help w/ dyno sheet...

[craaaazzy]

hi guys,
had my car dyno'd last night - on dynojet. here's the list of mods:

euro hfm kit - ecis intake, euro hfm, 24 lb injectors, conforti chip, etc.
aa track pipe

anyway, to record the a/f ratio, i had the o2 sensor out and the wideband sensor in. when i cranked the motor, the check engine light came on for the 02 sensor. well, looking at the chart, the ratio from 2k-4 remains pretty constant around 13 but there after, it dips to 12 all the way to redline. car is running very rich in the upper rpms. can this be attributed to the o2 cel? or do i need to get a new chip, tuning appropriately?

those w/ obd1 and track pipe, to dyno, did u do the same or have the shop put a bung in the pipe? thanks in advance.

http://images.cardomain.com/member_images/4/web/160000-160999/160173_17_full.jpg

[NickG]

Nothing wrong there that I can see. That's just the AFR that the chip is programmed to achieve. The track pipe most likely contributes to the richer mixture up top.

[mic_poo]

Most of the JC chips I've seen, including my euro HFM, 17lb/hr chip, start to lean the mixture a bit around 5300RPM... However, I've not seen any AFRs pre cat.

[Sean@ECIS]

anyway, to record the a/f ratio, i had the o2 sensor out and the wideband sensor in.

To get this reading absolutely correct, you have to have the Dynojet sensor put in BEFORE the cat. That means welding in a new bung fitting before the cat just down stream of the exhaust manifolds. Most people do not want to do this or spend the money (and I agree), but I had it done for free by ERT when we were doing some joint-dyno testing at their facility 2+ years ago.

With the 17lb injectors, I felt the car was running lean at points (before dyno proved this), so we decided to dyno the 24lb injectors to see if the fuel issues could be corrected. Sure enough, they were.

I am running the same setup you are and had zero A/F issues after installing the 24lb injectors. Everything was balanced perfectly.

I honestly believe that some 95 M3's with higher mileage will run lean (with mods) due to the 17lb injectors not being able to handle increased loads (cfm, etc).

The Conforti software is designed perfectly and will not negatively affect your car's operating system. The same cannot be said of the 17lb injectors. BMW learned their lesson and went to the 21.5's in the OBD-II M3.

I have the dyno sheets from that day somewhere....will try to dig them up.

[Mad Dog 20/20]

I don't think 12's are THAT rich. Gives you a margin of safety. But the track pipe should have leaned things out a bit. Before I'd get too worried, I'd make sure the plugs/filters/sensors, etc. are fresh. Also, because you have a track pipe, you could take an accurate AFR at the tail pipe and leave the O2 sensor in place. May or may not make a difference . . .

[craaaazzy]

new plugs installed not too long ago, new fuel filter, knock sensors, o2 sensors replace. the only thing was the car was due for an oil change - around 3k miles

i'll probably just re-dyno w/ o2 in and see if there are any changes sometime in the future.

mad dog, what was your a/f ratio. it's constant but i can't tell what it was from your graph.

sean, i'd like to see your chart.



Originally posted by Mad Dog 20/20
I don't think 12's are THAT rich. Gives you a margin of safety. But the track pipe should have leaned things out a bit. Before I'd get too worried, I'd make sure the plugs/filters/sensors, etc. are fresh. Also, because you have a track pipe, you could take an accurate AFR at the tail pipe and leave the O2 sensor in place. May or may not make a difference . . .

[Sean@ECIS]

I was off when I said I am running the same setup....I am NOT running the track pipe. Sorry...the track pipe will lean things out a bit.

I will try to dig up the graph.

[Ron17]

Seems to me that, with the O2 sensor not in place, your car would not be running correctly. I wonder if you would be generating far more power if the O2 was in and you just weren't getting your A/F from pre-cat?

[Armo95]

I just dynoed my car and I have AA's track pipe. They did absolutely NOTHING as far as plugging etc. to the pipes. Maybe that's why everything was so far off and the readings were sort of off and low.:dunno



Do you HAVE to do something with the track pipe as far as O2 sensor to make the readings more accurate? Thanks all...

BTW, you think 12 is rich, I'm a little lower than 11 up top! It's insane...can't wait to get a custom dyno tune done to see what my car really makes...

[craaaazzy]

Armo95 - so u had a bung welded and then dyno'd? or did they just place the wideband sensor at the tip of your muffler?

[Ron17]

As long as your O2 was plugged into the TP, you shouldn't have had any problems with your car.

How did they get the A/F readings, Armo -- tailpipe sniffer?

[mic_poo]

This brings up another question...

At WOT, I thought fuel control went to open loop control anyway.. reading pulse width information directly from the look up tables and not trimming based on O2 sensor inputs.

Am I incorrect? Are OBD I and OBD II different on the method of calculating the correct pulse width at WOT?

[craaaazzy]

here are some responses i received from the FI forum.

http://forums.bimmerforums.com/forum/showthread.php?s=&threadid=179585

[Armo95]

There was nothing hooked to the exhaust, and they didn't know I had a track pipe installed either, they never asked.:dunno

Tell you guys the truth, I don't know how the hell they did it...I was behind a closed window section where the customers have to stand.

All I saw were the latches for holding the car down, other than that, nothing else. They didn't take off anything after all was set and done...I'm beginning to wonder if these guys even did my dyno correctly to begin with...

[Ron17]

They made up an A/F curve for your car. lol

;)

[Mad Dog 20/20]

Originally posted by craaaazzy

mad dog, what was your a/f ratio. it's constant but i can't tell what it was from your graph.


It is right about 13.5 the whole way. The dyno operator actually pinpointed the AFR for me while we peeped it on the monitor.
This is with JC's OBD2 Cam Kit SW and a host of other mods . . .
I have a Track Pipe, too - my AFR was taken at the tail pipe with all O2 sensors in place.
I would just re-dyno with the O2 sensor intact and get an AFR at the tail pipe, since you are catless.

[johnnym3]

I was told regardless if its obd1 or obd2 when you go wot the o2 sensor is not in the loop . I talked to a few dyno guys and they said the afr difference from pre-cat to at the tail pipe is less than .3 afr.

[Mad Dog 20/20]

Originally posted by johnnym3
I was told regardless if its obd1 or obd2 when you go wot the o2 sensor is not in the loop . I talked to a few dyno guys and they said the afr difference from pre-cat to at the tail pipe is less than .3 afr.

I've heard that too. I'd still try a different method on the next dyno run, especially since he's got no cat and its just a lot easier to get the AFR at the tail pipe and leave the sensor intact . . .

[Armo95]

Originally posted by Ron17
They made up an A/F curve for your car. lol

;)

I wouldn't be surprised. Oh well, I guess we'll have to wait until March to see what my car can really do with some expert tuning.

:clap: