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Can you tell us what it is doing wrong? If the CPS dies, then there is no spark. If the TPS goes, then idle usually goes up too high (at least the last two times on my 1990). If you have an automatic transmission then a bad TPS will cause some weird dhifting- on mine I notice the shift points have changed- since the TPS also sends a signal to the automatic transmission. If your 1988 XJ is bogging down and threatening to die at idle, then it is likely the EGR (exhaust gas recerculation valve). Test the EGR by pulling off the rubber line from the accumulator/pot thing to the valve heavy part, and block it with a plug (golf tee works). If that solves the low idle then it is a faulty EGR. It could be other things- can you tell us how it runs? 4xBob
Yes I have problems with my CPS disconnect and connect when it does not start, but now the acceleration does not lower of 2500 this can be the CPS or this problem is only the TPS, and yes have problems of relations, is automatic.
I am live in Bolivia, and is very dificult change parts
At 15 years old both the CPS and TPS are close to the end of their lives. The unplugging and replugging of the CPS is the way to make a bad CPS work. I would replace the CPS first. Since you may go to high altitudes make sure you buy the High altitude CPS, the Jeep Part Number is 53005421.
There are internet sites that sell Jeep parts at a discount, I'd look at parts.com and see if you can find one of the dealers listed who will ship to Bolivia. I also found rockauto.com has parts for our XJ and they seller the better aftermarket brands.
Rodrigo,
With your automatic transmission, your TPS should have 2 connectors. You should be able to drive OK with the flat one disconnected -- the square connector provides a signal that is for the TCU (Transmission Control Unit). It would be best to leve the square one connected
Since you have an 88 model you have the c101 connector on the bulkhead above the engine on driver's side. All the sensor wires including the tps and cps pass through this connector on the way to the computer. This connector was such a problem it was eliminated starting in the 89 model yr. Often the contacts inside this connector get dirty and corroded. Clean them all and relube the connector inside the c101 w. dielectric grease. Also check your cps with a multimeter to see if it is still good. Often the problem is just the wire harness connector for the cps near the last fuel injector. Hook a volt meter to the two wire coming from the cps w. the connector disconnected. It does not matter which wires you hook the volt meter wire to. Crank engine and if you meter shows volts fluctuating between .5 and .8 or more volts (yes less than 1 volt) your cps is usually still good and the problem is just your connectors. If the c101 clean up does not fix the problem then your cps wire harness connector is bad. Replace the connector ends (on both sides of the connector) with something else to give a better connection. Since the cps generates such low voltage any loss due to a poor connection causes problems. Good Luck. Greg
Sounds like these guys are well on top of your problem.
My experience in layman's terms:
TPS- idle is high, transmission shift points messed up and shifts way to early or not at all.
CPS- engine starts either not at all, misses and shakes, or starts perfectly. You never know what you get when you turn the key from start to start.
EGR- EXPENSIVE TO REPLACE. I bought mine at the dealership. My wisdom there is MAKE SURE the cat. converter is ok BEFORE replacing it or you'll burn out the rubber hoses on your brand new and very expensive EGR.
My XJ is exactly the same age as yours and I've had to replace all of those things and a couple more after having the engine rebuilt. I was advised to change every sensor on the Chief which I have been in the process of doing.
