Air fuel ratios stay at 15. Stutters under boost.

No maf codes just a misfire code, vtcs solenoid low voltage. No vacuum leaks sits at 21 at idle. Air fuel ratios stay at 15 no matter what. Just replaced fuel pump that was going out but was having this problem before that. Clean maf with no change. Dont want to throw money at it. I searched all symptoms. Ill post all the mil codes once i get home. Any ideas?

Msp_tampa said:

No maf codes just a misfire code, vtcs solenoid low voltage. No vacuum leaks sits at 21 at idle. Air fuel ratios stay at 15 no matter what. Just replaced fuel pump that was going out but was having this problem before that. Clean maf with no change. Dont want to throw money at it. I searched all symptoms. Ill post all the mil codes once i get home. Any ideas?

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stuttering under boost? does it smooth out after a certain RPM or no?

if you have a misfire code, it is probably an ignition coil. try swapping the coils around and see if you get the misfire code on a different cylinder. I would also change the spark plugs while im in there.

it could also be an injector.

or, it could be a clogged cat limiting boost from exessive oil consumption or a rich condition.

It doesnt accelerate once any boost starts to build around 2300 rpms. Starts to shake and hesitate. Air fuel ratio dont change stays 14 - 15 no matter what rpm im at. Unplugged and cleaned maf no change. P0171 adaptive fuel trim too lean bank 1, p0300 multiple misfire, p2009 vtcs control solenoid valve circuit input low. Runs smooth at idle so i dont think coils or plugs are an issue.

Msp_tampa said:

It doesnt accelerate once any boost starts to build around 2300 rpms. Starts to shake and hesitate. Air fuel ratio dont change stays 14 - 15 no matter what rpm im at. Unplugged and cleaned maf no change. P0171 adaptive fuel trim too lean bank 1, p0300 multiple misfire, p2009 vtcs control solenoid valve circuit input low. Runs smooth at idle so i dont think coils or plugs are an issue.

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not necessarily, an ignition coil can misfire at high RPM or under load at low RPM, but can allow the engine to idle perfectly smooth.

however, you have a lean condition so i would check for vacuum leaks and inspect your o2 sensors.

code p0171

- Inspect all vacuum and PCV hoses, replace/repair as required

- Inspect all hoses and connections in the air intake system Inspect and/or test the intake manifold gaskets for leakage

- Check for a dirty fuel filter and proper fuel pressure

- Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool

- If you have access, you may want to run a smoke test

Read more at: https://www.obd-codes.com/p0171

code p0300:

- Faulty spark plugs or wires

- Faulty coil (pack) Faulty oxygen sensor(s)

- Faulty fuel injector(s) Burned exhaust valve

- Faulty catalytic converter(s)

- Stuck/blocked/leaking EGR valve / passages

- Faulty camshaft position sensor

- Defective computer

Read more at: https://www.obd-codes.com/p0300

code p2009

- Loose or binding intake manifold runners

- Defective IMRC actuator solenoid

- Bad intake manifold runner position sensor

- Open or shorted wiring in the IMRC actuator solenoid control circuit

- Carbon buildup on the IMRC flaps or intake manifold ports

- Faulty MAP Sensor Corroded IMRC actuator solenoid connector face

Read more at: https://www.obd-codes.com/p2009

good luck

i updated the list, please have a look again

Thanks for the help i really appreciate it. Im just going to take it into the shop. My diagnostic tools are limited to a basic scan tool and multi meter. Vacuum is at 21 at idle and 3in corksport catless, ssafc with a front mount w/ relocated maf and all the other supporting mods. Ive replaced about everything on the car but the block. Im gonna part it out and junk it once i get a truck in a few months.