hey on first start up my car will idle really high and then surge low and run real rough and then die. anyone know what might be wrong.

 

i have the same problem with the same motor

 

Same here. I've been trying to figure it out for about a month. Only thing I can think of is vacuum leak with mine.

 

Did the same with my car, I replaced my MAF and TPS sensors and that fixed the problem.

 

thats the same thing i was going to say. sounds like a vacuum leak. have you checked the vacuum on the vehicle or fuel pressure?

 

I replaced all vacuum lines and gaskets and it still acts the same. It ran perfect after I did all that, but that night after work it started doing the same thing. Maybe it's just scared of the dark.

 

Surging is usually due to the engine running lean. It could also be due to a bad IAC, or a stuck EGR valve. The CTS/MAP sensors going bad are also possible causes. As for vacuum leaks, with TBI, it does not matter like it would with MAF as its SD.

Does it run ok when you give it some gas? Or does it just crap out?

 

First i would make 100% sure you dont have any vacuum leaks. Then make sure the injectors are spraying nicely, with no drips. If an injector is dripping (it should be spraying in a cone) it is probably clogged. That can cause the symptoms you were describing. Run some seafoam or injector cleaner in the gas, and check it again. If the injectors are functioning properly, then i dont know, maybe change the fuel filter. Also, i would check the timing

 

I've replaced the IAC and MAP, cleaned the EGR and made sure it worked properly, checked every place a vacuum leak could occur that I can fix, and I've used the injector cleaner and both injectors spray like they should. I've replaced the spark plugs and wires too, so now I'm going to try the distributor cap just to be sure it's not an ignition issue. My uncle is probably going to sell me a 350, but I really want to find what the problem with this engine is since so many people with 305 TBI's seem to have this problem.

 

Mine runs perfectly while driving. However at idle it either:

1. Idles fine until the A/C kicks in, then craps out
2. Surges to 2500 RPM

 

I was told my 1990 has a rebuilt 1989 Blazer 350 in it. It has one throttle body with dual injectors. It idles normal the first couple seconds then idles very low almost dead but it pops back up to normal, it keeps doing this over and over. If I feather the throttle I can get up to 10 - 20 mph for a mile then it dies.
Or if I don't drive it if I feather the throttle I can keep it idling up and down
I can keep it running at 2,500 rpms then goes down then back up, it does this over and over. After a few minutes it dies and will start but idles same for a few minutes then it's dead, until I wait a couple hours than it starts and runs the same and dies after a couple minutes. The longer it runs the worse it gets. I fixed the fuel line it had a kink in the return line. I have replaced the IAC, TPS, a new throttle body that has the regulator in it. New starter, radiator cap and rotor, plugs and wires. I had the module tested it's Good. I haven't been able to get the 02 sensor to even move it's really frozen in the exhaust pipe, the front part of the 02 sensor fell off while I was looking at it but I can not get it to budge... it's in there good! I bought this car two years ago. I still haven't been able to drive it. The code I get is the 02 sensor which is stuck in the exhaust

Thanks

 

i have the 305 tbi and its doing the same thing, seems like a vacum issue becuz when i come to a stop the idle drops then car dies with no warning, doesn't do it all the time though,i have heard of the TCC solenoid have the same symptoms which i have replaced,map & IAC are new,i have a feeling its my EGR getting stuck its been a few yrs since i last replaced it

 

Mine does this because my fuel pressure is too high I lower it and it doesnt stall out. You probably have bad injector(s) spraying too much fuel flooding out the engine and killing it. I could be wrong. I changed every part I could think of. except for injectors and intake gasket, I then changed my heads, intake gasket and throttle body and didnt have this problem. Until I put in the bigger pump, and bumped up the fuel pressure because I needed more fuel pressure to not run lean. Then this problem arrived. So therefore it leads me to believe my old system had a leaky injector (the cones were not perfect) and therefore was getting too much fuel. Again, I could be wrong. And this all could be coincidence.

 

I replaced the 02 sensor. The fuel pump squeaks while it is starting to die. Might be the fuel pump or filter.

 

Try capping off the vacuum line going to the EGR, you will get a computer code so be prepared to reset. see if it idles more normally. If it does than you need to look at the EGR or solenoid. If it continues than I would suspect low fuel pressure and test. Also there is a pressure regulator in the TB you may need to rebuild the TB if the fuel pressure is good.

I think you said you replaced the IAC, if not check that.

 

Wow, Old thead. I would say prob a vacume leak as well. Mine does this to me if I dont start it up for a while. I'll start it and have to give it gas and manually idle it at like 900 for a few seconds to a minute, and then I turn it off, let it sit for about a minute, then I turn the key and it starts up and idles perfectly without my foot getting anywhere near the gas.