Stalling when stopping..

[87LB]

OK, Time for me to ask for a bit of help from those that know more then me.

I was given an 87 LB 4x4 with a 350. so far the truck has received a new distributor, coil from me. My Brother in-law has replaced the injectors and the TB gaskets ( with a FPR ), new fuel filter, thermo and I believe a coolant temp sensor.

And the truck will still stall out when costing or coming to a stop. It does not do it every time but it does it quite a bit, and it seems like it does it only when warm.

Now I am thinking it could be the EGR, but wouldn't I see the check engine light?

Any other ideas?

The good part of the day was fixing the A/C. That is always huge to have down south LOL

 

[RetroC10Sport]

I might suspect a bad or sticking Torque Converter Lock Up solenoid if it's an automatic.

 

[Jims86]

Sounds like a VSS issue(vehicle speed sensor) and / or a very dirty/ lazy IAC ( idle air control) valve.
Retro could be right to, but to check, go out and drive at 50 mph, and while listening to the engine, tap the brake just enough( keep your foot on the gas) to activate the brake lights, and if its unlocking, you will hear an increase in RPM.

 

[87LB]

Ya it is an auto. The IAC is new. But maybe the passage is clogged.

Beyond the driving at 50 and tapping the brakes do we have any other way to test the lockup?

Thanks!

 

[Jims86]

Ya it is an auto. The IAC is new. But maybe the passage is clogged.

Beyond the driving at 50 and tapping the brakes do we have any other way to test the lockup?

Thanks!

Thats about it really. Unless you have a tach. Does it sputter off, or does it seem like when someone doesn't put their foot on the clutch in a stick at a stop? Doesnt have to be 50, supposed to lockup at about 38.

 

[89Suburban]

Plug the vacuum line going to the EGR and see if it still does it.


Posted From Hell

 

[philjafo]

The plug with room for four wire (usually only 3 wires in it) is what tells the tcc to lock up, if unplugging that stops the stalling then the problem is likely in the wiring or switches. It rules out the internal parts of the trans.

 

[87LB]

thanks everyone. I may try to pull that plug and see what happens, along with the egr vacuum plug. But I did add seafoam transtune and so far I have seen a noticeable improvement. driving around the stalling has happened less often but not 100% gone as of yet.

The truck did sit for about 2 years before I got it started.

 

[87LB]

Update: the sea foam helped but it was still stalling out when coasting to a stop when warm. So I removed the vacuum line to the egr valve and plugged both sides with vacuum caps.

I drove about 250 miles after the egr plugs were in and it did 99% better. It only stalled one time when I was in reverse.

 

[89Suburban]

Update: the sea foam helped but it was still stalling out when coasting to a stop when warm. So I removed the vacuum line to the egr valve and plugged both sides with vacuum caps.

I drove about 250 miles after the egr plugs were in and it did 99% better. It only stalled one time when I was in reverse.

If unplugging the EGR made that much of an improvement but still a slight issue stalling next thing I would do is pulls the EGR and see if there is debris in it holding it slightly open when it is supposed to be closed. Do you have a vacuum gauge to test the idle vacuum levels?


Posted From Hell