Hi there,
Let me first say I usually spend my time on some other Prelude board, but I am coming to you all for assistance. I have had this problem for a while and have not gotten much help from the “other” place. Lets start off with some background. I have 94 Prelude SI. I blew the engine in the SI; I replaced the H23 with the H22. I kept my SI tranny. After many months (long story that’s not relevant) I get the car running. I am throwing a CEL 22, Vtec pressure switch. So I finally get time to start trouble shooting the problem. I crack open the helms manual and start on page 6-77. 1) Reset ECU 2) start engine 3) warm up engine 4) do road test 5) is MIL on and does it indicate code 22, yes it does 6) turn off ignition switch 7) disconnect the 2p connector from the Vtec pressure switch 8) check for continuity between the 2 terminals on the Vtec pressure switch 9) is there continuity, yes I have continuity 10) turn ignition switch on 11) measure the voltage between the blu/blk wire and body ground (I am using the ground on the battery) 12) is there approx 10v, no I only get 5.06v 13) inspect for an open or short to the ground in the blu/blk wire between the 2p connector and D6 terminal on the ECM. If wire ok substitute a known good ECM and retest. I will stop there. This is where I first ran into problems at. I ordered my engine and ECU from Hmotors online. The engine and ECU sat out side for about a month before I could start the swap. So I now think the ECU may be bad, and I send it off to have it rebuild. The company that was suppose to rebuild the ECU sent it back, said some fluid leaked out of a capacitor onto the circuit board rendering it unrepairable. So I buy a used ECU of a guy. I install the “newer” ECU and instanly get a CEL, and it reads 22. At this time I am beginning to question my wiring job, and I cut the D6 wire close to the ECU and test it from there, still I only get 5.06v. So with all that said, I ask, what could be stealing volts from my ECU? Has anyone ever run across the problem before? Any suggestions on fixing this problem?

I think it has to be electrical cause of how quickly I get a CEL after resetting the ECU.

Thanks for the help. Sorry for writing a book. If you have any question ask.
Again, thanks!

 

well, when i did my swap along time ago, i remember having some strange problem like that. No matter how i checked for voltage i dont think i ever got what it said in helms. I ended up cleaning out the vtec solenoid, and checking every thing that had to do with the vtec aspect. (i.e. dents in oil pan, oil level) I even re-wired the vtec wires just in case. Then i decided to move the ground wire to the area were the battery grounds to the car and it took care of my problem. Im not sure which of the many items i did that actually took care of the CEL, but maybe you just need to recheck all of the items that can affect vtec.

 

right now i have my ground tied in with the neg on the battery terminal. you suggest to move it to the other end, where it actually grounds into the car? i will give that a try. thanks for the tip. i'll keep you updated.

 

i agree, try a different ground location. I have mine grounded to the gnd location almost directly beneath the vtec solenoid... that has been working for me.

Also, just fyi, i had a 22 CEL after my h22 swap from hmotors too. turned out my vtec pres. sw. wire, which was prewired in my 93si was bad... i had no connectivity from the ecu pin to the switch... so i ran a new wire and

 

i have tried another ground location. but i do not know if it was really a big change. i am going to play around with it later, when i can get my car up and a lift. i am not using the pre wire. i ran the 3 new wires i needed. i have thought about replacing the pressure switch, and solenoid (i always mispell that word ), but thats a lot of money. i can reset my ECU and i throw the code almost instanly. with in a minute of start up. thats why i think its electrical, but what do i know?

i ll keep you all posted