AU XR6 HP running rich after tune?

FOCUSonTHIS · 22-10-2012, 10:16 PM

As the title states I think my car is running rich after I have had my new Crow Stage 3 cam and custom tune. When idling I can smell the petrol fumes and before I didn't have any smell coming into the cabin.

Also I when idling I have seen condensation come out of the exhaust with black soot (unburnt fuel?)

Also from JMM I was told I need a new O2 sensor as it doesn't start responding until the car is up to temp. I have purchased a new sensor, just haven't put it in yet. Is this a contributing issue as well?

I have attached the dyno sheet below for anyone knows about AFR. Do I need to go back to JMM and say my car is running rich? I am going though heaps more juice than I use to. I understand I have put a bigger cam in with a custom tune but wasn't expecting the huge difference in fuel consumption.

irdonn · 22-10-2012, 11:42 PM

Hi mate, if you're not happy then take it back.

Cam · 23-10-2012, 01:19 PM

Very surprised they did all that work to your car and didn't just replace the 02 sensor?! Put in a new sensor and take it back, that's sub-par service IMO..

MAD · 23-10-2012, 01:32 PM

How much has your usage increased?

I had a CMS stage 3 cam in mine and I went from 12-13 up to 16-17 per 100.
A big cam's ideal rev range is not what is generally found in everyday driving.

FOCUSonTHIS · 23-10-2012, 06:03 PM

Quote:

Originally Posted by Cam

Very surprised they did all that work to your car and didn't just replace the 02 sensor?! Put in a new sensor and take it back, that's sub-par service IMO..

I plan to put in the new O2 sensor this weekend. Just need to do it when the engine is cool as I don't want to burn myself. I will give them a call and see what they say

Quote:

Originally Posted by MAD

How much has your usage increased?

I had a CMS stage 3 cam in mine and I went from 12-13 up to 16-17 per 100.
A big cam's ideal rev range is not what is generally found in everyday driving.

I haven't done the exact figures yet as I was roughly getting about 600km to a tank and now about 450km a tank. I understand that the bigger cam would use more fuel but this is massive. I still rev to 2000-2500rpm every gear change, unless I am having some spirited driving.

b2tf · 23-10-2012, 08:17 PM

Yeh 02 will have a bit to do with it but it could also be the tuning. I do agree though that they should have replaced it prior to tuning it.

The Monty · 23-10-2012, 10:10 PM

Seems legit for running a cam. I used to get around 19-20l/100km around town......

FOCUSonTHIS · 25-10-2012, 10:35 PM

Changed the O2 sensor, doesn't run as rich now. DTE was climbing like no tomorrow. So maybe that sorted it out. Still not happy will call up JMM and see what they can do

Day-mow · 03-11-2012, 10:06 PM

i was told 14.4 was the magic number when it came to AFR when i got my car tuned.
while i dont have a cam at 173rwkw i am running bigger injectors i've not noticed excessive fuel useage and still get around 13-14L/100km around town and 18L/100km when i go for a dedicated fun fest cruise

**auIILTD** · 04-11-2012, 12:06 PM

Damo, 14.4 is rich for normal closed loop driving. 14.64 is considered Stoich (ideal fuel burn). Looking at Focusonthis' dyno graph above, which is of course at WOT (open loop), the afr or Lambda in this case is richening up as you would expect to see. In the graph above, you can see the Lambda at around 0.83 - 0.84, or 12.15 - 12.30 AFR. I would have thought that this is too rich at WOT, but that maybe deliberate by the tuner? I certainly not had experience with cams etc.

To see if it is running rich in closed loop, you would need to see a graph in closed loop - or install a wideband.

Cheers
Stu

Day-mow · 04-11-2012, 05:02 PM

Thanks for that stu. Was only going by what I was told by Bruce. He gets them to 14.4 and then the ECU does the rest.

dieseltrain79 · 05-11-2012, 10:01 AM

Aspirated , your looking for low 13's afrs at wot . Anything in the 12's specially bottom end is a tune suited to forced induction .

My 4.0l build many moons ago was run at 13.1afr's . And was pretty good on fuel round town as we road tuned it a bit to make sure it wasn't a pig .

FOCUSonTHIS · 05-11-2012, 10:56 AM

Quote:

Originally Posted by auIILTD

Damo, 14.4 is rich for normal closed loop driving. 14.64 is considered Stoich (ideal fuel burn). Looking at Focusonthis' dyno graph above, which is of course at WOT (open loop), the afr or Lambda in this case is richening up as you would expect to see. In the graph above, you can see the Lambda at around 0.83 - 0.84, or 12.15 - 12.30 AFR. I would have thought that this is too rich at WOT, but that maybe deliberate by the tuner? I certainly not had experience with cams etc.

To see if it is running rich in closed loop, you would need to see a graph in closed loop - or install a wideband.

Cheers
Stu

Stu,

Are you saying that my car is running rich at the start of the run? Also i know it may be run richer to keep the components cooler. I think I will seek advise from another tuner and see what their recommendation is.

Thank you as well for giving an insight into AFR and everyone else. Keep the information coming as I continue to learn.

**auIILTD** · 05-11-2012, 11:19 AM

Quote:

Originally Posted by FOCUSonTHIS

Stu,

Are you saying that my car is running rich at the start of the run? Also i know it may be run richer to keep the components cooler. I think I will seek advise from another tuner and see what their recommendation is.

Thank you as well for giving an insight into AFR and everyone else. Keep the information coming as I continue to learn.

At WOT (from your graph), I would consider yours to be rich, but I am fast learning (I am a rookie) that there are many different thoughts and theories on what is the ideal 'richness' at WOT. Like mentioned above, dieseltrain reports he aims for low 13s, whereas I have been instructed to shoot for high 12s at WOT. Many schools of thought I guess.

Stu

FOCUSonTHIS · 05-11-2012, 01:48 PM

I was reading an article and they didn't want to say what was the best AFR. As each car/tuner is different. I will go seek another opinion and go from there I think

Here is the article I read

http://www.bristoldyno.com/tech/airfuel.htm

**auIILTD** · 05-11-2012, 02:29 PM

Quote:

Originally Posted by FOCUSonTHIS

I was reading an article and they didn't want to say what was the best AFR. As each car/tuner is different. I will go seek another opinion and go from there I think

Here is the article I read

http://www.bristoldyno.com/tech/airfuel.htm

Good article. Highlights exactly what I was saying - many schools of thought and very vehicle dependant.

On the very thought of the article though, when I did my quarter runs at Heathcote back in June, my logs told me I was running low 12 AFRs - a bit rich. I have now changed mine to run high 12s and although not technical, the bummometer has told me it is better in the power delivery. Who know's low 13s might be even better, but I am not prepared to take that chance - going against advice of people that have tuned many windsors.

Cheers
Stu