94AnaHonda

Ok, 94 EX with CEL for VSS (speedo does not work), the light will only come on after approximately 5 to sometimes upwards of 15-20mins. Not a large issue to my knowledge other than no speedo, unless it operates more than what i'm seeing (as I know honda's are very computer related though). Question is when i'm traveling primarily interstate to and from work when I release the throttle fully for deceleration down the off ramp (which normally is when the CEL comes on initially) the engine rpm's drop to roughly 5-600 and then fluctuates between 300- roughly 800 rpms during the downshift (auto) and all. I would like to eliminate FITV as a possibility and things in that area as I've already did full tear down to throttle body and full cleanse and thorttle adjustment. Any ideas? Thanks in advance.

Also, to add, once I reach approximately 10-20 mph in second gear the fluctuation stops. It ONLY does it during deceleration with foot completely off the throttle.

nealnanoHX

Check the IAC and pull the codes.

94AnaHonda

Pulled the code, it's 17 for Vehicle Speed Sensor. Will IAC give rpm fluctuations on deceleration from 70mph and no other times? I mean it literally only does this during down shift and deceleration. I can sit at idle in park or in drive at red lights for ten mins & get no Flux. I shall take it off and replace it at lunch and test it out. Thanks neal

nealnanoHX

If it is an auto trans then the rmps will change as the car slows, is it down shifting to help stop the car. But I dont drive it so I really dont know what you experiencing. Fix the speed sensor because that in short has some control over the trans and the shift points.

94AnaHonda

Ok, thanks! It IS an auto and yes it does downshift to slow the car and I've never had a 4spd auto until this car so the shift points were already a different adjustment for me. IAC is fine, took one of my cousins z6 and it did the same exact thing. It literally is fluctuating during foot completely off throttle no matter rpm at the time or gear (long as it's past 2nd). If I'm traveling down the road at let's say 45mph and the light turns yellow I let my foot off the throttle and during braking and even before brake application the vehicle will drop in rpms and give a up and down fluctuation of roughly 3 to sometimes 700rpms. I will change the VSS tonight after work and see if same results. Appreciate the input. Although I do not feel VSS is causing the flux as it doesn't have to be while the vehicle is downshifting so shift points are not the cause neither is downshifting. One other question though I may toss in as i'm not a complete idiot when it comes to searching and that is could the TPS be a factor itself? Could it be that the TPS is operating ill-mannered and only doing so during 3rd and 4th gear foot off throttle?