Corvette Z06 Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
2,187 Posts
Discussion Starter · #1 ·
Many of you have been following the debate over the problems with the Donaldson "Blackwing" on the '02's. I put mine on my Z with 40 miles on it before I knew there was a potential problem. I had it on my '01 and had no problems with it. On Tuesday I started the car after it had sat for about an hour after a freeway drive. The "Service Engine Soon" light came on as soon as I started it so I took the car to my dealer. The two codes that were set were 171 & 174. My dealer told me these are Lean fuel condition codes and that the intake was the problem. They also told me that the GM zone service adviser told them that the oil used in these intakes messes up the MAF and causes problems. He also said that the dreaded air turbulance monster was a problem. I thought the problem with these intakes was supposed to cause a rich fuel problem, not a lean one? What do you guys that understand this Af ratio stuff think about this? I have a set of 30lb injectors for the car but I don't have them put in yet. :-?
 

·
Z06 Maniac!!
Joined
·
1,541 Posts
Tom, my understanding is that the car runs lean with the Donaldson because the injectors may be to small. The computer will then add fuel under wot to compensate and the car will go rich at high rpms and lose hp. Maf translator or pcm reprogram is the answer if you keep the Donaldson on the car.
 

·
Registered
Joined
·
1,384 Posts
What happens is when you add an intake mod (more air, remember engines are an air pump) which causes a lean condition (more air, less fuel) (this may be where your code is coming from), the O2 sensors re-trim the stoichiometric seeking (1-19 cells) back to 14.6:1 by adding pulse width to the injectors. This additional fuel is recorded in the fuel trim tables and added in, in addition to the WOT Fuel Enrichment code (fuel cell 22) which was designed to provide 12.6:1 ratios (in general). WOT is not subject to the O2 sensors since it is Open Loop, but the computer 'Snapshots' the added fuel percentage of the previous trim prior to WOT. You may see a/f ratios in the 10s or 11s, which means your WOT throttle is losing power bigtime.
By adding this particular "Snapshot" of the previous trim to WOT, your injectors will add TOO much fuel, even though they are close to 100% duty cycle. This is where the term Pig Rich comes into play.
The PCM will move from cell to cell under varying conditions.
There are 22 Fuel Cells, and are as follows:
1-19 – used to update fuel trims
20 – Idle Cell
21 – Deceleration Cell
22 – WOT (Power Enrichment mode)

:cheers:
 

·
Z06 Maniac!!
Joined
·
1,541 Posts
Now you have a laypersons take on the problem and an experts and we said the same thing, I think :-?
 

·
Registered
Joined
·
1,384 Posts
Rip,
I am 1 step below layperson, I believe armchair engineer:lol: :lol:
:D
:cheers:
 

·
Registered
Joined
·
1,185 Posts
Rippied.Z06 said:
Now you have a laypersons take on the problem and an experts and we said the same thing, I think :-?
Think I'll leave mine stock!


:D

:cheers:
 

·
Registered
Joined
·
1,071 Posts
Z0000006 said:


Think I'll leave mine stock!


:D

:cheers:
I think the trick is buying an intake where the manufacturer will stand behind their product. Maybe the manufacturer of the Blackwing will work with you to get the code fixed. I think that the benefits of a good intake have been proven many times. Bolt on, bolt off if required.

I think that Jim Hall at Halltech will stand behind his T1. That is why I ordered mine. :)

- Charley
 
1 - 7 of 7 Posts
Top