Got Dyno'ed --> Vanos problem

[m3f_CosmoM]

Good new/Bad news



I got myself and the M over to Dynospot Racing for a 'before' dyno run. The dyno confirmed the power characteristics I felt in my car. A real nice lump of torque up to 4k rpm, then flat power through redline.



Essentially I put 185 peak hp to the wheels. Right away the dynospot crew looked perplexed and started talking about why my car wasn’t putting down the expect 200 or so

hp. They overlayed my graph over another stock 99. I was making more power up to 3.5-4k, when the other car just took off and my graph stayed flat.



Long story short: they said the Vanos unit wasn’t working for the top-end power kick that would get me to 200 whp. They did a few tests and confirmed that the vanos solenoid was working, but it appeared the cams weren’t doing their thing.



I talked to my trusted BMW trained mechanic who did a full PPI in my car before I bought it. The tests he ran showed the vanos to be in working order at the time of PPI.



I’m really confused now. Perhaps the vanos system broke in the 5 weeks or so since I bought it?



My mechanic’s theory (since he believes the head has been removed at some point) is that who ever reassembled the head and vanos did a crappy job and that the lengthy vanos adjustment/install process was botched. Leading to slightly mis-aligned whatever which would lead to sub-optimal cam timing leading to power loss.



Does that make sense to anyone?



BTW, there are no weird noises coming from the vanos system.



What test can be run to nail down the problem? I plan to install new cams in the future and I’m thinking about leaving the issues as is until I get the cams. Then when the cams are installed the installers can properly setup the vanos and cam timing. Am I safe waiting?



Looks like my first engine mod will be to friggin fix my vanos!



-CosmoM-



PS you still reading this?

[m3f_astan100_7ef66fbe89]

Wow, that really really stinks. I'm not technical enough to help you out, but I at least read the whole thing.

[m3f_M3AN_5f4dc0ba80]

My mechanic’s theory (since he believes the head has been removed at some point) is that who ever reassembled the head and vanos did a crappy job and that the lengthy vanos adjustment/install process was botched. Leading to slightly mis-aligned whatever which would lead to sub-optimal cam timing leading to power loss.



Does that make sense to anyone?





This makes perfect sense... unfortunately. And even worse, the only way to diagnose and fix would be to take the head and possibly Vanos apart and recalibrate the whole lot.

[m3f_CosmoM]

This makes perfect sense... unfortunately. And even worse, the only way to diagnose and fix would be to take the head and possibly Vanos apart and recalibrate the whole lot.



Since the car runs fine,.. I'm going to leave it alone until I get the cams installed. At that point the installers should be able to tell if the vanos is screwed or if the previous install we done poorly. I'm obviously hoping for the latter!



At least I got to see your avatar again. Nice headlights.



-CosmoM-

[m3f_Gilbert_43a469a9d9]

Did your mech. inform you that the Head had been removed for your PPI? If yes, did you ask the owner why he screwed with the head?

[m3f_DoctorBentValve]

I'm thinking that if the VANOS wasn't installed properly you would have much larger issues than your dyno run being down 15 hp. There are differences in cars, dynos, temperature, barometric pressure, etc, etc that can make that much of a difference. VANOS is really a lot less complex than many think. More or less it just moves the intake cam gear a few degrees by way of a helical gear when the ecu tells it to. If it was misaligned, I can't help but think you would hear some strange sounds and/or FEEL a drastic decrease in power. Why don't you go back to the dyno shop and have another run performed with the VANOS solenoid unplugged? It is a simple two pin connector going to a piece that looks like a small starter motor on the front of the head. It controls the oil pressure that makes the VANOS gear actuate. Try a run with the solenoid unplugged and see if you get the same drop off at 4000 rpm.

[m3f_douglee25]

I'm thinking that if the VANOS wasn't installed properly you would have much larger issues than your dyno run being down 15 hp. There are differences in cars, dynos, temperature, barometric pressure, etc, etc that can make that much of a difference. VANOS is really a lot less complex than many think. More or less it just moves the intake cam gear a few degrees by way of a helical gear when the ecu tells it to. If it was misaligned, I can't help but think you would hear some strange sounds and/or FEEL a drastic decrease in power. Why don't you go back to the dyno shop and have another run performed with the VANOS solenoid unplugged? It is a simple two pin connector going to a piece that looks like a small starter motor on the front of the head. It controls the oil pressure that makes the VANOS gear actuate. Try a run with the solenoid unplugged and see if you get the same drop off at 4000 rpm.



Exactly! If the power drop is identical, then you know there may be a problem. If not, then your vanos is probably fine. 185 rwhp does seem rather low. My front wheel drive taurus SHO put down more than that. I suspect you may have issues elsewhere if your vanos seems to be OK.



Doug

[m3f_///sleeper_f29d08a5a4]

I'd bet your vanos fine...plus if they fail, they'll trip a check-engine light and you'd have no low-end power either.

[m3f_///sleeper_f29d08a5a4]

maybe your O2 sensor is shot?

[m3f_CosmoM]

OK,... so I took my car in for a couple of mods (including new cams).



Not the problem:

VANO -- working fine

Cam timing -- setup properly



We were all stumped until the shp decided to measure the cams that came out of the car. They are 328/325i cams! That explains all the low-end truck like torque my car made and the lack of top end.



More details and dyno plots to follow.



-CosomM-

[m3f_00poop6x_6dca3456a4]

OK,... so I took my car in for a couple of mods (including new cams).



Not the problem:

VANO -- working fine

Cam timing -- setup properly



We were all stumped until the shp decided to measure the cams that came out of the car. They are 328/325i cams! That explains all the low-end truck like torque my car made and the lack of top end.



More details and dyno plots to follow.



-CosomM-

How much more low end do you get from a regular stock E36?

[m3f_bmw4life13_0098c1d2b1]

why does your car have 328i cams? Which shop did you go to in houston?

[m3f_PurpleM3Pursuit]

yeah wtf.. thats weird.. screw it.. get some serious cams.. is that the M engine?

[m3f_CosmoM]

yeah it's an M engine alright. I changed the cams and a few other goodies for 241 to the wheels on CA piss 91 octane. I've been swamped after getting back from vacation, but will post plots when I get digital versions

[m3f_PurpleM3Pursuit]

im sorry did u say 241 to the wheels? dayum son.. lets see the graph..