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'99 S10 4.3 2WD RegCab
1999, S10, 4.3, 2WD, Auto, RC-SB, Base
Joined
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19 Posts
Discussion Starter · #1 ·
1999, S10, 2WD, 4.3, 4L60-E, 325K miles

I'm getting a weird intermittent slip when I'm accelerating from a full stop at a stop sign, light or whatever. It slips for a moment or two then catches and she drives along like nothing happened. It behaves 100% normal and shifts great between all gears. It was rebuilt around 40K ago, and has been doing this for about 3K miles as I've been trying to figure it out. The problem hasn't worsened over that miles/time span. I does not always do it, and it seems NOT to do it until it gets warmed up.

Engine hums along great, no misfire or anything wrong. TPS, MAF, and fuel system all check out, so its definitely something in the trans.

No CEL. No noises. No smells. No leaks.

Trans fluid & filter is freshly changed, and no improvement. Old fluid smelled fine, no burnt smell, and no debris in the pan.

I'm thinking I need to do a pressure test next. Could low pressure cause it to slip in the manner I described?

Perhaps the Pressure Control Solenoid is failing or partially clogged? And it isn't putting forth enough pressure until my RPMs get high enough? Or maybe that one valve (forget the name right now) that everyone replaces the spring on?

I'm not a tranny expert so I just thought I'd put this out here in case anyone else has dealt with this or has any help/advice on what I should check.

Pic for fun, it's her
350449
 

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'99 S10 4.3 2WD RegCab
1999, S10, 4.3, 2WD, Auto, RC-SB, Base
Joined
·
19 Posts
Discussion Starter · #2 ·
Anyone?
 

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Randy
Joined
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540 Posts
First is it a slip or a no shift condition?
A pressure test will help. Harbor Freight has a real nice pressure test kit for about $40.
Check your load % on a scan tool, it should go above 80%.
the EPC amps should go low as well.they work on a .1-1.1 amp scale 1 amp being low pressure and .1 is high pressure. Desired & Actual should match each other.
MAF sensor is the biggest factor in the PCM's ability to calculate pressure rise.
 

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'99 S10 4.3 2WD RegCab
1999, S10, 4.3, 2WD, Auto, RC-SB, Base
Joined
·
19 Posts
Discussion Starter · #5 ·
First is it a slip or a no shift condition?
Feels like a slip.
A pressure test will help. Harbor Freight has a real nice pressure test kit for about $40.
Just picked one up. Busy right now but I'll hook it up this weekend and see. What are the normal PSI levels I should be seeing?
Check your load % on a scan tool, it should go above 80%.
the EPC amps should go low as well.they work on a .1-1.1 amp scale 1 amp being low pressure and .1 is high pressure. Desired & Actual should match each other.
MAF sensor is the biggest factor in the PCM's ability to calculate pressure rise.
I only have a a basic scan tool (Innova 5210) but ill hook it up and share the results.
 
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