Suzuki DF60 2004 Won't go above 3000 rpms No error codes

[go2ski]

Okay I’ll look at the wires and also find a new map sensor. Also if the connection is bad and messing with it doesn’t help, would I have to replace the whole harness or could I replace that wire.

[redlowrey]

Don’t waste 300$ on a map sensor till you fix the sensor ground problem first, it probably won’t be needed. Make a temporary wire with an alligator clip on one end and solder a thin needle on the other end and connect the clip to battery neg, and slide the thin needle beside the sensor ground terminal on the map sensor and see if the signal wire white goes to 4 volts with the key on and start the engine and try it.

You may be lucky and there is only some corrosion on map sensor ground at the terminal block, multiple sensors use signal ground and it terminates I think on pin 11 at the computer

[redlowrey]

Hang on I just read your post again, did you change the voltage scale when when you went from the five volts on the red wire to checking the ground. Voltage.

[redlowrey]

So is it 1.8 volts or 1.8 mv if it is 1.8 mv forget about the jumper wire I have miss read the reading.

[go2ski]

It was 1.8 mv

[redlowrey]

Ok I have miss read the voltage and that reading is fine, forget about running the jumper, I would have removed the sensor and checked it on the work bench to be 100 percent sure , you haven’t got that luxury.
There are a couple of things that just don’t add up but definitely the low signal voltage is wrong with key on engine off, put a sensor in it and we will find out.

[go2ski]

I used another map sensor I borrowed same type from same engine and it gave me relatively same voltages when testing it with the hose off and didn’t change anything.

[redlowrey]

I had a gut feeling it would not fix it, see if you can borrow a computer, something has failed internally keeping the signal low.

[redlowrey]

Or you disconnect the plug from the computer and the map sensor and do an ohms test on the signal wire at the computer to the map sensor plug to see if there is high resistance in the wiring.

[go2ski]

I read the manual on testing the resistance on the harness and it didn’t say much about the map sensor so I tested the resistance of terminal 29 the map sensor to terminal 11 ground for sensors and got 1880 ohms which seemed way more than any of the other sensors. Just to make sure I tested the CMP sensors resistance and it fit within the range it said on the manual.

[redlowrey]

There should be no resistance between pin 29 on the computer plug disconnected from the computer and the map sensor plug white wire disconnected from the map sensor.

Sensor ground is a shared ground with other sensors. The white signal wire comes out of the computer to the map sensor, so it should have zero ohms on it testing it with the computer plug disconnected and the map sensor disconnected.

What I can’t work out is you get no change in that signal voltage what ever you do, yet I can see it changing on your sds and the computer can sense it when you disconnect the map hose.

[redlowrey]

I was originally going to get you to check all the voltages at the computer, that is where I check everything but I thought you may struggle with the pins because if you are not careful when you slide the needle past the pin if you push too far you will touch other circuits.

Now I know you know where pin 29 is check the voltage there with key on engine off and note the voltage.

[redlowrey]

You are at sea level aren’t you, not high up in the mountains. I did state you should see 4 volts at sea level.

[redlowrey]

What does not make sense with this problem, you say there is no voltage change on pin 29 signal wire no matter what you do, the computer must be sensing something because I can see the changes on your sds, I can see when you put it into gear engine running in the water, and I can see when you open the throttle and the manifold vacuum drops and injection increases and rpm increases to 2400 rpm, then I can see the manifold vacuum increase and injection decrease with the throttle in the wide open position.

You don't see a change in voltage, but if you remove the vacuum pipe from the sensor, the check engine light comes on when you start it, detecting a map sensor 2 code for an unchanging voltage, listening to the motor running you might think it has a fuel restriction but no port fuel injected engine could run like that with the throttle plate in the wide open position, plus if it was a fuel restriction on the sds with the throttle plate in the wide open position the manifold absolute pressure would be near 29 in hg and the injector opening time and amount would be at it's max, but it drops back to the part throttle delivery with the throttle wide open.

So if the wiring on pin 29 is fine, when you turn the key on, the computer is measuring the barometric pressure, the computer must be sensing some absolute manifold vacuum change and voltage change on pin 29, the map sensor circuitry in the computer must be failing. The reason the engine runs better out of the water is it only needs a fraction of the fuel it needs when it is in the water under load, that is why the rpm is higher.

I can't think of anything the computer would do to only allow 1.8 volts on that wire that should have around 4 with key on engine off. I cant get my head around how the engine runs when you are looking at the sds, it looks like the throttle is opening and closing, but going by the video the throttle is wide open.

[go2ski]

Pin 29 and the white wire pin for the map sensor have no resistance. When I test the voltage am I back probing pin 29 and putting the other multimeter wire to ground. If so it gave me around 1.7 volts. And yes I’m at sea level.