Hi guys, I bought a '97 EX 5spd coupe a month ago, bone stock and has 135k on it. Had a real bad bucking on normal accel, not so bad when you put your foot in it. Has had no CEL, I've done some work and diagnocing and its a lot better but still not quite right. Its somewhat inconsistent but if you don't shift it'll stumble till it hits around 4,800 RPM then like flipping a switch it'll clear up and run smooth as glass all the way up the RPM range. When it does it the Short Term Fuel Trim is in the negative, usually around -8 to -12 which isn't a whole lot. Seems like lack of ignition to me.

I'm pretty sure the previous owner had someone chasing the issue, has new MAP and TPMS sensors (Both are Denso), but I don't think they were too smart about since the T-stat was bad, it wouldn't go above 160F.

What I've done
-replaced T-stat (was stuck open)
-Adjust Valves, very little adjustment needed. Top end was clean
-New Beck Arnley distributor and plugs and wires
-BG induction and drove the hell out of it after to help clean it out.
-Checked and adjusted ignition timing after distributor install
-Checked T-belt and alignment marks, all good there.
-Several cans of injector cleaner ran through gas tank.
(1 can at a time and used up with mostly highway driving)
-Checked compression all between 170-182psi
(haven't been able to do a leak down yet)

But, when I was checking the T-Belt I found the bolt for the Crank Fluctuation Sensor was loose and it was flopping around a bit. It had rubbed on the reluctor wheel (proper term?) on the crank a bit but wasn't bad. I don't want to start throwing more parts at it, but I'm not sure how to check the sensor or if it could cause this problem.

Any ideas or thoughts would be awesome. I've been searching and reading but most problems seem to be worse when warm and mine are worse when cold.

 

Check the TPS to make sure it's within spec.

 

All I did was watch the live graph data on my scan tool I use. Smooth lines with moving the pedal. Is there anything else specific I should check with it?

 

Yes. You should use a voltmeter to make sure that it's at .5v closed, 4.5v open, and you're getting 5v at the reference wire.

 

Roger that, will do. Thanks for the input and I'll post my findings.