I have a 94 civic hatch with a turbo gsr w/ 300whp .s300, hard wired Walbro 255, b&m regulator and id1000's otherwise stock fuel system. I noticed two days ago I was running lean on my aem wideband at idle and part throttle. I borrowed a stock fpr thinking that might be the issue because I can bump the throttle and the pressure will drop about 5-7psi and then return to stock pressure. I removed vac line off fpr and it ran even more lean. I am debating on going a head and picking a new filter up in a few but I don't like buy parts not knowing if it's the solution. The walbro is only 2 years old. What are your thoughts??

 

how old is the stock filter?

they don't last forever....

 

2-3 years old. I went ahead and replaced the filter with a wix. No luck so I found a friend that gave me a 255 to try. Still no luck. I'm going to crawl underneath tomorrow and inspect my lines but I am at a lost. I put new plugs in, rotor cap, and ngk wires in very recently. I guess I could pull the id's and inspect. It was tuned by Johnny Adams and has ran flawlessly for over 6 months. Nothing has changed. Took my aem wideband out and put my mtx-l in to confirm wideband is working correctly. What else could it be??????????

 

fuel filters need to be changed way sooner than every few years... especially in a performance application

 

I have less than 30k miles since I did the swap in 2011 and it has had 2 filters and now a third in that time.

 

so then the filter isn't 2-3 years old?

I'm confused.

 

It's prob close to two years old if I remember correctly. It was close to the time I first boosted my car.

 

Only thing left is injectors. Put new filter in, swapped regulator, fuel pump, distributor, plugs, sensors, ecu, and still no luck. I am out of ideas at this point.

 

Not injectors. Someone mentioned map sensor which is a omni 4 bar that is less than 2 yrs old. Map sensor appeared to be working proper when we were data logging. Only other thing I can think of is something happened to my harness.

 

(Not sure they plug in the same )Just wondering but when you swapped over widebands did you also swap the sensor?.... I had a similar problem a long time ago that turned out to be a bad connection at the pump

 

Yes they used different sensors. The fuel pump is hardwired to the battery and all connections have been checked out

 

What Are you tuned on? Ems?

 

Posted in first post. I am on s300v2 tuned by Johnny Adams. It has been tuned on the new setup for 5 months and has ran flawlessly until now. There has been nothing that stands out in my mind that would of been the culprit of this problem. I am going to try another engine harness tomorrow to see if the problem is in my harness.

 

Have you datalogged anything?

Swapping parts isnt helping.

Maybe the tune is corrupt?

What is the harness going to change that you wont see in a datalog?

 

Yes we have data logged and nothing is out of the norm other than the air fuel ratio. Nothing has changed with the tune from what I see. The only thing I can figure at this point is there is some sort of short causing my motor to starve for fuel

 

Have you messed with your timing at all? Has the batt died or anything like that?

How exactly is your fuel pump wired?

 

no timing is same 16°. Battery is fully charged, never died or got low and alt is putting out 14.3 volts. Pump is hardwired off battery using a relay, signal wire is off original power wire

 

What changed from 6 months ago to now? Other then temp because that's a tuning issue

 

Have you monitored voltage before and after that relay?

From one side of the relay to the other? Maybe the relay is the problem

 

How lean is it going at idle and part throttle? Is wot going lean too? What did your wideband read before and what is it now? Maybe your iat compensation needs to be adjusted from the change in weather.

 

Idle whe warm stayed right at 14.7, now it will go 16.7-18. It does it at idle, part throttle, wot is also going lean. It will dip down into 11's and then jump 3-4 points. We have adjusted the iat compensation with zero luck

 

Ok that definitely sounds like a mechanical fuel related issue then. Good luck with it man.

 

Op check voltage at the pump under load with a multi meter

 

I have checked it before and after relay but I have been unable to check under load yet. To me what is odd is cylinder 2 is the only one not leaning out. Spark plug looks normal and it's the only runner on manifold that hasn't turned blue and purple. That is the reason I have thought it is a harness issue. I will check voltage under load when I can get a buddy over to give me a hand.

 

If ur problem doesn't exist on WOT then its def ur openloop , closeloop controls. Check the front o2