Ran a new personal best with the greddy kit on a stock D16Y8. Run was on 15 psi.
Tires were 205/50-14 BFG DR's.

60' = 1.948
330' = 5.236
1/8 = 7.930
mph = 90.22
1000' = 10.274
1/4 = 12.272
mph = 110.52

Notice the low trapspeed! I normally trap at 112-113, but have a strange problem I need help with.

Every single run at the top end, about 6200-6500 rpm in 4th gear, the car leans out completely as if it ran out of gas and falls on its face, decelerating to the finish line. You can see it on the datalogs, it just goes from 12.2:1 AFR to 20:1 all of a sudden. It doesn't die and runs fine after that. I normally finish at about 7000 rpm in 4th.

Fuel setup is:
Walbro 255 lph
RC440's
Uberdata 1.70
Stock MAP sensor

All parts including fuel filter have less than 5k miles on them. I have watched the fuel pressure during the run, and it DOES NOT drop off. Injector duty cycle is at about 82% according to Uber. Also, I've made pulls on the freeway from 60-130 mph and the lean out condition never happens. It only occurs at the strip at the top of 4th gear. Anyone have any ideas as to why?

I have ruled out bad injectors, fuel pump, and fuel filter as possibilities. It definitely seems to be the computer is simply cutting fuel.

Is it possible that running 15 psi of boost on a stock MAP is the problem? I've run it like this for 2-3 months with no problems till now. And the MAP sensor seems to check out when tested with a multimeter. Any help would be appreciated.

 

Nice time!

 

By the way I also tried a different ECU, different chip, different burn, closed loop enabled and disabled, etc. with no effect.

I also looked at the datalogs for the last 5 runs, and every run it leaned out more quickly and severely than the last. The map voltage stayed at 4.88- 4.9 the whole time, with an occasional microscopic dip to 4.82 volts.

 

a stock map sensor can read only up to 11 psi.
You need a 2 or 3 bar map sensor.

 

damn nice times!!! wonder if i can hit 12s

 

I realize that, but all that means is that I tune the highest boost column it reads in Uber to provide the proper fuel and timing for 15 psi. It's ghetto, but it works.

 

damn nice times.. where were those runs made? anywho i am running a bar of boost now with a stock map sensor with no problems at all.. i also have a 3 bar but yet to have to install it because i am not getting any CEL's for map.. btw did i say nice runs

im looking to break high 12's on street tires with my car.. i pulled a 13.61@105 on 7psi with a 2.2 60ft in spokane at about 2k elevation..

 

Thanks for the compliments.

The runs were made at Pacific Raceways in Kent.

Any experienced tuners run into this problem before?

 

what i don't get is how you say it leans out on the track, but not when doing 4th gear pulls on the street. Have you tried adding any fuel into that area to see if changing the numbers makes any difference at all? Also you say it only does it in 4th gear?

 

Yes, 4th gear only at the track. I've added and subtracted fuel at that point and in the other boost columns above and below it, and it makes no difference. I'm stumped. Car runs perfect under any other conditions.

 

That makes no sense at all though....there is no difference because the track and the street (which is like 100 yards from the track). Both have pavement/air/people/cars/dogs/trees/grass/you get the point, surrounding your car.

Running 15 psi on a stock MAP is a very bad decision. Buy a 3bar immediately if not sooner...if you can buy one yesterday then that would be even better How much power are you making?

 

great times

are you sure your not running out of fuel? really really weird scenerio

 

even though it's a chipped ecu have you tried pulling codes?? KOEO test would be a good look. might have a sensor going bad. I'm thinking o2 sensor.

but yeah, you need to get rid of that map sensor man. did you ever stop to think that your ghetto-rigged map ISN'T working and that's why it's leaning out. I mean obviously something's wrong.

I'll point my finger first at your rigged map with the overtaxed map sensor and second at a faulty sensor or something else.

you do realize a map sensor has a diaphram in it right. what happens to a diaphram that is pressurized more than it should be. it screws up and then breaks down. sounds like you're in the screwing up phase right now.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JFK78 &raquo;</TD></TR><TR><TD CLASS="quote">I realize that, but all that means is that I tune the highest boost column it reads in Uber to provide the proper fuel and timing for 15 psi. It's ghetto, but it works.</TD></TR></TABLE>

Works, yes, but to a point. 15 psi on the stock map sensor is the problem.

 

Always impressive

 

mmmmmm delicious time

 

Thanks for the suggestions guys. Yes it doesn't make any sense that it only happens at the track, and I know 15psi on the stock MAP isn't the best idea, but it was working just fine for quite some time, and it does not throw any codes.

The sensor checks out just fine when tested, and reads 4.8-4.9 volts on the datalogs, so it doesn't appear to be "broken", like dropping or fluctuating voltage or anything like that that would cause it to read off the wrong fuel maps.

I also swapped to another stock MAP and will go back to the track to see if anything changes- just until I get ahold of a 2.5 or 3 bar MAP sensor.

By the way, here are the dyno #'s. All runs were made in 4th gear on a Mustang dyno.

10 psi = 213.5 hp & 190.6 tq
12 psi = 228 hp & 204.8 tq
<U>15 psi = 244.1 hp & 224.6 tq (total timing was 12 degrees)</U>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JFK78 &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for the suggestions guys. Yes it doesn't make any sense that it only happens at the track, and I know 15psi on the stock MAP isn't the best idea, but it was working just fine for quite some time, and it does not throw any codes.

The sensor checks out just fine when tested, and reads 4.8-4.9 volts on the datalogs, so it doesn't appear to be "broken", like dropping or fluctuating voltage or anything like that that would cause it to read off the wrong fuel maps.

I also swapped to another stock MAP and will go back to the track to see if anything changes- just until I get ahold of a 2.5 or 3 bar MAP sensor.

By the way, here are the dyno #'s. All runs were made in 4th gear on a Mustang dyno.

10 psi = 213.5 hp & 190.6 tq
12 psi = 228 hp & 204.8 tq
<U>15 psi = 244.1 hp & 224.6 tq (total timing was 12 degrees)</U>

</TD></TR></TABLE>

OMG WTF 244whp on a STOCK Y8 on a Mustang dyno???!?!

 

The shop I dyno'd at said they've spent a lot of time comparing and calibrating their dyno with another local dynojet to try and get them closer, since most people use dynojet numbers.

They said the numbers should only be 3-4% lower than a dynojet, so 250-253 on a dynojet sounds about right.

 

eh, hate to throw the card but a stock block.....with 250 um i doubt it... if it isn't blown as i write this it will be soon.

 

its time to invest $18 on a motorola 2.5 BAR

 

I've got a 2.5 bar coming next week.

And yeah, it is 250 on a stock block, I never said it was the safest or most reliable setup in the world. But the motor has been in the car for 1 1/2 years now, with 30+ passes at the track and a lot of pulls up to 135mph on the freeway.

It's still going strong. If it blows, oh well. Not like it's a big deal to replace it.

 

wow 250whp on a stock d block??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2kTeg &raquo;</TD></TR><TR><TD CLASS="quote">eh, hate to throw the card but a stock block.....with 250 um i doubt it... if it isn't blown as i write this it will be soon.</TD></TR></TABLE>

Man you have no clue, ive got 80k miles on my setup at this power lvl. Daily driven also. See my sig!

 

nice times as always.