tuning question

[1badss]

a certain company tuned a buddy of mines car, and after logging a wot pass im registering 109-110% duty cycle on a bolton 99 z28(longtubes,gears, catback, lid, and maf) with stock injectors, and a racetronix pump. What is out of wack?

[mecanicman]

This may have something to do with it.....

[IDRIVEAG8GT]

This may have something to do with it.....

LMFAO!

[edcmat-l1]

Omg...........

[1badss]

that bad huh guys, treat me like a newbie i know the bare basics, what am i looking at? Oh and I appreciate all the help!

[DSteck]

Ha. Don't be bashful... Share who did that!

[1badss]

Ha. Don't be bashful... Share who did that!

Only if you tell me whats wrong with it

[PitchblackC3]

Well it should be a curve, not the Rockies.

[mecanicman]

That table is the maf transfer table, defines what frequency correlates to what airflow value. As stated it should be a smooth curve. This one ramps up an unrealistic amount then falls back to stock values.

So who done it?

[1badss]

Sent you a pm with your answer

[DSteck]

Tell me too!

FYI, if the car is seeing over 100% duty cycle, that means the injectors are done. If it isn't rich, then the tune can be as hacked apart as possible... the duty cycle PID still remains true.

[carlrx7]

could be the tuner is compensating for low fp...

[IDRIVEAG8GT]

Me too please! They just hammered the balls off this tune. Hey edcmat-l1, can we add this into the shitty tune repository?

[obzidian]

Would an over compensated Maf curve "cause" a higher than actual injec. duty cycle?

[DSteck]

Those mods shouldn't be killing the fuel system. If he had a cam... then maybe.

Would an over compensated Maf curve "cause" a higher than actual injec. duty cycle?

No. Regardless of how screwed up a tune is, the duty cycle is always accurate as long as it is getting an RPM signal and injector pulsewidth reading.

[1badss]

im aware that when i see an idc of over 100 percent they are done, that is what initially made me post in this section because i knew something was off, just did not know what in particular. The car does NOT have a cam, just your basic bolt on z28. The car has a racetronics pump in it so I don't believe there is a "Fuel Delivery Problem"

[obzidian]

Ok.

So, if the car has an upgraded pump and plenty of injector, what else would cause the injectors to read high. Is the stock Injector rate modified?

[mecanicman]

Ok.

So, if the car has an upgraded pump and plenty of injector, what else would cause the injectors to read high. Is the stock Injector rate modified?

If you are trying to understand why this particular setup maxed out the injectectors, its because the airflow numbers are to high in a frequency the maf hits. Computer thinks more air is present then there is and adds fuel accordingly.

[1badss]

ok so my next question is, how do I fix this, because I surely do not want the car going back there? I guess what I'm tring to say is, does anybody have a tune thats for a bolt on z28 that I can work with?

[obzidian]

If you are trying to understand why this particular setup maxed out the injectectors, its because the airflow numbers are to high in a frequency the maf hits. Computer thinks more air is present then there is and adds fuel accordingly.

Ok. Now I'm confused. My original question was just that. It would seem that the Maf was over compensated or the values were just to high for what the engine truly needs thus scewing the injector duty cycle. Just that, the pcm thinks that there is more coming then it really is thus increasing the amount of fuel to hit the desired afr.

ok so my next question is, how do I fix this, because I surely do not want the car going back there? I guess what I'm tring to say is, does anybody have a tune thats for a bolt on z28 that I can work with?

Well, the car has a new maf right? More than likely it was dialed in incorrectly. I would start there unless a more experience member on here has a better approach. You'll need a wideband to get the proper information to scale back down the maf values.