It's just a basic high compression lsvtec setup so I won't bore you with build details. Head is built as well, car has 400 miles on it or so broken in the mototune way (like all my other hondas) and this problem JUST reared it's ugly head. Have no problems with it up until last night.

Things I have checked/completed.

Jumper from A4-D6 just in case.
Grounded vtec pressure switch to cam cap instead of through ECU.
Shot wired from ECU to solenoid/pressure switch, checks good.
Replaced both pressure switch and solenoid with known good ones I had in my tool box.
Replaced screen
Changed oil/made sure it was full (last oil change, this time Mobile 1, problem started last night while still on dinosaur juice)
Taken oil pressure at block/head. 28ish psi idle both places, 75-80 WOT about 6k or so both places.
Checked T on back of block and line for clog.


Motor has perfect compression and runs like a top, just suddenly fell out of vtec about 8k in 3rd gear last night when I was doing a quick pull with the new exhuast. Oil pressure was fine when it fell out at 80 psi. Got a CEL, Code 22. Grounded the pressure switch and then switched it, it went away. Went out and did another pull, car didn't cross over and threw a CEL at 6200 rpms. This time code 21 so I go to the spool solenoid. Replace the whole thing, change oil, check motor over for leaks, do everything I know to do and nothing.

Car has 0 leaks, no pressure problems, nothing. I can park it on a white sheet after beating the breaks off it and not a spec of anything will fall out.


Anyone have any ideas what the hell could have caused this to happen? Only thing I can remotely think of is there is a problem in the ECU itself as I am an idiot and didn't unplug it when I welded up the new exhaust and "could" have hurt something I suppose but it's Easter and I didn't want to bug my tuner until tomorrow but I would hate for it to be something stupid and me look like an idiot because I over looked it.


If you guys want clearances or anything, I can give those as well as I built the motor but I can say it was built loose but within Honda spec, just on the free side.

 

Broken / intermittent (spelling) wire between ECU and VTEC-related solenoids/sensors?

 

I thought that as well man, I did a full wire tuck on the car as I was building it and thought maybe I just had a bad solder joint but all the wiring has good continuity.

I am lost.

 

Bump for some advice.

Come on guys, if I had posted up "which header will make the most power", I would have had 200 replies already telling me "search noob this is why there is never tech in here."


Well here's some tech, help me out lol. I am lost on where to go next.

 

did you run a wire from the battery to the solenoid....just to check the new switch to make sure that it is working.

 

Yep, that worked.

After all this, it's finally working again and I really don't know how. The last thing I did was start reversing crap and when I removed the jumper from A4/D6, it started working again, codes cleared and who the hell knows.


Damn strange problem when removing a common fix causes the cure.

 

Do you have a different VSS you could try?

 

i mean i guess its possible that the computer tripped out...

back in my EF, the wiring was a total mess and i never could get power to the main relay for my fuel pump so i wired it direct to my battery with a switch...well one day i was driving and as i turned to enter my driveway at the shop the car just died and the CEL came on...threw like 5 or 6 codes...and would not restart...

i pushed it in and popped the hood to see that the fuel pump power wire had come out of the battery terminal and shut off the pump...one way or another it tripped off the ecu to throw numerous codes....i dont know much about electronics but its possible whatever codes its throwing may have been set off by another malfunction on the same circuit.. i really dont know but i thought my past experience may help you in figuring out whats up...good luck

 

Put like 100 miles on the car the last couple of days. Problem never came back. I honestly have less than a clue wtf caused it to happen or what fixed it. But between the common 10 fixes and then removing one, it worked again.


I hate problems I can't explain away.

 

Is the speed sensor hooked up?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soulpwr &raquo;</TD></TR><TR><TD CLASS="quote">Is the speed sensor hooked up?</TD></TR></TABLE>

I had similar problems with my VSS, figured out it was bad wiring. The speed would read correctly, but vtec would mess up. It took awhile before the wiring going to the VSS finally took a crap on me and I didn't know how fast I was going/no vtec.

Stuff like this just pisses you off and makes you wish you had a v8...