Ok soo.. I’ve been posting trying to get help but have had no luck.. Here is the problem. My car is running very lean at idle and the idle is rough making lean backfires here and there.. the car was tuned almost a year ago and have had no problems since. I checked for vacuum leaks, exhaust leaks, and replaced the fuel regulator. The fuel filter is also new a few months old. I am a fully built b16 turbo. Also did a compression test and all cylinders are perfect. What could it be.. and thing thrown at me will help.

 

Did you check fuel pressure at the rail?

Get your injectors cleaned.

Check for exhaust leak letting air in before the wideband.

 

Fuel pressure at idle is 35 and when I give it gas it goes to 40. Also injectors aren’t even a year old. I checked for all exhaust leaks and didn’t find Any. This was all of a sudden.

 

Pressure should be 43.5psi with the FPR vacuum line disconnected.

You say you replaced the FPR, what kind did you use and is it adjustable?

 

how old is the fuel pump?

 

FPR is an oem one, and the fuel pump is a walbro 255 and a couple years old. Also I noticed when I would be driving say 5th gear low rpm it would backfire and cut out intermidialty.

 

Your pump isn't puttin out enough juice.

1.) Check voltage at the pump, may be a wiring or grounding issue. Or check alternator and battery + grounds.

2.) Check fuel pressure at the rail while crimping the return line. The Walbro should be able to put out around 100psi. If not, pump is bad.

You need 43psi with vac line unhooked.

What engine management are you using?

 

I’m using hondata s300. I pinched the return line and the fuel pressure gauge maxed out at 100. Seems to me that the fuel pump did as you said.. I’m really stumped on what this could be. However if I disconnect the vacuum line on my bov, the car goes full rich.

 

Read fuel pressure at the rail, with the vac line from the FPR disconnected.

 

Well looks like I found a leak in the manifold. A little leak can cause such a problem? The manifold had a sight crack..

 

Yep, that can cause those kinds of issues

 

I will keep this thread updated once it’s fixed!!