[Idaho7tree]

I recently bought a nice 7.3 powerstroke which had a lot of work done to it. But the main issue its having is a misfire, and i was wondering if the pcm could be the issue? It has ab stamped injectors ive been told, and recently got new under valve cover harnesses (he did them at my work). If anyone has any advice on what i should search for it would be very much appreciated by this newbie!

 

[Idaho7tree]

Starts fine, one rotation of the glow plus in 20 degree weather, i give it two just incase. Smokes a whole lot when idling ul to warmth and shakes. Smoke eventually goes away but it still shakes and misses. If yall can think of anything else i should put let me know!
Thanks

 

[Bugman]

I doubt that it is the PCM and without a lot more information we would just be talking shots in the dark.

There could be a couple of bad glow plugs if you are getting smoke on a cold start

Does it run fine once it is warmed up?

Does it light the CEL when it happens?

Have you checked to see if there are any stored codes?


On the glow plugs, it really doesn't do any good to cycle them off and on since they stay on for up to 2 minutes when they are first turned on. That wait to start light in the dash is just a idiot light and has nothing to do with the glow plugs except to get you to wait

Sent from my SM-J737V using Tapatalk

 

[Idaho7tree]

The truck has no codes, it runs well enough warmed up but you can still smell a lot of fuel in the exhaust and feel it not firing properly. Check engine light never comes on.
Thanks for reading my post!

 

[Idaho7tree]

Could it be the stock pcm with the newer engine and ab injectors? Would aa vs ab injectors even matter?

 

[Bugman]

If it runs fine once it is warmed up it isn't the PCM

Sent from my SM-J737V using Tapatalk

 

[Idaho7tree]

If it runs fine once it is warmed up it isn't the PCM

Sent from my SM-J737V using Tapatalk

Ill search all the receipts to find what all was done with it, or at least what is there and try to figure something out, thank you very much for the help!

 

[cjfisher]

Bugman.... Idaho mentions in post 4 that after it warms up there is still a strong smell of diesel. I agree with you, as the truck does run (even poorly) I would chase other ideas.

Idaho -

I would find yourself a Code/PID reader that is compliant with the 7.3. I like FORScan with an appropriate OBD dongle (a search on PSN will find you a number of opinions). The FORScan software allow you to do a cylinder contribution test. A couple of possibilities that I can think of:
Injector that has come loose and is leaking fuel past the copper gasket. Leaking fuel being dumped during the exhaust stroke..
Burned/bent/poorly functioning exhaust valves.
I have read of an instance in which a bad Baro sensor (membrane had come loose and caused the sensor to miss report the pressure) caused the engine to run very rough.
It would be a good idea to do a compression check on the engine. It will get you under the valve covers where you can check for loose injectors and valve functionality.

Cj

 

[Idaho7tree]

Bugman.... Idaho mentions in post 4 that after it warms up there is still a strong smell of diesel. I agree with you, as the truck does run (even poorly) I would chase other ideas.

Idaho -

I would find yourself a Code/PID reader that is compliant with the 7.3. I like FORScan with an appropriate OBD dongle (a search on PSN will find you a number of opinions). The FORScan software allow you to do a cylinder contribution test. A couple of possibilities that I can think of:
Injector that has come loose and is leaking fuel past the copper gasket. Leaking fuel being dumped during the exhaust stroke..
Burned/bent/poorly functioning exhaust valves.
I have read of an instance in which a bad Baro sensor (membrane had come loose and caused the sensor to miss report the pressure) caused the engine to run very rough.
It would be a good idea to do a compression check on the engine. It will get you under the valve covers where you can check for loose injectors and valve functionality.

Cj

I will for sure be diving into it as best i can once i have the ability too! Very excited for this! Thank you very much!

 

[Lt.Dan]

If you are running AB injectors with AA (single shot injectors) tuning, then it will create a slight miss, but WILL STILL RUN. The other way around, the tuck will not run.

I went through this when I bought my truck. Swamps refused to believe i had AB injectors in a 96 Cali truck, and gave me single shot tuning. It ran okay, but there was a slight miss, or something wrong

I would be looking at the pcm, or get a Hydra and get tuning to correct it

 

[Idaho7tree]

If you are running AB injectors with AA (single shot injectors) tuning, then it will create a slight miss, but WILL STILL RUN. The other way around, the tuck will not run.

I went through this when I bought my truck. Swamps refused to believe i had AB injectors in a 96 Cali truck, and gave me single shot tuning. It ran okay, but there was a slight miss, or something wrong

I would be looking at the pcm, or get a Hydra and get tuning to correct it

A hydra was ordered, I did not know there was a tuner so well developed out there for these trucks. Thank you!

 

[Lt.Dan]

A hydra was ordered, I did not know there was a tuner so well developed out there for these trucks. Thank you!

There are still companies out there that are dedicated to making strictly 7.3 parts, and they're growing! The aftermarket for the 7.3 powerstroke is still expanding.

Mainly because of their lack of emissions systems makes it easier to mod them, legally.