98 Windstar Jerk when Stopping

[drzoidberg]

My windstar has for a while been making moderate/slight jerks when stopping. It tends to happen typically just before coming to a complete stop, although sometimes it happens during low-speed turns when coasting (also sometimes have the issue where it shifts downshifts harshly after a "sweeping turn," as mentioned in one of the windstar TSBs). The RPMS don't appear to visibly drop when it occurs (although the tach in the 'stars seems a little slow sometimes). The only trouble code present is P0133 for the Bank 1 downstream O2 sensor slow response.

Also, it tends to worsen when the car is warm. The jerking is less severe when the engine is cool, and tends to worsen after the car warms up. Also it sometimes almost feels like the jerk occurs in two stages. I do not believe it is the TCC solenoid failing to disengage, due to the fact that it even happens if I get up to 15mph for a hundred feet, and then stop.

Probably unrelated, but the car also tends to run rough for 10-15 seconds after starting the first time if left sitting for a few days.

Anybody experience this? Any ideas on what it might be?

[C. Cleve]

Hi, One of two things, First, Possible low fluid in the trans, Two, Possible and most probable, Loose lube tube to the low intermedeate band servo, Necessary to drop the pan and check ALL the lube tubes in the trans, Hope this helps, Good Luck, Clay..

[garync1]

I too agree on the transmisson. Maybe bad fluid.. Dont know. If there is no code I dont think it would be the tranny range sensor.. Worth checking though..

[steve19761988]

Originally Posted by drzoidberg

My windstar has for a while been making moderate/slight jerks when stopping. It tends to happen typically just before coming to a complete stop, although sometimes it happens during low-speed turns when coasting (also sometimes have the issue where it shifts downshifts harshly after a "sweeping turn," as mentioned in one of the windstar TSBs). The RPMS don't appear to visibly drop when it occurs (although the tach in the 'stars seems a little slow sometimes). The only trouble code present is P0133 for the Bank 1 downstream O2 sensor slow response.

Also, it tends to worsen when the car is warm. The jerking is less severe when the engine is cool, and tends to worsen after the car warms up. Also it sometimes almost feels like the jerk occurs in two stages. I do not believe it is the TCC solenoid failing to disengage, due to the fact that it even happens if I get up to 15mph for a hundred feet, and then stop.

Probably unrelated, but the car also tends to run rough for 10-15 seconds after starting the first time if left sitting for a few days.

Anybody experience this? Any ideas on what it might be?

MINE JERKS TO WHEN COMING TO A STOP AND GETS WORSE WHEN WARM

[drzoidberg]

Thanks for the responses. I typically keep the trans fluid level at about the max. on the dipstick (and maybe a little over sometimes), so I don't think the fluid is low. Also, there is definitely no code for the range sensor. I have an OBD tool and all I get is the slow O2 sensor, which I'm dreading changing since it's the rear bank and hidden up in the engine compartment.

I siphoned and replaced about 6oz of fluid with Valvoline MaxLife Mercon III/Dexron a while back, and after a few days of driving the jerkiness seemed to subside some, although it was still present. Then, after I replaced my battery (which resets the adaptive memory) and about 20 more oz. of fluid , the jerkiness returned for a few days, and now it's back to pre-battery change state, although maybe a tad bit better.

Do you think it might simply be worn fluid or an engine problem (since the computer takes several driving cycles to re-learn optimal engine parameters)? The transmission fluid looks OK, and definitely doesn't seem burnt. It is a fairly clear dark red. The fluid I took out looks much darker than new fluid when compared in clear plastic containers. I made an attempt to change the fluid and filter by dropping the pan, but sometime before I got the van someone stripped a pan bolt head (and cross-threaded it too, I think). Winter has set in here, so taking care of that bolt will probably have to wait until spring, unless I want to pay the dealer $300 to change the fluid "the old way."

One other possibility I thought of was the Idle Air Control valve exhibiting a slow response, since it typically happens when I'm just stopping or turning with no throttle. I've cleaned it before, but those things are pretty hard to clean, so who knows?

[smokescream]

My Windstar just started doing what yours did. I know this was 2007 and you probably don't have the van anymore but did you ever solve the problem?

[drzoidberg]

I do still have the van, actually, but never really figured out what was causing the issue for sure. It doesn't seem to be too pronounced these days, not sure if that's due to something wearing in/out further or some other repair I've made that inadvertently improved things.

I did run across some information on a transmission repair website that indicated that a solenoid return spring fatigues/breaks in the AX4S trannies, and that manifests as a harsh downshift from 2-1, which may explain some of it. I just typically try to come to a complete stop or wait for it to downshift to 1 before giving it gas if I'm in that speed zone, and that for the most part seems to help keep it from being a big issue.

Items I've replaced since 2007 that may have helped include the idle air control (IAC) valve, cleaned MAF, replaced alternator/battery, spark plugs, and bank 1 O2 sensor (was causing a rich condition due to reading too lean, may have been giving too much gas when returning to idle and causing a near-stall - no code, though), PCV valve and hose (leaking elbow/Y). I changed the transmission fluid via a fluid exchange (no filter, because of cross threaded bolts) as well.

Vacuum leaks due to cracks in old hoses can manifest as the engine rocks on its mounts when you come to a stop, so I would recommend checking for those (especially those pesky elbows on top of the plastic upper intake manifold and the lines running back toward the brake booster). If you have a scan tool that gives you live data, it would be worth checking your fuel trim values to see if either bank is much different than the other, and see if your MAF reading is around 5 g/sec at idle. If you need any values for comparison, let me know. Good luck.

[smokescream]

Thanks for your reply and you have given me a lot of things to check.Thanks again for getting back so soon.