Starting Problems and Throwing Codes

**SOCAL WS6** · 08-26-2009, 11:06 AM

About a month ago the car began having some problems. It wouldn't start on the first attempt but always on the second try. I cleaned the MAF and TB (both stock) with the proper cleaner and that didn't work. I then cleaned the K&N filter and replaced the fuel filter with no luck. Then it threw the P0171 code for the lean fuel bank 1. I also noticed that at WOT it had a slight hesitation. A week later it began to throw the P0174 code for the lean fuel bank 2. I cleaned the MAF and TB again and sprayed carb cleaner around all of the vacum hoses. There was no change in idle. I also replaced the PCV valve just in case but no luck. After cleaning the MAF and TB the second time I didn't really feel the hesitation on WOT anymore but it continues to have the starting problems and it threw the codes again this morning. Just an FYI, I tried to turn the key to the run position without starting, then to start and it sometimes starts on the first time, not often though. I also tried turning the key on and pumping the gas then to start thinking it may be the fuel pump, sometimes it starts but not often.

I'm thinking it may be:
1. a vacum leak I'm missing
2. Either of the front 02 sensors
3. Either the fuel pump or fuel pressure regulator
4. or stock MAF is going out

The car has 170,000 miles and has had the plugs and wires recently changed.

**SOCAL WS6** · 08-27-2009, 08:13 PM

Stumped ya all??? Well then it's off the shop she goes....

**JaycenK** · 08-27-2009, 09:01 PM

put a gage on the fuel rail and see what it is doing. You should run solid pressure all the time. Very comon to have a fuel pump on the outs and cause lean, hezi, and intermitant starting problems.

**SOCAL WS6** · 08-28-2009, 06:19 AM

I'll do that. I guess I was just hoping it wasn't the fuel pump. They don't exactly make them easy to replace on these cars...

**tep98ws6** · 08-28-2009, 06:30 AM

mine is doing the same thing. i can't find a vacuum leak and at first it was p0171 & p0174, ended up being an o2 sensor. i've put 600 miles on since the o2 (bank1) and now i've got a p1133 for short circuit in the same o2 sensor. only difference is between ours is that mine hasn't been tuned up yet by means of plugs and wires. i guess o2 again. hate those damn things.

**SOCAL WS6** · 08-28-2009, 08:58 AM

Now see i've read alot of threads trying to figure it out before I posted. Everytime I think it might be the fuel pump someone mentions the o2's. Since it's easier and cheaper to replace the o2's, I was going to try that first, but I find it difficult to think the 02's would be causing that much trouble without throwing the o2 codes.

I don't have a fuel pressure gauge so I may pick one up first. The other thing that got me thinking was the at first it just threw the P0171. Then several days later it threw the P0174. Unless both o2's went out about the same time you would think that it would only affect one bank. Althought as far as I know these are the original o2's.

I'm digging into it this weekend to try and figure it out. I'll let you know if I find anything. Also keep the suggestions coming. I appreciate everyones imput.

**SOCAL WS6** · 09-13-2009, 10:09 AM

Just wanted to update this thread. I put a fuel gauge on the fuel rail and it was only reading 5psi while in the run position and 30psi while running. I bought the Walbro direct fit fuel pump from the WS6 store and installed it yesterday. This pump kicks ass. Plugged right in and now the car reads a steady 64 psi and runs great. No more codes.

I read somewhere else that when the car is throwing a P0171 and a P0174 the dealership says that it's the fuel pump. Hope this helps others with similiar problems.

**TA98** · 09-13-2009, 08:21 PM

Originally Posted by JaycenK

put a gage on the fuel rail and see what it is doing. You should run solid pressure all the time. Very comon to have a fuel pump on the outs and cause lean, hezi, and intermitant starting problems.

Agree with the fuel pump possibly being the issue. Especially since if you turn the key to on then wait a little to actually start the car. Thats allowing the pump to build enough pressure to start the engine.

**tep98ws6** · 09-14-2009, 01:43 PM

Originally Posted by SOCAL WS6

Just wanted to update this thread. I put a fuel gauge on the fuel rail and it was only reading 5psi while in the run position and 30psi while running. I bought the Walbro direct fit fuel pump from the WS6 store and installed it yesterday. This pump kicks ass. Plugged right in and now the car reads a steady 64 psi and runs great. No more codes.

I read somewhere else that when the car is throwing a P0171 and a P0174 the dealership says that it's the fuel pump. Hope this helps others with similiar problems.

i was just about to tell you! i found mine to be the fuel psi regulator ... my pump is functioning correctly, i just am running 30psi from the rail to the pump but the pump is doing it's job. still gotta drop the tank to do it so i'm in your boat! im guessing my fuel pump will be going soon too tho so ill do racetronix probs.