super lean after afpr install

[dboyle23]

Ok, so I just finished up my new afpr and have the pressure set to 43 without vac line.

I have a wideband and a 255 installed as well. Before the afpr went in my idle was around 15.2-15.4, which is a little rich but not too bad.

Now after the install, my AFR is 16.8-17.8 with fluctuation.

I have tried bypassing the fps but either way its still really lean.

It might be possible that I have an exhaust leak where the downpipe meets the o2 housing so I am putting on a new gasket, How can I tell if there is an exhaust leak at my EM? There might be one there as well since one of the studs broke off the head when I was installing the EM.

Any other ideas? I am hoping that a small exhaust leak is throwing off my wideband.

 

[overkill]

Maybe your wideband sensor is going bad. Are you running a narrow band as well and if so what does that say?

 

[dboyle23]

evoscan shows ~14.1

I am going to go pickup a new o2 housing to DP gasket right now.

Also, my wideband is in my rear o2 bung, but the cat has been removed, can this cause an issue?

 

[Black'95]

By 255 do you mean the Wally pump? Did you have that pump installed with the stock regulator for a while before you installed the AFPR? Reason I ask is I had the same setup: stock fuel system except 550cc injectors, and a 255HP pump. I also had a gauge, which showed about 45-50psi with the stock pump. The Wally bumped my base fuel pressure up to 75psi, with the stock regulator. I had to pull fuel with the AFC since the higher fuel pressure caused the injectors to squirt more fuel in. When I installed my AFPR months later, I turned the fuel pressure back down to about 55psi base, and consequently had to retune my AFC, this time adding some fuel to compensate for the lower pressure. Higher fuel pressure will make you run rich, if you don't change anything else, and the opposite is true for lower fuel pressures. Does any of that make sense?

And +1 for checking for and fixing exhaust leaks; those buggers can really mess with your readings.

 

[dboyle23]

yeah it makes sense, but I still have my stock injectors for the moment. After I fix whatever the problem is, then the 660's go in. After closer inspection, I think there is an exhaust leak near my wideband sensor.

 

[Black'95]

It won't matter what injectors you're using, the key thing is the changing fuel pressure.