Im getting my car tuned will mellontuning everything is going great except, he's been telling me to turn boost down because the load is hi. Boost was at 23 psi when we first started but load was 300. I had to turn down boost all the way down to 19 psi (spike) to get 270 load. the car feels much slower. I drive an evo ix and people with ix's are doing 25 psi on pump. Any help will be great. Thanks

 

wow thats a wierd one. and i guess your going off your boost gauge for the reading right? could it be that the gauge is off? maybe its a wild scenario that the spring in your boost controller is for higher PSI and the gauge is off

 

Well yes I am going of my gauge. It an auto meter gauge do they usually do that?

 

Mechanical gauges have been know to be off by as much as 6psi, my electronic feed back from my EBC says I am hitting 22.9 psi and my mechanical gauge says I am hitting 26 psi just as an example. BTW stick with Mellon, you won't be disappointed!

Josh

 

Also you can rescale the load in the fuel and timing map so it goes to 300 and beyond if you want to. There is a thread here about it, let me see if I can find if and I will edit this post so you can see it.

edit: here is the link to the tutorial! Enjoy!

https://www.evolutionm.net/forums/sh...d.php?t=211022

Josh

 

i dont think he wanted to raise his cells, i think he saying he was hitting to high of a load to really be at 23 psi.

 

thanks alot jmelocik. so do you think i should also try another boost gauge and see if theres a difference.

 

Doing pulls uphill????

It could be the boost gauge. My stock MR gauge (which is known to be pretty good) was reading 1.5 bar, but I was hitting 330-340 load cells. lol

 

I've also seen a scenario where a boost leak will cause high loads for the boost that's displayed on a gauge.

think about it...the turbo is overspinning to get you to your target 23psi so it's pulling in extra air through the MAS which = high load and lower knock threshold due to heat etc...

I've had customers that saw only 19psi on their gauge and were hitting 350kpa with a stock evo9 turbo.

it's extremely important to do a real boost leak test with a compressor (not just visual) before getting tuned.

 

Good point Chris! You can make a leak tester with stuff from Napa and Home Depot. I've made one and it works great. If you wanna go all techy and stuff then have someone that has a smoke/ leak tester do the test. Just make sure they check everything! LOL

Josh

 

I agree .. it sounds like a boost leak. I'd suggest doing a leak test before going further on your tune.

 

I also had a customer recently with this problem...his leak was at the gauge itself in the cabin. It was hard to find because while pressure testing he couldn't hear the leak from outside the car. Again, high loads, low boost, low knock threshold.

 

Could the BR MAF pipe help contribute to the high load figures? Throwing off some scalings??

 

the far more tell tale signs of a boost leak are lean at idle, and rich at WOT. the bigger the leak, the more this is compounded.

if you can't see that it is way richer then the tables would indicate, there most likely isn't a leak big enough to make any difference in what load cells are being hit.

 

I agree with everyone here. You either have a boost leak or your intake setup is screwing with your maf readings. Is you MAF scaled at all or stock settings? I think I've read many posts where people have stated that intake pipe alters MAF readings a lot.

For a sanity check, you can use this equation I created to correlate boost with load for your setup:

BoostEst=[(load*T)/(P*VE*280)]-14.7
T = actual intake air temp (not MAF temp) in degrees Rankin (degrees F +460)
P = atmospheric pressure in psi at the MAF(baro)
VE = VE of engine at the RPM being measured

If you use your data at 5000RPM, then you can assume a VE of 1.

I don't know what intercooler you have, but I know it's pretty hot in Kuwait, showing 97F today. If I assume your true intake temps of 120F and baro of 14.5, at 300 load, I get the following:

BoostEst=[(300*580)/(14.5*1*280)]-14.7
BoostEst= 28 psi

So, it looks like your boost readings are off by around 5 psi or so, if your intake temps and baro are what I assumed them to be. If your true intake temps are even higher than 120F, then your reading is off even more.

Test for boost leaks and if there are none, then use your MAF scaling to get back down to the correct loads.



Eric