HELP! Weird AW4 Tranny Quirks, Need Input.

Hi, I have a 2000 Cherokee with a 4.0L and an AW4 transmission and about 68K miles on the clock. I have noticed a couple funny quirks from time to time and I am wondering if they are common or a sign of a problem I should have checked out. If there are any transmission guys or anyone very familiar with AW4 transmissions on here, I would really appreciate your input and thoughts on my symptoms.

1. The first scenario occurs when cruising between 45-50mph on flat ground or slight downgrade. At this speed and situation the transmission upshifts as it seems it should so there is very little drag on the engine and RPMs are very low in the 1000-1200rpm range. What is funny is if I depress the throttle slightly to speed up as traffic pace increases the RPMs and my tach will jump up momentarily and then drop down again. So I sort of get a positive throttle response for a second then it drops off and I have to really depress the throttle further to maintain acceleration in the same gear or depress it much further to cause the transmission to downshift. Is this RPM jump normal, a sign of a transmission problem, or am I just paranoid?

2. The second scenario occurs again when cruising but this time at a slower pace in the 28-31mph range. Again at this pace RPMs are low. But this time when I step on the throttle I get a bit of an increase in RPMs but not much response and then the transmission sort of jumps into gear as if it was slipping for a second or had a delayed rough shift. Again is this normal quirky operation of the AW4, a sign of a transmission problem, or am I just paranoid?

Has anyone else experienced either of these issues?

I don't know if it is important to note that I have a high flow AEM DryFlow filter and intake tube, bored throttle body, Edge Products computer module and a Flowmaster 50 Series muffler and cat back exhaust installed. I also did change the transmission fluid about three months ago, using the correct fluid and I have checked the fluid several times since and it seems to be in the appropriate range.

Any input, ideas or experience would be appreciated.

Thanks,
Steve

ive read on here of this happening to others and i think my 98s done kinda the same thing at lo speed its kind of hunting between gears till it gets throttle and figures out what gear it wants to be in at hi speed sounds like your only disengaugeing the torque converter momentarily but it reingauges makin your tach jump you could probably duplicate that scenario by lightly depressing the brake pedal while maintaining throttle to kick out the od and see if it seems like the same feeling

Thanks for the input, the torque converter diagnosis sounds about right, I will assume that is a factor of operation. The description of searching for gears seems to be exactly what I am experiencing.

Do you think considering the shifting is all based on fluid pressure in the trans that maintaining a slightly higher or lower fluid level would remedy any of this? The "OK" fluid range on the stick is sort of large I wonder if a level at the lower or upper end of the spectrum would have any effect?

cant answer that question but i doubt it are you the guy i bought the rear springs from i have a white 2 door and drove from md to pick them up as you can see i live in fl now

If you bought them in Newark, DE I am gonna bet that was me. Nice to know you are still into Jeeps, looks from your avatar like you got that sucker built up now too.

Totally normal. Both of them.

i tthought that was you whats up thought your screenname was familiar you have a classic w/ sunroof and dk blue i think right? and the avitar isnt mine but i have a 3 in lift in part to your springs which i added to mine harsh ride but its atruck and im used to it the old girl has almost 304,000 on it now still no probs mtr never been apart

Both are normal operation for the AW4.
Going down hill when ypou lift your foot off the gas, the torque converter unlocks. When you put your foot down again the RPM and the MPH syncronizes or attempt to before the TCM sends the TC lockup signal. Below 43 MPH +/- the TC never lock up. You lift your foot, the XJ free wheels while the 4.0 returns to idle speed. Again when you put your foot down the RPM and MPH is sent to the TCM along with signals from the TPS which enables the AW4 toselect the correct gear. A momentary spike in RPM maybe up to 300 is normal.

techno1154 said:

............Below 43 MPH +/- the TC never lock up. You lift your foot, the XJ free wheels while the 4.0 returns to idle speed. Again when you put your foot down the RPM and MPH is sent to the TCM along with signals from the TPS which enables the AW4 toselect the correct gear. A momentary spike in RPM maybe up to 300 is normal.

Click to expand...

Would this apply to a '92? My speedometer went out yesterday. I plan on ordering a speed sensor on monday but, my tranny is definitely acting a tad bizaare.

I am going to assume that your first question is about a change in the performance of your transmission shifting in which case I suggest that is not normal. That said, I would seriously suspect that the Throttle Position Sensor, TPS, is developing some noisy spots in its signal to the AW4's electronic computer (TCU). If you are having a problem (changes in how the AW4 shifts) it is 95% probability that the TPS is going bad. The AW4 and TCU are probably OK. TPS sensors are a regular maintenance replacement item.

I wouldn't call my experience a change in operation of the transmission but it is intermittent and only occurs under certain conditions so I was trying to determine if it was in fact a transmission problem or an operational trait that only becomes apparent from time to time or under certain driving conditions. If Techno1154s explanation is correct and accurate than it explains my so called "quirks".

These kind of functional auto transmission built-in issues are the type things that make me wish they made more Cherokees with manual transmissions. Manual transmissions always seem so much less finicky.

Thanks for the input, it sounds like I don't have too much to worry about. I may in fact replace the TPS sensor for good measure. Is the TPS sensor a dealer only item or something I can get form AutoZone?

What is the other sensor attached to the throttle body called? I can't remember, is it the O2 sensor?

"What is the other sensor attached to the throttle body called? I can't remember, is it the O2 sensor?"

No, its the IAC, Idle Air Controller.

Everyone has the TPS sensors, prices vary a whole bunch. I recently bought one from (yours is the second from the top if it is 4.0, $41.95, everyone else is getting alot more for these right now!!!):

http://www.teamgrandwagoneer.com/cgi-bin/partsSQL/search.cgi?query=TPS&catid=

Ecomike said:

I am going to assume that your first question is about a change in the performance of your transmission shifting in which case I suggest that is not normal. That said, I would seriously suspect that the Throttle Position Sensor, TPS, is developing some noisy spots in its signal to the AW4's electronic computer (TCU). If you are having a problem (changes in how the AW4 shifts) it is 95% probability that the TPS is going bad. The AW4 and TCU are probably OK. TPS sensors are a regular maintenance replacement item.

Click to expand...

I didn't know if, you were addressing my question but, since you recommended TPS sensors to be regular maintenance I bought one. I figured that if, it didn't cure my problem then I'd have a spare in my trail kit.

It fixed me right up, thanks

Unfortunatly I don't have a spare since I broke the original TPS trying to get one of the friggin' torx screws out.

Great!:yelclap::yelclap::yelclap: