I'm having a major issue with my car and I'm curious if anyone knows what could be going on. I have looked up this problem and majority of people are saying it's either vtec engagement or in the tune. I can tell you, it is neither. I went to have the car tuned by 2 different tuners and neither of them were able fix the issue by messing with the tune. The last guy that tuned it said it's 100% something mechanical. Regardless of vtec being enabled or not, it loses so much power after 6k, so I don't think it's a solenoid issue. I'm running the golden eagle lsvtec kit, so the head should be getting adequate oil pressure. The first tuner said the issue was probably my log manifold, so I got it replaced with a ram horn and the same issue occurred. I'm so lost on what could be causing this issue, so any help would be appreciated. Since I'm pretty sure the issue is in the head, I will write down what's been done to the head.

I should add the car drives fine, not sluggish by any means until you hit 6k. Though I'm not driving it until I get the issue fixed.

One last thing I forgot to mention is that I just built the motor, it doesn't even have 300 miles on it, this wasn't just an issue that showed up, it's probably existed since the motor was built.

b16a2 head:
supertech 70 Ib springs and retainers
ferrea flat top valves (I just put these in before the second dyno, so I don't think this is causing the problem)
gsr cams
Stock b16a2 intake manifold
Stock b16a2 throttle body
OEM distributor
ngk spark plug wires
OEM cam gears

 

Whats your oil pressure past 6k rpm? if you dont have a oil press. gauge go slap your self and buy one assap.

Have you or the tuner confirmed Vtec engages?

Have you checked the ignition and mechanical timing?

What EMS are you using? Hondata? and is the timing synced with the ECU/EMS?

what spark plugs are you using and at what gap?

 

I have an oil pressure gauge, under full throttle oil pressure is above 80 psi easy. We confirmed vtec engages, but it bogs down even more. Timing has been checked multiple times and it is synced with Hondata, that was the first thing the last tuner did before we started tuning.

I'm using NGK 4644 and it's the stock gap for that.

 

Not sure by what you mean by stock gap but if these plugs are BKR7E's set gap between .028-.030

Check the valve lash when engines cold.

Have you inspected the Vtec solenoid and or cleaned it out? wouldn't hurt to pull it apart and clean it with brake cleaner and replace the gaskets.

Make sure the O ring and dowel is installed under the middle cam cap #3! or Vtec wont work or will have issues....

No Vtec.. confused... - Honda-Tech - Honda Forum Discussion (honda-tech.com)

 

I guess we can double check the valve lash, the vtec solenoid I've already checked and cleaned it twice, even replaced the gaskets both times, but I can do it again. I confirmed the oring was put under cam cap 3, but I'm unsure if the dowel is there, I can check that as well.

Would that cause it to lose power even with vtec disabled? because regardless of vtec engaging or not, it loses a lot of power past that point, but with vtec enabled, it's even worse.

 

YES

And check for all rocker pins. Make sure none are missing.

 

Check your timing belt timing... I have seen this symptom when one of the cams is a single tooth off. Also check all rocker arms as onefstgsr suggested to make sure that all dowel pins are there.

 

Mechanical timing.. The power loss without vtec is a dead giveaway here.

 

I have had the same thing happen to me on turbo single cam.
loss of power after 5200 rpm.
found out that it was miss firing at higher rpm.
i never found out what the issue was
i have changed all ignition components and problem still exist

vehicle is no longer in my possession but i understand the frustration.
i wish you the best of luck.

please update us if you figure it out

 

Also check grounds, and could be distributor cutting out, or failing fuel pump

 

Sorry for the late reply, life kinda got in the way and I haven't had time to look at the car.
I have confirmed mechanical timing is perfect we even checked by putting a screw driver down cylinder 1 to make sure it was at tdc. I still need to check the rocker arms, but I'm pretty sure they are all there, because we took the head apart this past January to install new valves as we thought my old ones were bent. Everything was reinstalled and nothing looked out of place. The issue has been the same even before we took the head off, but I will double check the rockers when I go to check the dowel pin under the 3rd cam cap.

Thank you, I will be sure to update, my tuner is just as confused as everyone else haha.
Grounds are good, we even added a couple with no change. Definitely not the fuel pump, I changed it twice with the same aem 340 lph and no change in the loss of power. The distributor is something I haven't checked, so I will check that now. It is an oem 94 del sol vtec distributor I believe.

If anyone else has any other input I would greatly appreciate it as I graduate in 4 weeks and will have lots of time to dig into it by then.

Thanks!

 

Distributors are one of the most common issues with these cars. They cause major issues, I’d check that next.

 

Okay, I have some updates on this situation, I finally got around to messing with the car, and I noticed that the center dowel pin was missing, I also noticed two oil passages in the cam caps were missing something as well. Does anyone know what is suppose to go here, it looks like something should go here, but I'm unsure.

 

Theres two jets that go there

 

Special oil control inserts go into those two holes... without them, VTEC doesn't work. This is why you are not making power past 6000 RPM.

 

I think I’ve seen this on other threads.

 

Okay so, some progress has been made. After buying and installing those parts, I was able to reach 7k, but it then falls on its face again. I was also now getting a vtec spool check engine light, so maybe something is wrong with the vtec solenoid? I've tried cleaning the solenoid, and unplugging the vtec oil pressure sensor with no change. My tuner recommended this.

 

I guess that’s the next thing I would try. I don’t think it’s your timing or distributor because wouldn’t they have gradual problems, not just at a certain RPM...? If you tried unplugging the VTEC oil pressure sensor and got no change then maybe that’s malfunctioning? I’m not sure what else I would try next except for those things.

 

I know this has been a long time since I updated this thread, but I wanted to provide an update to the issue for anyone else that may encounter this problem.

Ultimately, the thing that was causing this issue the entire time was my turbo exhaust housing. I bought too small of a turbo for the motor as the car revs too high and the ram horn mani I had wasn't long enough to prevent the restriction from the exhaust housing.

This was a learning process, but now the car can rev to the moon and doesn't fall on its face anymore.

 

What size exhaust housing did you have before ?

 

It was a 53mm haha, I didn't even realize the size until I looked up the invoice. That's smaller than my throttle body!

 

Housings are sized by aspect ratio (AR), wheels are sized by diameter (in millimeters). So you changed the exhaust wheel from a 53mm to a what? Or the exhaust housing was an AR 0.53 and you changed to a what?

 

Hey, sorry if my reply didn't make much sense. I don't really know turbos and what to look for. My old tuner told me about the problem and he sent me one he recommended. I can provide the specs of both below. I ended up buying a whole new turbo to fix the problem. Both were ebay.

Old turbo:
Compressor:
3" compressor inlet
2.130" Inducer
2.755" Major
2" Compressor Outlet
T04B/T4 Compressor Housing
Compressor .49 A.R.
Compressor .50 Trim
8 Blade T4 Compressor Wheel

Turbine Specs:
T3 Turbine flange
T3 5 bolt flange
Turbine .63 A.R.
2.205" Minor and 2.570" Major Propellar
T3 Turbine Housing
2.274" Outlet
12 Blade Turbine

New Turbo:
GT3582R

Compressor:
Trim: 2.24"
A/R: 0.70 A/R
Inducer: 2.416"
Exducer: 3.227"

Turbine:
Trim: 3.31"
A/R: 0.82
​​​Inducer: 2.668"
Exducer: 2.451"

I just didn't know what to look for and when I originally bought my first one, I just picked the one that stated it was for a 1.5- a 2.0 liter motor and can hit 400hp. I now know that is bs and I should always ask until I understand what I'm looking for.

 

56mm .63 to a 62mm .82

Yeah that would increase the exhaust flow a bit.

 

I was gonna say try taking off the turbo and running it N.A to rule out the turbo kit.. Great to hear its fixed!