’97 landrover Disco can’t get above 1750 rpm, TPS checks good
My ’97 Disco I is a great vehicle, with 200K on it, but this problem is beyond me and looking for some advice. While it starts and idles great, it can’t get past ~1750 rpm, just backfires and sputters, when returned to idle its fine, silky smooth rpms. Checked TPS from ECU connector, min-max, .7 – 3.7 kOhms, .6 – 4.3 V across potentiometer. Smooth changes in both as I cycle throttle. The 1750 rpm limiting would say TPS but with these results it would seem ok, I think. I can add that when I disconnect the TPS it jumps to the high idle setting, as expected.
I cant imagine there is a connection but this happened about the same time my coolant reservoir tank exploded. (missed that posting) I changed the tank out and then ran into this problem when I started it back up. Fluid level seems constant so not suspecting any head gasket issues. Maybe coolant got into something
1) Try at the first day: With the 1750 cutout, and your point about it being cooked by lack of flow through cooling plate, it has to be the TPS. Great idea on used or alternative part, will check that out. Seems like there may be some way to stroke it and re calibrate TPS map in the ECU.
2) Try the second day: While it was a good bet, the new autozone (went big) TPS sadly didn’t fix it, other than now it more precisely hits the 1750 limit, I can push it above that slightly for a 0.25 sec, but it backfires, sputters and immediately comes down. Idle is still very smooth.
When I installed the TPS RPM’s went to high idle, as if it were disconnected. Figured the “adaptive” learning, aka trim values, had to be reset, so turned ignition off, then left key in accy mode and and moved accelerator pedal to floor before lamp test was over. (something I’ve done with other ECU’s) That seemed to set the values. On the next start it idle exactly just where it should, but still no joy getting past 1750.
I did get a crankshaft sensor
3) Try the third day: It is about the same as previous, .7V closed, 4.3V WOT. Supply is a smooth 5V, when measured yesterday.
New development – Went after cover for crank shaft sensor, ridiculous, cover bolts inaccessible, cover deformed. In process guessing I pulled lead, or sensor fell apart, as I now (at least suspecting) have the classic “no start due to failed crankshaft sensor”. It is a PITA to r&r, D2 looks much easier. Any tips/links on getting it out appreciated.
If it fell apart that easy maybe it was on it way to total failure and part of the problem.
Solved – ended up being crank position sensor. It was loose in its mount, and wire to it was down to just a few strands. Runs fine now!
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