Jonathan Goss

My '97 XJ has a little over 189,000 miles on it and a CIL (P0705 code). There's the infamous knocking and,--I think due to the CIL code--it doesn't shift into the highest gear/overdrive. I changed my oil (10W-30 synth) about two weeks ago and bought some Lucas Transmission Treatment and Lucas Oil Treatment. Should I add either of these now or wait till my next oil change? My mechanic said I had some small leaks but nothing major, "Just watch the fluid levels", so I don't want to risk damaging anything, which is also my hesitation with using Sea Foam. Will adding the Trans Treatment help the range sensor malfunction?

Thanks,
J

2Evil4U

Those treatments aren't worth much. They're usually some form of chorinated parafin and really don't do anything.

If your transmission is not shifting into high gear, and you are throwing the P0750 code, one of the transmission solenoids has stopped working. They usually burn up so it will not get better unless you replace it. If you can figure out which one it is, they're not too hard to change if you can drop the pan.

tjwalker

That additive isn't going to help.

A P705 can be related to a faulty neutral safety switch (NSS). I've personally seen it and that is where I would look first. It really fits what you are describing.

I would try disassembling/cleaning/greasing/adjusting it. That may very well take care of it. Here is a link to a procedure.

http://go.jeep-xj.info/HowtoNSSrebuild.htm

Good luck and be sure to post back how you come out!

2Evil4U

Whoops. Dyslexia strikes. Misread the code in the OP.

lfhoward

I can't speak to the transmission issue, but I use Lucas oil treatment in my engine oil. It completely eliminated rough starts and a tick/knock sound I used to have. (I have only 115K on my engine but I think the PO ran it pretty hard.) If your engine oil is already full you'll have to wait until the next time you change your oil. The I6 takes 6 quarts, so I use 1 quart Lucas with 5 quarts of regular engine oil. I've been running Lucas for a year and a half now, and the engine is very happy.

Jonathan Goss

So the oil treatment goes in as a substitute for a quart of oil next oil change, but the trans treatment, when does that go in?

Also, I have a can of Seafoam I'd like to dump into the gas tank, any opinions on that coupled with a high grade gas?

tjwalker

Seafoam in a full tank of gas is not a bad idea. It contains a "stoddard solvent" which can help optimize fuel injector spray pattern. I prefer TECHRON, or BG44K, but Seafoam isn't bad in the gas tank.

Skip the high octane gas. It is of no value to you. Your 4.0 is designed to run great on regular. Thinking that premium is "treating" your engine is a myth that dies hard.

As for the Lucas, follow instructions on the container.

Jonathan Goss

The uselessness of higher octane gas in my I6 4.0 is based on compression rates, correct?

CJ7365

unless you have modified your compression, you are wasting your money on premium fuel, it will not make it run any better, or get you better gas milege

tjwalker

Absolutely correct.

Jonathan Goss

Yeah, from what I've read it seems like whatever benefits premium gas offers are neglible at best and probably not worth the price. I put a full tank of premium in just because it's been probably half a decade since I've done it, but I don't think it made any real difference. I DID add the can of Seafoam to the gas tank and next trip out the CIL disappeared. I'm sure it'll pop back up again some time soon. I'm still noticing lag in performance or possibly a lack of overdrive even with the CIL off (I assume this is directly related to the trans code P0705 and bad/dirty NSS), so in the next couple weeks I hope to get it fixed and get the ol' warhorse back up to full fighting strength.

The Lucas Oil treatment I'll hold off on till my next change (along with Seafoaming the engine possibly). The Lucas trans fix I was told requires removing the trans fluid pan and at that point you might as well ask me to perform brain surgery.

After skimming the forums it strikes me that part of the charm of XJ's is that they come with a myriad little issues and problems and flaws and quirks that develop over time...and yet they keep on plugging. Mine was never anything but a rough ride, but it has never totally failed me either. I'm sure I'm not alone.

ken72

The rough idle is common amoung the XJ. None of those treatments you are looking at will cure this problem. I will tell you that the Lucas oil treatment did make my engine knock go away. The engine does run quieter but not much smoother. I used it in two oil changes but I have not used it in the last couple of oil changes. I have tried them all with little or no results.

Jonathan Goss

Yeah, I see that the rough idle is kind of ubiquitous. That's alright, as long as it doesn't affect longevity or performance, I'm not too interested in resolving it, you know? Glad to read the Lucas oil treatment helped the engine knock. That's something I've had for YEARS now. I'll be eager to see if it helps mine. It seems the Lucas transmission fix doesn't get much attention. Snake oil or too risky to try for most? I wouldn't dare do hardly anything to my Jeep without a guide or mentor of some sort to show me how to do things right. Hopefully it's only a matter of time before I can find one. That NSS issue and power windows master switch fix look like they can be done at home and save a decent chunk of $$$.

peep

I'm go on the Lucas products (high on the oil content), no on the seafoam snake oil (too much solvent content). My XJ may run ruff and loud but it always runs. Why have all that bite without a little bark.

Jonathan Goss

Yeah, that's the only thing that turns me off of certain products like that: I'm not into "fixing" something and in reality just masking noise. I don't want to use any product that helps my engine run quieter if it's not ACTUALLY doing anything to help prolong my engine's life or improve it's performance or repair damage. A purring engine is alright, but a healthy engine is better and certain products seem to lie about being able to make those synonymous.