At Bedford on Monday my engine played up and I’m interested in all your thoughts for a fix.
It worked fine for about 4 laps (they’re long, 4+ miles) then the 5,500rpm limiter cut in. At this point the water temp was about 80oC and the oil probably low 90s. Sinclaires were supporting the day (and I was both highly grateful and impressed at their free service, would have no qualms about taking my car to them) and quickly spotted the connector to the air intake temp probe had come off. This seemed like a simple fix as it would have suggested that the ECU was getting upset at the point it started to read the air temp - yay! Sadly that wasn’t the end of the story.
Having done the ‘on ignition, 5 slow presses on the accelerator, off/on ignition’ ECU reset I went out again and the same thing happened. I returned to Sinclaires and we read the fault codes from the std Lotus 190 ECU (with safety re-prog upgrade). There were about 8 including things like ‘air temp fault’, ‘water temp fault’, ‘multiple random unknown misfire’ (nice one that ). We cleared them all and I went back out, it reoccurred, and I returned to have the ECU read again, it gave the same multiple results.
To try and see if it really was a misfire I felt the plug connectors and then ran the pyrometer over the top of the engine to see if there was any temp variation. The plug connector closest to the middle of the car felt hotter but the pyrometer showed a pretty even temp across the top. A bit of WD on the rear-wheel speed sensor and in the plug connectors made no difference (original leads BTW). [Big thanks to the Edwardz Boys for help with this part ]
The assumption was it was a silly electrical fault causing the ECU to get confused. The most likely contender was considered to be the Brown sensor so Sinclaires swapped it out - no change.
Interestingly, if I simply killed the ignition and turned it back on whilst on track (not overly recommended at speed!) the problem went away for a lap or so. Still, that’s hardly a fix you want in order to be confident braking from 130 in to a 90mph bend!
We couldn’t really get to the bottom of the problem, which is a shame as it seems like the type of fault that’s going to be hard to reproduce away from the track.
So, what are you thoughts? Any ideas/suggestions? Please bear in mind that I’m not overly mechanically savvy, so it may well need to be professionally investigated. But if there is anything I can either try myself or suggest to a whoever looks at it I’d be very grateful.
Does anybody know the temp at which the ECU starts to use air temp?
Thanks in advance.