I have just wired in the VTEC solenoid and pressure switch and I am running into a few problems. I have a 95 GSR head with ITR cams on a 95 LS block. I have a chipped (uberdata) P72 ECU. It seems my Vtec is engaging only intermittently. That is what I was thinking before b/c I had lowered my VTEC crossover to ~4K for tuning. However, it does not kick in until late 5Ks RPM. It is kind of like it kicks in at the butterfly crossover. I have an Edelbrock intake so I don't have the dual butterflies. I don't have any CELs.

It also makes a strange sound. I can hear a definite "click" when it engages and disengages but then it sounds like I hear some other ticking/clicking. Almost like valve noise or valve/piston contact. I double-checked my timing belt and it is still aligned.

I read somewhere that I had to wire the ground of the VTP to the ECU. So I wired it to A26, which looks like it is the IAB ground. Maybe this ground only works when the IAB is supposed to kick in which is in the high 5Ks as well.

I am running my vtec oil source from the oil pressure location on the back of the block along with the feed for my turbo.

I am going to change my oil today to see if that helps. I put in some "stop leak" and that may be messing with the vtec engagement. I have 5w30 in their now and maybe with the 95* temps along with the turbo and LSVTEC my oil is geeting too thin. I am going to 20w-50 for a little while until it cools off.

Any other suggestions?

Thanks!



Modified by LST2 at 9:18 AM 9/8/2005

 

How did you wire the vtec solenoid and pressure switch. Did you ground the pressure switch?? There's two wire coming from the vtec pressure switch and the black wire is suppose to be grounded and the other one run to the ecu. If you are using uberdata, you should be able to set vtec and it would only kick in at that point. I feed my turbo and lsvtec feedline from the back of the block as well and never had a problem. I'm even using 5w30 weight oil.

 

At first I grounded the wire on the pressure switch to A26... I read that you needed to do this on the P72. Then I thought that might have been the problem and I changed the ground to the thermostat housing. This did not fix it. I guess I am going to have to get an oil pressure meter to measure the oil presure at the solenoid.

 

I just changed the oil to Royal Purple 20W-50. The Vtec does seem to cick in a little earlier (5,300 RPM). This is still not where I set it (@ 4,400 RPM). Also, it sounds like it is clicking in and out of Vtec as the RPMs go up. You know that clicking sound you hear when Vtec kicks in, well I hear those clicks repeatedly like the pins on the rocker arms are not staying in. Is this what is like if you have low oil pressure? Or does it usually just not kick in at all?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LST2 &raquo;</TD></TR><TR><TD CLASS="quote"> The Vtec does seem to cick in a little earlier (5,300 RPM). This is still not where I set it (@ 4,400 RPM). Also, it sounds like it is clicking in and out of Vtec as the RPMs go up. You know that clicking sound you hear when Vtec kicks in, well I hear those clicks repeatedly like the pins on the rocker arms are not staying in. Is this what is like if you have low oil pressure? Or does it usually just not kick in at all?

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First off, A26 is a ground on the ecu. Next, your vtec engagement is way too low, and considering your oil feed situation, i bet the pressure isn't high enough to flip the cams. Set your crossover higher so that there is more pressure built up when the solenoid opens. Try setting vtec at 5300 or so (where you say it intermittently clicks in now), and I bet you'll be good.

 

I originally had it set at 5,800 RPM and had the same results. I just checked the oil pressure at port next to the vtec solinoid and I am basically getting no oil pressure. I am not sure if you have to activate the solinoid to get pressure but I had lower than 5 psi with it unactivated... then I wired the solenoid to the battery to make it live and the pressure went up to like 10 psi @ 3000RPM. That is way to low.

I loosened the feed line to see if I was getting any oil from it and I was. It was comming out fast with it just loosened.

I do hear a click when I hardwire the solednoid to the battery but maybe there is something else wrong with the solenoid. I really don't think so as the Vtec does kick in there is just not enough oil pressure to keep it engaged.

What are my next steps?

 

OK, it is defiantly an oil pressure problem. My oil pressure at the block and the fitting on the feed line where it attaches to the head is 70-80psi at 5,000 RPM... plenty. I then tested it at the VTEC test port while I was driving. I set the crossover low, at 4,200. I saw zero oil pressure until I hit 4,200 then I got 20psi. Then as I revved higher I heard vtec kick in at around 5,400 when I had about 30psi.. way to low. It is the low oil pressure that is causing it to "click" in and out of Vtec once it starts. So where do I start troubleshooting. I heard the following:

-Vtec Solenoid shot - Don't think so as I hear it "click" when I give it 12v and it is getting oil in where I set the crossover.
-Vtec Solenoid screen clogged - checked that, it was clean
-Dowel pins on cam journals... I think there is one on the third journal and two near the cam pullies.
-Cam journal bolts loose. I know that one or two of them did not seem to tighten all the way when I put the head on.
One thing to note is that when I purchased this head the cam journals were pretty worn so I had a shop bore them back to spec when I put the new valve train it. It is possible that the dowel pins or something like that got screwed up.
More suggestions?

 

Just put on the Golden Eagle oil sandwich adapter and the -6AN line and that was it! I did not get enough volume out of the -4an line.