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Discussion Starter · #1 ·
I installed a VCM OTR a few weeks ago and now I'm starting the process of tuning.

So I flashed my PCM with all the prelog settings specified in the tuning basics thread. (disable dod, disable VE, etc, etc)

I scanned and got the following MAF vs STFT. I have a VCM OTR and it seems all my readings are positive and HIGH. 15% error? seems real lean. Does this data seem reasonably? I don't want to start messing with fueling is this isnt good data.


http://s1343.photobucket.com/user/jvanalph/media/firstscanpic_zps87dc3837.png.html?sort=3&o=0
 

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I'll start with the most basic 2 things I can think of:
1. Did you ever scan the car before installed the intake?
2. Did you double check your install job, make sure you didn't leave off or knock off a vacuum hose?

Also, your STFT's may be a little higher than normal if you disabled and cleared LTFT's (I think I remember that being in the basic tuning thread when I read it).
 

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Discussion Starter · #3 ·
I'll start with the most basic 2 things I can think of:
1. Did you ever scan the car before installed the intake?
2. Did you double check your install job, make sure you didn't leave off or knock off a vacuum hose?

Also, your STFT's may be a little higher than normal if you disabled and cleared LTFT's (I think I remember that being in the basic tuning thread when I read it).
1. the VCM was installed before I owned HPtuners. So NO.
2. I did think of this so I looked for leaks. I even checked out the exhaust a bit.

I did disable the LTFT's as the guide suggest to do so.

I was thinking that my iat's may have been part of the issue. When I first turned the car on and lef tthe house to log I notice the iats were up to 110. It's 45 out side. so I drove around until the temps got below 80 before logging.

Is this ok?
 

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I would say your readings are accurate. I have had both otr and roto-fab and there were slight differences in the maf reading. I found the otr intake to have higher iat's while driving around in traffic as well. I would go for a long drive while scanning and multiply the histogram data by half and scan again. I find that more often than not the histogram data over shoots and you end up chasing your tail. What are you using the for you tuning references?
 

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Yea, you may be okay then. I would just run an iteration of MAF adjustment and then rescan to see where you are. If it doesn't improve then you know there must be some other problem. You can always revert your changes easily so no worries there. I installed my RotoFab and only seen my trims jump to between 6 and 8. I had already tuned before the intake though so things were already right around 1 or 2. In your case of your trims stock were around say 5 or 6 just guessing, then you could easily pick up another 7 percent error in some areas by adding the intake.
 

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Discussion Starter · #6 ·
Thanks guys, I was thinking along the same lines. I'll try fixing the tune tomorrow and see where I get.

rbooth, While scanning I was tracking MAF(HZ) vs STFT %error..... If thats what you are asking? You can see the screen shot of my scan above. I don't know how to post a tune/scan so... I wish there was an "attach" button.
 

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Discussion Starter · #8 ·

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It sure looks lean. What fuel are you using because you are getting alot of knock. Some of that is probably because of it being lean. If anything I would error with it on the fat side. One the first adjustment I would multiply by what the histogram error is.
 

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Discussion Starter · #10 ·
Hey guys I noticed that my car idles at 2550Hz and after a few MAF logs/adjustments things are getting much better BUT now my car idles at 2400HZ. And the reading at 2400 and 2550 is really lean.. 19% at 2400HZ and 12 at 2550 Hz everything else is between 2 and -2 now.

Should I be messing with Hz that low? Should I raise my idle? where is that located in HP?
 

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High positive trims at very low loads that go way down with light to moderate throttle is a tell-tale sign of a vaccum or air leak. There is no way any intake would cause that much of a variance I don't care which one it is. You need to find the problem and fix it rather than tune around it.
 

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Discussion Starter · #13 ·
High positive trims at very low loads that go way down with light to moderate throttle is a tell-tale sign of a vacuum or air leak. There is no way any intake would cause that much of a variance I don't care which one it is. You need to find the problem and fix it rather than tune around it.
Something I noticed is that when I'm driving and logging the low hertz trims (2550 basically only hit when in drive and stopped) looked decent. Put the car in park and the reading goes up. So I do know what your talking about. Thank you for the reply.

When I originally made this thread I had a suspicion of some kind of leak. I will continue to look, but I have been with no luck. Any tricks?

But I do have to say that now my logs look waaaay better than they did. So even with the leak (assuming there is one), I feel my car is running better and safer.
 

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Discussion Starter · #14 ·
I attached a link to my current tune and a log I took tonight. Please take a look and let me know if there is anything that would make you think there is an air leak of any kind.
I started the log while sitting in my driveway, after the car was warmed up. (It's 40 out side) I drove a mile or so to a parking lot and stopped to take a look at the log and then I continue logging and returned home. Over all I thing the log is decent.

I honestly think my early log when the car was running a stock MAF table resulted in poor data. I looked at older logs including one that I posted on HP tuners and I didn't let the car warm up to op temp. I also noticed that the car is very sensitive to iat heat soak when stopped. Both of these could have contributed to what I though was abnormally high STFT's at idle when stopped/parked.

Anyways thanks in advance for any help.
Look at post #12

http://www.hptuners.com/forum/showthread.php?p=319547#post319547
 

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I'll take a look at your log shortly but the easiest way to find a vacuum leak is to spray around the intake hose connections and vacuum lines with carb cleaner and if your idle changes and or the car starts to stumble you have a leak in whatever area you were spraying.
 

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Discussion Starter · #16 ·
I tried spraying carb cleaner twice Once yesterday when the car was already warmed up. Then again today when the car was cold first started and after it warmed up. I also totally redid my PVC hose with brake line to clean that connection up as well. The stock tube connected to the VCM intake is not that great. It barely connects.

Thank you. I hope a few others take a look as well. I need all the input I can get.
I'd like to move on to tuning the trans soon.
 

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I'm no expert, but it looks like you're pretty close to me. Unless you reverted parts of the latest tune you posted, it looks like you left PE enabled when you did the part throttle tuning, so that could have skewed some of your higher RPM trims, which would explain why your numbers are still off a bit in the higher RPM/MAP value range.

My stock tune had a decent amount of KR before my intake, so it's very possible for it to get worse after installing the intake. If I were you I'd probably go back and disable PE then scan again (making sure not to get real heavy on the throttle), just to double check to make sure your values are good, maybe tweak the higher RPM's that register to get those higher range values in check. After that, you'll need to tune the MAF in the PE areas. It's tougher to do without a wideband, but I basically err'ed on the side of caution and made my tune rich to get rid of the stock KR since I don't have a wideband. If you do have a wideband then there's no issue for you here.
 

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Discussion Starter · #18 ·
Sounds good. I was planning to tweak a few more things. I just wanted to get something posted for input.

Anyone else see any reason I should think there is an issue? Air leak.

At this point I think I'm good. I'll be installing LT's in a few weeks with a WB and then I'll have to go through and do this again. Including the WOT portion.
 

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Cool. Just be careful with the WOT tuning when starting out and monitor KR closely. Also, as mentioned by someone in your HPTuners thread, it's a good idea to add some fuel (he mentioned 2%) across the entire upper MAF area before attempting to tune this part. Basically you're putting your tune on the rich side to begin with and then you can scale it back or perhaps up a tiny bit if needed to get exactly where you want to be.
 

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Sounds good. I was planning to tweak a few more things. I just wanted to get something posted for input.

Anyone else see any reason I should think there is an issue? Air leak.

At this point I think I'm good. I'll be installing LT's in a few weeks with a WB and then I'll have to go through and do this again. Including the WOT portion.
Be sure that you don't have high positive trims under a load because it will lower transmission line pressure = not good. A leak the size of a pin hole can cause large trim variations - if my intake was leaking I would put a different one on, but then again I am prettty particular.

I went with Rotofab because the OTR intakes are dirt vacuums that blacken your oil several times faster for a couple extra hp :)
 
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