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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
I just fixed my 90' which had very similar issues to yours. What my problem was, was the throttle body gasket was leaking. Such a cheap simple thing to replace I overlooked. When it got hot the leak got worse. It also started a knock or tick sound that got worse as it warmed up. All gone now.
An interesting diagnostic trick I learned is that you don't need an O2, Coolant temp sensor, or Intake temp sensor for it to run very close to "correctly". So if you disconnect all those, and still have major issues with idle or a knock, it isn't those. You can essentially remove them from the equation. When it's close those sensors do smooth it out further but not so drastically as you might imagine.
The IACV, TPS, MAP, and CPS are the real base line sensors it cant sub out a default mapping for.
So, today I took'er to work. Its about a 45km trip each way.
Everything started fine, even sitting in traffic there is very little noise, its a tick that I hear now, could be lifters who knows.
But the oil pressure does drop down to about 2 widths of the needle above the bottom line, and only raises to the second line when I am moving. This is when hot, when I first start it there is a .5 second rattle and the pressure shoots up to 3 bar.
In that 45 km, I whent threw about 1/4 tank of fuel... Something ELSE is not running right. I will get to the bottom of this one way or an other.
From what I can tell that would be the cps, but if it wasn't hooked up it wouldn't start. Id look around for a relocation mod or something funky like that. I have heard there is such a thing you can buy for the cps. Either that or they direct wired it in or something. Hopefully cruiser chimes in with more answers.
Well, I know for a fact that if the CPS is unplugged, that it will run, albeit not very well. And have a VERY hard start... mine seems to burn threw a TON of fuel, and it has to crank for about 5 seconds before it starts.
Thats not right man, the cps is what the ecu times with. Mine will not start without it, so you have to have something going on that altered that system. There was a optional factory relocation kit for the cps that came out in 88 or 89, im thinking yours might have that but I dont know where it is installed at. My guess would be some other side of the trans tunnel easier to access from below.
The longish crank times are normal on renix as the ecu needs to see a certain rpm/signal from the cps to engage fuel and spark. Some mods can be done to reduce the time but it still cranks over about 3+ times.
So here is the current state of the Hotwire XJ.....
https://youtu.be/eG5NPPGkxj0
There is a separate wire running into the cab that is attached to the CPS sensor. But Why? And I picked up a MAP to test with. Next thing is an O2 sensor. I'm going to pull a plug to see how it's running.... I'm pretty sure its REALLY rich, hence the crazy fuel consumption.
I have found put there is a high flow oil pump available. So.... My pan may come down sooner then later anyways. I still feel that it is a bearing issue. But... Cam bearings? Crank? Rod? Should I just do them all? I really hope it's not a full rebuild.
Here is what I would try. Unplug the O2, Coolant temp sensor (right above the drivers motor mount on the block), and the Intake temp sensor close to your brake reservoir. Start it up and drive it around the block. Put it in park and see if you still hear it. If it went away, turn it off. Plug in one sensor. Start it up and drive it around the block then park and check. Do this until the problem returns. If you find that it comes back after plugging one back in, you found it. If it didn't make much difference you know you don't need to waste money on sensors right now and it is something else.
What I've found this does is uses the base maps and with them have a pretty decent running condition. Also my oil pressure moved around a lot before my throttle body leak was fixed but it's not a good reference anyways as they are often faulty- have you checked that gasket?
That cps connection looks to me like they relocated it. I've heard of this and also direct wiring to the ecu to improve startup times.
From what I can tell it doesn't sound major to me, it's an air/fuel mix or spark/timing issue.
NP man its always important to try the easy stuff first before pulling your hair and empty the wallet haha. Im a broke *** **** so I dont get a choice. Lol
From what I can tell that would be the cps, but if it wasn't hooked up it wouldn't start. Id look around for a relocation mod or something funky like that. I have heard there is such a thing you can buy for the cps. Either that or they direct wired it in or something. Hopefully cruiser chimes in with more answers.
Won't run with no CPS signal.
I'll tell you what happened. Your Jeep had the factory cPS bypass kit installed. the tech was supposed to eliminate that connector and tape the wires back.
07-26-2018, 09:28 PM
