Erratic idle, no power in gear (1 Viewer)

[lammbean]

1998 100 series. Engine starts fine then immediately starts to decrease rpms until just about to die, then increases rpm’s and start that cycle over. When I press gas it either does nothing or dies. In gear there is no power and pressing gas causes the engine to die. Replaced mass air flow. Replaced ECU. I would appreciate any advice anyone has.

 

[Trunk Monkey]

Any codes or pending codes from a reader?

 

[excessive]

my 1st guess was the MAF. Next i would look at the sensors attached to the throttle body. but look for codes first of course

 

[lammbean]

Originally it threw a P0171 System too lean Bank 1 and a P0100 Mass Air Flow Circuit. When I replaced the Mass Air Flow Sensor I cleared the codes. After I cleared the codes I drove it once with no returning code. It was then parked for a few days and started the erratic idle on my next attempt to drive it.

 

[Trunk Monkey]

Dig around with the last thing you messed with - check for a vacuum line or harness connector you missed reconnecting. Pull the + on the battery for a few minutes to let the ECU reset.

 

[lammbean]

Thank you for the advice. Missing a connection is always a possibility. I gave a quick look last night and didnt see anything. I have reset the ECU. Actually based on a friend having an issue that was slightly similar with his lexus LX470, where he ended up installing a new ECU, I installed a new ECU, thinking that might be the problem. It did not fix it.

 

[AlpineAccess]

Could it be a throttle body issue?

 

[87warrior]

Plug in your favorite OBD dongle and fire up your favorite app to view the MAF volume, Coolant Temperature, Incoming Air Temperature and Throttle Position sensors. I suspect the values of one of those sensors is either 'pegged out' or remaining at 0.

 

[Privateer383]

Plug in your favorite OBD dongle and fire up your favorite app to view the MAF volume, Coolant Temperature, Incoming Air Temperature and Throttle Position sensors. I suspect the values of one of those sensors is either 'pegged out' or remaining at 0.

Will a broken Engine Coolant Temperature sensor cause bad idle or bad acceleration?

 

[Malleus]

yes

 

[Privateer383]

yes

With a broken Engine Coolant Temperature sensor, my LC would idle ok (in Park gear), and I could, very slowly, increase rpm up to 3, 4, 5 thousand rpm and it would hold steady. But, if I applied a "normal" rate of acceleration (still in Park gear) it would sputter and die. This makes ZERO sense to me, but when I replaced the ECT sensor, my LC functioned normally- no issues at all. My engine problem is fixed, but I don't understand why a malfunctioning temperature sensor would render a Land Cruiser inoperable, and potentially stuck somewhere out in the boonies. While it can prevent a driver from inadvertently overheating his/her vehicle during normal use, this seems a very poor design feature for a vehicle designed for overlanding and cross-continent travel. Anyone know the motive behind this feature?