Friday morning as I was about to get on the freeway, the EML, SES and tire light lit up and the car went into limp mode. Shut off the car, restarted it, SES stayed on and drove it over to East Bay MINI to drop it off for them to look at (I've had the car two weeks, and this was its second service visit).

Diagnosis: DME Fault P1688 - Electronic Throttle Monitoring - Air Mass Fault. The checked the wiring and connectors for the MAP and throttle sensors, check for air leaks. Reprogrammed the DME and cleared the fault memory out.

Now today I'm out driving.. go to get on the freeway (after having driven for about 90 minutes on surface streets and such) and boom.. back into limp mode, same symptoms... pull over to the shoulder, restart and am back on my way.. except that now I also notice that I almost have to floor the car to get it above 3k rpm in any gear.

Finally make it home, and rev it to ~4k and the limp mode reactivated.

So obviously it wasn't just a software problem.. and I am starting to think they don't have mechanics.. just technicians who follow step by step procedures.

Not even 1000 miles on it yet.. and back to the shop it goes.

Car details: 2005 MCS (manual).. no mods done at all.

Any thoughts?

 

Same thing happened Friday night to me. Accelerated away from a stop and limp mode. Restart take off again and keep RPMs low and have no problem but not a lot of power. Try getting the RPMs up again and limp mode. Restarted and eased it home. Next morning, take it out on a section of road I really know and see what kind of power I'm lacking and to test different speeds and gears. I ran up and down the RPMs a bunch of times keeping it under about 4000 and after about ten minutes of doing this, bang, full power. Been good ever since. I believe it might have been the bipass valve stuck open because the engine felt like it didn't have a S/C, powerwise, and the return of power was instant; like someone through a switch. I haven't read the code yet so I don't know if it's the same as yours, but your description was exactly what I felt. Good luck.

Steve

 

'Friday' is back at the dealership today getting looked at, I mentioned the supercharger bypass valve being potentially stuck open, and the service writer included that in the comments.

Got a nice PW/PW MC with CVT as a loaner while Friday is being doctored. The CVT leaves a bit to be desired, I will say (compared to the wife's MC standard).

Will post more later when the situation is resolved.

 

You should have them replace the boot between the TB and the SC. It is prone to leaking (pitting) and would throw a code similar to what you got. I had this problem. Dealer replaced the boot and I have been fine ever since.

 

I had the waste gate valve replaced on my '05 MCS and the tech that worked on my car said they had seen a lot of '05s in with the same problem. I'll pull my paperwork when I get home and see if it tells what faults came up.

My symptoms were exactly what SRTech wrote above. The fault would only throw if I went above 3500 rpm.

 

Dealership called, they are replacing the supercharger bypass valve as the car apparently had multiple errors related to it. Another overnight stay at the shop (part not in stock) out of 18 days of ownership.. it'll have been at the dealer for 5.

 

Guess I should order a new bypass valve before it fails completely since I am getting some yo-yo and hesitation I didn't have before. No codes or limp mode on my 200 mile commute, though, and it seems as strong as ever except for the above observations.

Steve

 

Glad they got to the bottom of it. All this over a part that isn't even technically necessary on a supercharged car. BTW the specific fault codes weren't listed on my paperwork...it only says "fault code for 2/3 airmass calculation".

 

Same error code as before, they replaced the supercharger bypass valve, and so far so good. Sadly due to related circumstances, the car will be back at the dealer once again next week for two more days to get the driver's side aero kit skirt resprayed. Maybe then it'll really feel like its mine

 

My car threw this code over the weekend while jamming up to the Sierra. P1688 didn't put my car into limp mode thank god, but is making me wonder what the heck is going to happen next.

Anyone get anything besides have the BPV replaced, I doubt that part has anything to do with this error code?