Limp home mode

[mgainaussie]

I'm not a frequent user of this forum, but some of you may remember I have a S2000 engine in a 1960 MGA. I use the standard ECU, and today on a Club run, the car went into limp home mode 4 times. Each time, I would stop, turn the ignition off, wait a minute or so, then re-start the car, and it ran perfectly for another 20 minutes or so, then the problem resurfaces. I have noticed a little "pinking" in the motor, so would this be a knock sensor problem, and the computer puts the car into limp home? I can't understand why on re=start, the car is normal again?

Any info helpful, as I am from the SU carb brigade!

Cheers
Gary.

[curtis265]

Hi Gary, unfortunately i'm not too sure what's happened.. maybe you fouled a sensor or something. is it throwing a CEL? If so it might be worth trying to scan it. It might be normal because you might have it wired to reset the ECU each time it's shut down?

Also can we see some pix of this project of yours?

[AusS2000]

The combination of pinging and limp does sound like the ECU is hearing it and reacting to save your engine. What other mods do you have and what fuel are you using?

The real way to diagnose this is with a ping mic (set of headphones and a filter that allows you to isolate the ping frequency). Then you can address why you are pinging.

Whereabouts are you BTW?

[mgainaussie]

AusS2000...Gold Coast. I'll have to find someone in this area that can help, without going to a dealer.

[ECU-MAN]

wire up the MIL and SCS and check the ECU for codes. it will then tell you what is wrong

[mgainaussie]

Excuse the older vehicle ignorance, but what does SCS mean?...I have the large Honda workshop manual, but cannot see this mentioned.

[Boost]

Service Check Signal. There is a pin on the ecu. You can read the blinks off the dash to find out what error code its throwing.

[AusS2000]

The pins (actually sockets) are under the dash. They are blue plugs in a green sleeve. You short a couple of them out (check manual for which ones) and turn the ignition on. The CEL will blink out a pattern.

Of course all of this assumes you have the full F20C wiring harness and the dash cluster installed in your MGA (which would be a crime).

[mgainaussie]

Thanks for all you guys help. I was just thinking about when the LHM occurred, and it was usually just after a corner. I checked the engine oil level when I got home, and it was at the lower level on the check stick...I have of course now topped this up, but would the low level, and a slight surge, cause the LHM to cut in?

To answer AusS2000, yes, I have the F20C wiring harness ( less any items that are not needed for the MGA), but connected up to modern intruments similar in looks to the MGA. If I knew how to load some photo's I would.