I pulled the codes and this is what I came up with. I believe these descriptions are all right but I fould a couple different descriptions for a couple so let me know if I have one wrong.

2.8L 12v FWD, 205k mi

P0102 Mass or Volume Air Flow Circ Low Input
p0116 Engine Coolant Temp.Circ Range/Performance
p0401 Exhaust Gas Recirculation (EGR) - Flow Insufficient
p1101 02 sensor low voltage (pre-convertor sensor, bank1)
p1106 02 sensor low voltage (pre-convertor sensor, bank2)
p1408 exhaust gas recirculation temperature( EGRT)sensor - high input
p1504 IAC valve


I've done some searching and it looks like some people are saying the EGR issue could be tripping some of the other codes related to afrs such as the mas air flow and o2 sensors.

On the EGR issue I just read this article:

http://www.engine-light-help.com/egr-valve.html

basically stating it's probably something else in the system besides the valve itself.


I would appreciate any insight from anyone who has had this issue before on where to start. I would really like to be able to diagnose this problem without throwing parts at the car. They are expensive and with 200k+ on the clock dumping a bunch of money into the car is not worth it, I will just go get something new. GM is basically giving away cars right now.

 

I also have a 12v, and I also have P0401 EGR insufficient flow, comes around about once a month. Mine doesn't throw any of the other codes though, so i don't know about the EGR causing any of the other symptoms.... It's possible that some of the codes might be older/unrelated. If you have access to a code reader or VAG-COM, i would clear everything and see what comes back.

Also, when i bought my car it was throwing p0116 Engine Coolant Temp.Circ Range/Performance, turned out to be a bad coolant temp sensor. Hope that helps!

 

+1
But at 200K+ miles it's probably wise to replace the ects by default. They get gunked up and give a lazy signal which can affect your mpg and performance slightly. Also, regardless of the code, it's probably wise to remove and clean your idle air control valve. If you don't know when/if the the primary 02 sensors have been replaced, go ahead and do them too at that mileage. Other than that, clear em and see what comes back like cca4 says.

 

well, the car is intermittently running badly. Poor gas mileage, irratic idle, when it runs poorly its sputtering and backfiring, has nearly no accelleration unless i put my foot on the floor. And even in this case I basically just keep up with regular traffic pulling away from a light.

If I turn the car off and back on it will immediately run better for some miles until the symptoms return.

I don't have access to a vag-com, unless some one in NW-Indiana/Chicagoland wants to lend me one but I will get a scanner on it and clear them.

And I am assuming the failed open thermostat is causing the bad reading across the ETCS. I am blocking the radiator, otherwise the car doesn't warm up, but it still warms slowly which is probably what is tripping that code.


No, I don't have a service manual, yes i will get one if i decide to repair this car. But for the time being help a brotha out and point me towards the IAC valve so i can inspect/clean it plz?

 

Don't know where the iacv is on a 2.8, but if it's like any other car, it's near the throtle body/intake mani or wherever air is entering the engine. Probably has a few solenoids/plugs sticking out on it. Unplug your maf and see if it runs better. With your maf unplugged youll run rich, but not as rich/lean as you would with it being bad and plugged in. If it gets better after you unplug it, replace it. Do not clean.
There are probably a couple "plungers" inside the iacv that open and close to let more/less air flow to correct idle speed. Those little plungers get fouled up with carbon and become stuck.

 

when I unplug the maf the car dies immediately.

 

and if your 02 sensors are bad then they won't be able to correct the sudden richness when ungplugging the maf. Start with replacing them, the ects, clean the iacv and go from there. Your maf could very well be bad though. Bad 02 sensors, ects, and iacv, or egr issues would not make it so you have to floor it just to get going like you describe. A bad maf might though. It's just expensive so thats why i suggest replacing those other things that are also likely bad first.

 

you do realize thats like $500+ into a car with 200k miles.

I am trying to determine if **** like this is even going to be worth doing without spending money. If I am going to spend 800, 1000$ getting it running i will just go put a down payment on a new car. GM is basically giving away cars right now.

 

More like $300 if you DIY, but what does it matter if I realize this? It's your car, I'm just trying to help answer questions that you asked.

 

I realize that and I appreciate the help. But I would like to find some sort of diagnosis procedure other than replace parts to determine what is actually failed.