2007 SAN, ZR6 Sporadic Limp Mode

[matts]

Our engine goes sporadically into limp mode, usually after ca. 10mins of cruise. Most of the time power cycling is enough and the engine runs smooth for the rest of the day. No other issues (enough power, smooth sound, temp/pressure on dashboard fine)

The small codemate only shows a "81" = other issues.

any hints? If I got it right there are no more temp/pressure switches on this engine.

Thanks very much!!

[bradb]

This may not be relevant, as my only experience is with a 1994. In the '94, it was described pretty clearly in the manual that the only two things that will put it into limp mode are the temperature and oil pressure sensor. Your manual may have some info with respect to your model.

As well, (on the '94 at least) the gauge sender for temp/oil pressure is different from the sensor for the ecm. You may have a bad sensor but the dash gauges will still read fine. The sensors go high when triggered, so (again, on the '94) you could disconnect the sensors one at a time and if it stopped going into limp mode that was the sensor that was triggering it. Of course, just keep an eye on the dash gauges for high temp. Alternatively, the sensors were pretty cheep and could both just be replaced.

That said, there were a few other things that were known to cause it to go into limp mode when it shouldn't have. I've heard this referred to as "uncommanded limp mode" as neither sensor was actually sending it a signal to go into limp mode. These things included bad plug wires or connections, bad ecu, etc.

Good luck with your troubleshooting

[biacs]

Very curious as well. I had this happen twice yesterday on an average boat ride. I was told previously that your battery cables could simply be corroding from the inside even if they look fine. Our boats are both similar in age.

I’m curious about putting in new battery cables over the winter and see if that alleviates the issues. My oil pressure and engine temp both read normal at all times, but lose throttle until I restart.


2006 SANTE - Bull in a China Shop - Central IL

[matts]

Thanks!! If I read the manuals correctly, there was a (big) change from 2006 onwards where the binary switches were removed (and I assume replaced by software switches in the ECU).

Concerning battery cables: Sounds a bit far fetched to me, but could be checked by measuring the voltage (drop over the cable). During operation, the alternator is powering the electrical system, therefore the current in the battery cables is flowing in the other direction (charging batts).

So, still open for suggestions ;-)

[Hexa73]

Can you check if you have other code than "81" with a Diacom ?

Manual say MAP sensor fault can cause limp mode, see doc attached at page 108.

The MIL is off when engine running ?

Edit : I see you not far from me, i'm near to Geneva lake

[matts]

Thanks very much for that manual! Seems very extensive, not read yet, but was missing something like that.
Yes, MIL is off.
Was not sure, if it's worth getting a Diacom, mechanics don't rent it around here...
One mechanic told me, that there was an error code about over heating, but my trust in that shop is not too high

[matts]

finally some error codes, I happily accept explanations ;-)
otherwise I would check the throttle sensor.

\par \tab (81) Throttle Actuator Control (TAC) Malfunction
\par \tab (81) TAC Fault - PPS1 Range
\par \tab (81) TAC Fault - PPS12 Corr
\par \tab (81) TAC Fault - Lmtd Authority