Some may remember my woes in the past regarding an engine miss at all rps. And I've tried everything that I can possible think of to diagnose it's cause with no luck so far.

Today I got it fired up after a long winter to see how she ran after the long hibernation. Everything was the same as when I put her down for the winter. Engine miss is still there.

So I decided to pull the ICP plug off of the sensor to see if it would make it run worse or not. When I did, sure enough it ran noticeably more rough. The strange thing that happened was that when I plugged it back in, the engine did not return to running the way it had before unplugging the sensor. I continued to run as if the ICP was unplugged. The check engine light was still on after I had plugged the ICP back in as well. Turned the truck off, re-started it and then the check engine light was off and it ran as it normally does (the usual engine miss).

I know there is no problem with the wiring harness because it is brand new. The ICP sensor itself is less than 300 miles old.

Does anyone know what could cause this? I have a suspicion that the answer to this riddle may be what's behind the engine miss as well.

Thanks,
Drake

 

Do you have access to a scan tool?

 

Don't worry about the engine not returning to its normal idle after plugging the pressure sensor back in. If you were to plug it back in and allow it to idle for a minute or two, the PCM would once again start using the feedback algorithm from the sensor. The PCM doesn't immediately start using the data from the sensor once it's plugged back in (but the service engine soon light would remain lit).

 

have you messed with the ipr? im not one to throw pats at it, but i do believe in preventative maintenace. If you got a substantial amount of miles on oem ipr, i'd look into replacing it, and ruling it out..?

 

A Miss would not be caused by Oil Pressure. The ICP/IPR would solve none of these.

Perform a Buzz-Test and CCT and see what you come up with.

Rather electrical imbalance in the feed side of the IDM Circuit. Check the UCVH and 42 Pin Connector for anomalies, grounded circuits, and chafing.

 

I have an intermittent slight miss (fueling imbalance). This is because I allowed air in the fuel by a botched Hutch mod, and I am in the midst of having my 9th injector repaired to swap out the dud.

My dual EGT gauges, temperature gun, and PERDELs have verified the dud. My UVCHs are new (not 50-cent mod), the connections are solid to the IDM, and the problem exists with 3 IDMs - including the Swamps 140.

This may or may not apply to you, but I thought it worth sharing that it doesn't have to be electrical.

 

Perhaps I should have been more clear. A miss is either electrical, mechanical, or Both. But, not HPO related.