[dzenno]

Went for a dyno yesterday and didn't do as well as I thought...I've had cold start misfire issues on cyl 2 for a few weeks and now for the past 4 days weather has warmed up and the cold start misfire doesn't happen again...how could it just disappear with warmer weather? We're almost positive its the injector and I'm going in on Tuesday morning to try to get it replaced but NOW that its not happening anymore I really think they'll just ignore it and tell me to come back when the codes are back

In any case, considering there's nothing obvious wrong with the car now, why would this power taper happen 5000rpm onwards when it should still keep going up to about 5600? I've lost about 40-45 whp and about 15-20 wtq from my best previous run...the only difference is now I was using 91 octane and then i was using 94, and that was on procede V2...

I'm pretty sure its not the tune as another member on here dynoed the same numbers with just procede and intake...I tried contacting Shiv a few times but I think he's busy with the latest good stuff so don't blame him

I don't get why the curve isn't smooth as well...notice that second hump at around 5100?? after that it goes down...could this be attributed to an injector that only used to show faultiness on cold start and not under WOT?

Here's a little service history on the car:

1) Plugs changed 2 weeks ago, same issue happened before
2) Cold start misfire on cyl 2 was happening for a few weeks, diagnosed as faulty injector by an independent shop, hoping dealer will fix on Tuesday but since no codes now, most likely not..
3) About 20K ago, vanos solenoids changed at the dealer as they were causing codes at high rpms

Mods are stg 3 catless, no meth or nitrous..

[dzenno]

Here's my dyno from about 1 1/2 years ago, same boltons (stg 3 catless) just on procede V2 back then..see power going up past 5000rpm, but not yesterday...

[tomtom]

the recent dyno is using SAE and the former STD conversion...
convert it to STD and you should see another 10whp or so I think

[dzenno]

I know, still over 40whp loss though...i have the SAE graph for the old run as well, shows 383whp, STD is 393

[jpsimon]

get it done at the same dyno? what was the ambient temp? did you datalog the runs (this would tell us the most)?

[dzenno]

for some strange reason datalogging didn't work yesterday, logs only recorded the first 2 seconds, weird, must've been my laptop...these are 2 different dynos BUT 3 weeks ago I was at the same dyno as the one from year and a half ago and I had the same low numbers 330-340whp..temps yesterday were about 20C colder than before..

[bmwzimmer]

How does the car "feel". My butt dyno can easily tell if there's a 40hp loss

[dzenno]

Don't really feel the loss but it's only above 5000 that the loss is there..notice torque is still high, why the whp loss? The curve not as smooth as before, especially after 5k rpm..

[dzenno]

Here's the photo of dyno graphs from 4 weeks ago on 2-24 maps, from the SAME dyno...don't have the original printout anymore and the photo cut off the rpms, f*...but its a good compare...

GREEN is from July 2008, on stg 3 mods and procede V2...Blue is on stg 4+ 2-24 map with vp116 leaded, 100% UT, 0% ign corr..red is on 91 stg 3 map..

So even on this same dyno, power starts to dip now around after 5000rpm...see how before (green line) used to go up past 5000rpm to about 5600rpm and only then start going down..

what could cause this loss at high rpms?

[cn555ic]

Originally Posted by dzenno

Don't really feel the loss but it's only above 5000 that the loss is there..notice torque is still high, why the whp loss? The curve not as smooth as before, especially after 5k rpm..

Did you install the pulley??

[dzenno]

everyone keeps asking about it..never installed it, been in my trunk waiting to install but decided not to..there's a thread on here, I'm selling it if anyone is interested..don't have the ballz to run it..

http://www.e90post.com/forums/showthread.php?t=370531

[OpenFlash]

Need to look at datalogs of the runs to see if you are hitting boost target and running reasonable advance numbers. Wastegate dc logs will also help to see of there is a boost leak or turbo problems of some sort. I can't look at logs until tomorrow... Easter with the family.

Without any of this info, there is absolutely no possible way of knowing where to look.

[dzenno]

I don't have datalogs from yesterday as it wouldn't record any for some reason, never happened before(on my mac)...I'll use my windows netbook and datalog soon and send them in..

[dzenno]

Originally Posted by shiv@vishnu

Need to look at datalogs of the runs to see if you are hitting boost target and running reasonable advance numbers. Wastegate dc logs will also help to see of there is a boost leak or turbo problems of some sort. I can't look at logs until tomorrow... Easter with the family.

Without any of this info, there is absolutely no possible way of knowing where to look.

How do you tell from wg duty cycle logs that there's a boost leak or turbo problems? Don't think anyone has explained how to interpret this curve yet..if anyone has link to a thread please share it..searching didn't help..What're reasonable advance numbers to look for?

[Irishace]

If I recall you hit a peak boost of 17.3 on your vent gauge on the second run. I should have watched it closer beyond the 5k mark to see if there was a big taper prior to 6k when the proper tapering occurs from Procede.

[dzenno]

For that last in I ran 90% UT 100% ign correction so boost was peaking at 17.4 but remained at about 16.2 above 5000 and above 15 above 6000rpm from what I recall seeing..sucks that my datalogging didn't work .. This is why I think there's no boost leak as gauge showed min 15 to red line..I'll try dataloging a few times on the road and see what I get..

[ultimateracing335]

Ya your boost was holding well from what the gauge showed. It even held well up high. I'm curious to see what the problem is.

[dzenno]

Yeah, I'm putting procede back in on wed. right after my stealer visit then I'll datalog and see what's up..

[specialsauce]

Just to throw this out there isn't 17psi way to much for 91 octane? That requires race gas and methanol injection according to what I've read here. Maybe you will do better with lower settings?

[OpenFlash]

You'll need to datalog. Without basic engine info (timing, boost, wastegate dc) you can't rule anything out. So it's anyone's guess until then.

Shiv

[dzenno]

Specialsauce, you missed what I was saying up there..I only ran that 17 psi (90%) as the 3rd run just to see what happens..the problem was there (what I'm talking about) at 70% UT and 75% ign correction which is run 2 on the graphs, then I went to 80%ut then to 90%, obviously numbers didn't change.

I don't understand the first runs numbers..