I was tuning an Evo X today and the AFR was lean on the stock tune. The car had an exhaust, a drop-in, and had the wastegate arm adjusted 3 turns by the owner. When I added more boost to the mix the AFR became 1 full point leaner, indicating that the fuel pump is not adding fuel.

Is the fuel pump bad? I read a thread about the relays failing and not switching voltage on the pump. Could that be the case?

I am attaching three stock logs. The car was knocking like crazy. I ended up flashing the car back to stock with a safe timing map to prevent knock until the owner finds the solution to the problem.

The zipped file is a *.rar extension. I changged it to *.zip so I can upload to Evom. Change it bacck to *.rar and open it if does not open with winzip.

 

You added boost and mods but didnt change the tune and wondering why its lean? Im pretty sure you need to richen up the fuel map. Unless your saying you already richened up the fuel map but it wont add necessary fuel, then probably yes the fuel pump is bad.

 

Ok I took a look at the logs. Im not a tuner but when it starts knocking the afr isnt too bad 11.5 isnt that lean but the timing in that area looks pretty high so I would try lowering the timing.

The car is getting 19 counts of knock which is horrible. I recommend you tell whoevers car that is to not go wot until the issue is fixed

 

We flashed the stock tune back to the ecu and backed out some of the timing up top and the knock is down to 1-2 counts.

Does anyone have wiring schematics so that I can check the fuel pump circuits for proper power durring WOT?

Other than that, I would think that the fuel pump is just not flowing what it should be. I could take the fuel pump out and have it flow tested. I remember that AMS has some flow numbers on the stock X pump.

The one other thing that i'm reaching on as an explanation is the WGA mod. Changing the WGA has affected the boost targets perhaps. Im going to place the WGA arm back to the stock location and try to get some logging done again soon.

For now, the car is safe, with 1-2 counts of knock durring WOT all the way to fuel cut.

Thanks Naji for taking such good car of my car this morning, much appreciated

 

Let me clarify more than I already did. On the STOCK tune the car was running lean. We were BASELINING the car on the stock tune. STOCK means, the stock AFR, the stock boost, and the stock timing.

Evo Xs DO NOT run 11.4-11.6:1 lean by redline on the STOCK tune. They run in the very low 10:1 AFR by redline on the STOCK tune. Even if they have a drop-in and an exhaust.

When I added the baseline flash with a stock fuel map, the car got leaner with more boost. It should not. With more boost on the stock fuel map, the car should run richer. Why? More boost=higher load. Higher load=richer fuel cells in the fuel map. This car was the reverse. The fuel pump does not seem to deliver more fuel with higher boost as per the dictates of the fuel map. I suspect that the fuel pump is the issue.

I even tried richening up the stock fuel map and the AFR stayed lean. It did not change.

I am asking why is this happening on this car? If you have an answer, then please share it.

It is NOT the tune since it was running the STOCK tune and it was lean and it knocked up to 14-15 counts.

 

Have you logged a stock Evo X before? This is LEAN for a stock Evo X. That is NOT normal. The AFR is BAD for a stock Evo X.

I already backed the timing on the STOCK tune and that brought the knock down to 1-2 counts. That has been taken care of.

 

Place a voltmer on the pump side of the relay and see if there is a significant voltage drop under the load. Fuel pump flow is voltage dependent is a good place to start. If you see 12.5-14V under the load look somewhere else. Step 2 fuel pressure gauge....

 

Thank you zeb. Much appreciated

 

I only looked at one log, but is it really that far off from most evo x's running the factory map? I had the factory reflash #2, and my AFR's were between 10.5-10.7 on a completely stock car. Add in the intake/exhaust and that could skew things a bit. Just a thought - what were his IDC's like?

 

10.5-10.7 is almost 1 full AFR point richer than what this car registered stock. This car was 11.4-11.5:1 by redline. That is not normal for an Evo X. None of the ones that I have logged, modded or not, were that lean by redline.

The IDC was @ 100% on the stock tune.

The thing is when I put the baseline flash with more boost, retarded timing, and the stock fuel map, the car ran leaner at 12.4:1 by redline. With added boost comes added load, so the car should run richer on the stock fuel map. This indicates that the fuel pump is not delivering the needed fuel demanded by the higher airflow through the MAF.

 

Also, make sure the fuel pressure regulator is getting positive manifold pressure info so it can raise fuel pressure per each pound of boost. So inspect Senior Jose going to to the fuel pressure regulator.

You're welcome.

 

Good point! I forgot about that. Some people recently had issues with the hose going to the FPR (right under the engine cover on the left side). I zip-tied mine just to be safe.

Ahhh I missed the 100% IDC part. Hopefully it's something simple.

 

Checked the FPR line to the Intake Manifold and it's good. Going to look over the service manual and see what the voltage for the fuel pump is supposed to be durring WOT operation and try to verify it. If at that point the voltage is good and all fuel pump circuit integrity is good, I will most likely call it the fuel pump.

I wonder if there is anyone who would be willing to let me borrow their fuel pump to log a few runs and compar the results

 

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The bung for the vacuum line that goes to the FPR had no bead on it for the 2008 models. On the 2009 models Mitsubishi put a bead on it to prevent it from popping off. I guess Mitsubishi was aware of that problem