[Mk2] [NA] Hi all, new member with an old problem ECU ?

[mrtv]

Hi all, we own a really nice P reg sw020 t-top uk silver with a black roof she's an old girl and we have had her 4 years.... 90k from new and has been really good until 6 months ago... she started running on 3 cylinders (number 3 is out) as you look at the car from the rear... i have replaced all plugs leads, disi cap and rotor arm..... then the fuel injection rail complete....had a compresion test and all ok... but she is still out on number 3 cylinder.... Im thinking it's the ECU and this is the ECU number i cant find one for love nor money PN 89661-17550 for UK Rev4.... would another work for now until we find the correct one ? Thanks All Adrian

[Peter Gidden]

Welcome to the forum.

Before going and buying another ECU, can you find a garage with a 'scope? It would easily tell if there is an injector driver down, or any other electrical issue affecting the smooth running of the engine.

If you're anywhere near me, drop in, i'll check it for free.

If not, try pulling each injector plug one by one, or connecting a noid light, see if anything changes.

[leeclark2010]

If your closer to bishops stortford than Barnsley I have a rev4 89661 17550 and a rev 3 89661 17500 if you want to try a known good ecu. I have gone to turbo power so these were gonna go the way of fleabay soon if you want. I am off work Friday to Monday if you want to pop round pm me.

[Driftlimits Performance]

I doubt it's the ecu.

Is it definitely a lack of fuel that is causing it not to run?

This is an easy one to find and fix. I'd have it running in an hour!

[mrtv]

Wow thanks for the replys! We live in Colne Lancashire btw... I have swaped the fuel rail out complete with all the injectors already and its still out on number 3 ...can't think of anything else bar the ecu, but would be happy for anyone to have a look ! Cheers Ade

[Rogue]

Just a note on your ECU. Since your car is revision 4, the ECU is transponder coded to the key - no other ECU will simply plug and play with your car. If you do get hold of another '550 ECU you'll need a key from the original car to go with it.

If you get a '500 ECU then you can repin your existing wiring harness to allow it to run, but this will bypass the immobiliser security.

[mrtv]

Thanks again for all the reply's ... I've been busy working and will take up an offer of someone to have a look at it next week,( Im working flatout till Monday Eve - 15 hr days) as lot's have Pm'd me to say It's possibly not the ECU... Thanks again ....what a great forum with loads of knowlegable owners... it might end up being a re-pin with a 500 unit ? but will keep you all posted... Ade

[Driftlimits Performance]

[rs007]

My dad - an old school engineer, electrical wizard and all round genius - once told me that a lot of problems with anything electrical are down to faulty connections. Folk just replace bits, and, because this gives a new connector, fixes issues.

Reason I mention this, is because my '2 has corrosion in the ECU plugs. Quite bad in fact; a couple of pins were simply gone, the only evidence they were ever there being lots of green smudgy powder.

Inspect every plug you can easily get to; you never now, and with the youngest of these being - what - 12 years old now? - don't be surprised to find problems in these areas.

Just throwing that idea out there.

[KPARRIS-JONES]

As was just said, you'll find that most MK2 MR2's are now at an age one the "bathtub lifing" graph where electrical connectors are due to be the major failing components.

It is very unlikely to be the ECU but whatever you do don't go prodding round the ECU testing resistance because that will pop it and then you won't be any closer to solving the original problem.

Your best bet it to ensure that the injector on 3 is getting a constant live feed if the others are - the ECU itself completes the injector circuit in most cars, simply grounding the return for the injector to fire it.

If you have a supply to the injector then get an inductive coil ammeter to test for the current switching on and off.

If the injector is getting the correct supply then you know that you have fuel and compression so it has to be spark.

At this point just give everything a damn good clean carefully, especially with the ECU so you don't knacker the pins or the electronics.

KP

[dan4]

My rev1 went down on a cylinder after a lambda probe shorted due to melted wiring touching exhaust, it melted part of the ecu board. Its only 4 screws to open it up....take a peek inside