ChrisLe

Gents,

Newbie here who could use some advice. First, let me say this forum has been absolutely amazing in that just by reading I've gotten the grasp on pcm tuning and am well on my way to getting started. That said, I began logging with HP Tuners (2004 ZO6 bone stock) just to get a feel for what I'm looking at and how to interpret the data. Then I added the Vararam air intake and my Ltrims went real lean...Here are the pics:

Strims and Ltrims (Stock vehicle)


Strims and Ltrims (after Vararam intake)


Should there have been such a dramatic change? I drove well over 200 miles and reset Ltrims as recommended by the manufacturer but it appears the pcm has not adapted to the new air intake.

My first inclination was that I was running lean due to unmetered air entering somewhere between the MAF and TB. I checked and rechecked all connections and even went as far as spraying starter fluid on all connections to check for a change in engine rpms (indicating an air leak) but found none. Interestingly enough, when I go into SD mode (disable MAF), my Strims and Ltrims pretty much fall into line (+/- 10 at most). If this is not normal does anybody have any ideas where I should look next? Should I, instead, just leave it as is and start tuning/logging in SD mode and recalibrate the MAF? Thanks in advance...

Another_User

Very very weird. Sort of similar to the problems I have been having, but not exactly. I did have a ton of problems with my Vararam piece, which I promptly returned. Very interesting. I would not expect your trims to go lean so consistent across the board for any reason. Have you removed it and re-tried? I would be very interested in seeing if everything returns to normal.

ChrisLe

I was not looking forward to removing the Vararam and going back to the stock intake as it was a PITA to install. Barring any other suggestions, I might just have to do that......I'd like to nail this problem down before installing LG Longtubes as they'll just compound the issue (based on what I've read).


Thanks for the insight....

Robert56

iTrader: (2)

Welcome to the free flowing, lean induced, power adding, strip kicking VaraRam. After getting your LTFT's inline, did you recalibrate your maf. Because, if not it will just pull your ltfts out of whack again. The Maf has to match your new found free flowing air input.

ChrisLe

Robert56,

I have not done any tuning as of yet either before or after adding the Vararam. The pics were before and after Vararam install with no tuning done at all...I was just curious as to whether it was normal for a Vararam to cause the engine to go so lean across the board....I just wanted to confirm that this was normal (so to say) after a Vararam install. If so, then I'll proceed with VE tuning in SD mode and subsequently recalibrating the MAF with redhardsupra's spreadsheet....

Robert56

iTrader: (2)

Ok, yea mine went lean also, just shows that the Vararam is doing as claimed. The only real problem leaving them alone is the LTFT locks at the positive trims and adds this at wot in openloop causing a potenial rich condition. So, for all of us Vararam guys, tuning is the only way to see optimim power gains, across the board.

ChrisLe

Great. I just wanted to confirm that it was normal for the engine to run that lean with a Vararam...Now I can start tuning VE in peace...

Another_User

There is no friggin way those trims are a normal effect. You must be kidding. Or selling those things yourself. If that were true, then ported TBs would do the same thing.

txhorns281

iTrader: (12)

Those are some pretty lean trims, and at least on the F-body, only MAF mods really push fueling that lean... neat No intake leaks I presume?

Another_User

There would have to be. Porting my MAF never pushed my trims that lean.

ChrisLe

Despite the fact that consistent lean trims across the board would dictate a leak, I was not able to find any. I tried every trick in the book and could not find any....Any suggestions?

txhorns281

iTrader: (12)

exhaust leaks cause lean trimming, but i doubt thats the issue here... hmmm dunno, go log some more and see what happens, we'll be here when you get back

Robert56

iTrader: (2)

Well here's a way that may work to eliminate leak possibility. Disable maf and set fuel trim learn and you'll see the trims come down a bit. Then adjust VE table to get rid of remaining +trims. May have to do a couple times. Then you have to re-calibrate maf, or stock maf will just cause trims to go out of wack again. The claims for Vararam is upyo 40hp gain and 3/4 tenths in the quarter mile. These gains have been proven over and over. Does a ported maf give these numbers by itself? My trims were almost as red. Usually, you can hear a leak on the Vararm, it's sounds somewhat like a blower whine.

Edit: just look at histo again, yea a little high. My highest was about half that. Maybe a leak, but should hear a large leak when pulling. Some guys have added a strip of foam tape around lid to filter and silicone in places.

ChrisLe

Robert56,

Unfortunately, I do not believe that will work. I'm no expert, but a leak, by its very nature, is variable and not constant. Recalibrating the MAF while a leak is still present will result in wild variations in the trims depending on when and how much unmetered air is entering the system....If it is indeed a leak I need to find it first...


Have your trims stabilized after VE tuning and MAF recalibration?

2xLS1

iTrader: (25)

Was the filter that came with the Vararam just dripping with oil? The one I installed on a friend's car was. I blotted a lot of it off with some rags before I installed it. I'm sure it would have just coated the inside of the MAF with oil had I installed it right out of the package. I couldn't believe that such an expensive intake would come with such a cheesy filter. Makes no sense that the MAF would not meter the extra air entering it correctly.

TT_Vert

iTrader: (12)

my car stock then w/ a vararam did not look like that. W/ my stock tune and vararam im at maybe +6-+8 MAX. I can give you my VE table if you want. It should work well for you. I use a modded Z06 table.

Dave

ChrisLe

I'm using a K&N in lieu of the filter that came with the Vararam as its a POS. That said, I checked the MAF already and found it to be clean. Nonetheless I cleaned it out of principle and nothing has changed.....I'm still leaning towards an air leak somewhere btwn the MAF and TB.

ChrisLe

I was afraid somebody would say that. Obviously there's a problem somewhere (still thinking air leak).

Appreciate the offer but its not necessary. I'm running in SD mode where I've got all my trims btwn -3 and 0. I plan on staying in SD mode until I can rectify the issue with the Vararam. Once rectified I'll proceed with recalibrating the MAF. I'm this close to yanking it and sending it back to the manufacturer....

Robert56

iTrader: (2)

My opinion is that if you didn't find it with str fluid, there prob isn't a leak. You were lean to start with and you said after going into SD all trims were
+/- 10. now take away that and it isn't so bad. Every Vararam causes lean conditions. But, something is up. Call vararam and ask there opinion, or go to corvetteforum.com, as this has been covered many, many times. there is an ongoing vararam thread right now. Someone will know for sure. Good luck and stick with it, as it's worth the gains.

SSpdDmon

iTrader: (10)

I put a super sucker ram air on my f-body, which is about as close as you can get to a VR for our cars. It's not completely sealed, but close enough. Even so, I would be concerned with the mid-range increases you're seeing in your LTFTs. I saw 4-6% increases with my setup. Based on that and what was stated earlier, I would agree with the expectation to see a 6-8% increase due to a ram air install...not 17%. It may not be a bad idea to double check the exhaust & O2 gaskets/connections for leaks, check the O2's themselves (maybe replace the fronts), and possibly invest in an wideband O2 setup. Just my $.02.