Okay, what does "limp home mode" really mean?
Race Director
Joined: Oct 2001
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From: Melbourne Florida
Cruise-In IV Veteran
My car went into limp home mode once...ran real bad with no power...I barely made it home and into the garage...it would not start after that and I had to have it towed from my garage..turned out to be an ECM gone bad...
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,326
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From: Los Angeles California
I think that the MAF is the exception to the rule in this case. Most other sensors the car wouldn't be able to approcimate.
Didn't they at one point just have a MAF sensor or a MAP sensor depending on how the car was setup for that year, and only late in the C4 run have both MAF and MAP sensor installed? That seems to be what I remembered, but since I have a 96 I didn't pay much attention.
Didn't they at one point just have a MAF sensor or a MAP sensor depending on how the car was setup for that year, and only late in the C4 run have both MAF and MAP sensor installed? That seems to be what I remembered, but since I have a 96 I didn't pay much attention.
Le Mans Master
Joined: Mar 2004
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From: Ft. Lauderdale Fl
Le Mans Master
Joined: Feb 2000
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From: Kempner Texas
If I recall correctly, TPIS' Insider Hints booklet gives a definition of ALL the different modes the system has. If it's not in the TPIS booklet, it's in the FSM for the 86 Vette.
I believe there are about five of them and Limp Home Mode is one of them.
Jake
I believe there are about five of them and Limp Home Mode is one of them.
Jake
Safety Car
Joined: Dec 2004
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From: Poop land
Closed loop mode (all of the above happens, but excess enleanment/enrichment is corrected with the O2 sensor on normal throttle conditions, except WOT)
PE/open loop mode (ECM ignores O2 sensor output in WOT from the temporary rich condition)
Deceleration mode (ECM cuts fuel past 43 mph when it senses no throttle, coasting)
Limp home mode (ECM runs car on default lookup tables when a certain sensor isn't functioning properly, E.G. faulty MAF)
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Race Director
Joined: Jun 2004
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From: WI
Deceleration mode (ECM cuts fuel past 43 mph when it senses no throttle, coasting)
I've wondered about that one for a while. The car coasts much better below 43 MPH. That makes sense now, I had been wondering if the trans. was doing that.
I've wondered about that one for a while. The car coasts much better below 43 MPH. That makes sense now, I had been wondering if the trans. was doing that.
Safety Car
Joined: Dec 2004
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From: Poop land
Basically its when the momentum of the car is used to "spin" the engine with no fuel, with the torque converter clutch locked (automatic trans). Feels like the car suddenly "started" dragging something the moment you let off the gas, above 43 mph, which, in turn its just spinning the motor with the car's momentum. You can also tell the fuel is cut off when the instant MPG guage reads 99.
Race Director
Joined: Jun 2004
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From: WI
It was strange to me at first since other cars I have had did not do that. It was easy to coast a long ways to a stop sign. With the 'vette the speed drops like a rock. I always wondered why, thanks.
