ok Im a newb, but Not to the scene. I have a 04 c5 with only mods being a k&n Intake, and a tune. Its an auto. Stock exhuast, no intake or exhaust leaks.
I had it dynoed a while back and here is the slip 295whp/302wtq
Now the shop said it was running lean. We moved the sensor to different tips on different runs, but got the same reading. The a/f stays at about 14.0-1 most of the time at wot. And there is a nice pot hole in the pull at 5200 rpms.
What do you guys make of this? Is it really lean? or is the dyno sensor reading false? Supposed to be like 26-27* of timing, but no KR. Shop said If I threw some fuel at it I could see another 15whp or so... This true?
Last edited by 04c5owner; 10-05-2009 at 04:24 AM..
ok Im a newb, but Not to the scene. I have a 04 c5 with only mods being a k&n Intake, and a tune. Its an auto. Stock exhuast, no intake or exhaust leaks.
I had it dynoed a while back and here is the slip 295whp/302wtq
Now the shop said it was running lean. We moved the sensor to different tips on different runs, but got the same reading. The a/f stays at about 14.0-1 most of the time at wot. And there is a nice pot hole in the pull at 5200 rpms.
What do you guys make of this? Is it really lean? or is the dyno sensor reading false? Supposed to be like 26-27* of timing, but no KR. Shop said If I threw some fuel at it I could see another 15whp or so... This true?
Dyno O2 sensors typically do read a little lean when they're stuck up the exhaust tip. I wouldn't worry about it too much. Getting it tune probably could pick up 15 at the wheels. They're not exactly tuned for max power from the factory.
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When it's that lean it's hard to say if you'd pick up anything. Alot of the gains are made from leaning the usually rich WOT condition from the factory.
Depending on the knock retard, you may or may not have any significant gains. BUT, tuning an auto makes all the difference in the world. They usually have a much more dramatic SOTP feeling than the M6s do.
The big dip is probably knock retard. That would be my guess anyway.
Dyno O2 sensors typically do read a little lean when they're stuck up the exhaust tip. I wouldn't worry about it too much. Getting it tune probably could pick up 15 at the wheels. They're not exactly tuned for max power from the factory.
This dyno was with a custom tune/ from a friend/ on HP tuners. and an intake.
Quote:
Originally Posted by edcmat-l1
When it's that lean it's hard to say if you'd pick up anything. Alot of the gains are made from leaning the usually rich WOT condition from the factory.
Depending on the knock retard, you may or may not have any significant gains. BUT, tuning an auto makes all the difference in the world. They usually have a much more dramatic SOTP feeling than the M6s do.
The big dip is probably knock retard. That would be my guess anyway.
So you think the problem is the KR? You think running a little richer would help that? Does it look like it may cause problems?
Not that anyone cares. But I fixed the problem. here is the before dyno
Here is the after dyno.---
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Picked up 13whp and 17.1wtq no knock, better a/f and much better low end and way way better top end. What did I do you ask?
I had to take it to the dealer and reflash the ecm to stock. Because the guy that "tuned" it would not return calls, texts for over 2 weeks. Cost me some $$$ because the dealer likes people to grab their ankles. Would have been free if the guy would have just loaded the stock tune back on. Hope the motor didnt get hurt.
Last edited by 04c5owner; 11-05-2009 at 02:26 PM..
Scary results from a "friends tune". It is really sad how everyone fancies themselves a tuner because they own a laptop and can change oil.
Good to see you got it fixed.
Ya. I trusted the guy. Known him for a while. But he was too busy to return/answer phone calls and texts, but not too busy to make posts on other sites.
I mean I can understand missing a call, but its like he was avoiding me. Funny thing was I could hear knock, and caught lean codes... And they/he dismissed the a/f on the dyno to be a false reading. And didnt want to tune again without a wideband. I knew something was wrong. But they wouldn't listen.
Quote:
Originally Posted by Martin HD-28
Wow...good to see you got it straightened out....out of curiosity, how much did the dealership charge for reflashing the ecm and how long did it take?
Thank you. took about an hour. cost $99 but I had to drive to 3 dealers because first 2 were too busy. Then $60 for another dyno. Other dealers charged $157 and $128... the one that could fit me in, was also the cheapest.
damn dude after all this time and money you should have taken the car to a pro shop and had them do it. I noticed a huge difference when I self tuned my 03.
damn dude after all this time and money you should have taken the car to a pro shop and had them do it. I noticed a huge difference when I self tuned my 03.
I am. Funny thing is I usually have a pro do it. But this was a "discount" tune. I just payed for credits... $100, Dyno $60, dealer re flash $100 redyno $60 back to stock. about $320 plus hassle and gas driving all over the earth to have a stock tune made worse, then back to stock again. Last I checked The pro did tunes for $300 so yeah, would have been cheaper to get it done right the first time.
or you could have had a guy (who actually knows what he's doing) like me do it for 200. I can't believe he even used a dyno and still jacked the car up. Your car is basically stock.
Just wondering, what gear do you have? I had the 2.73 with a tune, volant intake, and some quiet catback and ran a best of 12.76@110.
or you could have had a guy (who actually knows what he's doing) like me do it for 200. I can't believe he even used a dyno and still jacked the car up. Your car is basically stock.
Just wondering, what gear do you have? I had the 2.73 with a tune, volant intake, and some quiet catback and ran a best of 12.76@110.
I did the dyno on my own. I knew something seemed off. I told him about the dyno... and he said that the a/f was reading false, because he had 12.7 as the command. Im not a tuner, nor do I know a lot about it. But when I told him I could hear knock, he said it was bad gas. I said maybe its too lean, because I get lean codes. That comment didnt really register to him I dont think, because he didnt respond.
I believe its a 2.73 gear and stock 4l60e. Stock I ran a 13.5 @105 with a 2.1 60ft. I am sure I can get the 60ft down with a little practice. I was hoping for a good 3-4mph gain with a "real" tune.
Lot of money and hard lesson learned but with all the variables you were dealing with I think the dealer setup was the right thing to do. This got you back to a known baseline from which you can work and understand going forward what modifications are working.
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a dirty maf will make them run leaner...thats a easy clean...also cats will make it look lean IIRC...you need a pre cat 02 reading
If this is true, then why on the second trip to same dyno did the a/f suddenly make sense? Im sure the a/f ratio is off a little, but to have a steady 14.0 a/f on the first run and a steady 12.5 a/f on the second run, with the only change being the tune, it would seem to be only off by maybe .1 or so.
So your saying that the tune was good, I just needed to clean my maf, and get a pre cat a/f??? splain the lean codes, and KR for me then.
Last edited by 04c5owner; 11-11-2009 at 04:46 PM..
If you have a 2.73 it will shift out of 2nd at about 100mph. I ran a 2.0X best for my 60ft. No tire spin at all, no brake torquing, no burnout needed. It was opening day too so the track may have been prepped well.
FYI the dyno uses a vacuum type a/f meter. From what I have heard it is about as accurate as a wide band. Also wanted to point out that the main reason, other than KR, that I had the ECM re flashed was because I failed emissions twice. Both from all of the systems being in not ready mode. I was going to put it off but I got pulled over. I tried driving it allot thinking that would fix the emissions system being we don't drive it a lot. But it didn't. The re flash fixed everything.
C5 dyno opinions needed 
Cost me some $$$ because the dealer likes people to grab their ankles. Would have been free if the guy would have just loaded the stock tune back on. Hope the motor didnt get hurt.
