Jeep XJ tips and tricks to keep your Cherokee on the road or trail
How to replace the harmonic damper on a Jeep XJ
Recently I heard a strange sound on my Dad’s XJ Wagoneer. It sounded like something hitting the fan. It took me a couple of days to find it but when I did it was obvious. The harmonic damper had come apart at the rubber joint and was working its way forward off the hub.
The Renix Engine fuel injection controller adjusts the idle speed by opening and closing a valve that bypasses the throttle plate. Often the Renix engines will have a high idle speed due to the Idle Air Control Valve leaking air past the plunger.
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How to replace the knock sensor on the Jeep Renix engine.
The knock sensor is used by the Renix engine control system to fine-tune the ignition timing. If it hears knock it will back off on the timing a bit. It will run the ignition timing as far advanced as it can to get the most power and fuel economy.
If the sensor fails or is damaged, it will read zero knock and the engine will run the default ignition curve. This may allow too much advance and cause the engine to knock.
My dad’s Wagoneer has a 4.7 stroker motor had has developed a taste for high octane fuel to limit knock. He thought it was because of his stroker motor.
However, testing with Nick in Time’s REM module showed no reading from the knock sensor. I decide to replace it. In the past, I had not been able to find these replacements but I was able to find the newer GM style available on Amazon. Part number: KS99
The knock sensor is located on the driver side of the block near the oil pan. It is best accessed from below. The connector looks like a fuel injection connector and is held by a clip in the same way. I used a pick to remove the clip.
I then unscrewed the old sensor from the block and saw that it was obviously broken. 24MM wrench.
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How to replace the Throttle position Sensor on a Renix Jeep Cherokee XJ.
My Dad’s Wagoneer has a 4.7 Stroker motor from Titan engines. It is lots of fun to drive. The wood grain panels make it kind of a sleeper.
Lately it has had a couple of issues. First the torque converter would not lock up causing excessive RPMS on the highway. This did not help the already poor gas mileage.
Second, it had a bad stumble transferring from closed throttle to part throttle. Sometime the engine would even stall if you did not give it enough gas or gave it gas too quickly.
Continue reading “Replacing a Renix TPS”
Here are the important sensors that tell your Renix era Jeep engine how to run. The Renix computer was used from 1987 to 1990 and operates very differently from the later MOPAR engine controllers. It was designed through AMC’s partnership with Renault. Parts are still available for most of these from Amazon.
Continue reading “Jeep Renix Sensors”