Bogging No Power
OK so I have no history on above truck. other then a fuel pump and MAF sensor
This is what the deal is. it ill start up and idle with no issues. Put it in gear and it has just enough power to move If you feather the gas.
No load I can bring engine speed up to about 2500 RPM Above that it will start to sputter and die. Sometimes pop through the intake
No fault codes at all
Timing has been checked and is correct. Yes On the correct marks not the"T" mark
Checked cam and crank signals and are spot on with a know good image.
Both oxygen sensors are toggling as they should. Snap throttle and both sensors go rich.
Removed both oxygen sensors to check exhaust restriction and same result.
Installed vacuum gauge and have 18-20 In vacuum with a steady needle. As I open throttle needle drops as it should and stays steady when it acts up
Just checked both App and accel sensors and both are in spec. according to SI
What am I missing. This has a throttle body with a cable and a motor
Every thing i have found suggests timing Looking into ignition now.
Thanks in advanced
Mass air flow is reading about 6.5-7 grams per second which is a little high. Fuel trims are around minus 4 percent
I believe this uses A/F ratio sensors, not o2 sensors. Maybe someone can double check me on that. If so, they shouldn't be toggling at idle, also on the scan tool a lean condition should be high voltage, rich will be low voltage.
What are your fuel trims when problems happen? What are your fuel trims in gear with the vehicle stopped? Also what are your A/F sensor readings at idle in park and in gear stopped? Last what are the A/F readings while the problems happen?
Take a look at the rear oxygen sensors. What is the voltage at idle, and when the problem is present? Since this engine will not produce enough power to drive, the diag process must be done in the shop. Is there any chance you can get some gas analyzer numbers? If not, you are going to need to rely on the oxygen sensors for this information. There is another place to look though, Capture some…
What is your fuel pressure and volume?
Rich is low voltage. and voltage is between 0 and 5. Won’t switch like o2 sensor Try giving it a rev and spray some brake cleaner into the intake at the same time and see if it revs up then.
Check your fuel quality sounds like u have water in the tank !
Did we look into the Air filter Housing for uninvited guests? Fuel Pressure/ Volume
So it is a fuel deliver issue. If I spay brake clean in the intake when it start acting up it runs properly. I now remember why i did not do fuel pressure and volume. I can not get the lines loose under the hood. And there is no test port I can find. At least I know what direction I need to go.
We have found that removing O2 sensors to test restricted exhaust is not always a 100% accurate test. In cylinder pressure test would show timing and exhaust pressure? or at least back pressure .
You said you checked the cam and crank sensors and they are spot on , I'm assuming you meant cam to crank alignment, But did you check the cam and crank waveform amplitude during snap throttle and during the sputtering event ?
Try unplugging Oxygen sensor and see what happens..
As it’s had a fuel pump and maf sensor and assuming they are good oe quality then the condition and contents of the fuel filter would be high on my list to check. And if bad possibly the condition of the injectors Or fuel pressure and flow. Whatever is easiest to do first. Has it got a steel fuel tank and fuel lines?