So we just finished swapping the del sol with a rebuild d16y8. When initially starting it had a 1.5 k rpm idle surge (going from about 1.5k-3k and dropping back down to 1.5k and repeating. So we swapped the OEM intake manifold back.) That PRETTY much fixed it but it still has a slight surge. Idles at 1.5k and jumps to maybe 1.6k not as bad but still weird. I’m aware of the tuner screw on the throttle body, which is tuned appropriately, what else could it be?. Also when reversing sometimes when put in reverse gear and let the clutch out it just goes nowhere, i have heard some Honda’s just suck with reverse and that putting it in 4, then reverse helps. Is this true or do i need to get the trans serviced? It was rebuilt right before the engine was built.

 

That’s true of manual transmissions in general. Sometimes you go to select reverse, and it doesn’t actually go into gear. Just let off the brake so the car moves a little bit, let off the clutch (with it in neutral), push the clutch in again then select another gear such as first, then with the clutch in select reverse again and it should go into gear. It just means the gears aren’t lining up perfectly, so letting the car move by letting off the brake, or selecting a different gear before going to reverse works.

 

Sounds like a typical honda thing with the reverse.. Before I rebuilt my trans and got rid of any slop from the shifter base bolt to linkage connecting to tranny selector shaft.. 90% of the time I had to go to 1st gear then into reverse or it just wouldn't go.. I would look into the same on yours and get rid of any excessive play from wear and hope it helps with your gear selecting. Also would think the iacv on the manifold you changed to probably has less carbon buildup inside helping your surging idle. Could probably pull your crappy one and flush it with brake cleaner then give a light shot of wd40 inside and put that on to see if it works better.