jeffkruse

Ok, so about a month ago I had my fuel pumps and fuel pressure regulator replaced because my fuel pressure was at 34psi instead of 50psi($1300.00 fix). About a week later I was driving down the interstate home from work and the car just died. I coast over to the side of the road and turn the ignition off. Turn the ignition back on and the car drove fine. It has happened 3 more times, but the last time when I could feel it about to die, I gunned the accelerator and the engine stayed running. Drove it home no problems. The only things I can think of that are constant when this happens, is there seems to only be a 1/4 tank of gas and it is always on the interstate. The following are the codes I get when it happens, these codes were NEVER displaying before I had my fuel pumps replaced. Otherwise I get no other DTC's. I have tried to clear the codes and drive again but when it stops I get the same codes. My mechanic says these codes would not just make the engine stop. Has anyone else had this experience or know what could be wrong? I have taken it back twice to my mechanic and he can find nothing wrong. Please Help


17831 - Secondary Air Injection System; Bank 1
P1423 - 002 - Insufficient Flow
17819 - Secondary Air Injection System; Bank 2
P1411 - 002 - Insufficient Flow
18666 - Oxygen (Lambda) Sensor B2 S1
P2234 - 004 - Signal Shorted to Heater Circuit - Intermittent
18663 - Oxygen (Lambda) Sensor B1 S1
P2231 - 004 - Signal Shorted to Heater Circuit - Intermittent
18847 - Oxygen (Lambda) Sensor B2 S1 Voltage too Low / Air Leakage / Sample Error
P2415 - 008 - - Intermittent
18846 - Oxygen (Lambda) Sensor B1 S1 Voltage too Low / Air Leakage / Sample Error
P2414 - 008 - - Intermittent

jeffkruse

So I set up an appt. to take it back, but before I got to take it it happened again. Both times with less than a 1/4 of a tank a gas I was starting to accelerate on the interstate and the car was about to die. I stomped on the gas peddle and the car hesitated and kick in without shutting off. Again this happened twice. So I took it in today and the mechanic said everything checked out fine. Fuel pressure, hoses, regulator etc... They did say now DTC code for miss fire on cyl 6 and 8. So with this new information anyone have any ideas.

Jack88

I can only guess. The secondary air injection is for emissions, injecting air into the exhaust at or before the catalytic converter, if memory serves me right. The oxygen sensors are nearly all the way upstream in the exhaust. So all of your codes from the first post have to do with that stretch of exhaust, and poor readings from an oxygen sensor can cause all sorts of havoc, including misfire if it's bad enough.

So, I guess my first thought is to start with checking those two oxygen sensors, but I don't qualify myself as an expert. Perhaps a different shop may be a good idea, as well.

MP4.2+6.0

I can't answer your fuel related issues with any accuracy or direct experience. But, it is clear to me both of your forward oxygen sensors are no good. Or if not the sensors, the wiring/connector leading to them. The code is unmistakable to me, knowing it well from my W12 where the connector terminals for W12's made in the first several years have issues--per a TSB and personal experience. Fix there is to replace the connector and close in wiring terminals. Both say your signal is shorted, so that's no fluke. Again, short could be O2 sensor, or could be in connectors or individual wires going into connectors.

The SAI codes also suggest your air pump may be disconnected, burned up or that or a hose has come off it or something. I expect it is also still like my C5 4.2 was with the combi(nation) valves driven by vacuum. If those vacuum lines crack, are disconnected or were pulled, that will probably generate those kinds of codes. Combi valves also run the EGR--the gas version of what is at the crux of the current VW/Audi small motor diesel scandal. Finally you have the last set of codes that maybe overlap the other two, and maybe suggest a vacuum leak.

None of this seems related to fuel pumps, but much off this stuff is located toward the back of the motor and on both sides. Makes me wonder some if someone poked around back there and maybe disconnected stuff or tore some things. In any case, the O2 codes to me are definitive and repair is in order, and something is up with your SAI. None of those should affect the running like you describe, but they would be a CEL light and a smog check fail. Thus should be fixed, but as your mechanic says would not solve your running related issue still. May make motor running somewhat smoother, and will end up as a smog test fail until addressed.

One other idea: when people with 4.2's have suddenly dying motors, the crankshaft position sensor comes to mind. Do a search on that. It will kill the motor and leave you stranded. Reports on it make it temperature dependent for some too, as opposed to your fuel tank level or running on the interstate. But that freeway running may be a proxy for a temperature condition that is triggering the sensor fault and then motor kill.

mishar

I believe your mechanic is right. Those codes, or faults they indicate, should not cause engine to stop. I would focus to pumps and plumbing there. If it happens only at 1/4 it could be related with transfer function of the right pump. When you push the pedal left pump kicks in and supply fuel. Check this. From page 34 is fuel system. Try to fit your symptoms in the fuel supply system. You know more than you are saying here. Just don't pay attention on pumps names. They are deceiving.