kenzinger

Hey Everyone,

New to XJ ownership and the forum and was hoping to get some input. I recently acquired a 2001 Sport with 117k miles and started to go through some tune up items: I replaced the spark plugs, cleaned the throttle body, replaced the power steering high pressure and return lines, and replaced a leaky steering dampener.

After cleaning the throttle body, I noticed that the idle was fluctuating between 800 and 1000 RPM, I don’t know if it was doing this before cleaning. Shortly after all of this work was completed (and minutes after my state inspection) I popped a P1294 - failed to reach target idle code. In response, I pulled the IAC and attempted to clean it. I also let the engine idle while spraying throttle body cleaner into the IAC orifice to see if that was plugged. Neither had any impact on the code but the Jeep wasn’t idling too badly.

I drove ~50 miles without much problem, then I was sitting outside of a store and letting the Jeep run for about 10 minutes while I was waiting on my fiance. I shut it off to run in and chat with her and when we returned to the car, I started to have some trouble. The engine would start, would idle at about 200-500 RPM for a few seconds and then stall out.

This happened several times and then I let it rest for a few minutes, after which it started right up and went back to fluctuating between 800 and 1000 RPM with a P1294 code. I took it to a shop and since it wasn't “acting up” they weren’t able to identify the exact cause but did claim to find an intake manifold gasket leak. I then drove ~100 miles home and haven’t had any problems since.

A couple more data points - when accelerating I hear a very high pitched whistle. It is only during acceleration, and not when I am coasting or braking. I also have known cracks in the CCV hoses/fittings.

I’m new to working on cars so looking for some thoughts on where to start troubleshooting. Any ideas on what this could be?

I’m terrified that it could be a cracked head that the PO was trying to unload. I have also thought that it could potentially be a vacuum leak. I intend to replace the IAC, TPS, CCV hoses/fittings, and potentially the O2 sensors because they seem like relatively quick jobs.

Thanks so much for any help!

kenzinger

tldr, in case that wall of text was a bit aggressive

• Cleaned throttle body and started getting engine idle problems and P1294 - failed to reach target idle code
• Cleaned IAC and IAC orifice with no change
• Mechanic said they found an intake manifold gasket leak
• I hear a high pitched whistle when accelerating
• Planning to replace IAC, CCV fittings/hoses (know they are cracked), TPS, and maybe O2 sensor and MAP
• Concerned the PO sold me an XJ with a cracked head, any chance a cracked head could cause these symptoms?

rwthomasjr

I don't see any further information on your issue - I'm having same problem. Intermittent/recurring P1294 code. Vacuum leaks can be difficult to find, intake/exhause manifold leaks can lead to unmetered air entering the engine which will cause it to idle high and lead to P1294 code. Also a lot of other places where unmetered air can be entering the intake (all the vacuum lines) like brake booster line, PCV line, etc. On line you can see some homemade leak detectors (including a guy who just vapes into his engine) or you can have a mechanic check with a machine. Cracked head - maybe, but not as likely as other sources. O2 sensors - maybe, just make sure they are tight. If the O2 sensors are original, its probably time to change them out anyway. Caution though, assuming you have 4 sensors, the 2 lower sensors are difficult to remove. I coudn't get mine out with a torch. Ended up having to get new collector. Here's what I did so far.
- new IAC
- new intake manifold (old one was cracked and I was sure it was the source of the P1294 code, unfortunately not)
- new exhaust headers
- new collector
- changed all 4 O2 sensors
- had previously installed a new throttle body (BBK) and cold air intake (aFe)

Any update on yours?

kenzinger

Is your issue the p1294 or the intermittent stalling? I'm all solved, my CEL was solved by replacing the IAC with an OEM Mopar part. I first tried to replace it with the pep boys equivalent and it was garbage. The OEM parts solved the code immediately


As for my issue with rough idle/intermittent stalling/starting problems, turned out to be heat soak! I got an insulation kit for my plugs and fuel rail, and replaced the plugs while I was at it, and that solved those problems.

Hope you have a breakthrough soon!

rwthomasjr

Intermittent P1294 code - never had a stalling issue. Idles maybe 100-200 RPM high (1000 vice 800 RPM) on occassion. Given the nature of the fault code, I'm going to check my grounds and replace the battery terminals (the + terminal looks original and is in kind of bad shape). I'm thinking it may be a spurious voltage issue that messes with the ECU or IAC. If that doesn't work, I'll go to a MOPAR IAC.

rwthomasjr

Source of my high idle and P1294 was PCV missing the orifice. Created a high vacuum and lean condition. $6 part cost me $$$ in troubleshooting and months of aggravation. New PCV in and idling at 600 rpm.