Stumble/Hiccup During Cruising and Constant Acceleration

[Stingy49]

Hey All,

I'm having an issue with a stumble/hiccup under constant acceleration and cruising. My TPS and MAP don't seem to be tripping AE and my VE table looked smooth to me. If anyone has any ideas please let me know. I've attached my MSQ and MSL. The motor is a ka24e from a Nissan 240sx.

The relevant sections are at 84-87s and 168-172s.

-Derek

[Quagmire]

I haven't checked your log so can't comment on your tune.

However I recently cured a misfire that was occurring at a very specific point (1000-1200rpm and 30-40kPa). Nothing on the MS side seemed to be causing it, and it turned out to be a duff HT lead.

I measured the resistance on all the leads and found one of the shortest leads to have a resistance substantially higher than the even the longest lead. It looked fine physically.

I made up a new lead, fitted it and problem was solved.

[Stingy49]

Thanks for the advice. I'll ohm those out tonight and see what I find.

[Stingy49]

I checked the cables last night and they were all good. I went ahead and ordered new plugs so I'll see how the old ones look when I pull them.

[Matt Cramer]

The abrupt lean spike suggests an ignition miss, but that's also a very tiny amount of spark advance for light throttle, even for four valve heads - and a KA24E will usually want more advance still.