I got my car back from the shop in April. They did a complete build on it. The car is running great. I did a pull the other day and it seemed alright. After 5mins of driving the check engine light came on.

I wasnt to worried becaue it still ran fine. I pulled the code and it was saying that there was a vacuum leak. The car idles fine hits full boost, I checked all the lines everything looks good.

I made a 3rd gear pull just to see where the a/f was at. well I was around high 14.s and boost hit 39psi just took longer to get there. This is where I find my problem.

The car is running tuned stock ecu, buschur double pump, e-85 tuned. I already checked the fuel filter and it was clean. Like I said before the car only has 800 miles on all new parts. not sure what to check next. No I dont have a cable or anything to provide a map of what is going on with the car. The car idles fine and drives fine just goes lean at wot. where should I go from here?

Thanks

 

I'm having the same issue with a stock turbo bolt-on car. Had a few vacuum leaks and fixed them, and even turned the boost controller down to 15lbs. It's still running lean...will be following your thread.

 

running an aftermarket fuel pressure regulator? or its possible the stock fuel pressure regulator isn't increasing pressure as boost rises. you got a fuel pressure gauge?

when it was at the shop did they tune it? 39psi on a stock map is going to be lean as ****.

 

If you did a boost leak test and everything checked out. I would get your injectors tested. Just to make sure they aren't clogged from the e85. This could cause the car to run lean. Also a bad batch of e85 can do the same thing

 

I just remember this!!!! I had an issue with my buschur double pumper. Car was running lean at wot. Come to find out, the worm clamps that hold the pump to the siphons came off.

 

39PSI!?!.....14afr's!?!.....do not be boosting the car again until the issue is fixed! you may also want to turn the boost down when you're testing to see if you've fixed the problem or not.

Do a boost leak test (seems obvious I know) and go from there. Is the vacuum line cracked on your FPR? maybe its not getting proper vacuum to increase your boost. Have you made any changes to the car recently?

 

Car was built by a shop and tuned. Aftermarket FPR. I will check the DP tomorrow. No IM not driving the car at full boost until fixed lol. boost is AEM electronic boost controller. I cant turn it down can I? I will do some more looking into the car tomorrow and see what I can find out.
thanks for all the advice so far!

 

If you are using an AEM Tru Boost EBC, you can reprogram the boost using the two buttons on the front of the gauge. It has two separate boost programs, so you can program a "low boost" program and a "normal/high boost" program, which you can switch between at will.

See here for instructions (starts around page 6): http://aemelectronics.com/files/inst...er%20Gauge.pdf

Thanks!

S.

 

How are your fuel pumps wired up? with a relay and 12v right from the battery so they are getting max voltage?
Also do a boost leak test and activate your fuel pump at the same time to make sure your fuel pressure is raising at a 1:1 ratio.

 

Possible that your Hobbs switch for the 2nd pump is not working properly. With the car off, hook an external pressure source such as an air compressor to the Hobbs switch and see if it turns the 2nd pump on while the ignition is turned to the on position.

 

ok so I finally had some time to work on the car. I replaced the fuel pumps and the car still leaned out worse this time. I cant even start to build boost without it going off the charts on the wideband. I checked the hobbs switch and it is working properly. I also did a boost leak test and that checked out as well. I know its got to be a fuel issue just not sure what else there is to check. Its probably time to get it into the shop.

 

Have you done a fuel pressure check yet? Unless you do that it will be very difficult to know if the pump is supplying enough pressure! I had a major issue with pressure. Replaced the pump, still the same issue.. turned out the O ring under the black plastic clip (right at the bottom with the ground wire on it) had become dislodged (a 10 second fix in the end!). Since that's inside the pressure-side area of the stock fuel pump housing, the pump flowed fine at 0psi, but couldn't create massive amounts of pressure without leaking inside the fuel tank (where I couldn't see it).

Since you use a Buschur double pump, the issue won't be the same, but a fuel pressure gauge is pretty essential to the testing process for fuel related issues!

I would test the pressure at both the rail and directly at the pump housing. I made my own pump housing-side testing rig by hooking the output of the fuel pump housing to some hose. I used 5/16" fuel injection hose with a hose clamp temporarily (although you can also buy the quick-disconnect female to AN -6 if you prefer - Russell makes them) with a T-junction on the other side. One side of the T-junction I routed to a Fuel Pressure Regulator (I just got a random 45PSI regulator from the local car parts store), and the other side of the T-junction had a Schrader valve for my fuel pressure gauge. I then hooked up 12VDC directly from battery to the pump for 10-15 seconds (make sure the other end of the test FPR goes in to a fuel container of some kind!) This allowed me to eliminate the pump assembly as the issue (in my case, it was the issue, so it allowed me to pinpoint it to the fuel housing).

Thanks!

S.

 

What pressure should I look for? My aftermarket FPR is showing high 30s. I don't know what the shop set my pressure at. Not sure what pressure should be with all the aftermarket parts.

 

uh im pretty sure you should be at 3 bar/45ish psi. is it rising proportionally with boost?

 

Can you see the gauge while driving? What pressure are you showing at WOT? When are you seeing high 30's? Idle? The pressure changes depending on injector flow and pump speed. Assuming you still have the high/low circuit, then at idle and cruise typically voltage at the pump is 8V and when the high circuit is energized voltage goes up to 12-14V, depending on your wiring (one of the reasons people rewire the pump with bigger or dual pumps is to bring that high voltage closer to 14V with heavier gauge cabling that can carry the higher current).

Do you also have a multimeter? Can you measure the voltage at the pump while driving too? To make sure the low voltage and high voltage numbers are good.

Thanks!

S.