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Sneedle Vision
10-02-2012, 11:38 AM
My brother is having an issue with his GC and I thought the great minds here at xjtalk might be able to help diagnose. Here's what he sent me.

When I take off (easy acceleration, not a launch) from a stop the Jeep accelerates like normal under constant throttle pressure, but seems to blow past the 1st gear shift point and revs up to 4500 RPM or so then shifts. If I take my foot off the gas around 2500-3000 RPM and wait a second, it'll go ahead and shift like normal.

When the RPMs get up around 3000 or so, there's also a noise I've not noticed before that sounds like something is spinning - but it's hard to distinguish from regular engine/exhaust/tire noise. The noise seems to go away after it shifts. I had my head hanging out the window listening this morning to see if could get a better description of the noise, but all I can describe it as is a mechanical spinning noise.

It just started doing this yesterday afternoon on my way home from work. The drive to work (about 10 miles) was normal. It started doing it after I came out of my parking garage at work. I did punch it a little bit to beat some traffic and spun the tires a bit, but I don't think that could have caused this.

cantab27
10-02-2012, 11:49 AM
auto...fluid fill...spinning noise , auto makes that when belts are slipping ...???

Sneedle Vision
10-02-2012, 12:50 PM
auto...fluid fill...spinning noise , auto makes that when belts are slipping ...???

He said he's going to check that and all his vacuum lines this afternoon. He did check fluids and everything looked good.

Mudderoy
10-02-2012, 01:00 PM
He said he's going to check that and all his vacuum lines this afternoon. He did check fluids and everything looked good.

Isn't it a bad TPS that can affect the shifting of the transmission? Certainly not the answer for the spinning sound, but if it fixes the shifting issue the other may go away.

I tend to lean to the slipping transmission as well, but I don't think that would explain the shift from 1st to 2nd at 4,500 rpm.

I know mine will shift around 3k, and if I step on it, it will shift at 4,800.

4.3LXJ
10-02-2012, 02:28 PM
Yes, I think the first order of business is to change the TPS

Sneedle Vision
10-03-2012, 06:35 PM
Well, through further research, we found that a common problem with those transmissions is that the anchor for the front band screw will break and/or come out and be sitting in the pan. It looks like we will be tearing into it, so hopefully we don't screw it up more. :pray:

We are still going to switch the TPS just to make sure, but it's being held up because our local shop only had then for like $85. So UPS is bringing one.

bluedragon436
10-13-2012, 04:24 PM
I was going to say TPS as well, cause that caused some fun on my XJ and shifting when it went out... luckily for me I had a spare on my spare TB, so I changed it out in the Wal-Mart parking lot after picking up the required Torx bit... Hoping it isn't the front band issue, but at least you have an idea what to look for if you do end up tearing into it..

Sneedle Vision
10-13-2012, 08:33 PM
Well, we tore into it today and it was the band anchor. It was laying in the pan. So we installed the new anchor and band strut and sealed it all back up. Followed the FSM for refilling.

It still seems to be giving problems though. When you shift into reverse or drive, it feels like it doesn't lock into gear and doesn't start to creep off the engine idle. If you give it gas, it delays moving like if you were holding the clutch in, and then it moves.

We're about at the end of our knowledge, but we're gonna think overnight and troubleshoot tomorrow.

Sneedle Vision
10-14-2012, 04:28 PM
Well! Back with an update!

It turns out that the FSM didn't account for the amount of fluid you need to fill if you drop the valve body. So we added about 3 more quarts and did a slight adjustment to the shifter linkage and the ZJ is back in business!

Still going to keep an eye on it, but it seems to be back to normal!

Mudderoy
10-14-2012, 05:35 PM
Well! Back with an update!

It turns out that the FSM didn't account for the amount of fluid you need to fill if you drop the valve body. So we added about 3 more quarts and did a slight adjustment to the shifter linkage and the ZJ is back in business!

Still going to keep an eye on it, but it seems to be back to normal!

Oh that's great news, congrats!

LizardRunner
10-16-2012, 01:16 PM
Glad you fixed it up.. the GC auto tranny holds 6 quarts or at least mine did after a full rebuild. I had more than just one band that was bad and they redid the valve body too. I've discovered that I've now had just about every big problem a WJ can have fixed.