Another weird problem.. help!

[bsamoul]

About 3 weeks ago this problem first started. I parked my car in a parking garage for about an hour while my buddy and I went to get ice cream. When I got back in the car I start it and it stalls right away. 2 times later I get it to stay running but the idle is very low, I'd say 500-600 in park. I drop it into gear and it goes to about 400, and my service engine soon light goes OFF (it's on because it wants a cat to be replaced). Anyway, on the way home I decide to pull off on a side street and try restarting to see what it does, does the same thing - takes a couple tries to keep it running. After about a week it does it again while I'm at school trying to leave. So last Wednesday I take a can of carb cleaner and spray the throttle body, and I seafoamed it. Last night I get in after a couple hours of sitting and it starts doing the same thing, doesn't stall this time, just idles very low, like it's barely hanging on to something, but at least it's running, so I hit the gas to get the rpm up and drop it in gear and take off.

Does anyone know what could be causing this problem and how I can fix it? I just wish I knew why it was happening, and why it would turn my SES light off because when it happens, it isn't throwing any codes.

Any help would be greatly appreciated. TIA

 

[96ProCompTahoe]

since its not happening everytime, kinda hard to say./

you check the plugs after you seafoamed it? when was the last time you checked the cap and rotor?

if the cat is really clogged it may be keeping it from running right, but i wouldn't see y it wouldn't do it all the time.

 

[96cherry]

check the fuel pump they're notorious on these trucks

 

[fyremanpat]

Check your intake and all the hosing. Especialy since you used Seafoam. It almost sounds like you're losing vacuum.

 

[bsamoul]

check the fuel pump they're notorious on these trucks

I replaced it less than 10k miles ago. And I can hear it when I turn the key before actually attempting to start.

 

[bsamoul]

Check your intake and all the hosing. Especialy since you used Seafoam. It almost sounds like you're losing vacuum.

But this isn't the first time I've used seafoam, and wouldn't I hear it sucking where I used the vacuum hose? And wouldn't it always run like it's sucking for air if it's loose?

 

[fyremanpat]

Seafoam probaly has nothing to do with it, but since you pulled off a vacuum hose to clean out the engine, theres a chance its not on all the way. And yes its possible you're not hearing it.

 

[bsamoul]

Seafoam probaly has nothing to do with it, but since you pulled off a vacuum hose to clean out the engine, theres a chance its not on all the way. And yes its possible you're not hearing it.

I just looked, and to double check, I pulled it off and replaced the springy clip with a radiator clamp. Problem didn't happen today, but the SES light came back on.

 

[fyremanpat]

What code is it throwing?

 

[bsamoul]

The same one, a cat is running below threshold

 

[clean95]

The same one, a cat is running below threshold

doesn't that mean its running to lean or to rich? what does the truck do right befor it stalls out like what does the rpms do? when was the last time u changed your fuel filter spark plugs...?

 

[clean95]

I drop it into gear and it goes to about 400, and my service engine soon light goes OFF (it's on because it wants a cat to be replaced). . TIA

r u saying u have bad cats or cat?, it could be clogged making it choke the motor, if u tap on the cat with a hammer or something and listen to it if it sound really really clogged that might be ur problem, my friend 95 silverado had a stock cat with alot of miles on it and it was clogged had the similar problems... idk good luck

 

[bsamoul]

doesn't that mean its running to lean or to rich? what does the truck do right befor it stalls out like what does the rpms do? when was the last time u changed your fuel filter spark plugs...?

That code has been on for as long as I've had it, for 20,000 miles. I replaced the fuel filter when I did the fuel pump about 10k miles ago. Before it stalls out, it starts normally, like goes up to around 1300 rpm I'd say. I can usually tell when cranking if it will die, because it takes a couple extra cranks to start.

 

[bsamoul]

r u saying u have bad cats or cat?, it could be clogged making it choke the motor, if u tap on the cat with a hammer or something and listen to it if it sound really really clogged that might be ur problem, my friend 95 silverado had a stock cat with alot of miles on it and it was clogged had the similar problems... idk good luck

So if it's really clogged it could choke the motor? What would it sound like? Like solid instead of hollow, or what?

 

[fyremanpat]

The infamous P0430 and P0420? Have you tried cleaning your MAF sensor. After cleaning mine I swear by it! I had a similar problem, replaced all O2 sensors and had the cats checked...Gunked up MAF sensor was the culprit...Dont use anything BUT MAF sensor cleaner though.

 

[clean95]

So if it's really clogged it could choke the motor? What would it sound like? Like solid instead of hollow, or what?

ya tap on it if it sounds hallow its good if it sounds like a solid hit its full/bad.

 

[bsamoul]

So today it happened for the first time with the engine stone cold. It stayed running but at low rpm. The rpm on starting never got higher than 8 to 9 hundred. I did happen to buy MAF sensor cleaner yesterday because I was planning on cleaning it today.

 

[mygreen98]

id start by checking fuel pressure, pulling spark plugs and inspecting for any fouled up or burning rich, as stated check MAF, check carbon buildup on iac motor and throttle plate.

 

[bsamoul]

I cleaned MAF today. Hope it doesn't happen again.

 

[bsamoul]

Ok, now it's taking a long time to start when cold. I have to keep cranking for it to finally start. Suggestions?