Hi guys

I am going to set up a adjustble fuel pressure regulator for my evo,because I am running out my stock injector's duty cycle. it hits up to 95% at peak boost of 23.4 psi.

what preuusre should I set up the fuel pressure reg and what changes I will need to make in the map please.

Another question what is the max boost I should run on a stock evo please. I am using pump gas 98.


many thanks


mark

 

After you install the new FPR into the car (gas lines, feed and return are connected), leave the vacuum line disconnected.

There is usually a nut on the top that you loosen, in order to adjust the fuel pressure, loosen it. Try and start the car, it may stall out, you will have to turn the screw in the top of the FPR until the car stays running. The base fuel pressure you are looking for is 43.5 PSI. Then connect the vacuum line back up. No ECU map changes required.

I ran 27 psi on a stock Evo VIII turbo, stock injectors, stock block, however this was 93 OCT.



-Bink

 

I don't see how how installing an AFPR will lower your IDC...

 

Becuase he thinks that by raising base pressure (which he isnt going to accomplish with the info above...) he will be able to regain some headroom, and also doesnt realize that his fuel pump will be the bottleneck, not the fpr.

The real solution to your problem is to get bigger injectors, fuel pump, and MAYBE a FPR. Anything you do to raise base fuel pressure (FPR, pump, etc) is only masking the problem of too small injectors.

 

Thanks for your reply. So what sort of peak duty cycle are for your injectors please?

cheers

mark

 

I do have a walboro fuel pump upgrade for my car though. Are you saying the only option to solve the problem will be upgrade the injectors right?

cheers

mark

 

1-So, to trick your ECU you can (for example and if your pump gas allows it) raise your base fuel pressure by +10% (47.8PSI) and in the same time raise your injector size scale in the ECU by 10% (512 -> 563 on stock inj). That's theory so do some logs to monitor IDC, knock and AFR... (The most common problem doing this is that your pump gas wont push enough at peak boost, that's why people get bigger injectors!)
2- You do not want to run more that 25PSI >5500RPM on stock turbo if you want it to survive a while...
Cheers,
C>

 

Thanks for your help, I am runing peak of 23.5 psi. so I guess that is still safe at this stage. I am wondering by doing the way you just state above how much % of injector duty cycle can normally gain.

cheers

mark

 

Raising base pressure won't suddenly increase your injectors' flowrate. And changing your injector scaling will mess up your fuel map and fuel trims, so that's a bad idea. If you're running out of injector, get better injectors, simple as that.

BTW, 95% IDC isn't that bad actually, I was getting ~105 before I upgraded and I could still richen the mixture if I wanted to, and others have gone as high as 115-120

 

I'm running at least 107% duty cycle up top.

 

They were at a high duty cycle, around 95-97%. If you do plan to put some power down, I highly recommend investing in bigger injectors.


-Bink

 

Hi

thanks for you advice. what brand will you recommand? I know I will need to reset the battery latency and injector size scaling. If the new set of injectors come with all these numbers, do I have to tune the AFR map again.

Cheers

mark

 

At the very least some adjustments to the fuel map will most likely be required. The injectors will have to be scaled properly and the latencies setup to keep fuel trims happy.