Hard shifting, no tc lockup

Suselman

Member
I just bought a 06 envoy with the 4.2, just at 100k miles, I noticed it shifting hard just like my Grand Prix back in the day would but it had a line pressure control sensor that I replaced that fixed it, well I can’t find where or if the 4l60 has one, I also own a 05 trailblazer with 220k that shifts just fine, also with the envoy I noticed that there is no 4K rpm park limiter which I find odd. Only code is Evap and 02 sensor bank 1. Anybideas?
 

MRRSM

Lifetime VIP Supporter
Welcome to GMT Nation...

If possible... Contact the Prior Owner and ask whether or not he installed a "Shift Kit" and then had his PCM "Custom Tuned" by Specialists like PCM0fNC or PCM4Less...and/or had any highly unlikely adjustments made to Remove the REV Limiter when the Engine is NOT under a Direct Load ...or included Adjustments to the Torque Management Shift Points. Beware getting on that Gas Pedal with "Too Much Ooomph" until you can dope out the actual mechanical situation. Here is a "Legacy Thread" that covers 'Shifting Issues' with the 4L60E Transmission:

 
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Suselman

Member
I’m positive on no mods made as it was my grandmas vehicle since day one, just started out of no where going into gear hard and shifting hard, no trans codes but then again I have a cheap basic scanner that might not read trans codes
 

MRRSM

Lifetime VIP Supporter
In many instances... Shooting a Video of the Instrument Panel in Good Light (or better yet... At Night...AND ...as Safely as Possible...) while taking the SUV down a Straight and Level Road from a Dead Stop...all the way though the entire Shifting Pattern ...can be quite revealing, if you are inclined to do so.
 
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Suselman

Member
Throttle position is 21.2% at idle and calc load is 31% at idle according to my scan tool which seems odd
 
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Suselman

Member
In many instances... Shooting a Video of the Instrument Panel in Good Light (or better yet... At Night...AND ...as Safely as Possible...) while taking the SUV down a Straight and Level Road from a Dead Stop...all the way though the entire Shifting Pattern ...can be quite revealing, if you are so inclined to do so.
How would I post the video? I could take one tomorrow
 

MRRSM

Lifetime VIP Supporter
If you have a Google Gmail Account ...and by extension... a Youtube Account... You could Post the Video(s) there at (YT) and Drop the Links to them back here in your Follow On Posts.
 

gmcman

Well-Known Member
Was anything done to the Envoy prior to the trans acting up? Any service, including trans fluid change/flush, pressure washing, anything?
 
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Suselman

Member
Was anything done to the Envoy prior to the trans acting up? Any service, including trans fluid change/flush, pressure washing, anything?
It sat for 3-4 months and battery had to be replaced, other than that no recent service other than me changing engine oil but it was acting up prior to that
 

gmcman

Well-Known Member
So it was acting up prior to the 3-4 months of sitting?

I would possibly check the wiring harness going into the trans for any signs of a rodent chewing on the wires.

Check the cooler line inside the heat wrap for rust and/or leaks.

Unlikely... but double check the coolant for any froth which would indicate a ruptured trans cooler in the radiator.

You didn't mention it but I'm assuming you checked the trans fluid with a hot trans, engine idling?
 
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Suselman

Member
So it was acting up prior to the 3-4 months of sitting?

I would possibly check the wiring harness going into the trans for any signs of a rodent chewing on the wires.

Check the cooler line inside the heat wrap for rust and/or leaks.

Unlikely... but double check the coolant for any froth which would indicate a ruptured trans cooler in the radiator.

You didn't mention it but I'm assuming you checked the trans fluid with a hot trans, engine idling?
No problems until after it sit, update on codes, I plugged it into a better scanner and got a p2119, would that cause my issues?
 

gmcman

Well-Known Member
Have you recently cleaned the throttle body?

I would pull the resonator box from the throttle body and take a peek into the throttle body..is the throttle butterfly severely caked with a dark oily crud?

Searching that code it appears it's a throttle position error. A likely culprit would be too much PCV residue around the throttle plate not allowing it to fully close.

The TB can easily be cleaned. Removal and cleaning doesn't take long at all.
 
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Suselman

Member
Have you recently cleaned the throttle body?

I would pull the resonator box from the throttle body and take a peek into the throttle body..is the throttle butterfly severely caked with a dark oily crud?

Searching that code it appears it's a throttle position error. A likely culprit would be too much PCV residue around the throttle plate not allowing it to fully close.

The TB can easily be cleaned. Removal and cleaning doesn't take long at all.
I took it off and cleaned it with carb cleaner, tps Went down to15% at idle still shows 30% calc load at idle which idk what the calc load means honestly
 
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Suselman

Member
Here’s my data at idle
15% tps
Idle rpm 600
Calc load 36%
Maf flow 5.65 gr
Map kpa 35
Any of this seem off? I also checked all fuses to see if any was blown and all checked out good
 

gmcman

Well-Known Member
Calculated load will show a high value at the lightest throttle settings, It's not linear and I'm not sure exactly how it's calculated.

The area to pay attention to are the edges of the throttle body near the actuating arm.

I would pull the two PCM fuses at #10 & #28 for about 5 min or so, replace the fuses then turn the key to ON and don't start the engine, let the TB go through its paces. You will hear the motor inside the TB move around, leave it like this for a min or 2 then start the engine, don't touch the gas pedal, let it warm up with the AC off until the idle settles at 600 RPM.

Then re-check the codes and maybe this might fix the issue.
 
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Suselman

Member
Calculated load will show a high value at the lightest throttle settings, It's not linear and I'm not sure exactly how it's calculated.

The area to pay attention to are the edges of the throttle body near the actuating arm.

I would pull the two PCM fuses at #10 & #28 for about 5 min or so, replace the fuses then turn the key to ON and don't start the engine, let the TB go through its paces. You will hear the motor inside the TB move around, leave it like this for a min or 2 then start the engine, don't touch the gas pedal, let it warm up with the AC off until the idle settles at 600 RPM.

Then re-check the codes and maybe this might fix the issue.
No change, going to order a 1-2 accumulator and a pressure control solonoid and see what that does
 

Mektek

Well-Known Member
Had a similar hard shifting problem in a 4t60e - poured in a bottle of trans-medic and that cured it. To access the valve body in that car required the engine/trans to be lowered on the cradle - a very big job and I was glad that the "medicine" worked.
 

Mooseman

Moderator
Have you tried fixing the codes you do have? Even though not related, I've had a situation where I accidentally left my MAF unplugged and it shifted hard like with a racing shift kit.
 
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Suselman

Member
Have you tried fixing the codes you do have? Even though not related, I've had a situation where I accidentally left my MAF unplugged and it shifted hard like with a racing shift kit.
Waiting for o2 sensor to come in, the throttle body code was fixed by cleaning it up really well, one thing I noticed today was my reverse lights aren’t working and bulbs and fuse was good so I’m wondering if my neutral safety switch could somehow cause the problems I’m having, who knows I guess I’ll just keep fixing things and hopefully find the culprit
 

Mooseman

Moderator
Quite possible if the PCM doesn't see that it's in D, it mmay shift in aa default manner. Is the PRND321 display working!
 
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Suselman

Member
Quite possible if the PCM doesn't see that it's in D, it mmay shift in aa default manner. Is the PRND321 display working!
Yes, it displayes correct gear, but I’m not sure if that goes off of trans or if it’s sent to cluster from shifter
 

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