Transmission/engine issues and some others

I have a 1989 XJ with 4.0L, NP242, Asin-WarnerAW4, and I believe its still stock height. It has 213k miles on it. I put new tires on and had it aligned 3k miles ago, I've only put 4k miles on it since I bought it so I'm just now driving the problems out...

1) When driving it seems to shift, but when it down shifts it actually slows down. So when I get to a hill or try to pass somebody the jeep will actually slow down instead of going faster. This has been getting worse (the past 3 days) and it is now almost impossible to go any faster than 60mph. Its almost like after 2,200rpm there isn't any power. Can this be fixed by some adjustment on the trans?

2) I took the steering stabilizer shock off when I changed my rear main seal and took it for a test drive without the shock on and at 20mph if I shook the steering wheel back and forth or hit a bump in the road the steering would start to act like a death wobble. With the steering stabilizer shock on the shake is at 34-40mph and is barely noticeable. The XJ also seems to shake when taking right hand corners fast, I haven't noticed it on left turns. I had someone shake the steering wheel while I looked at the steering and there didn't seem to be any play. What would be the most likely cause?

3) After changing the rear main seal when I turn the key to the on position the oil pressure gauge gets pegged above 80. Is this probably just a bad sensor?

4) Is there a check engine light on this vehicle, is this even OBD1? When I turn the key to the on position only the "Brake" and seat belt icon light up, should anything else?

3. Oil pressure sending unit, threads into oil pressure filter adaptor (right behind the filter, one prong connector, pulls off)

4. It has an ECM, though sensor data is only obtainable by a voltmeter or a scantool. Doesn't have conventional codes-and no there is no check engine light. Not OBD-I.

2. Check that track bar bolts on both ends are tight. Leave stablizer on.

1. If you stomp on it in any other gear is there power? Like, if you rapidly accelerate from a start will it still have torque after 2kish?

Its doesn't accelerate like it used to (in any gear), there is no rapid acceleration at all. I tried running it in "1-2" but once it gets a little over 2k rpm it loses power and starts to slow down.

89Daytona said:

I have a 1989 XJ with 4.0L, NP242, Asin-WarnerAW4, and I believe its still stock height. It has 213k miles on it. I put new tires on and had it aligned 3k miles ago, I've only put 4k miles on it since I bought it so I'm just now driving the problems out..

1) When driving it seems to shift, but when it down shifts it actually slows down. So when I get to a hill or try to pass somebody the jeep will actually slow down instead of going faster. This has been getting worse (the past 3 days) and it is now almost impossible to go any faster than 60mph. Its almost like after 2,200rpm there isn't any power. Can this be fixed by some adjustment on the trans?

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No, but a new TPS may fix the problem. It fixed mine. See OEM forum thread the "RenX Files". There are other possible causes, like fuel or ignition problems, by I would get a volt-ohm meter and check the TPS first. Fuel pressure and fuel pressure regulator can be tested with pressure gauge.

89Daytona said:

4) Is there a check engine light on this vehicle, is this even OBD1? When I turn the key to the on position only the "Brake" and seat belt icon light up, should anything else?

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No. It is a Renix computer, ECU, control. Lots of details on it here. Just search Renix.

The bogging down could be a bad TPS. Or maybe a plugged cat converter. The shifting is electronically controlled, based on rpm and throttle position (the TPS specifically). The TPS can be tested with a meter.

On the wobble. Crawl under the front and have someone turn the wheel back and forth while you look at and feel the track bar mounts, and steering components for looseness. I would also jack up the front, turn the wheel full over and spin the tires by hand. If they're jerky when turned but fine when straight, that would point to a bad ujoint. Oh and put the steering stabilizer back on.

On the oil pressure sender, I believe it will peg the meter if the sensor is disconnected. It's by the oil filter.

Nope - no check engine light. Just a service reminder that runs on a timer to tell you when to replace the O2 sensor. Most people have removed it by now.

I adjusted the TPS to the 0.83 specification ( BD/AD = 3.81/4.59 ), and it seemed to make a little difference for a day. But then it returned to the same symptoms. I changed the TPS and the new one has not improved the syptoms. The ground wires on both sides of the engine are made from welding cables and are clean.

When flooring the gas I can step on the brake and the rpms increase ~300rpm, so I'm assuming the torque converter is functioning properly.

I also found out that my reverse lights aren't functioning, the fuse and bulbs are good. I haven't had any problems starting my jeep yet, is it possible the NSS needs adjustment or cleaning?

Plugged exhaust, cat or muffler or pipe...., bad fuel pressure regulator, or missing vac line to the FP regulator, or low fuel pump delivery, bad fuel pump or fuel filter, dying HV coil, or dying HV primary wire, late computer timing due to a bad sensor, dying distributor (bearing going out), partially plugged fuel injectors, or a REAL dirty air filter.

The past couple days the engine coolant temp has gone into the red, the last time it shut the engine down on its own. It only took 5-8 minutes of highway driving for it to get that hot. So I decided to do a cylinder compression check (no spark plugs in, at operating temp, and throttle wide open):

Cylinder : Dry : Wet
1 : 100 : 100
2 : 90 : 120
3 : 72 : 78
4 : 85 : 103
5 : 104 : 130
6 : 120 : 125

The Haynes manual says no more than 30psi difference between cylinder and it should be between 155-185psi, so I am thinking that I will have to tear into the engine to see what is really going on. I am thinking it might be a headgasket although neither the crankcase or coolant bottle show signs of oil and coolant mixing in them.

Any way you go it sounds like it is about time to pull the head off, check the head for valve problems, leaks, and replace the head gasket. If your not lucky, it might be worn piston rings and cylinders, from a leaking injector(s).

My son's was that low recently, Dec. last year, and we kept it running (it just pasted state emissions tests) by changing the oil and adding Restore (Silver can) to the oil, and also changed the antifreeze and added a package of the dry brown pellets to the coolant mix, the pellets that help seal small, early, head gasket leaks. We monitored the compression for a week and it climbed from 81 to 111 and 115 to 150 on the two worst cylinders. It is still running with out overheating. About 10,000 miles since last Dec.

If you try that route, be real careful what you do untill you know the head gasket is OK, and that compression has been restored. I did short trips in the neighborhood, and ran it for hours in the driveway at first. Watch for sudden temp spikes, oil pressure drop in case the head gasket dies anyway.

My 88 FSM say 120-150 for the 4.0 (155-185 for the 4cyl). Either way, the middle ones are unquestionably toast. You'd be lucky if it were only a head gasket. Could be a warped or cracked head, maybe a burned valve or two.

#2 and 5 have a big jump with a little oil. This generally points to rings. #4 also has a big jump but it's too low anyways. #3 a goner.

Saudade said:

My 88 FSM say 120-150 for the 4.0 (155-185 for the 4cyl). Either way, the middle ones are unquestionably toast. You'd be lucky if it were only a head gasket. Could be a warped or cracked head, maybe a burned valve or two.

#2 and 5 have a big jump with a little oil. This generally points to rings. #4 also has a big jump but it's too low anyways. #3 a goner.

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Very good point on the oil and the rings wear! That makes them a candidate for using Restore if he wants to delay the engine rebuild. #3 is a candiadte for the head gasket sealer. About a 50/50 chance of it working for a while with a sealer on #3. My daughters was down to 25 psi on #4 and #5 both, the head gasket was gone between the cylinders, and only between the cylinders. My son's was down to 81 psi dry and wet, but we got it back up with the dry brown pellets. It has held for 10,000 miles so far.

I know this is bringing up an old thread, but I wanted to update after all the fixes

So I took the head off and the problems just started to jump out at me...
-The pistons and cylinder walls all looked good
-The head was warped, I ended up having 0.018" shaved off of it.
-Thermostat housing was cracked, so I replaced that with one for a 98 because it has the sensor port on it.
-The injectors were either leaking or the nozzles on them were in rough shape, so I replaced them all with ford orange top injectors.
-The exhaust manifold had multiple cracks on it, so I welded them all up.
-I used a die grinder to gasket match the intake and exhaust ports.
-The cat had chunks of the ceramic element rattling in it so I gutted that out.
-The heater control valve blew up the week before I took the head off, so thats new now
-The blower motor had to be replaced after that because it sucked in a ton of vapor and siezed up.
-I replaced the old coolant tank that was bulging with one from a '96 Concorde and fabbed up a bracket to hold in the same location as stock.
-made an adapter ontop of the renix throttle body so that a rubber intake tube from a 98 would fit on it.
-Fabbed an airtube kinda like Rusty's and put a 6"x8" AEM dryflow (21-2038DK) on it.
-I made an intake shield to keep the filter dry and cool.
-and finally installed a new radiator, as the old one was leaking

I had driven it for about 2k miles after getting that all fixed and the rear driveshaft univeral blew a bearing cap off taking a tab off of the pinion yoke. Instead of getting a new yoke or girdles for the u-joint, I used a piece of copper pipe to help shape and build up a weld bead to make a new tab. The u-joint fit like a glove between the end tabs I welded on the yoke. I have driven it about 500 miles so far and it seems to be working great.

My compression readings are now
Cylinder : Dry : Wet
1 : 120 : 140
2 : 125 : 132
3 : 124 : 129
4 : 127 : 135
5 : 129 : 135
6 : 113 : 118 this cylinder reading doesn't seem right given the previous readings for the cylinder

I have also cleaned the CCV system, but it is still blowing oil out the front ccv tube towards the airfilter. I am hoping a '99 valve cover might fix this as it doesn't have the vent tubes under the ccv fittings on the valvecover.

Thanks for the update! #6 still looks odd. Did you replace the rings?

You might want to try restore now, for the low cyl pressure.