Lots of problems with the XJ!

1999 4.0

Problem 1 - Takes forever to start (15-20 seconds), even worse when its cold. When it does start, it stutters, lags really bad on acceleration, and if Im not careful it will stall.

I think it could be the IAC? CPS was replaced about 5 months ago. Could a bad check valve cause the starting issues?

Problem 2 - If it rains hard or long enough, I end up with an inch of water in my passenger side floorboard (only the front). NO idea what could be causing this. Ive read it could be the cowl drains? Do I need to take the whole cowl off?

Problem 3 - Check gauges light has been on for some time. Oil pressure is showing as 0. Im assuming its the sender unit (again, had to replace this on my TJ). Could it be anything else? What is a reliable replacement unit? I dont want to spend 60 at the stealer again. Any tips to replacement? I remember it was a PITA when I replaced it last time, and I think I could have used a specific tool to make the job easier.

Problem 4 - Temperature gauge works sporadically. Is this a problem with the temp. sending unit, or a problem with the thermostat? Would I be better off replacing both? Again, what is a reliable temp. sender that isnt from the stealer?

So, LOTS of problems, but I really have had 0 time to do the maintenance work this thing has needed. Kinda disappointed with the XJ. My TJ had 50k more miles and was the 4 cylinder and needed almost nothing when I had it.

Problem 1 - It could be the check valve. One of our later model XJ's has this. If I switch on the key, listen to the soft humming coming from the pump, I can hear it shut off. Then turn the key off and turn it right back on. Wait for the humming to stop again (about 3-5 seconds), turn the switch to on and give it a try. If the symptoms go away and it acts and starts normally after this, its probably the check valve. You can confirm it with a pressure gage. You could also depress the stem on the schrader valve on the fuel rail (cold engine only- don't want to start a fire) and see if fuel spits when you have this problem.(If no fuel is present) This would tend to cofirm the check valve issue.

It's probably not the IAC. Seems like when this happened on my 89, it was always sticking in the fast idle position. Removal and dousing its screw with REMOIL (a light gun oil aeresol) and repeatedly working it solved that problem. If its sticking in the slow position, then give it some gas and see if that prevents the stalling out. Do we have IAC on the post-RENIX engines? I can't remember seeing that.

CPS - how about the connection to the cps. Can you jiggle it bit when you have this problem and see if it helps?

Finally, think about the simple things. Could the distributor cap ( I think 99's still have them) be cracked? Had a Farmall with hard starting problems and that was it. Weak fire, weak starting.

Good luck with this and the other problems.

Problem 2 - THis may be a long shot, but there is a drain in the heater core enclosure on the passenger side firewall. Mine has plugged before and during driving and sloshing around I got some drips on the passenger floor and I could hear the sloshing. Air compressor and a bit of wire cleared the drain. Hope its not some hard to find windshield/cowling leak.

My bet is a failing CPS for #1. You can remove the IAC and clean it, along with the throttle body and valve, with good throttle body cleaner. At 150k miles, my IAC was filthy and I replaced it. Did not solve my hard starting and stalling problems, but the CPS fixed those issues. I'm sporting a new CPS, IAC, cap, and rotor and my Jeep is running great.

Many people complain about water on the floorboard and there are a ton of threads on this. I have water that pools on the passenger side after a good rain, but only if I am on a slight incline (driveway). I have not pinpointed the problem. Could be several areas, but search and ye shall find.

I had water that pooled all over my interior when it rained, but i DID cut the roof off from the b-pillar back soo...

I second the CPS. My first 89XJ had that same problem, i cleaned the IAC, replaced the IAC, adjusted TPs.. did all kinds of things and it was that CPS.
Good luck.

*edit* I see that you already replaced the CPS. Of course parts are known to not always be of the best quality especially if they came from certain retailers

The oil pressure sender will peg the gauge when disconnected and drop to zero when shorted, so the first thing I'd do is unplug it and see what you get. I gather that late XJ's sometimes have issues with the instrument cluster connection needing to be cleaned and reseated, so that's a possibility, especially if you have problems with more than one gauge.