Loping at idle
 

My 87 has a slow, steady "lope" at idle. It is not really a miss, can't feel it from the driver's seat. If I put it in drive it almost completely goes away, and raising the RPM slightly also makes it go away. New delivery valve seals, new vacuum pump, motor mounts, glow plugs, belt and tensioner system. The lope was there before all the new parts and was even more noticeable as it was causing a vibration/noise which I think was the two piece shroud which was broken. The first video is in Park, the second in Drive. You can see the stop lever rising and falling with the "lope", which I assume is an effect rather than a cause? Any ideas where to start?

http://youtu.be/fnqy7DTYYQQ


http://youtu.be/ki9qzCuzPHQ

never assume...

the stop lever should not move.

So then it might be a vacuum problem, or the idle is too low? I don't understand why shifting into gear smoothes it out.

neither video plays for me...

hmmm. I did make them public. If you want you could go to youtube and search for "603 loping in park" and "603 in drive" or just search for "bossmonkies" videos. Thanks

I went in and chose the videos from your list. played them ok from the site... anyway, the lever moving in park, but not in drive is a mystery to me.
search 603 stop lever...

I believe you're right near the edge of the capability of the governor to hold idle that low. Why not bump it up about 100 rpm? It sounds like it's below 600 rpm right now.

You know about the electronic dial that sets idle..........??

I second that, sounds like the electronic idle control is wandering.

If you unplug the electric device butted onto the rear of IP the engine should drop to about 550 rpm and stay there rock solid.

See if that happens

Thanks guys, I'll check those things out in a little while and post back.

I raised the idle to the next number and it seems high, the tach on the dash seems to be around 800. All it does is increase the loping with the lever "floating" up and down even faster. Put the idle control back where it was, seems to be around 750. I unplugged the connector on the back of the IP and it dropped like Scott said it should, didn't lope but it wasn't all that smooth/steady either.
I don't think my injectors are all that great, only a few thousand miles on them but they are Bosch remans from India I think. Going to try building a pop tester and getting some Monarch tips.

Any other things I should try on that idle? I did unplug the vacuum line to the shutoff valve with no change.

I noticed today after a good hard run it will smotth out, but after shutdown if it is restarted even a few minutes later it will begin to lope again.

This is so minor itsa live with condition, pretend your car is purring!

If it's electrical you have a list of things to check out: all devices, connectors, and grounding on ELR circuit, tach / engine speed sense, and anything speed signal touches (cruise?), etc..

If it's mechanical, the ELR rack in the IP may be binding or have a flat spot.

try a LM diesel purge, might help.