Ok ive had the car with the greddy TT for 1 week exactly (AT tranny). When i first got it the A/F on idle was at 14.4 to 14.9 stable didnt move that much.
But tonight i noticed that when i sarted it up it would be around that area but then when i would got to WOT my A/F was around 10 to 10.3 which i heard is good. Now when ill shut it down and got back down to idle it will jump from 14 to sometimes 15.4 and even sometimes 13.6 to 15.4 not alot just every minute or so but i hadnt had this problem.

Also when i stop from a run when the RPM's get all the way down it jumps around 1k to 1250k again all this has been today.

The greddy kit is at out of the box setup and is at 5 pounds with everything stock except megan testpipes. I also have a J&S Safegaurd thatretard half a degree every PSI

My question is this ok or should i get a little worried.

Please let me know thanks in advance.

 

Those lean mixutures at idle are fine. You want to run lean at idle to keep the plugs clean. You cannot detonate at idle, so don't worry about that. An engine has to be under load to detonate.

Your mixtures at WOT are actually too rich. 11:1 would be better.

 

How do you figure? I've personally heard motors detonating at idle before.

I've also heard of people cracking ring lands while cruising at 25 mph in 3rd gear and that is barely any load at all (and ring land cracks are almost always detonation related).

That said, almost everyone I've heard of has an idle A/F of around 14. Rememeber, this is approaching the "ideal" A/F ratio. People just tend to keep it a little lower at high load and rpms to be on the same side because the potential for damage is much greater when you "detonate" (as opposed to burning) that much fuel.

Also, I agree that 10.3 is WAY richer than neccessary... I'd imagine that if you don't have black soot on your back bumper now, you will real soon. You have plenty of room to lean that out safely. Go take it to a pro and have your baby tuned right!

 

i know that the 10 to 10.3 A/F ratio is rich but thats how greddy comes out of the box but my question is that when i first got the car it would stay at the 14's A/F ratio but now it goes sometimes to 15.4 and then straight to 13.7 or something like that and when i first got the car it didnt happen.

Thats why my question is if that is ok or i should be worried?

 

Anyone help please!!!!!!

 

Don't you have test pipes? If you do thats what's most likely causing it. Your ecu needs time to relearn now that you have turbos. By the way my car does this as well. Weather also is a factor. I wouldn't worry to much about this. When your ready bring it to roger and get it tuned.

 

Here is what I know (I am not an expert):

Under idle or cruzing speeds you A/F ratio should be stoyciometric (or A/F ratio of 14.3). This will give you the best efficiency of your engine. Since this is a feedback loop, it won't be perfect so you will see it fluctuate. You should just be concerned about boosting under these conditions!

When you put the engine under load, the A/F ratio should be less than 12. A lower A/F number will mean that the map is using the fuel to cool the engine to prevent detonation. You should not see boost above 9psi unless you have done some other modifications to your engine (lowered the compression ratio, or have water injection).

When you are coasting, your A/F ration should be high (usuall unreadable).

One great tool is to add EGT's to your car, to see if you really have a problem. You can use them under cruzing speeds to see if you are harming the engine with your turbo and/or fuel injectors.

 

I know that my fuel at idle should be in the 14's area and when i went into boost the car would go to about 10 to 10.3 but what i was worried about was that when i first got it it wouldnt do that. Thats why i was asking about it. Well thanks alot.

Anyone else got some input on this let me know thanks.

 

14.7 is stoich, not 14.3....your idle A/F is fine. anywhere in 14's or 15's is ok at idle.

 

Not sure if you are talking about when you disconnect the battery? You will see some weird things happen then as you car re-learns the correct A/F ratio.

 

You are right - 14.7 - must be all the food over the holidays or maybe the wine?

 

You are fine relax.

 

Ok guys already talked to roger at japtrix he told me everything was ok. Thanks alot for the inputs.

 

Fuel really doesn't cool to prevent detonation.

 

But short of WI a rich mixture is the only other way to cool the cylinder head temps without doing it via decreasing backpressure.

 

Then why do you think they go rich under load? To waste fuel?

A rich mixture runs much cooler temps than a lean mixture, since there is not enough air to detonate all the fuel. Thus, the left over fuel acts as a heat sink and "cools" the temperature.

 

i run about 14.5-15 at idle, and 15.1 +- .2 at cruising speeds to get better mileage. wot, i'm about 11.5-12.

 

o ok thanks i waqs just curiouse since i had never seen it on the car since i got it back. Really appreciate the info

 

Yes fuel can be a coolant, but no this is not the right way to explain it

A rich mixture does not automatically mean cooler temps

but to answer the posters question, yes you are ok

 

You must have missed the memo.

The VP of Engineering @ Innovate Motorsports posted an article on their website stating that this is not true.

If I remember correctly, he essentially changed the laws of physics by presenting some algorithms and discussing specific heat and other highly technical mumbo-jumbo.

So ever since then I have been tuning cars to run 14.7:1 at full boost, running 6 degrees of advance, and my water injection is pumping about 3 quarts a minute at full throttle. So far so good