I have a fully built jdm b18c. had it tuned made awesome power on low cams but high cams are weak. when vtec comes on i lose power. no engine light, oil pressure is good, i know my vtec solenoid is getting its power. have a test light hooked up to it. we hear it engage but it sounds muffled. its weird, but can c it on dyno, power drops after vtec 6200rpm. bugging the hell out of me. could a vtec solenoid be weak? anyone ever come across that before? need some advice...


sleeved itr block, 85mm 12:5:1 pistons, pro2 cams and valvetrain, 780cc rc injectors, victor x mani, ssr rep header, 3in exhaust, hondata tuned on e85

 

The VTEC cross over seems to be okay at 6,200RPM with Pro2's and a Victor X. Don't make it any higher. (RPM wise)
At first glance, I can tell your high cam is not working. The way the engine dies at 7,200RPM indicates that you are still on the primaries. If you can most definitely hear the VTEC cross over, then at this point it would become a tuning issue.

What's a street sweeper header? Is it the SSR one?
Do you know the size of your primaries? Collector inlet and choke sizes?
Were your Pro2's degreed?
You should be around 245whp with an 85x87 set-up with Pro2's and a Victor X.

Have a read through my thread. You might get some answers.
https://honda-tech.com/forums/all-motor-naturally-aspirated-44/my-b20vtec-revised-2858137/

 

Yes its a ssr replica tho. Its a 2.5outlet to 3inch exhaust all the way. Cams were degreed. Not so sure what the ssr replica header choke sizes are. I had my car tuned at a pretty reputable shop. See what i dont get My buddy has the exact same setup as me except a ls block and hytec Rep header and we both tuned the same day. His powerband is awesome and vtec screams basically. O yea when it was tuned last month I had a bisimoto replica header . i was told the header was holding me back So just got this ssr Rep and the crossover still sounds the same. i tested the vtec solenoid to power and ground and the solenoid clicking sounds weak very quiet. dont have another noid to compare it.

 

Ask your friend if you can borrow his.

 

LOL tried last night didn't change. I may try adding a oil line from my sandwich plate to the back of the head. My oil pressure is good at least at bottom end but I don't know if the head is getting enough oil.
Motor does not make any abnormal noises either. Hmmm idk.. LOL

 

where is your oil line feeding the head?

 

change your tuner

 

I dont have an oil line yet. Its a b18c block and head. But I was thinking of adding a line like lsvtec is setup

 

What why would u add anothere feed line no need. Seems like the cams are not in sync,there crossing over but ur lossing power,did the tuner even move the cams or do anything to figure out the drop?

 

Out of all the high hp cars I've built or seen I've never seen an added oil line on a b18c. Something is wrong and I'm pretty sure it's on the tuning end of this

 

Hmmm.. yes tuner moved cam's. He zero them out and moved them a few degrees and it didn't help it out at all. Where there set now is actually the better reading shown on the graph. He actually spent a good time on it moving things around adding fuel and timing and nothing worked out.

I never seen an added oil line either it was really just a thought. Maybe I can swap ecu with my buddies to rule that out..

 

Test another set of cams and see what happens. High cam could be faulty. Or maybe the vtec solenoid is engaging but the ecu is not changing over to the fuel and timing maps for the high cam. It is weird because as someone pointed out already the graph looks like the engine just stays on the low cam.

 

Yea I thought that to with these cam's but there brand new cam's straight out of box from import dps. U think its possible? I see what ur saying with the Ecu I'm gonna swap ecu tomorrow and see what happens guess its a good thing my buddy has the same setup lol

 

Let us know your findings. Even a little thing as a faulty wire connection can cause these gremlins, but once sorted you should have an awesome ride.

 

O yea ill deff let ya's know what I find. Thanks

 

Randy is a great tuner, like the op said the other car with same setup made great power . It is a mechanical issue and it is the responsibility of the owner of the vehicle to bring a healthy running car to the dyno session. Go back over the car and hopefully find the problem

 

True he did an awesome job and I'm going back to him when I'm done figuring this bullshit out.

 

So the cams were properly degree'd in with a dial indicator and degree wheel then the tuner just zero'd them and messed with them? To me, that would negate any degreeing that was done. Was the valve to valve clearence checked?

 

Yes cam's were degreed. He moved the powerband and put the cam's back to where they were dialed in.

Would vtec kick in if oil pressure was low but not low enough to set light? Its jdm head so don't have oil pressure sensor. I'm trying to go over things b4 I say something is wrong with the tune. I tried another solenoid today that I know works and it didnt change anything. Drove it today and i know vtec definitely crosses over it just feels like maybe its breaking up.

I found another graph that id had tuned by someone else with this same setup except the header intake injectors exhaust and e85. Vtec was fine. Ill c if I can post it. its not the best tune but i didnt have a prob with vtec. had the same cams here too

 

 

yes machine shop had checked valve to valve clearance.

 

I'm certain that it wasn't. It's irrelevant at this point though. His high cam isn't coming on. Pro2's seem to work on the quick settings anyway.

OP:
I believe you have a hydraulic leak somewhere in the rocker assemblies. I would suggest using compressed air to check your VTEC operation.
This is what I mean:


All you need to do is apply air pressure to the front of the head and have a buddy use his finger to block the inside of the head.
If you don't see your rockers actuate, you might have worn shafts or worn pistons.
Also, did you replace the dowel pin and o-ring underneath cam cap #3?

 

Get a different tuner.

 

Not sure if you did this or need to but worth a try:

Under VTEC parameters:




Enable VTEC for VTEC engines, disable for non-VTEC engines.
For JDM engines and JDM ECUs disable the VTEC oil pressure sensor.

 

Im gonna jump on the tuner bandwagon too. A good tuner will be able to tell you what to look into not run your session and send you on your way.

His power doesnt die out, it flattens out. Theres a bit of a difference and its not an indicator that hes on his low cam still. That dip in power is normal on a NORMAL vtec crossover but tuning is supposed to tune this out for a seamless transition. Tuner problem? Cough. That dip also tells me hes in vtec because you see the bump in torque after that. Low cam wont jump in torque like that unless it was severely under tuned prior to that rpm, still dont see that happening since you also see the flat torque curve prior.

If vtec cuts out you will feel it. Guaranteed. Either completely or intermittently. If it does not come on you will see no power increase.