MAF readings at different RPM's
 

Doing a quick survey to you guys..

Turbo size:

MAF Hz ad idle:

Max MAF reading at peak torque (about 4000rpm)

Max MAF reading at redline

and boost levels..

..

My car:

53hz at idle
2000hz!! at 4300rpm (HOLY MOLY!)
(haven't gone through redline yet)
13.5psi of boost

GT35r Buschur Turbo..

All I can say is either my calibration on the blowthrough is fouled up, or its moving a SERIOUS amount of air..


I'm still running my car very detuned and rich so I can log data, and of course, thanks to that I am getting a misfire at around 6000rpm or so.. Time for some new colder plugs and some other adjustments.

Way too much HZ IMO for 195Kpa +/-. I would stretch it out more.

I have seen every car that uses the GM MAF have much higher HZ numbers then what the stock MAF was reporting.

Here are my stats with stock MAF:

Stock 05 Turbo
37 HZ at idle 960 rpm
1117 HZ at 4000 rpm
1801 HZ at 7000 rpm
1849 HZ at 7600 rpm

22psi spike to 21psi dropping to 18psi at redline

Highest I got while on MAF prior to speed density using MAFTPro was 1951HZ on INJEN intake.

And what do you get now?

My maf signal is simulated. :)

It does however max out according to evoscan which I think is an error in the programming.

1604HZ I believe is the max it logs.

Yea like 1G pocketlogger. :(

Yeah I started having some trouble with the calibration the other day, which is why I asked.. I have to get my MAF reading back down to 35hz at idle and it should peak around 1600 again, then at high boost I should see 2300-2700hz which is what I'd expect to be normal..

And yeah, EvoScan clips at 1604hz, its actually a byte limitation in that ECU Register and not the software...

The last 2 days I was hunting down a recurring P0300 code at idle, I think it may be the downpipe rattling against the crossbar again, but since I rescaled the load column I need to look closer at the areas I fiddled with and see, if you push a little too much timing at idle I have found I'd get a P0300 on occasion... I have a really conservative map (10.5 afr's or richer and very low timing numbers under load) car runs nice but its of course, down on power..

I want to sort out the drivability quirks I'm finding with the injectors..

The ones I got from buschur (1000cc's) are scaled around 860cc with a 1.006 voltage latency for 11v and 14v.. Either something is acting weird or my injectors have a huge amount of dead time.. I'm thinking the latency is too high simply because my higher RPM driving in closed loop is shifting the trims (-15% or so, Damn Evoscan doesn't log trims correctly and makes this nearly impossible) so I may have to reduce the value again, and add a bit more fuel at idle since the injector scaling itself seems right...

FWIW I'm waiting on some new programmable electronics to replace the older analog unit so I can calibrate my own curve to the GT35r

The big issue is I need to compare around the(2000-4000rpm) same region for about 15psi of boost on a GT35r that still has a stock MAF.. I loaned my MAF to someone and haven't gotten it back yet to get these measurements.

I have a set of FIC 750's and I tried scaling them to around 650 and then used latency values of a similar type and size injector without much luck. The fueling was quite a bit off everywhere and would go pig rich at WOT (9:X AFRs). This prompted me to start moving the scaling up towards that actuall size of the injectors and playing more with latency. What is working for me right now is a scaling of 733 and latency @ 14v of 1.008 and .792 @ 11v. This has yeilded fuel trims that stay in the 90-100 range , in Evo Scan terms, and my WOT is within .5pt of what I will most likely be runinng. I need to drive it around some more and I will check STFTs and LTFT with a scanner to see how things compare to the EvoScan's numbers.

I think I fixed my issue, at least I'll know on the drive home now..

Turbo size: 50 trim
MAF Hz at idle: 44.03 to 50.32 (~1050 rpm)
Max MAF reading at 4000 rpm: ~1000Hz
Max MAF reading at redline: unknown in Hz, according to OBD-II the max values I've reached during various runs are:
44.81 lb/min @ 7184 RPM
45.49 lb/min @ 7930 RPM
47.59 lb/min @ 7691 RPM

Boost is ~21psi, usually starts at about 20 psi and climbs by 1psi by the time it hits 7000 RPM.

Just for grins, here are some estimated VE numbers for my car based on the air flow rates generated by OBD-II. I have to say estimated, since I do not have an accurate means of logging boost yet, so the boost values used to calculate the VE were taken off my boost gauge.

The numbers:


RPM__VE (%)
3840 85.71
4262 103.92
4734 106.79
5246 106.87
5746 108.23
6234 106.06
6695 104.42
7184 103.79
7645 97.27


l8r)

Evo IX stock turbo.

idle is 25Hz
4000rpm is 1250Hz (apx 23psi boost)
maxes at 1603 at 5500rpm.

Girlie

That sounds more like my values when the car was stock.. Since I put the 35r on, the calibration of my blowthrough is freaky, Have to get it figured out since I can end up in a 310 load site at 4000rpm with the way its reading (almost 2000hz)

However the car runs real smooth.. so now its just a matter of getting the MAF dialed in again...