Wierd problem, please advise

[tahiti350]

Hi all,
It's been a while since I've been on the forum,. Both Subbies have been running well, but that's come to an end.

My White Wagon is acting strange, feels sluggish from a stop (especially compared to Wife's Blue wagon), but getting excellent milage. Getting 22.4 back and forth to work, all in town driving in traffic, and got 25.4 on the last tank with an 80 mile freeway run in moderate traffic mostly at 65-70 mph. Last all highway run was 28.84 MPG.

It's shuddering at idle in gear, but in neutral it levels out. RPMS are solid at 720, and if I knock it out of gear at lights, let it stabalize and put it back in drive it runs smoother.

It's also unlocking the torque conveter every time I coast, but locks back in after I pick the throttle back up (The Blue Wagon doesn't do this...).

Last work was an IAC solenoid, which fixed my high idle, vacumn leak issue, and I messed with the TPS, but put it back right where it was originally (paint mark alignment). It has been running well until about a month ago and doesn't seem to be getting worse.

I'm closing in on 200K (less tha 120 miles to go) and want to keep it going for as long as possible.

[tahiti350]

no one???

I've wondered about a possible bad injector, but that shouldn't affect teh TC unlocking, unless I actually have 2 different problems???

[ericem]

maybe just needs a tune up like plugs fuel filter and wires. Even some injection cleaner in the tank. Another possible solution is resetting everything by unplugging the battery and then hitting the brakes then wait a hour or more and hook it up start it up let it idle till it warms up. Then go for a drive. Forgot to mention replacing the coolant sensor as its pretty cheap the ecu one.

[iluvdrt]

My 98 does that shudder thing in gear and I have no idea why. If I place it in N it goes away. I thought it may be a bad tranny mount but they appear to be OK.

Although my TC stays locked at coasting, it does have a hard time finding 3rd gear.

Also when it is floored it will fall on its face between the shifts, but in manual mode will stay strong all t he way to red line. As soon as it shifts though it will loose power until it finds the gear it wants.

I figured it might be a fuel/spark thing. Might be time for some new plugs, and fuel filter.

[Legacy777]

Are you sure it's your torque converter unlocking/locking?

[tahiti350]

Are you sure it's your torque converter unlocking/locking?

Yep, running 70 mph on I-5 this weekend, will go from TC locked under power at 3000 rpm, to coasting TC unlocks and rpm will fall to around 1500 rpm, then apply power rpm's go to about 3300 rpm, then drop down to 3000 rpm again as tc locks back in.

I've been working on/driving cars for over 25 years, and know what a TC locking and unlocking feels like... I just don't know WHY it's doing it.

Would a bad injector cause the rough idle and sluggishness? If so could the computer trying to bring things back in line be flaking out the TCU? Or is the TCU reading the TPS and with my messing with it maybe I'm still off a little?

[Legacy777]

The TCU has a TPS input on it. The TCU shouldn't have any control of the engine idling. However may be acting up due to another issue.

Have you checked both the ECU & TCU for codes?

[tahiti350]

The TCU has a TPS input on it. The TCU shouldn't have any control of the engine idling. However may be acting up due to another issue.

Have you checked both the ECU & TCU for codes?

Not yet, didn't6 have a CEL, so hadn't thought of it. I know what I'll be doing this weekend.

[iluvdrt]

Mine doesnt have a cel in either system. I do know I have slightly low compression on my number 2 due to worn cyl walls, but its only out of range by about 15psi. You dont even notice it while driving. The idle is fine, just not in gear.....

[tahiti350]

Well, instead of pulling codes today I went out and bought another Leg... '92 L in Ice Blue (found out the wife's '90 is actually "Bermuda Blue". Check out my post in the Misc forum for more on the new one.

I've thought about playing with the TPS a little to see if that helps or hurts, and I picked up a set of grey top injectors and a coil pack to swap in and see if that helps the idle.