Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hi my name is ***** ***** I will be happy to help with this today.I need a little more info to assist better.
Can you tell me the fault code numbers that are setting for the oxygen sensors?
Is the engine rattling at all when the lack of power occurs?
Let me know so we can continue,thanks Pete.
Were the catalytic converters removed and is the sensor wiring still in place but no sensors?
When you accelerate or rev up the engine does the fuel pressure drop off briefly then come back up or does it continue to drop at all?
O.k.,with the key off after the pressure builds to the 60 psi range does the pressure start to drop off on the fuel pressure test gauge rapidly or within a few minutes time?
O.k.,does your scan tool show the oxygen sensor data signals and if so are the pre cat oxygen sensors (bank 1 and bank 2 sensors 1) showing below .5 volt or below 500 millivolts and dropping as the issue occurs?
O.k.,the engine is running lean then and this is what these codes are indicating.I suspect this may be a mass air flow sensor fault with all that has been checked and done for this already.I have seen the mass air flow sensor act up and not set a code,this can be common.In some cases you can remove it then remove the screws that hold it together and remove the screen from it and use mass air flow spray cleaner from a local parts store and spray off the thin sensor wires on the inside of the sensor to correct this here.In other cases I have had to replace it.In some cases you can tell it is this sensor if with your key off you unplug it then start the engine and operate it very briefly to see if the issue still occurs.If it doesn't then the mass air flow sensor needs replaced.
If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete.
O.k.,it is best to take it apart if you can when you spray it to clean it so you can clean it off really good.Let me know if this corrects the fault here.
Yeah,if the injector or any of the injectors were an issue you would have a misfire.The engine is definitely running lean,it is possible all injectors are slightly restricted causing a lean condition if there was some kind of contamination in the fuel at some point or even now.You can try adding cleaner to the tank and see if it clears up.
Other then this I would think with the pump,regulator and filter being replaced already this leads me to believe the mass air flow sensor is at fault,there is a vacuum leak or possibly a timing issue.
When you rev up the engine I believe around 1500 to 2500 rpm stopping at each 500 rpm interval does it go over -20 at all?
O.k.,timing is o.k. then.
To me from here this does sound like a fault with the mass air flow sensor if there are no vacuum leaks and the fuel in the tank is good.
Your welcome.Let me know if you need anything else and feel free to rate my help if you don't mind.