dave1123

Oh, I get it! I did the front struts on my Chevy Citation and took it to an alignment shop and asked them to JUST check the camber. 45 minutes later, they showed me a list of $600 worth of parts that needed to be replaced before they could align it! I asked for my keys back and got the **** out! They wouldn't give me the list though.

I'd set the camber with a protractor bubble level before and after tearing it apart. Must be I did it right because it handled good and the tires wore evenly.

mfisher2112

NTB is one of the few places left that won't charge some ridiculous "diagnostics" fee just to spend 10 minutes telling you what is wrong.

mfisher2112

Hey guys. What diff fluid should be in the front diff? I'm going to change out the front diff fluid, it appears to be leaking. I found that the rear should be 70/90, but I can't seem to find what should be in the front.

Deloy3

75/90 in both. If u have a tow package then 75/140.

mfisher2112

I do have the tow package (thus the 3.73 gears) but I don't tow. Should I change the 75/90 in the rear to 75/140?

Deloy3

Honestly I'm not sure. I use 75/140 just because that what I was told even though I don't tow either. I really can't see it causing a problem though. I think its just because of the extra load from towing for the thicker fluid, that's my guess though. I think the 75/90 should be ok.

dave1123

If your jeep is going to be exposed to extremely low temperatures, use the lighter weight fluid. I've seen 140 jell up at 30 below. Likewise, for extremely hot temps, you'll want the 140. Specs say 75/90 rear
90W front
75/140 synthentic rear (tow)
That's for the Slectrack 242 eguipted jeep.

To my way of thinking, it really doesn't matter as long as it gets lubed!

mfisher2112

I'm in southern NJ. We don't really get super cold winters or super hot summers (maybe a week or 2 of 100 degree days, mostly upper 90's for a month or two).

Think I'm going to stick with the 75/90 that's in there.

dave1123

Sounds sensible. I'm from Syracuse, NY and I have seen 30 below, not recently, however.

What amazes me, is people up here that say " My CD player didn't work this morning!" My answer is always "Did you let it warm up?

mfisher2112

This thing is going to be the death of me.

About a year ago, I developed the dread "buck,boom,stall". It would just out of nowhere start bucking, lose power, backfire and stall. Sometimes it would re-start, often you had to fight with it or let it sit and settle down to get it to restart. It was random, and not rfeproducable.

I replaced tps, cam and crank sensors, cap, rotor, coil, plugs and wires, fuel filter, cleand the maf, re-strapped the chasis ground, new starter and re-ran starter wires, new cat (and exhaust, since the backfiring was detonation of unspent fuel in the muffler, it blew to hell).

And thru it all, it never threw a CEL.

Eventually, I found the "spacer" trick on the ecu retaining screws, the theory being a bad connection was being flexed and causing intermittant breaks in said connection.

It worked, for about a year.

Well, guess what? Its back! And with a vengeance. And its daily, and constant now. And this time, I'm showing codes p0108 and p0351.

The jeep starts cold and runs great for about 15 miles, and at the same point every day, it will start violently bucking, losing power instantly, backfiring and then just stall. You can feel the engine fighting to stay alive, then you'll hear the rattle of "nails in a jar", a bang or 3, and then nothing. Rarely, it will restart, but most of the time, it will behave like an old carburated motor that has been flooded.

Am I finally screwed into replacing the ecu here? The cat is shot again because of this, and the muffler is blown out again from the backfiring as well.

No smoke to determine lean/rich. Avg mpg is 17.1 combo highway and local. When it stalls, you can definitely smell the excess gas while trying to restart, but prior to it stalling, the exhaust smell becomes excessively strong (which would lead me to running too lean right before the issues start).

mfisher2112

Ok, so I did some playing around today. Because of the issues and research I did before, and based on what I've found today, I think I have definitely narrowed the issue down to the voltage regulator circuits on the PCM. The furthest right connector handles most of the 5v regulation to the rest of the sensor system (TPS, CAM, CRANK, VSS, Trans Vaccum, MAF, etc). Yes, 2 wires carry +5 volts out to the sensor bank throughout the motor. Brilliant design...

At any rate, when "wiggling" that connector, I can force the jeep to stall and have been able to reproduce the problem that formerly I was unable to reproduce as it was random. This leads me to the conclusion that whatever solder connection was previous bad, has just gotten worse.

Apparently, when you pull apart the PCM, there is the main body of the brain encased in protective gel, and a secondary system that will pop off. This system is the voltage regulation system that takes the 12 v in and redistributes the appropriate lower voltages to various sensor systems through the vehicle.

There is a connection that bridges this system to the main brain via a long series of pin and pad solder connections. The first 3 carry the main 5 volt out feeds, and apparently, they fail over time, causing intermittent connection, and confusing signals to and from the PCM, ultimately resulting in the bucking, backfiring and power loss/stalling.

Heres a video I did early just to show the reproducing of the issue (forgive the sideways angle, I did it quickly on my phone)


I also found a guy (you tube is probably one of the greatest (and potentially worst) inventions of the modern age) who shows exactly which connections break on that pin/pad system on the voltage control circuits.

I'm going to attempt to repair this on my own.

Wish me luck...

mfisher2112

Oh, and you'll also notice in the video that the CEL I got last night (and still had this morning) is now mysteriously gone.. More indication that there is an intermittent issue in the PCM.

mfisher2112

Ok, new problem...

Repaired the solder connections on the voltage control board. They were VERY loose and the connector to pad slot had alot of play on pins 1 to 3, just as described.

Got everything back together, and it started right up, idled like a dream. Let it run for about 10 minutes, no issues. No stumble, no threat to stall, nothing.

Got in, threw her in reverse, backed out of the yard into the drive way, no issue. Perfect response.

Put it in drive to pull away, and it suddenly felt like I had a dead 4 cylinder running on 2. No power, no pick up, no nothing.

Got it out on the road, hit the accelerator, and it sounded like the bottom of my engine was going to hit the pavement. Rattled horrible. Wouldn't accelerate. And it felt like it was in "limp home" mode on the transmission. Wouldn't shift into 3 or OD and rattled something horrible when I hit the accelerator.

Now I'm getting codes p0351 and p0748, but am NOT getting a check engine light. Only know the codes are there because I put the reader on it.

I'm completely lost on this one. This problem did not present until AFTER I re-installed the PCM. My trans was fine before I pulled the PCM and repaired it. The only thing I did on the PCM was strengthen 3 solder connections that control +5v circuits out of the PCM, so I can't even begin to imagine why the trans is suddenly throwing control solenoid codes and operating in "limp home" mode.

Any ideas?? I'm absolutely lost, and I still have to get to work tomorrow and Saturday... Ugg...

Deloy3

http://www.obd-codes.com/p0351

Deloy3

I don't know if it will be the same solution but I had a very similar problem. It wouldn't shift correctly and I had no power when on the accelerator. My issue was my TPS I replaced that and now runs fine. I had a rattle sound underneath as well and that turned out to be my torque converter plate. I tightened up the bolts on that and it stopped the rattling. Like I said, it may be different solutions but sounds like similar issues.