Stumble

[neanderpaul]

I sprayed starting fluid around the throttle body, pcv, and air tube on cream puff. Can't locate the cause of a stumble. It REALLY feels like a vacuum leak. Under mild acceleration it loses power for a moment then recovers. Under heavy acceleration it hits a wall and then recovers. It also has a weird idle. It will fall to 500 rpms and stay and sometimes it will go to 1200 and stay. It is also a little rough. You can feel it in the pedals. As oppoesed to a perfectly smooth festy idle.

When I got it it had that rough idle and varied by 200 rpms. But it had no stumble.

What I've done since then....
Plugs, wires, distributor cap, rotor button, fuel filter, air filter.
Installed ac.

[getnpsi]

Pinched ignition wire harness? Could be losing your timing advance and get it back all of a sudden. Under heavy accel it should go open loop and just be leaner but still rev up with a small vacuum leak.

[getnpsi]

Put the old wires back on and see if you got a bad new one, or one that needs to be persuaded to make better contact. It happens.
Fuel filter is not backwards? I dont think it matters but if it does that could be the hesitation until the pressure pushes fuel thru.
VAF area is clean and wire harness is plugged in perfect over there too? I've stranded myself because of that.

[Damkid]

It almost sounds like something to do with the spark advance, but since I'm not exactly sure what controls spark advance on an EFI car I wouldn't wanna start suggesting what parts to replace on a guess

[neanderpaul]

I've been driving this tank easy trying to get some good mpg #s. It's more noticeable like that. If I floor it it will wake up to full power but then when I shift it will stumble again.

[neanderpaul]

And when I sprayed the starting fluid all around it did not change at all.

[FestYboy]

vaf may be slow to respond (i.e. sticking flapper door) or you may have a crack in your intake tube, causing simmilar issues at the VAF.

[getnpsi]

yeah i dont think you have an air leak at this point, more like a sensor connection, timing or at the vaf

[neanderpaul]

Is it safe and or effective to spray starting fluid or brake parts cleaner into the air box?

[FestYboy]

nah, use PB blast or WD40

[perucho]

Does this car have a carb?

Nevermind, just saw it's for your 90lx...

[getnpsi]

Swap vafs and full intake tract with another car

[neanderpaul]

I solved it today. Unfortunately I'm not sure which thing fixed it. I swapped the pcv, wiggled all the plug wires at the plugs and the cap, and I loosened wiggled and tightened the air tube at the air box and the throttle body.

[getnpsi]

I'd put on the aspire tube unless you sold it. Good that the problem is gone but a bumpy road could bring it back if a wiggle is all it takes.

[neanderpaul]

I feel like it was the air tube.