Hi everybody, this is my first thread, be gentle!
I'm more or less mechanically inclined, a small engine mechanic actually, not a vehicle mechanic yet, but learning as I go.
I have a '99 WJ, inline six, selec trac, 148 thousand miles.
My oil pressure usually rides around 40 idling, and 55-60 while moving.
Lately, once the engine warms up, the oil pressure drops to around 19-30 when idling and no more than 40-50 when moving. It's accompanied by an barely perceptible erratic "shiver" when idling at the low oil pressure, when moving it seems to have lost a little bit of its power, and noticeable shifting hesitation. there's a very rich almost propane-like, or "chemically" exhaust smell (but not quite like a cat converter rotten egg smell) along with abysmal fuel milage. When coasting along after a complete stop, it idles roughly and has trouble coasting smoothly.
No codes or engine light so far. RPMs seem fine.
Oil looks fine (but high time to change) and at normal level, using wix filter, tranny fluid good, coolant at proper levels. No leaks besides the tiny age-old tranny pan leak which I've kept up on.
I'm wracking my brain on what it could be. Thinking maybe clogged oil filter, bad oil sending unit, or clogged fuel injector, but any one of those wouldn't cause all those symptoms would it? I keep wondering if it's the exhaust valves, but I tested the exhaust pressure and there's no obvious back-suction.
You guys and gals have seen it all when it comes to Jeeps, what's your educated guess?
Last night the check engine light came on. Ran the code and it came back "bank 2 too lean." so part of the problem is the fuel injection system (?) it seems. Does this shed any more light in the issue?
When you say a "shiver" does it accompany around a shift point and not in another gear, like mainly on take off in first gear or between first and second?
or is it with an rpm in park?
Seafoam is cheap and easy to do, lots of writeups on here on how to "seafoam my engine" using 1/3 in oil, 1/3 in tank, and 1/3 in vacuum hose into intake...
After that, new sparkplugs are a big plus, most prefer the regular champion plug as the "special or awesome" plugs don't work as good in these engines
Tranny filter and fluid change date?
If you suspect a injector, run the seafoam through it first and see what happens. YOu can also disconnect the battery after you seafoam and see if the code comes back.
The "shiver" is when it's sitting still, idling. The barely perceptible vibration of the engine is accompanied by slight random "misses" here and there.
I've added Seafoam yesterday evening, and have driven it about 14 miles so far with no change yet. Tranny fluid has not been changed, but it leaks from the pan seal at the rate of a quart every few months, so I add more ATF+4 as needed.
I discussed dropping the pan and changing fluid/filter with a mechanic friend of mine who is also a Jeep enthusiast, he refused to change it, stating first off it is never intended to be changed, and secondly, after all this time it would destroy the transmission if we drained the fluid now, said to just keep up on fluid levels. Sounds bogus to me, what are your thoughts?
I'll disconnect the battery tonight and see if it shows up again.