Transmission Hunting between 3rd and 4th

[yodawill2000]

Hey guys.Last weekend I pulled the resonator out in preparation for getting a few glasspacksand now that I can really hear the exhaust Ive noticed that while cruising at about 40/45 the transmission cant decide on 3rd or 4th if I barely try to accelerate.

TPS is dead on 4.75.

Any idea's ??It was probably doing the same thing all along but I couldn't hear it shifting like I can now. Can't really "feel" it at all as the shifts are so smooth.

[GerryO]

I've read that between 4.0 and 4.5 is the correct setting. Before I set mine to about 4.38, after previously trying to set things by "feel" without using a multimeter (or a consult), I drove the car under both high and low conditions. Low produced hunting at freeway speeds, higher crusing rpms and poorer gas mileage. High produced a high idle speeds, harsher/later shifts and better gas mileage as compared to low.

What are your crusing rpms at 60 and 70 mph? 40-45mph is probably right on an edge of a shift point and at pretty low engine rpms.

[yodawill2000]

Dang .. It might be at 4.25 then.I remember is was within spec per the FSM.Time to hook up the consult again !!Thanks once again GerryO. Might need to bring it up a tad.

[alex61089]

That's exactly what my transmission does.. It hunts between 3rd and 4th.. I'm going to have to check out the TPS again.. I still havent figure it out.. But when I go to step on the gas it shifts into 4th then the slightest decrease in the pedal results in it downshifting to 3rd. It does it back and forth.. Pretty annoying on the highway lol.. If you figure it out let me know Yoda! Cause this would solve a 4 month problem for me! lol...

[yodawill2000]

I'm hooking up my Consult tonight after work and bumping it up some and will report back after my drive to work.

[alex61089]

Sweet, Hopefully we can figure this out

[yodawill2000]

Crud .. Bout to leave work and there's a nasty thunderstorm bearing down.Might not have the hood up tonight.We shall see.

[alex61089]

patience my friend lol

[yodawill2000]

Just got home ..As soon as it cools down a bit I'll get-er-done.

I can test it after when me and my boy head to the local dirt track.. Lubs me some Outlaw racing !!

[alex61089]

I took a ride on my uncles 4 wheeler for the first time the other day and it's almost like driving a mini j30 on the dirt roads lol

[yodawill2000]

Sounds like fun !!!But these boys are doing a little over 100 when the lift for the turn And its a 1/4/mile track !!Zooooom !!!

[alex61089]

yeah thats too fast for me lol.. i'd probably kill myself on one of those things

[yodawill2000]

Think I have found the issue with mine.Fired up the odb1 software and my TPS was at .65

thats really weird because less than a month ago it was dead on spec and the idle hasn't changed a bit.I went completely to the right and it topped out at .89. ???

Idle went up as well.I bumped it to .75 and will see if the hunting has changed.I also need to figure out why it changed so much.Cleaned both throttle bodies to no avail.Weird.

[alex61089]

Hm... I'm going to have to check my TPS voltage.. Maybe mine is off.. I thought it was supposed to be set at .50? you have had yours at .75? i'm going to set it to this and see if my hunting stops.

EDIT: I mean 4.50, Im going to try 4.75
Modified by alex61089 at 10:46 AM 8/9/2009

[alex61089]

I just want to say thank you Yoda.. i've had my TPS set at .45 and everytime i was crusing between 55 and 65 and i let off the gas the transmission would shift down and everytime i stepped on the gas the transmission would upshift.

Today i decided, why not set it on .75 and see what happens? To no avail i set it and took it for a spin the the most wonderful thing in the whole world happened. my transmission stopped downshifting and upshifting when i step on the gas and let go of the gas at 55- 65. This has been a 6 month problem for me and it's finally solved .

Just one question. It seems the transmission shifts hard into first.. Is this typical?

[yodawill2000]

I measured the resistance at the TPS connector and bumped it up a bit and mine quit hunting too !!

Do you mean its a hard shift from first to second ??Pretty common on the J especially before its fully warmed up if so.

If you mean from park to first whats the idle RPM ??

When i moved my tps too far counter-clockwise it ran the RPM up above 1K.My sweet spot was turning it till the rpm jumped up then backed it off till it went back down.



The thanks should go to GerryO !!!Thanks again bud !

[alex61089]

i meant from shifting from 1st to second but yes the idle is about 1,000. The shift is hard but as the car warmed up it became a lot better. You have no idea how happy i am. and to think.. I was ready to spend 120 for the Revolution sensor and probably 200-300 for the labor. I'm in heaven now... and for the first time in 6 months since i've had the car. I'm going to take it on the highway and not worry about this problem ever again wooot!

[yodawill2000]

1000 is a bit high.you might try backing it off a tad and see if it still doesn't hunt.Mines about 700/750.

[GerryO]

Let's see how well this all adds up.

The TPS is a variable resistor that's attached to the shaft that rotates the throttle plates open and closed, taking a constant input voltage from the ECM and changing it according to the position of the throttle plates as determined by the amount of pressure on the gas pedal, and feeding proportionally altered output voltages back to the ECM, that also communicates with the transmission.

The idle speed determining output voltage (fully closed throttle plates) should always be the same provided the throttle and cruise control cables move freely, the throttle bodies are clean, enabling the throttle plates to always close to the same point, and the TPS is in good condition.

Engine timing by itself, accessory load (mechanical and electrical; AC, Alternator, Transmission P/N/D), vacuum leaks and engine temperature affect idle speed, so they need to be corrected/adjusted before adjusting the TPS and finally the idle speed adjustment screw with the connector to the AAC valve disconnected (no signal to the ECM to increase idle speed due to accessory load).

Idle speed adjustment using the screw on the IAC/AAC valve is used to manually set the idle speed to a point that is just below the otherwise ECM controlled idle speed as determined by the engine temperature, accessory load, transmission selection and the reference TPS output voltage stored in the ECM.

Disconnecting and reconnecting the TPS with the engine running clears the old and enters the new TPS reference voltage (for closed the throttle plate position) in the ECM. Variable resistors can wear out.

Now if I just hadn't cut-off and removed that length of tubing that warms the AAC valve as the engine warms up, my idle speed would correctly fall while the car is moving. And the dealerships don't sell that part (14053-10Y01) anymore; time to hit the yards.

[alex61089]

the FSM says 0.4-0.5... I put it to .75 and my shifting was delayed too much.. however.. I took it on the highway and the hunting continued. Sigh... I changed it to .5 and it still does it... maybe it is my revolution sensor..