Can't get rid of code 45

[supermailman]

90 with a 350. New plugs, wires, cap, rotor, o2 sensor, egr valve, egr solenoid, map sensor, ecm coolant temp sensor, rebuilt the tbi, cleaned and flow matched injectors and I'm still getting a code 45. "Running too rich"

I have tested all sensors with a meter. All grounds were cleaned and or fixed. All vacuum lines were checked and or replaced. Truck runs and idlid smooth as silk. What gives? The only sensors I haven't messed with are the knock sensor and idle air control valve. When I rebuilt the tbi, I measured the end of the iac and it was exactly 1 1/8" extended iirc. Any ideas?

 

[evilunclegrimace]

Check for high fuel pressure, 9-13 psi is spec
Check for a leaking fuel pressure regulator, wet with liquid fuel
Check for leaking fuel injectors, improper spray pattern or dripping injector(s)
Check for an open ground on circut 453 ( ignition system reference low),This may cause induced electrical noise that the ECM can interpret as reference pulses and increase fuel delivery thinking that the engine is running at higher than actual speed.
Check to see if your purge canister is saturated with fuel,
Check for high manifold pressure (low Vacuum).
Unplug the map so that the ECM sees a fixed valve for the MAP. If the rich condition goes away swap out the MAP sensor.
A faulty TPS sensor can cause the system to go rich.
Test the value of the coolant temp sensor to verify that has not shifted values( meaning that has the correct resistance for the proper temp)

And one other thing,just because a part is new does not mean it is with in specs.

 

[evilunclegrimace]

I forgot 1 thing, make sure that your IAC is actually moving and not frozen in the fully extended position.

 

[supermailman]

Check for high fuel pressure, 9-13 psi is spec [running at 13psi currently]

Check for a leaking fuel pressure regulator, wet with liquid fuel [it was leaking before the rebuild, no problems after]

Check for leaking fuel injectors, improper spray pattern or dripping injector(s) [they were removed, cleaned and flow matched. they dont leak and have a very fine cone shaped mist when running]

Check for an open ground on circut 453 ( ignition system reference low),This may cause induced electrical noise that the ECM can interpret as reference pulses and increase fuel delivery thinking that the engine is running at higher than actual speed. [I am not sure how to do this. More info?]

Check to see if your purge canister is saturated with fuel, [it's dry]

Check for high manifold pressure (low Vacuum). [I replaced my MAP sensor because I had this code, it has since went away]

Unplug the map so that the ECM sees a fixed valve for the MAP. If the rich condition goes away swap out the MAP sensor. [I haven't tried doing this since replacing the MAP]

A faulty TPS sensor can cause the system to go rich. [tried 2 known good TPS. both checked out perfectly with a meter. .5v to 4.5v WOT, no dead spots]

Test the value of the coolant temp sensor to verify that has not shifted values( meaning that has the correct resistance for the proper temp) [I tested it on a cold engine, about 44degrees or so outside and its resistance was spot on. Will have to check after it warms up.]

The IAC valve seemed to be very, very stiff and looked rather dirty when I took it out while servicing the throttle body but I did not clean it or try to do anything with it. Might be worth another look.

 

[supermailman]

Also worth noting that previous owner replaced the distributor, it still looks brand new. And the timing is correct.

 

[supermailman]

Swapped in another known good IAC valve and coolant temp sensor with no change. I was doing a bit of research and found a thread elsewhere where the person was chasing down a similar problem and ended up fixing it by converting to a heated oxygen sensor. The stock single wire sensor wouldn't heat up enough because they had a free flowing exhaust system. I have true duals with small cherry bomb mufflers and no cross over (all previous owners doing) so with that do you think it's possible I'm seeing a similar problem?

 

[c1500deathtrap]

Wouldn't hurt. just pick up a 95 o2 sensor they are 3 wire, and get a splicin'

 

[supermailman]

Upgraded to a three wire sensor and wired it all in. Truck seems to run a little better. Still getting code 45 but it takes a lot longer for it to show up now.

 

[randomguy]

Where is your O2 sensor located?

Purely speculating here but if the sensor is too far down the pipe and at a location where moisture collects that could explain the issue. If it’s in the stock exhaust manifold disregard.

 

[supermailman]

Stock manifold/location. It's funny that you mention moisture though. I have true duals and only the driver side bank smokes from the exhaust pipes. And I did notice just now what looked like moisture collecting on top of the manifolds where the gaskets are. I'll have to get a pic real quick.