MR2 Owners Club

It would be worth checking that the injectors are working and not gummed up with old fuel.

It is the signal to the injectors. i just wired 1 injector straight to the battery and the car ran and responded to the throttle, but only on the one one cylinder.
I only ran it for about a minute as i know running a 4 cylinder engine on just 1 cylinder is not the best also one of the o rings on an injector was leaking petrol but got spare o rings so can easily fix that.

I had tested the injectors out of the car and they all work fine, i ran neat redex through them when testing just to check if they were clean.

After reading all of the symptoms and tests you have done it appears to be a power supply issue to the injectors, however you mention just powering one injector but all of the power side pins are connected to each other so if you T'd into one it should have powered them all, please confirm details of that test you did.

If it is lack of power check the N1 connector in the boot, it suffers from corrosion badly and the injector power supply is in there.

If that is ok and still no power check the fuses in the engine bay fuse box and replace the inj relay.

Where in the boot is the N1 connector. To power the injector i peeled back the insulation cover and inserted the ends of the multimeter leads one to each wire and connected the other ends to gje battery.

Oh wow you ran the ground side to the battery as well? Did you try just power to the power side? That would confirm lack of power alone, the ECU grounds the other pin to varying degrees which controls the injector duty rate from 1% at idle up to 85% under full load.

Switch ignition on and check the power side pins all show 12v ,The power feeds are all the same colour across all four plugs.

Confirm if there is power or not.

The N1 connector is in the boot next to the ECU. Take off the trim panel on the engine bulkhead to access it.

Have you established if there is power or not to one side of the injectors?

I've got the car to run better by just connecting the injectors of cylinders 1 and 4 to thd earth only on the battery. Sound like it now running on 2 cylinders now. I'm going to make a wiring loom connecting all 4 cylinders to earth this weekend and report back. The supply to the injectors is supplied by the car.

I'm sorry but what you are doing is completely wrong, please do not connect the injectors to the negative on the battery! They are supposed to be triggered by the ECU and only that, you are flooding your engine with fuel and it will never work like that, please don't make a loom up to power them from the battery, you're heading in the wrong direction with that, also if this is a Mk1b they will be low impedance injectors, they are not meant to have full power applied to them, there is a resistor pack near your coil which throttles back the power going to them, you risk damaging your injectors wiring them straight to the battery, a very bad idea.

I asked if you had power only to one side of the injectors, reading between the lines from what i can tell if you are only supplying ground to them i presume they are getting power. Please measure the voltage at the power side of all four injectors to confirm.

If there is power at all four that means you have an ECU signalling issue, so either bad capacitors in the ECU or the main ECU ground is poor, you will find that located on the inlet manifold, it's the only ground point on the manifold, clean it and make sure it is tight, if that doesn't improve things i suggest another ECU, send me the part number from yours and i will send you a free one to help fix it, the part number will begin 89661-xxxxx

^^good advice. Hope you can test properly and solve problem.

Thanks for the advise. I will check the ground on the inlet manifold if it stops raining and take note of the part number as well.

benckj wrote: ↑06/09/18 9:52 ^^good advice. Hope you can test properly and solve problem.

+1
If you do the testing exactly as Paul asks and report the results he will guide you to a solution
I doubt there's anyone in the UK with more knowledge and experience on MK1's than him

I have checked the ground from the manifold only wire i can see goes from the bolt that also holds the engine lifting lug to one of the bolts that secures the radiator cap and pipe work to the body.
The number on the ecu is 89661-17070.
I have just tried it with jump leads cause my battery is now low on charge one to the positive on the cars battery and the other to the other lifting lug but with no joy.