velasco581

Hello all,
I recently installed a set of GSC S1 cams and head studs. The whole install went by easy but when I tried to start tuning it, the wideband is just reading lean past 3400 rpm at WOT all the way up to redline. I have tried to richen it up a bit but it will still read lean. I have also turning the boost all the way down and it still does the same thing.

I finally took it to a shop so they can go ahead and tune it for me and they said that there is something wrong mechanically with the car. They said to replace the fuel pump and the FPR because one of those have gone bad. I have replaced the fuel pump and it still does the same thing.

The car ran fine before the cam install but I can't get this sorted out. How can I check to see if the FPR is failing? The car runs fine at idle and at cruising speeds with the AFR's in the 14.x. When WOT the AFR's go down to around 10.9-11.2 but they don't last longer than a second till it reads lean.

Can anyone help me out? Any advice? Thanks for your time.

Mellon Racing

iTrader: (38)

did you put in an upgraded fuel pump or another wimpy stock evo8 pump? you should install a walbro 255lph fuel pump and get it retuned.

l2r99gst

iTrader: (2)

Did you make sure the vac line going to the FPR is connected and not damaged in any way?

velasco581

Yeah, it already had a walbro HP 255 on it. And I just replaced it yesterday with another to eliminate that possibility. I've checked the fpr about a dozen times now and it appears to be okay. Is there any known way to check to make sure its working right? Thanks for your input so far.

Kracka

iTrader: (49)

Recalibrate your wideband, maybe that went bad.

StreetEvo

Does all of the timing marks line up correctly? Do you have adjustable cam gears? If you have too much valve over lap you'll suck the majority of your fuel charge directly into the exhaust. How does the car run since you installed the cams?

velasco581

I have a PLX devices wideband. I don't think they are able to be recalibrated. It seems to be reading fine up until I hit WOT. For example, when idling and cruising speeds it reads in the 14.x area and on decel it reads lean.

The car runs fine up until WOT. I checked the timing marks on the cam gears and they lined up fine. They are the stock gears. Besides having a lopey idle it runs fine. Any other suggestions?

Thanks for the help so far guys.....this is driving me nuts.

Mellon Racing

iTrader: (38)

might be worthwhile to check the voltage at the fuel pump and put a gauge on the fuel line to see where the base fuel pressure is.

SuPeRNeT

iTrader: (13)

Are your injectors scaled properly?

codgi

iTrader: (22)

Did the walbro use the Evo specific installation kit?

W2J

iTrader: (12)

had the exact problem last week when I installed my HKS272's. Changed Fuel pump, fuel pump filter, fuel pump sock, Fuel Relays, fuel Regulator, cleaned injectors, check backed timing. It turned out to be a vac line that runs from the compressor discharge to the greddy solenoid had a tear.

velasco581

I had the walbro in the car before i had the cams and it ran fine then. Then new one i put in was also for the evo. The injectors that I have in the car right now are stock. In Ecuflash the scaling is set to 513 which sounded about right to me.

How would I go about installing a fuel pressure gauge without having anything really permanent?

What I am thinking of doing is Checking the timing marks at the cams and at the crank. It is going to be a pain to get the cover off. I don't think the timing is off but I guess I have to try to eliminate that possibility. The other thing that I am going to do today is buy a new o2 sensor for the wideband.

I am wondering honestly if its the wideband that is reading inaccurately at WOT. When I do logs with Evoscan I am registering about 9 consistent counts of knock at 5000 rpm. Even though I see that as a high count of knock I don't think it's high enough for the afr's reading the way they are. My wideband reads lean at anything above 20.1:1. If the afr's were really that high I would think that my knock count would be much higher. That's just me though. Does that sound about right or am I way off on that?

Mellon Racing

iTrader: (38)

there comes a point where there's so little fuel that it won't knock because it's not making any power but you would feel it hesitating terribly if it were that incredibly lean.

make sure the vacuum line to the fuel pressure regulator didn't pop off. That would keep it from raising the fuel pressure 1 psi for every 1psi of boost.

velasco581

Okay, I'll check the fpr vacuum lines. I know they are plugged in but I will remove them and check for any holes. I'm also going to recheck timing and probably by another wideband o2 sensor.

W2J which line are you talking about exactly?

warp9

iTrader: (35)

+1 on the FPR vac line, pull it off and check it over. If thats not it check for any other vac/boost leaks.