Tail_Gunner

Nun your map sensor is showing .94 volts at 1600 rpm that's not right have you changed it at all?

nunnink23

Just got done taking the timing cover off. It's perfect. Not going to be easy to put this back on now.

I'm just in disbelief. I really don't even believe the Injextors are the problem. Idk wtf is the problem now. All my scan readings came in good right?

nunnink23

Yes. I swapped it back and forth with the old one too. could that indicate a vaccum leak?

Arent map sensor readings inaccurate when the engine has the wrong mixture? I'm still positive it's running lean. And I think you get high pressyre with lean right? Low volts = high pressure? Or te other way around?

SB

If the engine, or when your engine, runs okay at idle, the vacuum will be near o at normal. So check it when warm and running okay.

It really is too bad EFI marine engines don't have wideband 02's...much easier to locate vacuum leaks, false air, etc when you can watch fuel trim levels.

nunnink23

Those reading were when the engine was warmed up, and idling smoothly.

Can I buy an AFR gauge? I mean I really just don't know what to do. It's 100% a fuel problem now. We removed all doubt.

SB

I still rest my case.

SB

That may or may not help.

What I was saying was The WBo2 and modern automobile computers will 'talk' and show you what it's trying to adjust outside of the factorry progaming. The specific item I'm talking about is fuel trims, which is in a % +/- over what the computer progammming is. Helps you see if there is a false air leak or vaccum leak and with the use of propane or etc see this change real time when watching the fuel trims live, and narrow the issue faster.

BUP

Are you sure that the float and level of fuel in the cool fuel section is working properly - Do you have fuel in the vent line out of the cool fuel line going into the throttle body spacer ?

when engine running if you unplug TPS connector what happens to the engine running conditions and if no change rehook connection ?

next If MAP signal voltage is low - unhook connectors from ECT and TPS - since MAP and ECT and TPS share common circuits - did the engine change running conditions for the better - if not ECT and TPS most likely not the problem.

next install a vacuum to a correct manifold vacuum source - start engine what is your vacuum readings

Next with scan connected to the DLC - have ignition OFF , remove MAP connector at MAP sensor - jumper together harness terminals very carefully B and C - then turn ignition ON is the MAP sensor reading now above 4 volts - IF SO - checked for leaking sensor vacuum fitting or its plugged - if none of this and all okay - you have a faulty MAP sensor.

The MAP sensor responds to changes in manifold pressure - vacuum. The ECM receives all of this info as a signal voltage that will vary from 1 to 2 Volts MAX. (Actually 2 V is a tad on the high side) when the throttle plate is closed idle - idle is high vacuum and WOT is low vacuum. Signal voltage of MAP at WOT should be 4 to 4.9 volts.

If a bad MAP sensor or fails - the ECM will sub a default MAP value that will vary with RPM. MAP sensor is a 5 volt reference and is delived from J2-4 to the MAP sensor connector termainal C. J2-3 is the ground circuit for the MAP sensor A terminal. The MAP sensor B terminal will send Voltage to terminal J2-27 of the ECM according to manifold pressure.

These are good test to see if all of this is working correctly.

BUP

forget this, scan tool hooked to DLC. ignition OFF unhook MAP connector - turn ignition on BUT DO NOT START ENGINE.

Is MAP sensor voltage less than 1 volt ? if NO possible short in circuit from ECM J2-27 to MAP terminal B. If all of that is good and no corrosion - resistance - or short then possible bad ECM connection or POSSIBLE BAD ECM.

BUP

To double confirm / check

Ignition back to OFF

again connector off at MAP sensor. Connect a DVOM to the harness terminals A & C - then turn ignition ON but do not start. Is the MAP sensor reading now above 4 volts ? if yes the again check for plugged or leaking vacuum fitting. If all good there then replace MAP sensor.

If your reading is below 4 volts possible open in the circuit from ECM j2-3 to MAP terminal A - if all of that is in great shape - no corrosion, no resistance, no breaks or shorts then POSSIBLE BAD ECM connections or POSSIBLE BAD ECM.