Limp home mode & Unlisted ECU codes

[wipash]

2000 Legnum 2.4L GDi from NZ


I was on my way to work a few days ago, and lost pretty much all power in the middle of the motorway.
I coasted over to the side of the road and pulled up.
The engine didn't stall, but was idling pretty low. In neutral, when I stood on the peddle, it only revved to about 3000. Check engine light was on. Is this a form of 'limp home mode?'
When I was coasting over to the side of the road, gear selector light showed, D, but I don't think it showed which gear I was in.

Turned the car off for 5 minutes, restarted it and all was fine. Has been since.
Checked all the fluid levels, engine oil, ATF. Everything's fine (ATF may even be a bit overfull).

I pulled 2 error codes from the ECU (check engine light) using the flashy dash method today, it showed 77 & 78.
Transmission didn't report any codes, nor did the ABS (not that that would be relevant anyway).
I've searched the forum, but can't find these two codes described anywhere. Any ideas?


Edit:
Have just cleared the codes by leaving the battery disconnected for an hour or so. Took it on a quick 10 minute drive down the motorway and so far no codes have reappeared.

Edit 2:
Happened again on a drive this evening. Power lost but gear selector still worked (in tip tronic mode I mean, so wasn't stuck in a particular gear). Check engine light came on, and those 2 fault codes were back again as soon as I stopped. Argh! Car worked fine again after switching the ignition off for 2 minutes or so.

[alex k]

trouble code 77 and 78 means faulty acceleration sensor. you have to check wiring first and if there is no problem you have to install a new one.

[wintertidenz]

Check your air filter - it may have come apart and covered up the MAF, I think it was the HKS ones that were particularly bad for that.

I would also suggest checking all intake piping as well - something may have come loose or off.

[alex k]

trouble codes 77 and 78 has nothing in common with the air filter or MAF.

[ryanjames.powell]

Did you figure it out yet? It sounds very much like something to do with the Fly-By-Wire throttle system, either the APS, TPS or the throttle motor itself. Contact Steve at Mitsi Spec (http://www.mitsi-spec.co.nz), I've dealt with him before and he's very knowledgeable about these things. He can recondition most of those parts quite cheap.

[wipash]

Replies came a little late, and I took it to a mitsubishi dealer who told me as much. I've been having exams so haven't had time to look at it closely, but the air filter's all properly in place and the wiring in the plug looks sound. I'll have a proper look tomorrow. As for fixing the position sensor, would I be best to get an entire replacement throttle body? Or can you get just the sensor? I'll investigate the costs of reconditioning it as well. Perhaps I'll ring some wreckers also.

[Davezj]

you must be able to get second hand parts locally, that would be the cheapest and esiest to do

[alex k]

sorry but what's wrong with my answers? trouble codes are for acceleration sensor at your accelerate pedal, NOT for throttle body and NOT for airfilter!

[wipash]

Sorry Alex, I didn't read your reply properly ><
I took the throttle body to the mitsi-spec guy and he confirmed that there was nothing wrong with it. I just had it in my mind because that was what the mitsi dealers told me was wrong.

Now as for removing the accelerator sensor. Is there some way you can remove just the sensor? Or do you have to remove the entire set of pedals? The accelerator set up seems to be welded onto the brake pedal mounts, so I guess it all has to come out?

[alex k]

You just have to remove the sensor. please notice that you have to adjust after reinstalling it.
Maybe you can try to adjust it first for solve the problem.
For this you need Mitsubishi diagnostic tool.

[wipash]

Okay cool. For adjusting it, can I just use EvoScan via the ODBII port?

[wipash]

Replaced the sensor, everything seems to be fixed =] Thanks for the help