Thanks for reading, Im gonna try to make this as short as possible while trying to describe this issue

I bought my 03 evo 8 about a year ago, It already had a MAP o2 dump and was already tuned.. at wot it always held a steady 11.2 ..but whomever installed it didnt use the separated gasket from map but instead was using a stock gasket..therefore it was dumping exhaust all the time..(was really loud)

I put the map gasket in about a month after i bought the car But suddenly at wot my AFR was in the high 9s and low 10s..i called the tuner and asked him if the problem could be that he tuned with the wideband while having the dump open..he didnt think so and it sorta makes sense because at wot the wastegate is open anyway..

wanna make clear whats really throwing me off is although the wideband is showing me super rich the car feels and felt no different no power loss and no issues whatsoever...

IDEAS?!!

 

At idle is it reading 14.7 give or take ?

 

Weather change and removing a leak in the exhaust.

 

I think you need a new tune due to no leak now. also the the a/f at idle is normal

 

AFR is good at idle

 

If AFR is good at idle then you can baby it until you can tune for the rich afr's at wot.

 

I had this same problem.. If the car was tuned with the incorrect gasket, then all the afr Baselines were wrong, and it would be best to retune. Also, just because the wg is open at wot doesn't mean that the leak doesn't matter. It's like if you're using a warped plastic ruler to make measurements, and assuming the numbers were all warped uniformly; it doesn't work like that.

 

why would my tuner not think of this? and why not say yes its messed up when i asked

 

Possibly he doesn't understand that air entering the system post turbo causes AFR to appear leaner than it really is? I believe there are plenty of tuners out there that are pretty clueless

 

So would I be better off reinstalling the other gasket as it was tuned with or do you think those numbers are probley flawed rite from the get go..this tuner is pretty well known on this site..

 

Whether the new or old gasket is installed on the car the actual AFR is overly rich. The wideband is just showing a false reading when it shows it being the AFR you want.

 

what if i told u my spark plugs read perfect.....

 

From another forum -
By driving the car in normal driving situations you are skewing the results of the plug reading and it doesn't give you the actual reading you are attempting to get.

I suggest re-tuning the car and not wasting extra gas while going WOT.