Engine swap from October still not working PLEASE HELP

02-10-2005, 03:12 PM
Ok had been a relaly long time since ive been on but here is the deal. My H23 locked up and i had a family mechanic(which had no prior experience dealing with honda let alone vtec) swapped in a vtec engine with 5k miles into my 93 lude. After buyin a conversion harness(that didnt work and was the complete opposite of what i need...convert obd11 harness to obd1 computer) to convert my obd1 harness to the 01 obd11 ECU, i have been thru 3 different ECUs trying to get it to work. The non vtec ECU makes the car crank and it runs properly with no skipping studdering or knocking at all, just of course no vtec capabilities. The 3 vtec ECUs (ordered off of ebay 1 was off a 95 and 2 were off a 93) would let the car run but check engine light would come up as soon as you cranked the engine with the new ECU. The car would run but would sputter and just plan run roughly. Pressing the accelarator actually would make it seem as if the engine was not gettin any gas and it would stall out and almost die.

Weird problem ive noticed, my car came prewired for vtec so i plugged the vtec solenoid wire to the solenoid and then the vtec oil pressure switch wire to the vtec oil pressure switch and then the ground to the block and when doing so my tachometer would quit working. Found out after unplugging each one it was not working when the oil pressure switch wire was connected but would work with the solenoid wire connected. This happened when nonvtec ECU was connected or when it wasnt running smooth with p13 vtec ECUs connected. Either way though, with the wires connected or disconnected, tach working or not, car doesnt run smooth with p13 and does not have vtec capibilities. I just thought this might help to find out what was wrong with it knowing the oil pressure switch wire shuts the tach off.


Have had vtec engine since October and still no vtec yet :(

Thanks again

02-10-2005, 03:15 PM
And when i mean not "running smooth" i mean it will not rev up at all just stall out when accelrator is pressed and if you put it in gear and try to pull forward it dies

02-10-2005, 08:32 PM
What year Prelude is the motor from? Pre-'96 Ludes use OBD1 so there is no need to buy the conversion harness to switch to OBD2.

02-10-2005, 10:29 PM
Undoubtedly a wiring error. When any of my three VTEC wire come loose, or I disconnect it, it will throw a CEL and VTEC will not work. A P14 runs it without throwing a CEL, but there is no VTEC.

02-15-2005, 01:01 PM
Aces that is what was probably causing the problem, i was just really hoping no one would say that considering i did not put the engine in it will be extremely hard for me to track the wires back to see where the problem is. By the way the engine is out of a 01, that is why the conversion harness was needed. Can not getting a good enough ground off of the pressure switch ground cause this problem?

12-04-2016, 10:20 AM
hey guys im having the same problem! but I had the vtec working before using my vtec prewire in my 94 si body with my h22a1 engine. and si harness. then it stopped? now if I try to touch anything to the blue shock tower wire it will make my tach sit on 0. I unllug the blue wire and tach works fine. any ideas? thank you!

12-04-2016, 09:40 PM
The H22A1 was one of the options available for the 4th generation Prelude and yours is a 4th generation (1992-1996), so it really shouldn't be that big of an issue. Even if yours originally came with an H23 (the non vtec one) it is still pre-wired for vtec. Here's the thing... the wiring is 22 years old, so you may want to change out the wiring harness for a fresh one and also make absolutely certain the ECU you're using is a specific match for the H22A1 and not any other H22 series engine. JDM and USDM ECUs are not always interchangeable, and 4th and 5th generation ECUs DEFINITELY arent interchangeable. You're better off making sure your engine and ECU are a 100% match.
One more thing about H22 series engines; when they say "premium fuel only" they absolutely mean it. These engines were built with a well above average compression ratio, so anything less than 91 octane and your engine won't run right. Spark knock, detonation, misfiring, etc will happen on regular fuel and damage the engine. Good luck and keep that Prelude alive, they really are an amazing car Honda should have never stopped making.

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