Hi, all

I bought a 2000 XJ with 112k on it last year, and I'm loving driving it. It grew up in Delaware, so there isn't any rust (unusual for an XJ in upstate NY, I've gathered) and it runs a little stiff but for the most part, totally OK. I just lurked on these XJ boards but now I think I need some help.

I've recently acquired an engine hiccup, when I'm idling (around 650-750 RPM) and I've taken steps to try to figure out what it might be. No check engine light. I've cleaned the throttle body and IAC valve, and attempted an ECU reset (I dont think I drained the capacitors entirely but have no way of knowing). I recently got a new muffler installed which seems to be putting the engine under a bit more strain (I had a hole develop in the muffler and just decided to pull the trigger on the repair), but now that the noise level is down the hiccup seems worse. Another note is when I slip the AT into neutral, the engine hiccup doesn't go away but a distinct rumble stops... so, probably whatever that hiccup is is sending vibrations down the transmission? I'm not sure, and was wondering if there was anything else I should try before taking it into the shop. Also, a final clue might be that the hiccup causes my RPM to bounce ever so slightly, the needle moves maybe less than an eighth of an inch. I just remembered that as soon as you give it some gas, there's a little hesitation and then it runs smooth.

Thanks

 

This issue should get 6,152 suggestions.

I'll go with dirty injector(s).

 

Hmm, so best way to see if that's the case? I'm poking around the forums for that information, but want to know your thoughts.

 

It seems like fuel injectors could be the case. Is cleaning the injectors something I can probably do by myself? I'm a fairly inexperienced but very cautious budding mechanic.

 

I just yanked all mine out (and it may be hard!) Cleaned out with carb cleaner (don't tell Pat but I used a Q-tip!) Built a little rig with some tubing and a syringe, I'll try to find a picture stole the idea from somebody else. Blow out because they need to ABSOLUTELY free of anything, especially Q-tip fibers. Put in all new O-rings.

That said, it's very trendy to put in rebuilt Bosch 4-hole injectors, the OEMs don't last forever.

 

This might have been it. I used a PC power pack for the gate opener:

https://www.google.com/search?q=cleaning+feul+injectors+syringe&rlz=1CAPP DO_enUS840&oq=cleaning+feul+injectors+syringe&aqs= chrome..69i57j0.14906j0j7&sourceid=chrome&ie=UTF-8#kpvalbx=1

My application called for 2 different O-rings, don't have that info handy tho. Others will.

 

Any codes? Even if the CEL is not on, i would still pull codes. You never know. When removing injectors, try not to tweak the fuel rail pulling it off as it can stick to the injectors, and the injectors can stick to the intake. And if you reuse the old injectors, buy new o-rings.

 

I'll check for codes after I leave work, there's the three-time-key-turn thing, right? And then a professionally done injector cleaning doesn't look too expensive nor will my car be out of commission for too long, so I might actually go that route. I don't trust myself just yet.

Thanks!

 

You can check the pressure at the fuel line for free by "renting" a gauge form the parts store. I'd verify that for free before I pulled the fuel rail off. It does seem to be an air/fuel issue. Whenever I have issues like this I like to do a "tune-up" by replacing the maintenance parts. That is spark plugs, spark wires, distributor cap, distributor rotor, air filter, and fuel filter as well as adding a fuel injector cleaner into the gas tank. All of those things are meant to be replaced periodically.

 

Well, you gotta start somewhere!

Cleaning the injectors is simply applying 12V to the gate so it opens and shooting the cleaner through. The O-rings are tight, so that's really the toughest part.

Consider the Bosch remans, they're about 80 bucks on eBay. If you go to a "professional" to clean the injectors, they could break one, say they're too old, and/or need to be replaced as a set (none of which is really wrong) but then you're going to pay full retail plus labor, and that could be about $350 (plus or minus who knows what)(and if they come up with a real low ball number the injectors are probably knockoffs or poor remans). Just be real sensitive to anything that sounds fishy.

 

For the record - the Pat referred to is definitely not me.

 

I sat and tried to pull codes last night, did the on-off-on-off-on and the check engine didn't do anything. Good news? I also did the "odo-trip while turning the key" and nothing appeared. Did I reset the codes when I grounded/reset the ECU? Is it possible that I have no codes at all?

 

I trust my guys enough, I think. With regards to cleaning it myself, I'm not sure what you mean with the 12V bit. I'm reluctant to take the injectors out myself, for fear of causing more damage (twisting the rail, for instance), as well as everything I'm seeing with regards to keeping the injectors in the engine involves having an air compressor of some kind which I also don't have. I'll keep looking to see what I'm comfortable with, like I said I'm trying to learn but I think my overcaution keeps me from trying some fixes that might be relatively easy.

Thanks for your help so far, everyone.

 

Alright, here's an update. I had the injectors cleaned after talking with my shop, they agreed it would be a good idea and took $20 off, which made the whole thing $110. I'm OK with that. Picked it up today and there wasn't any change in the hiccup, so now I'm back to square one. Actually, the engine coded while I was sitting for my breakfast at DD's (in neutral so I didn't get a rumble), but neither method (odo button or on-off-on-off-on) pulled a code. I'll probably try Autozone after work.

Any new ideas on what this hiccup could be, and what a next step would be? Spark plugs/wiring? Sensors?

I appreciate the help so far.

 

Get the code first. Change parts if they're due-- how many miles on the plugs?

Check all the vacuum hoses.