 which turned out to be the alternator which and the end of the long list I decided to replace. The engine was sometimes hard to start but would then run well until 4000 rpm when it would cut out and idle for a few minutes. If anyone else comes across this problem, the altenator would be one of the places to look.

just another point. If the car is running/moving, and as you slow down, idle drops off and the car dies, it's the speed transducer on the speedo cable! Do not buy a new one for $100.... the part is a $.10 resistor you can replace at home. In the mystery box is a resistor, magnet and a reed switch. On mine, water shorted the resistor. Simple fix discovered after I spent money on a new one. Again, it will not idle if the car is coming to a stop. The box sends an idle mixture message to the ECU. Mine's a 91 plus 4/M16.