HPDI 200 - how smooth should it run at low RPM?

SoLucky

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I know the HPDI V6s run as a V4 at lower RPM to minimize fuel consumption. That's all fine and good, I guess. But my outboard is decidedly unsmooth when in V4 mode and in gear. Idle in neutral is OK, but when in gear and running slow between 600 & 1200 RPM it shakes noticeably and sends vibrations throughout the boat. Once the RPMs come up to 1300+ things begin to smooth out and then from 1600 on up it is awesome (smooth, powerful, puts out a nice growl, and really moves the boat). So my question for those of you more experienced than I with these HPDI motors -- is this normal and something I have to live with or should the engine run relatively smoothly in V4 mode with little or no shaking felt forward at the helm?
 

co1063

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as far as i know the hpdi only cut off cylinders when in neutral once in gear all cylinders fire i have twin 200 hpdi n love them
 

seasick

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I assume the motor is in the water and not on muffs.....

There are several things that can cause roughness but it's not all that easy to identify the specific cause. I have a few thoughts; if your motor idles at 600 revs, that may be too low but don't adjust right now.
The fact that is runs smoothly at 1200 is a clue because that is where all cylinders kick in. That can eliminate 2 cylinders as the culprits. I am not 100% sure what cylinders deactivate on the HDPI. On mine I think the lower two deactivate.
So now we look at what can cause the roughness in those 4 cylinders.
The first test is to removed the plug wires on the working cylinders, one at a time and see if the motor gets rougher. It should for each cyl. If you pull a plug wire and the motor doesn't get rougher, that cylinder is having a problem, probably spark or gas.

A cylinder could be getting spark but intermittent gas. In the first case a coil could be bad. In the latter case an injector could be sticking, clogged or not working at all. If you get a plug tester that connects inline with a plug wire and had a lamp that flashes, you can look for consistent spark at idle. You can get a really cheap tester at Harbor Freight.
It is also possible to kind of check injectors by holding a screwdriver on the injector housing and pressing your ear on the other end of the screwdriver. They also see stethoscopes with pointed ends to do the same thing. You should hear a regular clicking as the injector gets triggered.
If you have a bad coil, it is more obvious at lower speeds since 1 out of 4 cyls is not working. As you rev up, that becomes one out of six and the only symptom might be a drop in WOT revs.

So do the 'pull the plug wires" test, and go from there. I suggest that you loosen the wire at the plug first and lightly insert it. Then use an insulated pliers or the like to pull the cable with the motor running. That will reduce the chance of you getting zapped:)
Good luck.
 

co1063

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at idle in neutral cylinder 3 which is middle cylinder on starboard side and cylinder 2 which is top cylinder on port side do not fire. once in gear all cylinders should be firing even at idle. youtube hpdi cylinder deactivation and check it out
 

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the Throttle position sensor voltage is critical, as well the o2 sensor housing needs regular cleaning, depending on oil type used they can build up enough carbon that the o2 sensor becomes blocked and doesn’t read properly. you really need the yds software to interface the ecm to read sensor voltages. I bought it online fairly cheap along with hpdi manual and you can look at a lot and learn a lot about the hpdi.
 

SoLucky

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Thank you all for the very helpful answers!

It's good to learn that it should run as a V6 once in gear, although I was pretty sure (based on reading elsewhere) it stays V4 even in gear up to a certain RPM and then goes to V6 mode. Either way y'all have confirmed that I have a problem of some sort. Now to figure it out and fix. I do have YDS, so I'll give that a try. And I found a thread on another site about the TPS voltage and will look at that as well as make sure all 6 throttle butterflies are properly synchronized.

Could it be that some butterflies are not closing all the way (at idle) or open faster or slower than they should as throttle is slightly advanced off idle and cause fuel mixture issues in one or more cylinders?

I will also do the preventative maintenance on the O2 sensor, but can someone educate me on how to clean it without causing damage? I read mention of a map gas torch but haven't found clear instructions and would hate to ruin a $300+ part.

And Seasick I will verify spark as you suggest.
 

seasick

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Be careful using a map torch. You can overheat the sensor. That said, you don't need heat to clean the O2 sensor. You can soak the tip of the sensor in a jar with Ring Free or even brake cleaner. Do not completely submerge the sensor tip, only just past the slots. Let it sit for an hour or so and wipe off.
To test, use a multimeter on the sensor leads ( the smaller gauge wires) and carefully heat the tip. A propane or butane flame is OK. You are looking for some voltage output as the tip heats up.

While you are at it, connect the multimeter in ohms setting across the two thicker wires. They are the preheater leads. You should see resistance, zero resistance means the heater coil is open and the sensor needs replacement. A bad heater will cause improper operation of the O2 sensor when the motor is cold and/or warming up. Once hot enough, it doesn't matter.
 
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bartoma

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Thank you all for the very helpful answers!

It's good to learn that it should run as a V6 once in gear, although I was pretty sure (based on reading elsewhere) it stays V4 even in gear up to a certain RPM and then goes to V6 mode. Either way y'all have confirmed that I have a problem of some sort. Now to figure it out and fix. I do have YDS, so I'll give that a try. And I found a thread on another site about the TPS voltage and will look at that as well as make sure all 6 throttle butterflies are properly synchronized.

Could it be that some butterflies are not closing all the way (at idle) or open faster or slower than they should as throttle is slightly advanced off idle and cause fuel mixture issues in one or more cylinders?

I will also do the preventative maintenance on the O2 sensor, but can someone educate me on how to clean it without causing damage? I read mention of a map gas torch but haven't found clear instructions and would hate to ruin a $300+ part.

And Seasick I will verify spark as you suggest.
One thing I ran into a coupe years ago was that the switch that detects neutral would intermittently get stuck... So, I would be in gear, running on four, and when I advanced the throttle, that engine ran slow and weak (obviously)... Was a simple fix, but something to be aware of...

I highly endorse getting the manual and the old YDS software - this will give you (or your mechanic) a good deal of insight into how the engine is running...
 

Fishtales

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Are you running Ring Free in the mixture? I've had good luck with Seafoam on 2 stroke motors cleaning the carbs out. Also ran it in the oil and fuel of a few GDI vehicles to clean as well.
 

SoLucky

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Fishtales: Yes, a proper dose of Ring Free Plus goes in every time I add fuel.

Glacierbaze: Excellent info on the O2 sensor. $29 via Amazon Prime so I ordered one -- splicing the Yami plug onto it (and saving $300 in the process) is a task I will enjoy.

Bartoma: I do have YDS on an old laptop, just didn't have it with me when the engine was running rough... I'll bring it along on my next trip and check all the parameters. I have an electronic copy of the Z200 workshop manual... I'll start studying that tonight!
 
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DennisG01

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The OX66 drops #5 between about 700-1200 rpm, then #5 and #2 from 1200 to about 2000. I could be off a tiny bit on those RPM's, but that's the jist of it. It's strange that the HPDI would be different - I "thought" the main difference was just direct injection as opposed to EFI?
 

seasick

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If, indeed, the HPDI does engage all 6 when put in gear, is it the same technology on the OX66?
I don't think my SX150, OX66 works the same. As far as I know, it drops 2 cylinders at idle. I remember testing that with a spark tester. I also don't think there is a neutral switch on the shift linkage on the motor itself. I am going to look at the service manual later to see if my memory is correct (lately it's been spotty)
 

SoLucky

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I finally had a chance to work on my engine and hook up YDS. TPS voltage was 0.64V with throttles closed. I adjusted it to 0.5V as the service manual specs. Was it off enough to cause rough running at low RPM and in gear?

Now at wide open throttle TPS reads 4.0V which YDS says is 79 degrees for the throttles. Does that wide-open voltage sound right?

Also the shift switch is “on” in neutral or forward. In reverse the switch reads as “off”. Is that correct?

Sadly I didn’t have time to run It, so I don’t know if resetting the TPS has made a difference.
 

seasick

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Voltage sounds OK, the more important check is that the voltage changes smoothly during rotation.
As to the neutral switch question, I thought that the switch is activated when the gears are in neutral. I am not sure if that is an open or a closed electrical state but I don't think that fwd and rev should be different. As I remember, there is a 'cam' like spot on the shift linkage that activates the switch as the level goes through neutral
 

DennisG01

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Are we talking about the switch that prevents the engine from starting in gear?

Or the one that is used to help "release" the engaged gears when shifting back into neutral (I think Yamaha uses something like this... other manufacturers do).

If it's the first one, then it sounds like you'd be able to start the engine in Fwd, which is obviously wrong. Try it out.
 

SoLucky

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Are we talking about the switch that prevents the engine from starting in gear?

Or the one that is used to help "release" the engaged gears when shifting back into neutral (I think Yamaha uses something like this... other manufacturers do).

If it's the first one, then it sounds like you'd be able to start the engine in Fwd, which is obviously wrong. Try it out.

I took the boat out today and it runs better now with the TPS voltage calibrated and the butterflies synchronized. Still kind of a loping idle, but smoother than it was and no hunting/surging. Next up will be the O2 sensor and housing -- I'll clean those up good and may swap to the new sensor I bought if the current one is too dirty. My last two Yamahas have been four strokes, so I'm used to a quietly purring engine and a smooth idle... so maybe I just need to get used to the 2-stroke idle?

I also tried to start in both forward and reverse and it wouldn't crank, so the neutral switch is good. Overall it runs very well. 4 people on board, ice & drinks, with light chop and running into a 14 mph wind we topped out at 38 mph at 5100 rpm with engine trimmed up most of the way. Running back with the wind and waves we hit 41-42.
 

seasick

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If you pull the O2 sensor, also pull the spool thimble that is in a hole in the cylinder wall where the gasses from the combustion flow to get to the O2 sensor. They tend to clog up, especially earlier models.
The new part has a different shape to the barrel.
 

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Definitely check the O2 sensor and O2 Sensor Draw Tube. I have found that this is the culprit of my idle issues and cold start issues when the carbon has built up and starts to clog the air flow.
I have tried everything to reduce the carbon, but now down to each season, do a Seafoam decarb, pull the O2 sensor and clean out all the carbon, soak the parts overnight, except the O2 sensor itself, must be careful not to damage it. When put back together, starts perfectly and idles right at 700rpm like it should.