Occasional "lurch" at highway speed

[8450]

well ive got mine all back together,and im still not sure the results. i drove it about a mile and boom it did it again. on the way back home about 10 minutes later i pulled over and nailed it in some grassy spots. usually it wouldve made the same boom as it engaged the clutch, but it was actually pretty smooth and agressive at the same time. it was always violent when a wheel sliped before. naybe the new fluid did something and hadnt had enough time to go through the case when i first left the house. i dont know. what i dont uinderstand, is if the problem IS that its trying to go into 4x4,ut dioesnt make any sense,. the front and the rear are spinning exactly the same speed going down the highway, so if it did engage the 4x4 clutches, it really shouldnt be noticable at all i wouldnt think. i hate this thing

 

[ejbeach]

Same problem

My 99 just started doing the exact same thing 2 days ago. It feels to me as if the fuel pump might be shutting off for a split second, almost like my 97 ranger used to do if you hit the speed limiter, the pump used to pulse on and off at 105 mph, causing a really quick jerk. I am sure it's not a transmission problem, I watched my tach and it doesn't move a bit when it does it, and my tranny was just rebuilt by Aamco a few months ago. I am also sure its not my 4wd because my 4x4 motor isn't even on the transfer case because it jammed up a few weeks back and I disconnected it and shifted it manually back to 4 high. The lurching started the day I accidentally ran out of gas, that's what makes me think it's a fuel problem also, I'm gonna try changing the filter.

 

[BrooklynBay]

Running it on a very low tank of gas could cause sediment to get pushed into the injectors, regulator, and filter. Add some fuel injection cleaner into your gas tank, and see if there is a difference.

 

[8450]

justbecasue your tranny was rebuilt by aamco means nothing. and i have heard of cases where it could be the transfer case even if you have the motor off. apparently, the rod the shift fork is on gets really worn out and sloppy and it can kick out of 4 auto on its own. this isnt the problem in my case though since ive already had it all apart

 

[gijoecam]

does anybody know if the shift motor actually shifts into the N point at any time. i dont see why it ever would.all the way clockwise is high,then as you turn left it goes to neutral, then goes to low. seems like it would only need high and low,since theres no neutral on the dash knob

The only time it stops in neutral is if you have a neutral tow kit installed.

Engagement of the front driveshaft is handled by the transfer case clutch coil, and, as you mentioned, all the drivetrain components are already spinning at the same speed. Locking the shafts at that speed occurs the same way when you flip the switch to 4high, so I highly doubt that's your problem.

It's not likely a shift rail issue either. That's not going to cause your symptoms. An oblong shift rail bore results in the dreaded whizzing sound when coasting, not a solid clunk.

It does sound like either a trans or fuel supply issue to me, but it's tough to tell. I suppose it could even be a differential issue as well... tough to diagnose it over the interweb.

-Joe

 

[8450]

well, the differential is not it cause i just went through it when i had it in the air for a leaky axle seal. . i hope its not the trans. seems like the rpms would jump pr move somewhat,but they dont. but i have no clue what in the trans would cause this even if it was it

 

[VTOSS_Man]

For those of you wondering how control trac works, I dug out my shop manual CD. Here is the description:

The Control-Trac transfer case uses an electromechanical clutch assembly to control torque to the front wheels. In the Auto mode, while at rest and under cruising conditions, the GEM activates the transfer case clutch at a minimum level. This allows for the slight difference between the front and rear driveshafts which occurs normally when negotiating a corner on dry pavement. Under any of the following conditions, the GEM will increase the torque sent through the clutch to the front wheels in order to prevent or control slip.

l Slip is detected (by monitoring the front and rear OSS sensors in the transfer case)

l Throttle position (by using the throttle position signal from the EEC)

So, reading that, if you had a faulty OSS sensor, you would definitely have 4x4 control trac issues. Also, if you had a faulty TPS signal, that could also cause 4x4 control trac issues, although I'm sure you would notice many other issues as well if the TPS was faulty.

 

[Gianni D]

Any updates from anyone??

My X has been in the bodyshop for a week and I haven't been able to check it out.

This might sound dumb, but I'm gonna give it a shot ... if the GEM module is acting up and it's causing this jerk ... how about just running the X on 4x4 high after experiencing a jerk ... if the jerk goes away does it mean that my GEM is bad???

I'm thinking about just doing that to see if the GEM or my hubs are bad ...

What do u guys think??

G

 

[8450]

well ill be the guinea pig here...i seriously think its the transfer chain being loose and wore. mines pretty sloppy in my opinion,so im getting a new one and trying that. i cant see buying a new or rebuilt transfer since everything else looks new in there except the chain. i tihnk the problem is its jumping a tooth every now and then which would account for the big clunk im getting

 

[8450]

i guess no one else has this problem anymore???

 

[kevin25.4]

I started having the mistery lurch about 2 months ago. Found the tranny was about a quart and a halve low. So far so good. I thought I had it fixed with a new fuel filter.the old one was 6 years old. But it came back after a couple of days of replacing it.

 

[Gianni D]

i guess no one else has this problem anymore???

My X started doing the lurch a few days ago ... The road was wet and the weather was really cold. As soon as it lurched ... I switched to 4wd high and the lurch went away. I haven't experienced since ...

I just think my lurch is actually the 4wd kicking in when there's uneven wet pavement ...

I will keep informing you guys

G

 

[8450]

no, this lurch happens when cruising steady at about 60+mph. oon dry pavement going straight. its definately not the 4wd kicking in,cause even if it was you shouldnt feel it when all wheels are rolling the same speed

 

[8450]

well, the chain is in and ive drove about 30 miles so far and no lurching so far...knock on wood...the new chain was substantially tighter then the old one. i could almost pull it ahead a tooth just by hand,so we'll see if this helps anything. if it does it was a 75 dollar part to fix it

 

[BrooklynBay]

Where did you buy the chain? How many parts were replaced total?

 

[8450]

i got it off ebay...it was the factory chain that came in it too. made by morse. all i replaced was the chain and the rear seal since it was leaking a litle.the sprockets had very very little if any wear,so i didnt spend the money to buy them. everything else in there was in excellent shape

 

[8450]

yeah nevermind....it did it again today...starting to think ill just burn it

 

[8450]

well i put over a 1000 miles on it over vacation and at times it would go over 200 miles and nothing. then it might do it every 20 miles. ive noticed it will do it always over 80mph,but at 70-75 it will almost never do it. from 50 -70, it will do it occasionally. im convinced its not in the transfer, i had it unplugged the entire time. so im lost now

 

[Gianni D]

I haven't experienced the lurch since the last light snow fall here in Cleveland. I'm not a mechanic, but I wouldn't be surprised that a loose or dirty ABS or Hub sensor is causing this issue because it only happens when the temp drops and there's snow/water on the roads. I'm prolly going to have my mechanic check my hubs in a few weeks ...

I'm not too concern about it because at least it's not the tranny

G

 

[8450]

im worried it is the tranny,but noone seems to be able to figure out what it is...