Stuttering under acceleration when warm

[NckT]

I'd recommend to finish off with throttle plate adjustment as described in Post No. 19 onwards in:

http://dmctalk.org/showthread.php?15...umpiness/page2

Good luck

NickT

[Trstno1]

Got my shims installed and after experimenting with a few different combinations, I've got the Primary Pressure set right at 5.4 bar now. I then tested Dwell from cold and initial readings are fixed at 45. After getting into closed loop, the dwell fluctuates between 36 and 44. If I press the WOT switch at this point, I get a fixed 46-47 or so. I did not adjust the mixture given that these values seem to be more or less where they should be.

I then drove her around for a little while and I can say that it is a massive difference compared to before. The stuttering when accelerating was gone as far as I could notice. Steady power throughout the RPM band!!

However, when I got back to the shop, I checked the dwell again, and the dwell is no longer fluctuating while idling. It shows a fixed 46-47 now just like the WOT was pressed or if I had my O2 sensor disconnected. I'm assuming this shouldn't be happening, but confused on why Dwell reads correctly early on but then acts like it's in open loop. Could this be a bad O2 sensor that works sometimes and doesn't others?

Thanks!

Quick side question. Where do you install the shims you are talking about? My pressure seems to be about the same as yours prior to the shim installation.

Thanks

[bueller]

Quick side question. Where do you install the shims you are talking about? My pressure seems to be about the same as yours prior to the shim installation.

Thanks

There's a 16mm bolt on the passenger side of the fuel distributor that faces the rear of the car. When removed you will see something that looks like this pic:

Prim-press-regulator-1.jpg

If you don't see the leftmost part, use something non-abrasive to reach in there to get the last part out. Shims can be found at https://www.deloreango.com/us/fuel-p...tor-shims.html

[bueller]

I'll check the WOT switch tomorrow if I can. Hoping this can be cleaned so I don't have to drop $60+ if it's bad. I don't suppose anyone knows of a cheaper cross reference part?

I will also do those throttle plate adjustments that NckT when I get the chance. I saw those a while back and was curious if those would be helpful.

Thanks all!

[Trstno1]

There's a 16mm bolt on the passenger side of the fuel distributor that faces the rear of the car. When removed you will see something that looks like this pic:

Prim-press-regulator-1.jpg

If you don't see the leftmost part, use something non-abrasive to reach in there to get the last part out. Shims can be found at https://www.deloreango.com/us/fuel-p...tor-shims.html

So do you just replace the shims that are there or do you add to the ones that are there to get the desired pressure?

[bueller]

So do you just replace the shims that are there or do you add to the ones that are there to get the desired pressure?

I added to what was already there.

[MikeWard]

Out of curiosity, what size did you need to bring it back up to 5.4 bar? I would guess a .50mm or .75mm shim (those appear to be the norm)?

[bueller]

Out of curiosity, what size did you need to bring it back up to 5.4 bar? I would guess a .50mm or .75mm shim (those appear to be the norm)?

Wish I could remember If I recall correctly (and I don't really), I think it was the 2 middle size shims .. pretty sure the thickest and the thinnest were not used, but I tried a few combinations so I might be wrong.

[bueller]

It's great your making progress. I would suggest your WOT switch is intermittent. I've seen a few go bad. Just unplug one of the wires off the switch and see if that cures your problem.

I warmed her up today and went for a little ride. She's still running great and when I went to check the Dwell after getting back from the drive, and the dwell is swinging again as it should. I'll keep an eye out for the WOT switch and check again over the next several runs to see if I can duplicate the issue, but working fine for me this morning.


NckT -- On the Throttle Plate adjustments that you linked to. Can you clarify which 3 screws you're referring to? Is it the #1-3 screws mentioned on page D:01:13 of the DMC workshop manual or are there some other ones I'm not aware of? Just want to make sure I'm working through the right adjustments later this week when I'll have the time to work on it.

Is this it: idleadj.jpg


Thank you everyone for the help!

[NckT]

Hello. Yes, I'm referring to those brass hex headed bolts as in the picture.

Don't forget the metric feeler gauge (or whatever the imperial equivalent would be)

Re the wot switch, try spreading electrical switch cleaner or wd40 at the point where the full load switch presses on it. Disconnecting it will prove if it is the wot causing it to go into a fixed dwell or not.

Good luck with it all.

NickT