A while back I had a local mercruiser garage to take a diagnostics on my engine.
It's a 4.3L MPI 220 HK 2003 mod in a Bayliner capri.
I had a problem with the engine being difficult to start, the cranky was fine, but it would often stopp abruptly when it got ignition.
I had checked that gasoline pressure, nozzles and ignition were working.
I told you about checks I had done earlier, like disconnecting different sensors and that it didn't seem to matter on engine performance.
I was just told that I should leave it as it was originally and not think about it any more.
When I returned after making the diagnosis, the answer was that I needed a MAP sensor and a cooling water pressure sensor.
But from what I have read, an error on the coolant pressure sensor typically puts the engine in "Limp mode" and does not make it difficult to start.
When I returned to the boat to check the engine, several of the pistons were full of salt water.
So it was the condition that the engine was left in after 2.5 hours of diagnostics.
The conclusion from the diagnosis was that the engine starting problem would be solved by buying these two sensors.
I installed the two new sensors, but still the same problem.
I went to get to the problem, and long story short, it was a bad grounding to the MAP sensor that led to the ignition timing to be very "advanced" during the cranking which then caused the engine to start the opposite way and suck in water from exhaust.
So the 1200 dollars I paid for diagnostics and sensors resolved very little of the engine problem.
Instead, I risked sitting with a broken engine if I hadn't emptied the cylinders shortly after.
Now I'm back to a problem that had for the last 2 years before this event. The problem is that the engine stagnates at about 4000 RPM under WOT when driving (5000 RPM at WOT in free) with the MAP sensor plugged in, while the engine is running at 4500 RPM at WOT when MAP is disconnected.
The acceleration is bad without MAP but come still it reaches closer to the max speed it had previously.
By the sound, it sounds like it is the same rev limiting mechanism that holds it within 5000 rpm when free, as the one that holds it within 4000 rpm when in drive. I have tested different trim tilts and propellers, to the point where the propeller is almost free spinning. Still the rpm limit in drive is quite constant.
I would have liked someone to look at it, but have to say I'm a little lost to see who I can trust to solve this problem.
I hope this is something someone here may have the opportunity to find an answer to?
Current status is that I have now changed all the sensors, except the crank shaft sensor. I have checked this sensor with oscilloscope and it looks like the readings are fine.
plugs, cables, distributor cap are also changed.
It's a 4.3L MPI 220 HK 2003 mod in a Bayliner capri.
I had a problem with the engine being difficult to start, the cranky was fine, but it would often stopp abruptly when it got ignition.
I had checked that gasoline pressure, nozzles and ignition were working.
I told you about checks I had done earlier, like disconnecting different sensors and that it didn't seem to matter on engine performance.
I was just told that I should leave it as it was originally and not think about it any more.
When I returned after making the diagnosis, the answer was that I needed a MAP sensor and a cooling water pressure sensor.
But from what I have read, an error on the coolant pressure sensor typically puts the engine in "Limp mode" and does not make it difficult to start.
When I returned to the boat to check the engine, several of the pistons were full of salt water.
So it was the condition that the engine was left in after 2.5 hours of diagnostics.
The conclusion from the diagnosis was that the engine starting problem would be solved by buying these two sensors.
I installed the two new sensors, but still the same problem.
I went to get to the problem, and long story short, it was a bad grounding to the MAP sensor that led to the ignition timing to be very "advanced" during the cranking which then caused the engine to start the opposite way and suck in water from exhaust.
So the 1200 dollars I paid for diagnostics and sensors resolved very little of the engine problem.
Instead, I risked sitting with a broken engine if I hadn't emptied the cylinders shortly after.
Now I'm back to a problem that had for the last 2 years before this event. The problem is that the engine stagnates at about 4000 RPM under WOT when driving (5000 RPM at WOT in free) with the MAP sensor plugged in, while the engine is running at 4500 RPM at WOT when MAP is disconnected.
The acceleration is bad without MAP but come still it reaches closer to the max speed it had previously.
By the sound, it sounds like it is the same rev limiting mechanism that holds it within 5000 rpm when free, as the one that holds it within 4000 rpm when in drive. I have tested different trim tilts and propellers, to the point where the propeller is almost free spinning. Still the rpm limit in drive is quite constant.
I would have liked someone to look at it, but have to say I'm a little lost to see who I can trust to solve this problem.
I hope this is something someone here may have the opportunity to find an answer to?
Current status is that I have now changed all the sensors, except the crank shaft sensor. I have checked this sensor with oscilloscope and it looks like the readings are fine.
plugs, cables, distributor cap are also changed.