Knock/Air Fuel Issue...

[SonySlave]

My modlist is up to date in my profile...

Anyway, my mods are nothing over the top,and have gotten me to 13.33@102 so far which I'm not very happy with...

First is a problem with my fuel. My Keydiver is made for 37bfp, PTE 680s, 1G MAS, etc.., but when I set the pressure to 37bfp, my low fuel trim goes to about 130+%, and my mid and high trims hardly move, but they are going lean. So I did a few pulls and my WB air fuels are in the low 13s almost all the way through, then I just get knock and get off it. So I turned the Aeromotive up to 46bfp and the fuel trims didn't move, they just stayed lean. But my WOT air fuels looked a bit better, mid 12s and no knock until about 6k when my air fuels go crazy lean into the high 13s almost instantly at 6k. So I tried richening up the S-AFC some. Went to 20% rich across the maps on the AFC just to see what would happen. Air fuels were high 10s til about 3.5k, then low 11s until about 5.5k then my air fuels go crazy lean again and knock hits again at about 6k. So I richen up 5k-7k to about 35% just to see, and the knock didn't go away and my air fuels didn't change either. Same problem as before.

My only guess here is that my PTE 680s aren't actually 680s, but maybe 580s instead. They are definitely PTE injectors, but there are no markings on them, so no way to tell without flow testing them.

Help would be appreciated. I'm dying for a 12sec. pass before the season is over...

 

[zippyshoe]

Does the vacuum line connected to your AFPR look to be in good condition (leak-free)? I'm wondering if your AFPR may not be raising fuel pressure 1:1 with your boost for some reason. This could cause you to run lean at higher boost pressures.

Also, how much boost are you running? Both the 1G MAS and 2G MAS have limitations on how much airflow they can accurately measure. If your airflow exceeds a certain threshold, the MAS will start to report an airflow value to the ECU which is less than your actual airflow (a.k.a. MAS overrun). This would cause a lean condition at higher airflow levels since the ECU will not deliver adequate fuel for the actual airflow. This airflow threshold value for the 1G MAS is significantly lower than that for the 2G MAS.

 

[JayRolla]

I agree with zippy, make sure you have no leaks at the vacuum line. I also would like to know how much boost you are running. It also sounded like your pump may have been running out but you should be ok without a rewire, with that small turbo. Also timing is at 5* btdc right?

 

[SonySlave]

Sorry, I have the boost at 18psi and it's pretty solid. My vacuum in the car is perfect, 18-20in./Hg. I'll check the hose tomorrow morning. But the MAS overrun would make sense. It just seems odd that the knock and abstract A/Fs hit almost exactly at 6000rpm every single time.

 

[JayRolla]

I dont think over run would cause all that. You would get fuel cut. With the amount of fuel you need to add to get a good afr I would say your keydriver chip may have been programmed incorrectly. With those injectors you would pull fuel not add. Something is wrong somewhere. Make sure fuel filter is not clogged.

 

[SonySlave]

My fuel filter is brand new, just replaced maybe 1000 miles ago. Like I said before, my Keydiver chip was programmed for PTE 680cc injectors, unhacked 1G MAS, etc... My best thought on the situation is that my injectors aren't PTE 680s, but PTE 580s instead, thus my need to add about 20% more fuel using the AFC to get a decent AFR. I'm going to get my injectors flow tested to find out for sure. It's the best thing I can come up with because I have no boost leaks anywhere, my MBC holds rock steady at 18psi, my fuel filter, o2 sensor, and knock sensor are all only 1000 miles old, and I have no exhaust leaks before the wideband. I haven't changed my BPR7ES plugs or plug wires in a while and I could be getting some ignition cut up top, which could screw with things as well...

We'll see I guess... Looks like that 12 second pass this year might not happen...

 

[JayRolla]

The plugs and wires could be giving you some knock but its not going to cause you to go lean at high rpm. Even if the injectors are wrong you should beable to tune it out. Something is causing you to go lean at high rpm, so it has to be a fuel issue.

 

[1993TalonTsiAWD]

You really need to log your mas air flow readings around the time of the said problem. I thinks its mass air flow related however someone said something about fuel cut. If you have a chip it could be removed and you wouldn't hit it. I hit fuel cut at about 15-16psi on a evo 16g with 580's. You could hack the 1g mass,but I perfer to buy a 2g mass. Make sure your fpr is doing its job, if it doesn't raise fuel pressure like it should that can cause it to go lean no matter what you mess with on the safc. You could also check for a restriction in the fuel system some where. if you have excess to a amp clamp to measure amperage. check wht it is around te said issue. if it reads higher than it should its a indication of increased load which culd be possble blockage or dying pump. you can find the fuse..can't remember which fuse and put a wire where the fuse would go with a fuse in that line and measure the amperage off that wire. The above works pretty well,but you the info with grain of salt as with othe data could be miss leading. do know though mechanical resistance raises amperage and electrical resistance decreases amperage or current.

 

[SonySlave]

Well I got a brand new set of NGK BPR7ES plugs and some brand new NGK plug wires in yesterday. Didn't help my problem. So I finally rewired my Walbro 255HP tonight. Didn't help my problem either.

All that's left to do is getting the injectors flow tested and I also think I'm going to pick up one of Import Evolution's upgraded fuel feed line and high flow fuel filter kit just to eliminate the stock filter. We'll see what happens.

 

[kazzam]

So any word on your problem?