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Discussion Starter #1
Hey All - Yesterday (Tuesday I think, but the days are starting to blur) I started up the Defender ('94 NAS 90). It started up normally but the CEL was remained lit. Rolled down the driveway, put it in first, hit the gas, and got a very delayed response. Pulled up on the clutch, and the engine immediately bogged down. I sat there for a few minutes letting it idle, which it did normally. After a few minutes, everything seemed fine so I headed out of the neighborhood. Of course, as soon as I hit the main road I got a similar type response, and about 100 ft later lost power. It was still running but if I hit the gas and RPMs went above 2000 or so, it would buck and die. My son got a kick out of it. We limped home and as I pulled into the garage, it stalled. I let it sit for a couple of hours, and went back to check for any codes. Of course, it started normally, and ran perfectly fine. I checked the code display, but it was blank.

If helpful, I spent Saturday replacing my binnacle mount, and it ran well afterwards with no CEL or dying. Sunday I reconnected my reverse light switch (was never connected as far as I can tell because the switch had an econoseal and the harness has bullet connectors). Didn't drive it Sunday, but on Monday I noticed the CEL remained lit, although it was still running fine. The battery was disconnected periodically while I did my work. Might this just be the ECU relearning after a battery disconnect (which I have seen before, but without the CEL)? Any idea how to begin to troubleshoot this without a code or do I just sit around and wait for it to happen again?
 

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Exactly as it indicates, bad Throttle Position Sensor. Either attempt to clean it or replace with the Colvern Adapter kit.
 

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Discussion Starter #5
Thanks guys. Found this as far as cleaning procedures go:

TPS Advice

I haven't tried it yet because I cleaned the sensor and harness contacts, and disconnected/reconnected battery. All seems fine for now but I'm guessing it's only a matter of time until it occurs again. ECM is behind the A/C, so it's difficult to do the second part of the test with the ECM plug. I did get the 5v for the first part though.

I was looking at the adapter kit on Rimmer Bros. I already have a round 3 pin female harness on the vehicle side. Does the adapter accomplish something else?

444159
 

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Before you “fix it or replace it”, test it. It probably is it as that code is pretty specific, but there is also a test and the habit you need to develop with these trucks is replace what is known to be bad. Test test test.

TPS SENSOR:

To troubleshoot the Throttle Position Sensor, first disconnect system power and then disconnect the EFI Cable Harness from the ECU. Using an Ohmmeter, verify that resistance between terminals 3 and 25 is between 4000 and 6000 Ohms. Next, reconnect the EFI Cable Harness to the ECU, and turn the ignition key switch "on". Take voltmeter readings from pin 20 to ground. With the sensor in the throttle-closed position, you should read 0.085 to 0.545 volts. With the sensor in the throttle-open position, you should read 4.2 to 4.9 volts. In between these extremes, turning the throttle position sensor should produce a smooth sweep of voltage readings.
 

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Discussion Starter #7
Definitely went down the path of testing, but my ECM is behind the A/C (so dumb) and my clumsy hands couldn't get the plug off with such little access. Is there a trick there? Will have to try again. Thanks.
 

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the adapter kit is something cooked up by the TVR nerds that go through these sensors like candy. it converts a generic racing throttle pot to fit the rover plenum.

ACT performance is where you can find them cheapest. Shitpart resells them on the LR sites for a little extra.
 
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