I keep getting KOER codes 21r and 41r and 34r.

I have changed the engine temperature sensor, EGR valve sensor and oxygen sensor. The EGR valve is new and tested that mechanical it is working and holds vacuum.

The engine starts immediately but hangs at a low rough idle. Smooths out at higher RPMs, and has all power when accelerating.

In addition to replacing these sensors, I have another perfectly running truck and tried swapping the IAC valve and intake temperature sensor.

​​​​​I have checked my vacuum lines over and over, they are new and are definitely in the right places.

Adjusting the timing while running doesn't effect the idle, and I can make it die by going enough to the left or right and can make it start in two turns so it can't be a timing issue.

Thanks.

 

Sorry to bump, still having trouble.

I took the EGR vavle off again and made sure again it is working correctly. I did notice if I blow really hard on the input I can get a tiny bit of air to push through to the output hole, really tiny. I have another positioning sensor and plugged it in just hanging there and pressed its actuator up and down and was no difference. The EVP is being fed vacuum and is off when cold and slightly open when warm.

The truck as it starts, I definitely hear an electronic click somewhere and starts a cold fast idle for a half second. After that I hear the same click and it drops the idle to like 600rpms and is rough.

​​​​​​When I give it gas it is right on with the timing with no hesitation.
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Thanks for reading.
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The 2 wire ECT?
Engine Coolant Temperature sensor, near the thermostat housing.

You changed this with new? OEM ? Aftermarket ?

What year is your truck?
You should put your truck details in your signature block.

 

Check that you have power to the Purple/Orange wire at the O2 connector with the key on.

Check the Black wire at the O2 connector to verify the ground path.

 

Did you replace the EGR-Valve & the EVP sensor at the same time?

 

Sorry about that, 89 F250 460 EFI.

Yes the two wire engine temperature sensor.
I changed the manifold air temperature sensor.

List of things I did/checked for this issue-

-TPS reads correct ohms
-IAC was changed
-ECT and Manifold air sensor changed
-New O2 sensor
-EGR valve is working mechanically and holds vacuum.
-Both vacuum solenoids are working correctly.
-Air valve for cat/smog pump is working correctly
-Distributor was taken out and I checked its function and made sure the pickup wasn't Rusty and is fine.
​-I made new grounds from block to frame and block to chassis.

As for timing it will only run and start right at 32 degrees BTC. The truck dies at 22 BTC and somewhere around 38 BTC I have three other EECIVs and I can stab those things in right the first time everytime and time by feel every time. Even with my DurasparkII. I am very sure where my TDC is on this truck and I have put it in about 6 times and still times to 32 degrees.

​​​​​​I just rented a fuel pressure check kit yesterday and will check that when I got time.

There's no check engine light, but I still get code 34 and 41, after I have unhooked the battery long enough to forget its memory 10 times over.

I am open to any suggestions, thanks!

 

Thanks for your replies guys I will check those things. My posts have to be approved so I ended up making a long reply as you guys posted.

The EGR valve and sensor was changed together, I tried another sensor from a working truck and no change.

Thanks!

 

The EVP issue may just be that the two new component shaft lengths do not match OEM.
Too long or too short.
I think your EVP shaft is too long, or your New EGR-Valve shaft is too long.
So, measure the voltage on the Brown/Light Green stripe wire, key on.
Then loosen the EVP screws and shim the sensor up using match book paper pieces, don't re-tighten, but barely snug the screws.
Re-measure voltage. it may be lower. if not, double the shim thickness. if voltage is lower, re-run the self test.

Are you getting this Code 34 if you run the KOEO Self-Test ?

 

Disconnect connector.

Measure the voltage on the ECT Light Green/Yellow wire with key on.

Very ground resistance on the Black/White wire.

Measure the resistance across the two pins of the sensor.

 

You are removing the Spout connector to check base timing ?

Are you able to set the Base Timing @ 10 deg ?

 

Normally for a true cold start, you will get a minimum of a 30 second high idle, 12-1800 rpm

 

With a rough ide condition, you will have to weed through the process of elimination, for a majority of the components can be the cause.

First fix all know faults.
The regularly scheduled maintenance items should be replaced, like Plugs, Wires, Dizzy Cap. Rotor, Air & fuel filters, PCV-Valve, O2 sensor, gas line antifreeze, etc.…

Vacuum leaks can affect the engine in many ways.
The timing must be set properly.
The IAC cleanliness and operation can cause a rough idle.
A compression check should be performed if tune-up is unsuccessful smoothing out engine.
Distributor condition can be a cause of a rough engine.
Fuel injector cleanliness and seal can affect the engine.

Also, ultimately the EECM controls the Idle, so when it becomes faulty the engine can run rough.

The original EEC & Fuel Pump Relays were substandard, and should be replaced.