[Technical] Engine lost its power

[apardal]

Hi

I was trying to post this on a more suitable section, but couldn't for some reason.

I have a 1985 MK1a and it's been a year since I last took it to a 24h endurance race in Ascari Spain where I had a problem with the engine. It was only after a good 14h of race that the car developed a loss on power when hot that kept us from running hard till the end. For 3 laps it would go fine, and then it would rev very slowly. We tried to rule somethings out right away, changing spark plugs and reading spark leads' resistance, without results. It all looked ok but the car would go when hot (without being too hot). We eventually finished the race and it's been a year. We are preparing the next race on march next year.

After all this time, the car now doesn't need to get hot to loose power. Even cold it has almost no power. I would say 80bhp tops. Looks like it is working on three cylinders @ low revs but when idling, if we unplug the spark plug leads one by one, we can't say one cylinder is not working. When idling, we can hear some pops from the exhaust and the engine stutters a little when we press the accelerator. The ECU gives out error 11 which is related to TPS, but TPS reads correct resistance on the plug.

I think the engine is not from this car and I'm yet to discover what do I have in terms of electricals. The car was imported from Germany in 1999 but the speedomoter/odometer is in mph. The engine has 42mm crankshaft journals and 20mm piston pins. ECU is 89661-17030. Grey injectors.

What we've done already:
- compression test ok
- fuel pressure ok at idle
- installed wideband and it reads rich all through the rev range (11.5-13.0)
- we can hear the T-VIS working
- changed to a different stock ECU and it idled the same
- tried different coil and ignitor
- adjusted timing with terminals E-T1 shorted and read 10ºBTDC
- we found some broken wires on the loom and repaired them
- measured all the loom coming to the ECU for continuity, voltage and resistance.

What we are thinking:
- does it make sense to change fuel pump and fuel filter even with rich fuel mixtures?
- test injectors?
- going to try new spark plugs and different wires just for the sake of it

Thanks in advance for your time!

Best regards
André Pardal

[apardal]

For later reference, it was one faulty injector that was causing the problem. Changed it and the car ran fine.