Engine stutters / stall at low speed close to idle, letting off throttle it pops

[L05edSS]

1987 Monte Carlo 4.3 TBI.

This only appears to be occurring when the engine has fully warmed up. I have two separate issues that I suspect may be connected.

1. While at low, creeping speed, often with the brakes on the engine will idle real low and stall. It has no issue restarting. Notice this mostly entering the garage or parking the car.

2. This does not occur when the car is in gear. I rev the engine above 3/4 throttle and let off quickly. Multiple pops, similar to backfires will be heard.

Any ideas where to start to look for this? I had thought fuel or timing but other than these two instances it drives fine. The plugs all look good, and the wires and plugs have under 5k on them.

start cheap go around with a prpane torch not lit make sure no vacuum leaks.

 

[tkruger]

Replaced the ignition module and all seems ok. Also did the breather, air filter and PVC just because they were due and I had to remove the aire cleaner to get the jo I needed to do done. Thanks for the help.

I looked at the cap and rotar and both looked good. Neither has many miles on them.

 

[78Delta88]

Check the TPS. There are you tubes that show how but you need decent VOM (volt ohm meter).

If you are near an O'Reilly's rent the fuel pump test kit. It has the fitting for the TBI. Pressure relief is set at 9 psi and it is common problem.

Sounds like just dirty injectors, all thing else being equal. Other possibility is vacuum leak some where.

As suggested go around engine with propane gas from torch, or spray of starting fluid, even WD40 is combustible.

If you shoot near where a leak is, RPM will flare and then drop back down.

 

[78Delta88]

One item commonly over looked is the vacuum booster for the brakes. These do get leaks over time and if enough, is possible to affect idle and kill engine.

Edit: another item is EGR. When the EGR doesn't fully close, this also can cause issues with poor idle, and could be enough to kill engine.

 

[spongbob]

Do you have small leaks in your exhaust sys.you could try limiting the de vancement of your vacume advance(if applicable) with a little tube over the actuator stem to stop gap the de vance motion.if you got a nice smooth dead lyke idle then you obviously don't have valve problems. That isn't to say your timing chain isn't worn down ask yourself ? I might look into an idle air adjust ment or pull the tbi and set the base idle ear or screw (from bottom??