7.3 Fluctuating Idle When Warm

lucasm12798 · May 7, 2015

Hi guys! I have a 2001 7.3 that recently went to the shop to get an oil pan leak fixed and injectors upgraded. The guy called and said that he is having an issue with the truck, when started it will rev to around 1000 then drop back down. It will do this constantly until it dies. He hooked up his laptop to it and the high pressure oil is fluctuating, causing the fluctuation with the idle. He changed out the icp and ipr sensor and it still continues to do it. From what he said the ipr is a valve and the sensor is only a part of it meaning there could be an issue with the actual valve. But here is where things get interesting, the truck had to be tuned to run the injectors and one tune on the chip lets the truck run absolutely perfect and idle at around 750. Which leads him to believe it is not the ipr at all, nor the icp, and he believes it can be cleared up by messing with the tunes. Has anyone else had something like this happen? If so, what solved it?

Sent from my iPhone using Tapatalk

Justin@DP-Tuner · May 7, 2015

Depending on the size of injector and manufacturer of them, this can be pretty common. You may want to contact your tuner about the issue at hand. Bumping up ICP at idle usually clears it up.

CurtisF · May 7, 2015

Any time you upgrade injectors, you need tuning.

If you switched from the stock split shots over to single shots, your idle will be crap until you get correct tuning.

There's nothing wrong with the IPR or ICP. Sucks for you because now you'll probably be paying for those parts because the guy doing the work doesn't realize that bigger sticks need tuning, and he just tried to band-aid it by throwing parts at it hoping for a miracle cure.

This is why I keep telling people to talk to their tuner first before ever picking out injectors.

lucasm12798 · May 7, 2015

Thank you.but even before the truck had the new injectors (baby swamps) it still had this problem. Is it still pretty common?

Sent from my iPhone using Tapatalk

lucasm12798 · May 7, 2015

And I was unclear in my original post, he did not replace the sensors, but had new ones on hand and tried them out to see if that solve the problem. The truck was tuned for the injectors when the problem was noticed by him

Sent from my iPhone using Tapatalk

cbf9703 · May 8, 2015

lucasm12798 said:
Hi guys! I have a 2001 7.3 that recently went to the shop to get an oil pan leak fixed and injectors upgraded. The guy called and said that he is having an issue with the truck, when started it will rev to around 1000 then drop back down. It will do this constantly until it dies. He hooked up his laptop to it and the high pressure oil is fluctuating, causing the fluctuation with the idle. He changed out the icp and ipr sensor and it still continues to do it. From what he said the ipr is a valve and the sensor is only a part of it meaning there could be an issue with the actual valve. But here is where things get interesting, the truck had to be tuned to run the injectors and one tune on the chip lets the truck run absolutely perfect and idle at around 750. Which leads him to believe it is not the ipr at all, nor the icp, and he believes it can be cleared up by messing with the tunes. Has anyone else had something like this happen? If so, what solved it?

Sent from my iPhone using Tapatalk

lucasm12798 said:
Thank you.but even before the truck had the new injectors (baby swamps) it still had this problem. Is it still pretty common?

Sent from my iPhone using Tapatalk

So, help me understand here.... your first post made it sound like this issue of it revving and dropping started happening after it went into the shop for the injector upgrade. The later post makes me question this.

You also said the truck was tuned for the injectors when he noticed this and that it ran perfectly fine in one tune on the chip, but not the rest? Have you talked to your tuner?