Got a CEL on the way home this evening. I had been running the car hard and boosting to 11 psi or so. No particuliar problems when boosting except a possible misfire once. No CEL at that time. I ran the car another 5 miles at 60 mph (no boosting) with no problems. Stopped at an uphill stop sign and while idling, the car started sputtering badly, the AFR dropped to 9-10, and the CEL started flashing. Drove the car .5 miles to get home (still sputtering bad) and AFR still 9-10.

Checked CEL code :P1399 (misfire)

Any ideas?

I did install a Walbro 255 fuel pump a couple of weeks ago. Also had a CEL (P0132) earlier this week that I cleared and then reset the ECU. I thought the P0132 may have been caused by using the AF targeting feature on the emanage ULT.

 

What is your gas gauge reading? Did you re use the old filter sock? If not you may be out of gas. The sock that comes with the pump won't let the float rest all the way down and your fuel gauge will have 3 bars but really you have no fuel.

 

It's got about 1/2 tank. Based on the mileage since my last fill up, the fuel gage looks to be accurate. I reused the OEM fuel pump strainer, so it should be OK.

 

P1399 the temporary DTC for a random misfire. You are missing another DTC that is stored. It will have another P0300-P0304 stored that indicates what cylinder misfired.

I'd be yanking the plugs and checking to see if you fouled them with too much fuel.

The P0132 can be set by your AFR corrections in the e-manage.

 

Is there any way the extra pressure from the Walbro could have damaged the fuel pressure regulator or some other fuel system component to cause excessive fuel delivery?

 

The regulator maintains the same pressure as the stock pump.

The E-manage running the big injectors is the most likely cause. Are you removing fuel at low RPM to keep the fuel trims close?

 

I do not map below boost. I only enter the new injector size and lag time (per WLaurent) and all the correction below boost is done. Up until now I have had no problems with the 550 injectors maintaining around 14.7 AFR below boost.

Mark had previously suggested to drill out the return port on the FPR (per Vortech instructions) to help maintain normal pressure.

 

If you can swing by saturday I can pull the DTC's and freeze data which will tell you under what conditions the misfire occurred.

Do you have a fuel pressure gauge installed? I wouldn't drill anything until I verified the fuel pressure.

 

Drilling out the stock PFR is something that vortech has you do when installing there kit.

Wonder if this would fix Neptuners problem of an over rich condition; I was thinking that there is to much pressure in teh fuel rail causing the over rich condition. However a number of other ppl are using the Walbro 255 with the stock FPR with out any problems.

Main question at this point what is making the stock computer open the injector so much causing the rich condition?

Neptuner do you have access to an OBD reader that can show you the Short and long term fuel trims.

 

Only the AP2 Vortechs with an Aux injector drilled the FPR. The 00-03 kit did not.

Chances are this isn't a fuel pressure issue.

My car and wilbur's old car still have 255lph walbro's and stock FPR's. No problem with to high fuel pressure. when I checked mine it was the same # with both pumps.