Viper

iTrader: (6)

Any resolve to this? I have the same issue now.

When starting off, car feels like it's falling on it's face, but if I step through it, it's fine.

Started yesterday real bad when I had the AC on.

As this post suggests I'll check the fuel filter and pressure.

I thought it was injectors so I swapped to 42lb's FORD's tonight, recalibrated the PCM and took it for a drive. Same problem. Put the car in SD mode to eliminate the MAF being the problem. Same problem only not as severe. I thought today perhaps a faulty coil pack ( intermittent ) but after searching tonight the symptoms don't match.

Motor is new , installed 6-18-05 , have about 600 miles on it. I had this same issue last year RIGHT before my motor let go. However the bogging/hesitation started real bad less than 100 miles ago, not as soon as I started the new motor. So I'm a little concerned now in resolving this so I can drive it.

Any ideas?

Racehead

I had forgotten all about this thread so I guess an update is in order. In short, once I got my laptop back the problem became obvious on my first logging run. My o2 sensors had gone bad. I must have killed them upon first fire up with the ASA cam since it was pig rich for about 15 minutes while I tuned it in my driveway. I checked their telltale signs of failure for about 2 day just to see what a failed o2 sensor looked like in a log and this is what they would do. For about 15-20 minutes they would switch normally and then would start to "narrow" their switching range until they flatlined at 200-300 mv. I threw some new Bosch sensors in it and all was good again. I did have to do some more VE tuning in SD since my previous tune was based on failing o2's, but was able to dial everything including PE in within a day. Thanks again for all the suggestions.

WAHUSKER

iTrader: (4)

Glad you get her figured out Bill. You can come help me tune the blower.

TwoFast4Lv

iTrader: (8)

You see that is the main reason you should rescale the MAF and plug it back in

Racehead

You know I'll be there Mark I really enjoy the tuning process and I need to be involved in an FI tune anyway .... I'm making some preliminary, tentative type plans for an FI setup on the WS6 I don't believe it's a wise decision for an ORR car, but with a baby due to arrive in 6 weeks I'm forced to re-evaluate my involvement in ORR at all. I've had a total blast doing it , but have to admit that I'm "rolling the dice" each time I go. I'm thinking that it's time to move in another direction, I won't be building a drag car, but an open tracking terror DOES have a certain appeal

Racehead

Why IYO should I rescale the MAF and plug it in ? Are you referring to it's self-compensating abilities on the tune ? I am going to do exactly that just to see what the differance might be, just want to hear your reasoning behind it that's all. With the car in SD mode running as good or better than any other LS1 I've seen with an equivalent cam I don't really have a huge motivation to "get 'er done" I AM going to re-scale the MAF and plug it in just for comparisons sake though.

SeaHawk

iTrader: (1)

With so much that can go wrong so quick in these motors, take advantage of any "backup" you can!

I haven't tried my hand at it yet, but sometime in the near future perhaps I'll enjoy the same "problem" of tuning a large cam to idle with the MAF still active. (Hopefully someone will find the missing table by then )

TwoFast4Lv

iTrader: (8)

To be honest most of what the PCM does is qued off of what the MAF reads. SD mode is a back mode and fine for race only cars. IMHO tuning the way you are going is fine but finish it up with the MAF scaling. Getting results like you have is very easy with a M6 but as we have seen many times an A4 putts an entirely different load on the car and makes it a bit harder to be very drivable with out the MAF.

Every thing from the Idle to the Timing to the transmission pressure is scaled off the correct MAF reading. With out the MAF It will use back-up table or self generated(not measured) tables in place of the MAF. With a M6 car it is just easier to use the clutch and accelerater to comensate for a drivability problem. With an A4 you just do not get that option.

Then yes there is the point you have there. The self compesating or Learning process. Dail it in and forget it

Then again there was me just taking a shot at you for the fun of it A dead O2 is a dead O2...I see them alot! That is why I tell people to change them like spark plugs

Glad it is going good for you!

Racehead

Yes I realize that SD is only a MAF failure mode who's entire existance is for the sole purpose of getting you home in the event of MAF failure. However I'm going to have to disagree about it being fine only for race cars. My car has been in SD mode for 2 months now and in every possible street driving situation it has proven itself to be quite excellent in the role of daily driving. No hunting hot or cold, AC on or off. No dying, great throttle response/WOT etc. It is true that A4's have a much tougher time in the tuning department and so possibly my opinion would be differant if I had one. I would certainly welcome the chance to tune an A4 in SD just for my own knowledge. Mark and I spent a day on his, but ironically his o2's started failing half way thru the day and so were "tainting" the changes we were making. For the first half of the day great strides were made though. How exactly is the A4 shift schedule derived while in SD mode ? Have you ever tried to "dial" an A4 while in SD ?

True again, we M6'ers have it easy in comparison SD does have a very robust timing schedule however, which is still derived from much more than just a "look up" table. If this were not so then I would only see my programmed values in my logs. It seems to still be able to encorporate temps, both engine and ambient, as well as transitionary throttle and possibly others into an, at least "somewhat" sophisticated algorithm to determine final timing. Certainly more than capable for daily driving, at least to an M6 equipped car.

It is this that is going to make me re-scale my MAF to at least see if there is an improvement, or if there is not, then at least to see if it is "on par" with my SD tuning. I'd love to have that self-compensating factor for air density changes. Definitely a desirable trait.

You taking a shot at ME ? I just can't believe that I kind of flies in the face of ...... err... oh nevermind And damn those $60 spark plugs huh ?!

Thanks, you've been a big help to me. Muchos Appreciatos Pepito

WAHUSKER

iTrader: (4)

I think I need to install my wideband & get some new O2s & spend the day tuning before I can voice an opinion. I will say Bill & I seemed to be making a lot of difference SD tuning my car, right up until the O2s starting weirding out on us. So based on what I saw I do believe you can get the car dialed in via SD tuning.

On the other hand, with the MAf in the loop, it runs fine. That tells me that what Ellis said is true too....the MAF will compensate for a TON of error. Otherwise they'd never be able to sell these cars, because we all know they don't install precision parts & tune for them on these cars at the factory.

So if you tweak it up via SD, and then plug the MAF back in, what have you gained?

If I was going to try to tune around any sensor it would be the O2s. The readings off those have such a huge imapct, & can vary so dramatically, and then how the car runs will be so whacked for NO reason, that you are totally screwed. I want to tune my car with a wideband & then disable those ******!!!