Sorry that post was directed towards the OP, I just thought you were the OP and figured I'd throw that in as well. Yes when you said Helm, I was thinking of Haynes and the like.

Re: '89 CRX HF + D15Z1 troubleshooting...
 

Hey buddy, did you ever end up resolving that bucking issue on your crx ? Im in Australia and I have the exact same problem ! Cant figure it out !!

Re: '89 CRX HF + D15Z1 troubleshooting...
 

Sadly, I never really figured out the cause. I continue to drive the car on weekends and for fun, maybe 4-5k miles a year and the buck issue comes and goes, right now it's in full force. Definitely irritating, but other priorities are taking up time. The Shift light still flickers before staying lit and the bucking seems to get worse after I've hammered her a little. Eh, I'm out of ideas but my guess is wiring or vacuum related. It's the only thing keeping this car from being 100% success tho. Mak

P.S. on the upside, MPG has been a consistent 55-60 this year!

Re: '89 CRX HF + D15Z1 troubleshooting...
 

Overdue update time...

I had a spare minute today and decided to play around with this everlasting buck problem that has persisted so long. I warmed the car up and drove her back to back with the TPS hooked up like normal and then without (with CEL glaring) and it was like night and day! With the TPS hooked up she's a temperamental beast, lower idler, studders mid-shift, and bucks randomly in gear w/ no throttle input. W/o the TPS hooked up, she rides like a caddy, accelerates without fuss, and DOES NOT flinch when decelerating in gear! If it wasn't for the high idle (1.6k-ish) I would just leave her unhooked and say f-it. Anyone want to chime in on how I can make this problem go away (with no CEL & high idle)? Thanks, Mak

P.S. The ECU has been checked w/ a known good one, the TPS (with sensor) has been checked before, and the wiring reports correct respective voltages as reported literally years ago in this thread.

Re: '89 CRX HF + D15Z1 troubleshooting...
 

bad wiring bad/intermittent failure of TPS sensor?

Re: '89 CRX HF + D15Z1 troubleshooting...
 

Perhaps in the wiring between the sensor and ECU.

Re: '89 CRX HF + D15Z1 troubleshooting...
 

I'm more than frustrated on this problem, as it has plagued me since day one of the successful swap. My next free day I'll rewire the sensor directly to the ECU pin-outs and then I should have my answer...or more difficult questions...hopefully it was a simple switch of the wires, a worn piece of wire grounding out, or possibly a Rywire fault on the conversion harness, altho that's remote.

Thanks, Mak

Re: '89 CRX HF + D15Z1 troubleshooting...
 

Spent several hours Friday tracking wires and voltages, long story short the TPS cannot be my problem, nor can the MAP or conversion harness. Considering that when I disconnect the TPS, the ECU artificially raises the idle to compensate & all my problems miraculously disappear, I'm going to reset the idle according to HELMS and go after the IACV and that other manifold sensor (TW in the book IIRC). After that, it's on to the O2 sensor and I do not want that to be a costly lesson in bought-but-didn't-fix lesson. Mak

Re: '89 CRX HF + D15Z1 troubleshooting...
 

if you do go ahead with cleaning the IACV, I suggest taking off the throttle body and giving it a thorough cleaning. I know on my throttle body there was a lot of gunk inside of the passages, especially in the passage for the the idle screw. Btw, have you replaced the PCV valve? Checked for vacuum leaks, etc?

Re: '89 CRX HF + D15Z1 troubleshooting...
 

When I swapped TB's I cleaned the newer one before installing, no change. I've cleaned the IACV recently, the mesh looked fine, now I'm leaning towards electrical issues with both sensors, something I haven't tested. The PCV valve is new, and with the straight-through VX design I don't see how it can fail, it's just a hollow elbow. I've sprayed at least a solid can of Carb Cleaner on every hose/intake manifold before trying to find vac leaks, but have never witnessed changes in idle. Has anyone ever deleted the IACV to get a more predictable idle, and erase common Honda surge issues or is this just more trouble than it's worth?

Mak