93 f-350 7.5l automatic 2wd

I changed the battery and now the truck runs like crap, it stutters and the check engine light flicks on/off.

It seems to me changing the battery couldn't do this, I'm thinking it has something to do with the amount of rain we got.. I had the hood cracked open while the battery was out... I did notice water on the engine... I've checked the distributor and it's dry but it's running like it's wet.. what else should I check?

 

Battery voltage and alternator output. Why did you change the battery? The computer needs the correct voltage to run. If it's too low that's how it will run.

 

It was starting slowly and the battery wasnt holding a great charge. The voltage is around 13.5-14v at idle so I dont think thats the problem..

Pretty sure its a moisture issue, but the distributor is dry so its gotta be something else that can make the truck run bad and miss.

 

Pull the codes to see what the computer thinks is wrong.

 

Nothing KOEO

KOER
21
77
74
65

 

"Nothing" as in no codes at all or did you get the System Pass Code 11"


Code 21: ECT out of self test range 0.3 to 3.7 volts.

Did you warm up the engine before running the KOER tests?


Code 65: Overdrive OFF switch was not cycled during KOER test (user error).


Code 74: Brake On/Off switch not actuated during KOER test (user error).


Code 77: System failed to recognize brief WOT during Dynamic Response Test (user error).

 

I got the code 11 for KOEO

I warmed it up a bit but the temp gauge doesn't move much so it's hard to say.. plus it runs like crap so it's hard to warm up

The ones about user error.. was I supposed to do things during the test?

 

It's important to know if you got the System Pass code.


It might be worth a shot to pull the connector on the Engine Coolant Temperature (ECT) sensor to look for signs of corrosion. You can use a meter to measure it's resistance.



Yes you are....

This test requires up to three inputs from the driver during the test. The first input requires that the brake pedal be depressed, the second requires that the steering wheel be turned at least one-half turn and then released. Finally on cars equipped with an E40D automatic transmission, the Overdrive Cancel Switch must be deactivated, then reactivated.

I believe there is no need to perform the steering wheel turn since your truck does not have a power steering pressure switch.

 

On the KOEO test did you get just two code 11 and then stop the test?
To get a clear of codes with the KOEO self-test you need to get "11, 11, 1, 11, 11".
The second two 11's are for the stored codes (CM codes) that were flashing the MIL.

 

thanks guys, I will do some more investigating based on your feedback.. I'm having a really hard time believing I have component failure tho because it ran perfect right before I disconnected the battery.

We have had epic rain here the last few days, really leads me to believe it's a moisture issue

 

I took readings at the sensor
It's about 85-90 F here
4.6V
26k ohm

 

One leg of the ECT connector is VREF (Gray/Red). This is the supply voltage for most of the computer sensors. VREF should be in the 4.5-5.0 VDC range. The output is on the Light Green/Red wire. I believe you should get the listed output voltage by placing your meter reference to ground and the other lead on the Light Green/Red wire.

The resistance measurement looks reasonable for the listed temperature. Perhaps the engine was not warmed up enough to satisfy the KOER test parameters (greater than 180F (82C) to pass the KOER Self-Test).

 

So I know obd2 will trigger for misfires and stuff.. should I just replace cap/rotor/plug wires to be safe?

 

Since the code check is pretty much okay, I was going to suggest pulling the distributor cap to look for moisture. If any of those ignition components are of unknown age, might as well replace them anyway.

 

This problem is super intermittent... what I noticed though is that when it's running bad the computer won't run codes (the code scanner just says 000 and the self test won't start), it also seems like the fuel pump will just continue to run. It's hit or miss.. when it runs bad it has no power, seems like it's trying to move out from second or third gear and idles terribly.. check engine light flickers on and off. Then, the next minute it runs perfectly.

It ran perfectly before changing the battery and ever since has problem.

Just tried pulling the codes again and got KOEO/CM it got a 10,20,30 and that was it... what's weird is it took quite a while for that test to run and even when I removed the code scanner the stuff under the hood continued to click and actuate... I want to say it's the computer but just hate to guess..

Any advice is appreciated.