1996 LSS surging and stalling....

[moscow913]

Also drop by autozone and have them read your computer. Let us know what codes popped up.

[TCHRISD]

the surging and stalling usually only happens when I get to or am coming to a stop.
My "low coolant" light keeps coming on and off ever since I got the tensioner pulley and bypass tubes replaced. I told this to the mechanic and he said the sensor is probably off. I have not noticed any considerable drop in coolant levels in the 2 or 3 weeks after having that service done. I check it every couple days. I haven't notice steam coming out but will keep an eye out.
would there be codes if the check engine light is not on?
I will try to go to an autozone today or tomorrow.

[Hmanor3]

It seems you have not ruled out the MAF. With the engine running, tap on the top of the MAF with the handle of a screwdriver. If it is bad the engine should stall or surge. My 98 LSS had a similar issue and it was the MAF. If you need to replace it, use GM part, they work better.

[TCHRISD]

Originally Posted by Hmanor3

It seems you have not ruled out the MAF. With the engine running, tap on the top of the MAF with the handle of a screwdriver. If it is bad the engine should stall or surge. My 98 LSS had a similar issue and it was the MAF. If you need to replace it, use GM part, they work better.

OK i will try this. I just drove it to AR from houston. It surged and all that stuff on and off the whole drive. I got back last night. When I started the car this morning a bunch of white smoke came out the exhaust for a minute or two. When I started driving it went away. Any ideas what that is?

[Hmanor3]

If the weather was cool when you started it, it is probably just condensation. The fact it went away suggests that. However, coolant can sometimes seep into the intake, and down into the cylinders. If this is the case you should notice it needing coolant, frequently.

Now, if you tap that MAF, and it seems ok, try unplugging the EGR valve, and drive it to see if it drives better. My EGR valve was bad and didn't throw a code, or turn the engine light on. That also caused a surging, stumble while driving.

I just replaced the upper intake, the lower gasket set,(with the metal frame), belt tensioner, bypass tube, plugs, wires, and EGR valve. I replaced the MAF a year ago.

[TCHRISD]

Originally Posted by Hmanor3

If the weather was cool when you started it, it is probably just condensation. The fact it went away suggests that. However, coolant can sometimes seep into the intake, and down into the cylinders. If this is the case you should notice it needing coolant, frequently.

Now, if you tap that MAF, and it seems ok, try unplugging the EGR valve, and drive it to see if it drives better. My EGR valve was bad and didn't throw a code, or turn the engine light on. That also caused a surging, stumble while driving.

I just replaced the upper intake, the lower gasket set,(with the metal frame), belt tensioner, bypass tube, plugs, wires, and EGR valve. I replaced the MAF a year ago.

I needed to add a slight bit of coolant after the trip to AR. But have not needed to since (3days) and haven't before.
The dying in the morning and stalling have gotten happened less. I am not nearly driving as much. From observing it for a while it seems to happen more often when I drive at highway speeds for a while and then have to slow down. Does that say anything about it? have not replaced the MAF yet.

[Hmanor3]

The coolant level sounds normal.

If you tap the MAF, and the engine surges or stalls it is bad, otherwise check the EGR valve. Then go from there.

[TCHRISD]

Originally Posted by Hmanor3

The coolant level sounds normal.

If you tap the MAF, and the engine surges or stalls it is bad, otherwise check the EGR valve. Then go from there.

I tapped on the MAF and no real difference. I unplugged the EGR and no big difference. I just let it idle for a while to see if anything would happen. It doesn't surge all the time.
the problem seems to be getting a bit worse. It seems it is getting kinda jerky. it surged the other day while coasting thru a parking lot and has only starting with the surge coming to a stop prior to that. I am getting a shaking sometimes thru the steering column it seems.

[Hmanor3]

Originally Posted by TCHRISD

I tapped on the MAF and no real difference. I unplugged the EGR and no big difference. I just let it idle for a while to see if anything would happen. It doesn't surge all the time.
the problem seems to be getting a bit worse. It seems it is getting kinda jerky. it surged the other day while coasting thru a parking lot and has only starting with the surge coming to a stop prior to that. I am getting a shaking sometimes thru the steering column it seems.

Did you drive it with the EGR unplugged or just idle? I would drive it with the EGR unplugged.

[TCHRISD]

Originally Posted by Hmanor3

Did you drive it with the EGR unplugged or just idle? I would drive it with the EGR unplugged.

No I didn't drive it. I will try that today.

[TCHRISD]

Well I drove it with the EGR unplugged. I went at least about 5 miles. Probably long enough to get a surge from it. But it made no surging and idled pretty smoothly for the most part. Now the check engine light did come on but I am guessing that is just from the EGR being unplugged.
Should I start looking to replace it?

[Hmanor3]

The engine light will come on with the EGR valve unplugged. I would recommend driving it a few days to make sure it makes a difference, then plug it back in and see if it goes back to the surging......

The EGR valves for these are expensive, usually 150-200. That is why I would double check it like I said above.

I drove mine for a few months with it unplugged.....just because I was always on the road.....but as soon as it was plugged back in it would act up.

[TCHRISD]

Originally Posted by Hmanor3

The engine light will come on with the EGR valve unplugged. I would recommend driving it a few days to make sure it makes a difference, then plug it back in and see if it goes back to the surging......

The EGR valves for these are expensive, usually 150-200. That is why I would double check it like I said above.

I drove mine for a few months with it unplugged.....just because I was always on the road.....but as soon as it was plugged back in it would act up.

I have been driving it around for the past few day with the EGR unplugged. It has only surged a couple times and never more than 500extra RPM's and for just a little bit. It has not died at all. I am thinking this may be the problem. I looked closer at the EGR valve and it looks as if someone put some kind of fabricated metal thin plate in place of where the gasket goes. ??????? I will try to post a pic if I figure out how to do that.

[TCHRISD]

Well today I drove this morning on what was similar to my old morning commute. About 30miles one way in rush hour traffic. the surging came back and it even died one time. I not sure if this is tied in to the prob but the temp gauge started getting high ... like pushing the limit but not quite in the "red zone". I got nervous and put on the heat. that lowered the temp. I am in Houston and it is already starting to get really hot. It was during the time while I was in bumper to bumper traffic. Acted basically the same when I drove it home.
FYI... had the EGR unplugged on the way this morning and plugged back in on the way home this afternoon.
Is this looking more like a MAF sensor? Would that have an effect on the temp?

[Hmanor3]

"FYI... had the EGR unplugged on the way this morning and plugged back in on the way home this afternoon. "

With that info I would say the EGR Valve is not your problem. If you feel like replacing the MAF you could try that, that may or may not fix it....