“Lag”?

[tooturntdad]

Noticed a little bit of lag in my truck. Not sure if its transmission related or not. Maybe it is and Im just thinking by default my 5.7 is old and tired and just on its way or whatever.

This is more of the “get up and go” deal when getting in short on ramps while in congested traffic and you basically have to shoot the gap to get on (I live in a metro area thats pretty fast paced)

So example, Id be coming on the highway just under highway speeds and if I were to just give it a little more throttle to match highway speeds or better itll feel like it neutralized. But if I just lay off and let it do its thing gradually its fine.

Some factors to consider. Truck is a 96 tahoe. Has 207k and its all stock mechanically as of now. I dont know much history of any prior maintenance but what I do know is that it was a one owner truck that has been in the previous owners family since new back in 1996.

I dont have any codes except for the EGR that comes up every now and then (i clean it with TB cleaner and it clears it out)
I dont have any form of smoke, my oil pressure reads just about normal and doesnt spike. I dont have any leaks anywhere.

Only small issue which Im fixing is the fan clutch failed (based on several other members suggestions on prior post I made about the e-fan conversion)

I do plan to do some preventative maintenance in the coming weeks but that mainly consisted of suspension, brakes, and belts.

Could this just be a transmission issue or maybe computer related? Its not all too big of a deal but some pointers would be nice to sort of get me to the righr direction.

Overall, its been a great truck and it drives great. Surprisingly the transmission doesnt give me problems other than just that issue alone. Shifts fine when driven casually. I know these things arent meant to be dogged on and thats not my end goal. I just wanna be able to merge into traffic without binding people up behind me cause Im driving like an old man

Thanks

 

[stutaeng]

Does the engine rev up and you either maintain speed (but not acceleration) or lose speed?

If so, then it's transmission flare or slip.

 

[tooturntdad]

Does the engine rev up and you either maintain speed (but not acceleration) or lose speed?

If so, then it's transmission flare or slip.

yeah, basically its what it does. but any other time it doesnt do it. just under heavy acceleration.

 

[df2x4]

Based on what you've said here, I'd be preparing for the imminent death of your 4L60E.

 

[Caman96]

So I was doing a little research on transmission “flare” and this kept coming up:

https://wiki.ad7zj.net/wiki/images/a/aa/2010-02-07_003951_no_2-3_upshift.pdf

You must be registered for see images attach

Could this be related to OP’s issue?

 

[stutaeng]

I'd check everything on the engine side first, but if everything seems ok, drop the transmission oil pan and look for any excessive friction material.

I don't know what the shift mph are for OD, but probably it can be confirmed with a more advanced scanner that it's doing it when 4th engages.

Probably needs the oil changed anyways, since you don't know the history.

I think the flares can be caused by many things. There's a lot of threads on pt.net about the issue.

Edit: the rebuild service manuals I've seen define a "flare" and "slip" as the same thing.

 

[thinger2]

Yep. Having killed a few 4l60s myself.
It does sound like a trans failure.
But, I would try to track down that intermittant EGR problem first.
And do the normal fluid checks.
Make sure it isnt burnt etc..
Sometimes what seems to be a trans failure is actually a performance or system manegment failure.
An intermittant on an egr is just a classic root cause of drivability problems.
It is probably the trans.
But chase everything else first.
Then you can decide

 

[letitsnow]

If you have access to a decent scanner - it is sometimes fun to leave it hooked up while driving, and watch what the timing is doing.

 

[tooturntdad]

Alright folks! Sorry for being stupid late with an update.

So,
So far I have replaced my EGR valve and cleared the code and seen a relatively small difference in throttle response.

This lasted a few days and then it just wants to bog out on me again under load.

Just replaced the plugs tonight (12/9) and took it for a test drive still same issue.

Decided to test a theory and see what it does at revs. Full throttle the truck acts like it has like a launch control. Itll reach to about 3500-3800rpm and just hold there and sputter. Half throttle and I can full rev.

On standby I have a new distributor cap and rotor along with new wires. On the way I have the jumped wire for trans flare.

Now Im starting to believe my issue may be throttle body related? cause normally when you floor a pedal of any car itll hit the limiter or bounce off it. Mine? Half way then it just bounces like launch control. Its just wild.

Anywho, currently as of now i have zero codes. Any thought?

 

[stutaeng]

Transmission slip...if it revs and you go nowhere, it's slipping.

A lag would be you press the accelerator and there's a delay until the engine actually revs up, but as soon as the engine revs, you will start accelerating.