Unexplained Limp Mode

Pharmacist · 10-24-2009, 06:48 AM

like someone said before, could be a sensor that malfunctioned or was accidentally disconnected. things like these can confuse the heck out of the ecu. i remember once i was doing work on my old intrepid, and forgot to reconnect the camshaft position sensor, which caused the ecu to cut engine rpm at 3500

Modshack · 10-24-2009, 09:57 AM

Quote:

Originally Posted by Pharmacist

like someone said before, could be a sensor that malfunctioned or was accidentally disconnected. things like these can confuse the heck out of the ecu. i remember once i was doing work on my old intrepid, and forgot to reconnect the camshaft position sensor, which caused the ecu to cut engine rpm at 3500

Yes....Limp mode can be caused by any number of things. It usually involves a sensor that is not outputting enough of a signal, or one that is out of range. The ECU sees this and decides it is not happy with allowing the engine to rev above XXXX RPM's with that particular sensor value where it is.

It's either a Glitch or a genuine problem. Re-boots fix the glitches..

370Zsteve · 10-24-2009, 10:54 AM

Somebody please find my old Buick that only had an engine with 8 spark plug wires and a couple of coolant hoses outside the block and nothing remotely resembling a computer. Thank you in advance.

vipor · 10-24-2009, 10:59 AM

Quote:

Originally Posted by 370Zsteve

Somebody please find my old Buick that only had an engine with 8 spark plug wires and a couple of coolant hoses outside the block and nothing remotely resembling a computer. Thank you in advance.

got a 71 c10 c/d sitting in storage. has a very similar motor

Dallas-Z · 10-24-2009, 02:17 PM

Well this news is decent good news that others have seen the same problem and even mention the exact rpm (3500) that I saw. I just want to see if the there is a common cause for it that might need a recall or at least documented so it can be fixed later under warranty.

ChrisSlicks · 10-24-2009, 03:09 PM

Stage 2 limp mode, otherwise known as drive it to the dealer mode. In this mode the engine power is cut by disengaging the variable valve timing, limiting fuel and air intake and limiting RPM to a low number - 3500 in our case.

Typical reasons are:
- Engine overheat past 300 degrees (not applicable here)
- Bad readings from crankshaft position sensor

It sounds like a software glitch given that there is no code thrown. Who knows, the programmer could have left some test code in there that was supposed to be removed but never was. If it never comes back I wouldn't worry about it. If it repeats try to drive to the nearest dealer without shutting off the engine.

BGTV8 · 02-05-2015, 07:36 PM

Quote:

Originally Posted by 370Zsteve

Somebody please find my old Buick that only had an engine with 8 spark plug wires and a couple of coolant hoses outside the block and nothing remotely resembling a computer. Thank you in advance.

My Buick 215 with 8 spark plug leads, coolant, and quad Weber carb's .... lo-tech and it works !!!

smoothtransit · 04-17-2015, 11:56 AM

Im having the same issue with my 09. It feels like it stalls for a second around 3500 rpm then regains power then does it again in another gear. Went away for a couple months then just came back... I really wish i knew what was wrong with ti so i could fix it..

10-24-2009, 10:54 AM	#3 (permalink)
370Zsteve A True Z Fanatic Join Date: Sep 2009 Location: Gold Coast CT Posts: 10,599 Drives: 2019 Corvette G.S. Rep Power: 43	Somebody please find my old Buick that only had an engine with 8 spark plug wires and a couple of coolant hoses outside the block and nothing remotely resembling a computer. Thank you in advance. __________________ SOLD MY Z MARCH 2018 - another Core OG moves on - new ride 2019 Z Corvette Grand Sport - no mods necessary but already have eyes on HFC and intakes LOL IT NEVER ENDS.

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10-24-2009, 06:48 AM	#1 (permalink)
Pharmacist A True Z Fanatic Join Date: May 2009 Location: Toronto, Ontario Posts: 1,249 Drives: 09 370z Sport 6MT Rep Power: 19	like someone said before, could be a sensor that malfunctioned or was accidentally disconnected. things like these can confuse the heck out of the ecu. i remember once i was doing work on my old intrepid, and forgot to reconnect the camshaft position sensor, which caused the ecu to cut engine rpm at 3500

10-24-2009, 02:17 PM	#5 (permalink)
Dallas-Z Base Member Join Date: Aug 2009 Location: San Antonio Posts: 40 Drives: 370z Rep Power: 16	Well this news is decent good news that others have seen the same problem and even mention the exact rpm (3500) that I saw. I just want to see if the there is a common cause for it that might need a recall or at least documented so it can be fixed later under warranty.

10-24-2009, 03:09 PM	#6 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 654	Stage 2 limp mode, otherwise known as drive it to the dealer mode. In this mode the engine power is cut by disengaging the variable valve timing, limiting fuel and air intake and limiting RPM to a low number - 3500 in our case. Typical reasons are: - Engine overheat past 300 degrees (not applicable here) - Bad readings from crankshaft position sensor It sounds like a software glitch given that there is no code thrown. Who knows, the programmer could have left some test code in there that was supposed to be removed but never was. If it never comes back I wouldn't worry about it. If it repeats try to drive to the nearest dealer without shutting off the engine.

04-17-2015, 11:56 AM	#8 (permalink)
smoothtransit Base Member Join Date: Dec 2014 Location: Seattle Posts: 63 Drives: 09 370 BS 6mt Rep Power: 11	Im having the same issue with my 09. It feels like it stalls for a second around 3500 rpm then regains power then does it again in another gear. Went away for a couple months then just came back... I really wish i knew what was wrong with ti so i could fix it..