Active e36 HKS Stage II Installed

[Mad Dog 20/20]

Ok, so Karl of AA revised my tune. Got the ECU back last night and drove the car around a bit. The engine felt much smoother but I could not really tell if the car was making more power or whatever. I could tell that the car was continuing to do that "thing" up above 6k rpm under load. Specifically, in 4th gear WOT pulls, the car would misfire/backfire up above 6k. Again, it did this when NA, as well, so its not related to the SC kit. However, it stands out like a sore thumb w/ a centri SC because they can easily make 50+ whp in that last 1k rpm. So I've got to get the issue sorted, and will likely drop the car at RRT for diagnosis.

Anyway, although the ECU prolly did not have enough time to adapt, etc. I went ahead and took the car to a dyno day at Moore Automotive in Fairfax VA today. Fun time. This is what she put down:



On Moore's elevated dynojet . . . a good shot of the stealth FMIC and SC core.

[DavidsM3]

Nice numbers, but what do you think the misfire issue could be? bad coils maybe?

[pbonsalb]

At 6000 rpm, you are beating AA's peak power for the kit on a stock car. The stock car with the stock kit picks up only 30 rwhp from 6000 to 7000 rpm, but your breathing mods should substantially increase that gain.

What boost do you see on your gauge at 6000? The boost graph is all over the place.

[EBM3WSNC]

wow you should be around 430whp+ when you get the issue worked out!

[busterhax]

Yeah, it seemed all of our boost graphs were all double helixified. I think that dyno was a bit beat..boost read .5 psi at all times too.

[Mad Dog 20/20]

Nice numbers, but what do you think the misfire issue could be? bad coils maybe?

Maybe. Maybe cam timing. Maybe VANOS timing. Maybe knock sensors.
Who knows. I have not had time to really troubleshoot this issue, but that's what I need to do: test/replace all the old sensors, pull the valve cover and check timing and VANOS, etc.

What boost do you see on your gauge at 6000? The boost graph is all over the place.

Boost at 6k rpm is about 8 psi on my gauge. As Busterhax said, the Moore Dyno boost gauge was all over the place for all the cars I watched run.

wow you should be around 430whp+ when you get the issue worked out!

If curing this misfire thing results in a linear power curve of the same pre-5k rpm trajectory from 6k rpm to redline, I'd say your estimate is about right. That is best case scenario, though. But even if the power curve trails-off in an "acceptable/normal" fashion as it gets closer to redline, the motor should still be well into the 400's.

I will have to set aside a weekend to give my best crack at troubleshooting this 6k+ rpm issue, and if that fails, I'll be dropping it at RRT.

[DavidsM3]

Good luck man. Keep at it.

[mcoupemindy]

Great numbers! Sorry that I couldn't stick around to see your run - had some things to do in the afternoon.

I also ran on a "learning" ECU as I just got a Bosch 040 Motorsport Fuel Pump in the tank Fri night.

[pbonsalb]

Below is the AA dyno for the stock stage II HKS kit on a stock OBD2M3 that made about 335 rwhp at 6000 and 365 rwhp at 7000. Looks like you are about 40 rwhp up on it at 6000 rpm, which should account for your engine mods (you won't maintain all the NA gains since the tune is different and there is less timing). I think you will maintain that advantage and easily cross the 400 rwhp threshold.

I am curious as to whether your exceptionally good rwhp to torque ratio at 375/335 will survive once you have your final numbers. Even AA had more like the 20% difference that is usually seen with centrifugals when it dyno'd the HKS system on the stock OBD2 car, at 365/298. You would really be bridging the gap between centrifugals and turbos if your torque stayed within about 10% of horsepower.

[PDP M]

top end misfires usually indicate an ignition issue. probably want to start w/ a fresh set of 1 step colder plugs properly gapped. just speculating, because i dont know the last time you changed plugs, but f/i takes a toll on plugs, especiallyold ones.

[savage217]

Have you replaced your knock sensors? My car would seem to studder/die at roughly 6500-7k for a second or two. I guess you could say hiccup. Once I changed the knock sensors the problem went away. Even if you dont get a CEL the knock sensors can still pull timing. Not saying this is the cure but something to def consider replacing. Mine were both cracked. Strong numbers even still!

[Mad Dog 20/20]

Below is the AA dyno for the stock stage II HKS kit on a stock OBD2M3 that made about 335 rwhp at 6000 and 365 rwhp at 7000. Looks like you are about 40 rwhp up on it at 6000 rpm, which should account for your engine mods (you won't maintain all the NA gains since the tune is different and there is less timing). I think you will maintain that advantage and easily cross the 400 rwhp threshold.

I am curious as to whether your exceptionally good rwhp to torque ratio at 375/335 will survive once you have your final numbers. Even AA had more like the 20% difference that is usually seen with centrifugals when it dyno'd the HKS system on the stock OBD2 car, at 365/298. You would really be bridging the gap between centrifugals and turbos if your torque stayed within about 10% of horsepower.

You posted AA's C38-2 dyno, not their HKS-2. Their HKS dyno results are 370/315. So I think the HKS does seem to have a better hp/trq ratio than typical centri's.

top end misfires usually indicate an ignition issue. probably want to start w/ a fresh set of 1 step colder plugs properly gapped. just speculating, because i dont know the last time you changed plugs, but f/i takes a toll on plugs, especiallyold ones.

thanks for the suggestion. I think it's a logical one, but the problem seems to have preceded the SC install. Im running new one step colder ngk's gapped to .28.

Have you replaced your knock sensors? My car would seem to studder/die at roughly 6500-7k for a second or two. I guess you could say hiccup. Once I changed the knock sensors the problem went away. Even if you dont get a CEL the knock sensors can still pull timing. Not saying this is the cure but something to def consider replacing. Mine were both cracked. Strong numbers even still!

I think the knock sensors are likely candidates. Your experience kinda mirrors mine, so hopefully new knockers will do it.
Thanks

[SiGmA]

Cracked means nothing fwiw, but knock sensors are possible. I may have missed it, how old are your coils and plugs?

[GGray]

if the knock sensors were put on and over torqued it kills them... I think you can test them with an Ohm meter. You may want to check the bentley manual. I had a bad one on a GTi one time caused all kind of problems.

Power curve looks nice so far even witht eh misfire.

[savage217]

Cracked means nothing fwiw, but knock sensors are possible. I may have missed it, how old are your coils and plugs?

Mine were showing the metal skeleton or w/e is under the plastic and every now and then I would get a cel for knock sensors. So maybe in some cases cracked knock sensors dont matter but I def would replace them if they are.

[spdu4ea]

If new knock sensors don't fix it, you might try having AA increase the knock threshold over 6000rpm. Perhaps your NA mods have changed the harmonic frequencies of the engine enough to trigger false knock readings.

The other, less likely culprit is valve float. Usually valve float drops quite a bit more power (here's a dyno with valve float on an American V8:

[SiGmA]

Mine were showing the metal skeleton or w/e is under the plastic and every now and then I would get a cel for knock sensors. So maybe in some cases cracked knock sensors dont matter but I def would replace them if they are.

I agree on replacing them if there is any physical damage (cracks), but from talking with some dealer techs, cracked doesn't mean they are bad per say.

[Mad Dog 20/20]

If new knock sensors don't fix it, you might try having AA increase the knock threshold over 6000rpm. Perhaps your NA mods have changed the harmonic frequencies of the engine enough to trigger false knock readings.

The other, less likely culprit is valve float.

The more I search around, it seems a lot of NA M3's have had the same issue, stumbles/hiccups when under load above 6k rpm at WOT in 3rd/4th gear. Seems most are focusing on the cam and knock sensors. Mine have 150k on them . . . I knew I should have swapped them out when I did the HG. We'll see what those do.

Yeah, I doubt its valve float. The S52 is an interference engine. Valve float = massive carnage.

I agree on replacing them if there is any physical damage (cracks), but from talking with some dealer techs, cracked doesn't mean they are bad per say.

When I did my HG, I removed and inspected my knock sensors. They looked fine. I thought nothing of bolting them back in. But apparently, according to RRT, they are very sensitive to improper torque. Since I did not use a trq wrench to put them back in, I'm sure they are torqued oout of spec.

I'll just replace them w/ new and trq to spec.

[savage217]

Shit I didnt torque mine to spec but I havent had any issues at all since putting the new ones in. I guess next time I have the intake off Ill be sure to torque them for good measure.

[LukeG]

My 95 threw a code for one and I realized I over torqued them. Loosen both up and tqed them. All good now

[PDP M]

ive over torqued knock sensors before. usually throws a code. its possible that they've seen better days. im interested to see the outcome.

[Mad Dog 20/20]

I think the high rpm misfire/stumble was caused by the coil/plug boots:

I forget which vendor sold me my old 65k mile spark plug boots, but they were bremi's w/ the bmw logo/info ground off of the rubber casings. They also looked slightly different from the ones I picked up from the dealer yesterday - just different ridges on the casings.

Anyway, the new ones seem to have cured the issue. Repeated 4th gear WOT runs to redline were unable to generate a misfire/stumble. She pulled clean/hard to redline.

I'll dyno again at some point and report back.

[SiGmA]

Sweet! I've seen that before on stock cars, tho never quite like that. They usually had mild runability issues all around.

If you don't mind, would you measure resistance through all 6 of your old boots?

[Captain]

I think the high rpm misfire/stumble was caused by the coil/plug boots:

I forget which vendor sold me my old 65k mile spark plug boots, but they were bremi's w/ the bmw logo/info ground off of the rubber casings. They also looked slightly different from the ones I picked up from the dealer yesterday - just different ridges on the casings.

Anyway, the new ones seem to have cured the issue. Repeated 4th gear WOT runs to redline were unable to generate a misfire/stumble. She pulled clean/hard to redline.

I'll dyno again at some point and report back.

Dude!!!! Congratu-f*cking-lations!!!

I've been reading the whole thing and hoping/praying for you to work the issues out! I'm looking into the 328 HKS system, and have the same NA mods you do, just no 3.5" HFM, bbtb? and...?

ECIS CAI w/custom ram air from brake air duct.
Custom, True Dual, Borla exhaust w/Quad Magnaflow tips.
ACS Delete w/Samco silicone boot.
Eurosport M50 Manifold kit
Port and Polished stock Headers
S52 cams
Jim Conforti "cammed M52" Shark Injector
UUC Underdrive pulleys
Fan Delete
AFPR
M3 3.23 LSD

Cant wait to see the new numbers, way to stay on it!

[pbonsalb]

Aren't there lower resistance boots available? 1.0 versus 1.5 ohm?