My turbo LS/VTEC Civic will boost and go into VTEC fine when I first start driving the car. After a little while, while boosting, the car will break up a little bit. After that, the car won't go into VTEC high lobe anymore. What could be the problem? I've checked all wiring (I have a VAFC installed), swapped in a good working VTEC solenoid and made sure oil level is good. The VTEC ON lights up when the VTEC controller switches the car into VTEC, but nothing happens. The check engine light doesn't give off any codes at all. Where can my problem be? I'm thinking maybe we forgot to put the little rubber O-ring back into the head, under the cam holder thing in the middle, but would the car shouldn't go into VTEC at all if it's not there, correct? Could fuel or spark have anything to do with it (remember, no check engine codes). Please help. Thanks.

 

****, now that I think about it, the problem might not be in the VTEC system. Could be that the car is going into limp mode or something, but it doesn't trip a check engine light or anything. The car does feel more "fat", like runs richer than normal after the VTEC dies out.

Somebody help me.....

 

Your CEL does work, right?

 

Yeah, my CEL works fine.

 

how's the temperature?
any overheating or over coolling??

 

Re check your VTEC solinoid, as well as all the wires, i have heard of your problem happen to some people who do the frankenstien set up.....

 

Temperature is fine. No overheating.

VTEC solenoid and all the lines are in good working order.

 

maybe running lean or too rich when the cam goes to vtec?

 

could low oil pressure be the culprit???

 

I don't think the car is too lean/rich when VTEC is engaging (when it does engage).

Oil pressure might or might not be the problem.

I've found that when the car is cold, or at least somewhat cool, VTEC will work. Once it gets driven for a while, no more VTEC. I tried shutting the car and disconnecting the battery to reset everything, still no good. Ran at the track tonight and got VTEC on my 1st pass, but was breaking up in 4th gear a little bit. (depressing ET's tonight, best of 12.20 at 112MPH). After making 2 more passes with no VTEC, I slapped street tires back on the car. VTEC worked again for a little bit on the way home, but died out again.

Oil level is fine. What can it be? Please help.....

 

I think I found my problem. Oil pump might be hit. Does anyone know what the oil pressure is supposed to be? Also, does oil pressure stay constent, or does it change with load/rpm?

At idle, oil pressure was 25psi, and at high rpms, it goes up to 65 to 70psi or so, then drops.

 

before i read the last post i was gonna say it sounds like oil pressure problem. You may have to upgrade your oil pump. I'm not sure if oil press is consistent thru high rpms or not, I want to say it would increase with more rpms.

 

On my GSR my PSI is at 25.....during normal rev's, between 25 and 75 psi...

when im on the gas, it tachs out to 75psi...

anything lower than 25 means you need more oil....anything higher than 75 i belive means you got to much oil...i might be wrong though

 

Terry,

I know what the problem is....you need a better driver....hahaha....j/k

 

My oil press gauge on my car sits at about 1.5 bar at idle, and climbs up to 6 bar until VTEC is engaged, then it suddenly drops to about 5 bar.. why this happens, I don't know, but it does...

 

did you swap out your LS oil pump for a GSR/SI oil pump when you built your motor? You might just have to do that so it can compensate for the Turbo feed and the feed to the head.

 

Paul, you're right. Maybe my car does need a better driver, hehe. Wanna run it?

About the oil pressure thing. 1.5 bar at idle, 6 bar to VTEC then down to 5 bar? Is this what VTEC motors are supposed to have in oil pressure? From what I know, 1 BAR IS 14.7 psi. 1.5 bar would be 22.05psi, for idle. 6 bar before VTEC would be 88.2psi before VTEC, then dropping down to 5 bar would be 73.5 psi, holding VTEC. My LS oil pump was putting out 25psi at idle, which seems OK, but at 7000rpms, no load, it was only pushing 65 to 70psi, then dropping once it hits that.

We're putting an Si oil pump in right now. This should be the problem.

Going to the track tonight. We'll see what happens.

 

any update on the prob...

 

Loose head studs may be the problem. Also, there's a small leak from the oil return line (doubt that has anything to do with it).

 

Two of my friends expierienced the same thing with their frakenstein set-up also .. we spend all day elimintaing variables.to what could happen till this day the only thing i can think of is low oil pressure .. Good luck though