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

[redlowrey]

Tacko is the rev counter it may be sending over revving data to the computer which is wrong, disconnecting the temp sensor will tell me if the computer is in control, make the check engine light come on and substitute a value for the sensor, I am trying to see if the computer is controlling the rpm stopping it going higher. Now that you have said that you can see that the throttle is wide open I am thinking the the computer is controlling the rpm because there was plenty of fuel injected to make the rpm go to the rev limiter. the computer controls spark as well.

The reason I want you to spray some carbi cleaner into the throttle body is to make sure the engine will go over 4000rpm. I am not saying it could be the neutral switch just a slower version in the changing rpm than the neutral switch normally does when it is faulty, If the rpm shoots up over 4000 rpm when spraying carbi cleaner into the throttle it will tell me that the computer is not controlling the rpm to 3000.

If you had a fuel restriction and the throttle was in the wide open position there is no way it could duplicate that problem of reving to 2500rpm and then back to idle and keep idling impossible. Different story if it was a direct injected engine

[go2ski]

If the engine was going into fail safe and it was substituting a value for the map sensor that could make the value change even with the throttle wide open, but there are no lights indicating that, disconnect the tacko and try it, then pull the wire off the temp sensor, the computer should bring the light on and substitute a value for it, same with the exhaust temp sensor. Try this also with the engine running and the throttle in the wide open position as it is running spray some carbi cleaner into the throttle plate and the rpm should shoot straight up.

It just sounds like a slower version of a failed neutral switch problem.
,

Could you explain this a little further what’s the “tacko” and what’s the purpose of unplugging the sensors. Also what do you mean by the last comment could it still be the neutral switch?

[redlowrey]

Don't replace it yet something does not add up here, on your sds with the engine in the water at for ten second there is plenty of fuel being injected into the engine with the throttle in the wide open position it should have went straight up to the rev limiter. what I can't fathom is how the engine can idle with the throttle wide open.
It is impossible for the manifold vacuum to start heading back to the idle measurements with the throttle in the wide open position.

If the engine was going into fail safe and it was substituting a value for the map sensor that could make the value change even with the throttle wide open, but there are no lights indicating that, disconnect the tacko and try it, then pull the wire off the temp sensor, the computer should bring the light on and substitute a value for it, same with the exhaust temp sensor. Try this also with the engine running and the throttle in the wide open position as it is running spray some carbi cleaner into the throttle plate and the rpm should shoot straight up.

It just sounds like a slower version of a failed neutral switch problem.
,

[go2ski]

redlowrey the throttle does indeed open all the way I took off the intake and looked. I’m not sure if I have the proper equipment to test the map sensor I might just replace it tomorrow if it’s cheap enough.

[redlowrey]

listening to the audio the engine revs evenly to a bout 2500rpm and then back to idle with the throttle in the wide open position, the manifold vacuum is at absolute 29in hg, or 4 volts on the map signal line, it should be still injecting the same amount of fuel as it was at,34 seconds but is doesn't. With the throttle in the wide open position the map sensor signal voltage should be stuck on 4 volts and only change as you change the position of the throttle.

I want you to tell me that you can physically see the throttle plate sitting in the wide open position when you are doing the wide open throttle test, something is not adding up, The map sensor signal voltage will be jumping from 4 volts to 1 volt back to four volts instead of staying at 4 volts with the throttle wide open.

[redlowrey]

Ok looking at the sds, in the water I can see that at 35 seconds you go to wide open throttle looking at manifold vacuum, injection pulse width12ms, 34mcc, then at 45 seconds injection and vacuum starts to change and at 51 seconds nearly back to idle injection and manifold vacuum, how can that be with a wide open throttle.
Your engine has a hose connected to the map sensor make sure the hose has no restrictions or cracks and make sure the little hole in the manifold is not restricted.

Check the operation of the map sensor it has three wires power, signal and ground, at idle signal voltage around one volt, wide open throttle around four volts.

[go2ski]

ECU1984 In the water it runs as it would if you wanted it around 3000 rpms, out of the water it sounds perfectly fine when in wot.

[ECU1984]

Is it starving for fuel when wot?
Would fuel pressure gauge tell us?

[go2ski]

So for some reason now it runs fine out of water and when put in the water something is limiting the rpms again. I have recorded the engine service data in and out of water switching gears. I have put timestamps in the video to help explain because there is no audio. I have also recorded audio of the engine the best I could out of the water.
Engine out of water
Engine in water
Engine Audio
Also when the engine was in the water it would sometimes die when switching gears.

[go2ski]

I have checked all fuel lines and the fuel definitely has pressure and spark plugs are new. The oil is fine I check that too and the oil pressure switch is new. The regulator & rectifier is fine I tested that and the IAC valve is new. Most of the stuff I replaced had lots of corrosion and/or it was giving errors. When I plugged the computer in the other day it showed the neutral switch going on and off I’m not sure if that completely means it’s working though. I will post the service data with it in gear today. The engine does not backfire when it runs in gear just bounces between 2800-3000 rpm like when you hit your rev limit on your car.

[Moonlighter]

I guess I am still suspicious about the switch Red!

Im not aware of too many other conditions that dont throw a fault code that would be stored on ecu that would limit rpm to about 3000rpm? Especially if things like spark plugs have been changed and fuel flow/pressure verified to be OK. Not sure if he has addressed those issues though?

The only other thing I can offer apart from your suggestion re throttle not fully opening is a low voltage issue to the ecu - not long after I added NMEA2000 interface to my engine, we had the intermittent issue with no acceleration past 3000rpm on occasion, and it turned out to be a false low voltage signal somehow caused by the interface connection to the ecu that threw it into safe mode and limited rpm. It felt very doughy even below that rpm. Re-routed power supply for the interface cable to a different source as per the Service Bulletin they subsequently issued, problem solved.

So perhaps there could be a bad wiring connection to the ecu or something? Bad white wire?

[redlowrey]

The hunting coming from the engine is so obvious from a failed neutral switch when the rpm is over 2.500 you could not mistaken it surely. The impression I am getting that it runs to 3000rpm when the shifter is all the way forward and the engine runs okay, which is impossible if the throttle plate was in the wide open position and was only injecting enough fuel to run at 3000rpm, it would lean out back fire and stall.

I think his throttle plate is opening less than half way, unless he can't pick the hunting action from the computer switching the injectors on and off. I understand that you think he is in neutral while he has the throttle wide open I told him in post 7 to have it in gear when tying it.

[Moonlighter]

Just a reminder that if the engine is in neutral the ecu will limit rpm to about 3000rpm, it will be like a race car on the pit lane limiter, it will miss and fart and run bad if you push it to that limit.

[go2ski]

redlowrey when I put it into full throttle it hit 3000 rpms and it was kinda bouncing between 2800-3000 rpms without me moving the throttle. I’ll check the throttle plate as soon as I can and put screen shots up.

[redlowrey]

Have you actually checked and made sure the throttle plate is in the wide open position when the shifter is all the way forward, because if the computer was limiting the fuel and the throttle was wide open you would hear the engine struggling with too much air and not enough fuel, for the engine to run ok at 3000 rpm with a supposed wide open throttle does not make sense. Put up a screen shot of the sds with the throttle wide open.
There is no way the engine can run fine at 3000 rpm unless the throttle plate opening and the amount of fuel were matched, if the computer was only injecting enough fuel for it to run fine at 3000rpm when the throttle is opened to the wide open position it would die. Your throttle plate is not going to the wide open position, pull the cover off and check it.