White Smoke (now only when idling downhill)

[jrm]

So my truck (19) is heavily modified (CRP stage 4, manifolds and fuel injectors, etc) and I used to run e85 but now just use the 91 daily driver tune from MPT.

I am seeing white smoke when I'm idling at a decline. White smoke when I accelerate and then for the next couple of minutes. This doesn't happen on flat levels (haven't tried incline).

Background to this story: this summer I started getting lots of white smoke and I felt like the engine would "skip" if I WOT. I took the car in and they changed the spark plugs and that seemed to fix it. I just noticed white smoke on the decline.

 

[FordTechOne]

Does the smoke have an odor? If not, it’s water, which is nothing to be concerned with.

Water is a byproduct of combustion. At idle, the exhaust is cooler and exhaust flow is low. Water will accumulate in the exhaust pipes and muffler, and then turn to steam as is slowly burns off. Facing downhill will prevent the water from reaching the muffler drain holes, so there may be additional moisture buildup.

 

[Graybeard]

It could also be fuel.

Due to your listed modifications, I would be inclined to monitor short term fuel trim if you were able. Have you changed the HPFP as well?

 

[jrm]

Thank you for these ideas. I don't have a HPFP and have tried to get the odor when there was white smoke several months ago before the spark plugs were fixed.

But here is the kicker: when we had this problem several months ago when there was white smoke every time (huge plooms), there were also stutters on the engine if I put it over 3k rpms. I literally had to drive it with no throttle at all. Then we change the spark plugs and the power was way more consistent.

I'm wondering if these two are related or if it's a coincidence.

Also, I created a log to send to MPT when I had the problems where it would be 0-60 in 9 seconds (or the like) because of power loss and lots of white smoke and I was told that the logs didn't indicate anything.

 

[jrm]

Well, it all seems to be fixed! Just a bit of water. The other spark plug issue was unrelated.

 

[smurfslayer]

It’s truly a feature, not a bug.
Glad it’s worked out.