car on dyno quick question

[johnnie27]

Hi all, i recently removed my secondary cats.. we put back in the (2) O2 sensors (that where with the secondary cats)

i then drove a few miles to the dyno shop to have my Apr software updated, (i also had a new OEM) N75 installed , as i figured it couldn't hurt

the dyno folks sent me this email last night


Thanks John, we installed your new N75 valve no problem andran her up on the dyno… your car is running lean, but itis not the calibration. Something is causing the car to under-fuel, potentiallythe O2 sensors, so we will continue investigating in the morning (car is stillon the dyno).

i have spoke to them today , they are doing some more tests (table readout) or something..any thing i should ask...as a mechanical potato (me) ..i just though someone may know what may cause this?

thanks john

[V8weight]

The secondary O2 sensor's only job is to monitor catalyst efficiency, they do not effect the fuel trims. A general rule of diagnoses is "don't shoot the messager" when it comes to O2 sensors....The lambda's (primary O2 sensors) monitor fuel trims, and the ECU makes the necessary adjustments to suit. If you are experiencing a lean condition, I would be looking for un-metered air leaks or issues pertaining to fuel pressure, not pointing the finger at the O2's themselves...

[lswing]

Guessing that if there were any air leaks it would show in the boost pressure fluctuating for no reason?

[Shoppinit]

I'd definitely be looking to eliminate vacuum leaks first.

Can you log your MAF readings?

[johnnie27]

thanks everyone, for the past 8 years the car has run faultlessly on the APR software

however as soon as we uploaded the cat delete Map, its lost some 25-35RWKW . i am feeling that the issue is in the map, as the car has no fault codes is making and holding boost pressure etc

i havd this issue with a ducati i own, (thats the challange with this generic map stuff) (that company had 4 goes at adjusting there so called map for my mods till the AFR was safe at WOT) it simply cannot suit all cars...i am seeing if apr will modify this map for me, (based on my data and dyno logs) or we will put the cats back on , re-load the original map and be done with it..as it flew anyhow (i just got a bit excited about this cat delete thing)

john

[Shoppinit]

If you've got the original map, why not send it to Rich at Viper so he can just edit out the cats for you?

[johnnie27]

If you've got the original map, why not send it to Rich at Viper so he can just edit out the cats for you?

ok so 1. i am in australia? (not sure if i can handle another few weeks off the road)

and 2. apr OZ promised me this would be fine (as the std ARP tune with 4 maps was very good) , and they are asking APR HQ if they can do a custom map based on my dyno data and tables (as there was only 31 rs6's in oZ they have never done a cat delete map on an OZ delivered car here_)

where is viper USA or UK? do you have a contact number?? actually i shall see if they have a web site

many thanks for that info

johnny

[Shoppinit]

http://vipertuning.com/

HTH

[johnnie27]

http://vipertuning.com/

HTH

thanks mate sent a generic email to them saturday..hopefully i can get a ph number or something...

[johnnie27]

Hi all, i recently removed my secondary cats.. we put back in the (2) O2 sensors (that where with the secondary cats)

i then drove a few miles to the dyno shop to have my Apr software updated, (i also had a new OEM) N75 installed , as i figured it couldn't hurt

the dyno folks sent me this email last night


Thanks John, we installed your new N75 valve no problem andran her up on the dyno… your car is running lean, but itis not the calibration. Something is causing the car to under-fuel, potentiallythe O2 sensors, so we will continue investigating in the morning (car is stillon the dyno).

i have spoke to them today , they are doing some more tests (table readout) or something..any thing i should ask...as a mechanical potato (me) ..i just though someone may know what may cause this?

thanks john

car fixed was a issue in the mapping ..picked up 16 rwkw with the new map and secondary cat delete

picking it up in 1.5 hrs

thanks everyone

[Amar]

You had your secondary cats deleted? As I understand it, it is the pre cats that are restrictive and are 600 or so cell, the secondary cats are 2/300 cell so if you were removing any, it should have been the pre cats. No?

[johnnie27]

You had your secondary cats deleted? As I understand it, it is the pre cats that are restrictive and are 600 or so cell, the secondary cats are 2/300 cell so if you were removing any, it should have been the pre cats. No?

so they are the cats next to the tranny..weigh a ton and you cant see thru them! (pre-cats) to hard to get to for the trouble, just did this b/c apr had a map for it and it was cheap to do...john