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Intermittent grey smoke when feathering throttle at moderate speed, possible power surges

3235 Views 39 Replies 8 Participants Last post by  OkDually
My old step van sometimes blows light grey smoke, but only under specific operating conditions. When driving at speeds from roughly 30 mph to 45 mph (not idling, but not highway speeds), if I encounter a gentle downgrade or hill, not steep enough to let me take my foot entirely off the throttle, I produce a light grey smoke. Some freeway off ramps have a decline that's just right to do this. I feel as if I'm just feathering the throttle to maintain my chosen speed.

Sometimes the smoke is sporadic. Not a steady smoke, but bursts.

Today, I think I felt small power surges coinciding with sporadic smoking at a speed of 40 mph, again, gentle downslope. At this speed, I only observed this in 4th gear. It doesn't do this at 40 mph if I first lock the torque converter by bringing the van up beyond 52 mph for a moment. The converter remains locked until slowing below 35 mph.

There are no operating issues with the motor. None at all. I track fuel consumption at every fueling, no changes there. No engine oil consumption. Smooth idle after easy starts, every time, hot, cold, or very cold. The high idle solenoid still works! The pitch of the combustion changes as the injection timing retards after the engine warms, just as it should do. It just runs great, all the time.

I think my usage may not be helping. I only live a couple miles from my work spot, so the engine doesn't get very hot sometimes before I park it. This may contribute to carbon deposit build up fouling an injector or two, but I am guessiing about that.

Today, I treated it to enough Seafoam to reach their recommended dose of 1oz per gallon. After work, I took it ten miles down the freeway, taking a long way home. The last four miles was 40 mph again, and it produced some grey smoke, but noticeably less than before I fed it the Seafoam.

i think I'm on the path to solving this, but I don't know what is causing it.

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There is a special socket for them. I've read some people have use a regular socket on them with success but when I did mine I bought the socket. I don't know how easy it is to access yours in a van but when I did mine I pulled the inner fender and turbo on the passenger side. I see you are N/A so that helps. I had a hell of a time with the little plugs that go on 7&8 return lines. Don't plan on reusing the old return lines buy new ones. I also did one side at a time. When I got the passenger side done I started it and let it run a few minutes to get the lines and injectors primed back up on that side. The lines i just took loose and carefully moved them out of the way enough to get the socket on and injector out and back in. If
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