I got a 91 crx running a full rywire obd1 harness on hondata s300. Motor was tuned in spring on the Dyno with no issues until now. When turning the key to the on position, the check engine flashes 2 codes. 14 and 43. Iacv is deleted in hondata and fuel issue? My jumper wire is NOT connected though so I shouldn't be pulling any codes. Once the car is started, there are 0 codes to show no flashing check engine.

About a week later and maybe 25 miles, I am now getting code p1258 on hondata and a unknown code. Takes a few minutes to trigger on and I do not engage vtec. Other symptom that has developed is low idle and what seems to be light throttle bogging like the injectors get shut off for a second.

Any ideas? Would this be a bad ecu/hondata going bad? Grounding issue at thermostat? So far I have messed with fuel and spark components since I have excess parts laying around and have noticed no change

 

grounding at the thermostat is a culprit for most things, but before I jump to saying it's a bad ecu/S300 (which it might be) I would try a different jumper harness.

 

best bet would be to try a different known working ecu and upload your file to it, see what happens.
definitely clean and tighten grounds though either way just to eliminate that as a possibility.

what version of s300 do you have? green = v1, red = v2, white = v3.

have you asked on the hondata forum?

 

Running a full obd1 tuck harness and the sub harness I wired in. Can't really just swap a jumper harness. Everything looks good as far as the harness goes though. And I'm running v3 white board. It seems like I can upload because I have a few very similar tunes saved but different tps %/idle and the car will slightly change idle. But I do not get any readings on my laptop when plugged in and I can't data log. Only readings I'm able to get is on phone with the hondata app/blue tooth.

I will look around to see if any friends are running hondata so I can give it a try using a different ecu. But I'm convinced atm that my issues are ecu related. Won't have time to dig in until Tuesday though.

Also I did not post on hondata forums. Worth a shot thanks

 

it does sound like it's ecu related, but every tucked harness I've ever had in my shop had issues. Even the best professionally done harnesses. You should never solder any wiring. If you want it to be reliable, keep the wiring as OEM as possible.

 

Software version V2.6.0 released on Sept. 1 2017 does this automatically... codes are flashed WITHOUT jumping the MIL service connector until the engine is started. Clear your codes and the flashing should stop... until you throw another code. The light throttle bogging may be your TPS settings... double check this. There should be no "unknown" codes when being checked by the Hondata s300 software... and your P1258 is an OVERHEATING code, so if you have hurt the engine by overheating it, your idle and general operation can be altered.