Help mercruiser 4.2L D Tronic wont rev past 2500rpm under load

[wetspot]

the engine is a Mercruiser 300hp 4.2L VM D-Tronic inline 6 cyl diesel engine

I have had this engine fitted for 2 years and spent a lot of time and money to get it fixed, but it still wont rev past 2500rpm under load, no one seems to know anything about it , since the engine was fitted it has had a brand new loom & harness, new sensors all round, new #1 injector, re-built turbo (as the turbo bearings had failed and veins were scraping the housing). new wastegate valve (as the old one had seized and badly corroded) , new ecm Bosch part number0 281 014 229 (engine was bare engine which had sat at Barrus (uk importer at the time) for a couple of years) , but it still wont go past 2500 rpm, it is fitted in a 1991 Bayliner 2556 command bridge (gross weight with fuel & water 4.2 ton) 9'6" Beam,with a brand new Bravo diesel X 2:1 ratio, origionaly fitted with 22" props, re-fitted with 20"props and no change at all, and has had a new stainless steel fuel tank made (no contamination), I have had the engine read with the diagnostics tool on several occasions and no faults are present (Rinda), and no warning light has come on (brand new dash and gauges), after I reconditioned the turbo, the top speed increased from 7mph to 9.8mph, with the Rinder attached and under load the engine runs fine upto 2500 rpm and throttle position sensor is showing correct position upto that point but as soon as it reaches 2500 rpm the engine wont increase but the throttle position sensor continues upto 100% in line with the throttle position, engine idles at between 600 and 800 rpm, flywheel rpm is same as tacho, no problem there, when I disconected both fuel feed and return (fuel lines are diesel suction fuel lines wo they wont colapse,with internal diameter of about 10mm) from the fuel tank and run the engine from a 5 gallon drum (at same height as the engine and at 1 metre distance from lift pump) at 1000 rpm in neutral fuel return was about 1 litre every 2 mins, when at 2500rpm return was less than this, when in drydock (with water attached) engine will run both in neutral and gear throughout the engine range with no problem, the engine dosn't apear to be strugling at all, but apears to be running in limp mode as far as fuel is concearned, I have just replaced the lift pump, still no change, since the engine was fitted, the battery light has been on (on the dash) but the battery is charging fine and the dash volt meter is also fine, could this be the problem? as the workshop manual states if a reading of bellow 9volts is read by the ecm the injectores dont open fully that is I assume limp mode and the Rinda tool still wont pick up any codes, I have just tested the alternator as per manual tests, it tested ok, as for the battery light, this turned out to be an issue with the split charge relay, now resolved, this is very frustrating as nobody in the UK (Cummins Mercruiser) US EU seems to know anything about these engines, so far I have contacted J Omalley in the United States (mercruiser), Thierry Hardouin (cummins mercruiser) in France,David Jonson (Cummins mercruiser) UK, and several other dealers and technicians worldwide, and still no one seems to know anthing about this engine, please help as Cummins technicians only apear to know about the common rail engines,I have spoke to the nearest dealers to me, most recently Windermere Aquatic, who when questioned wheather they could attend the boat replied 'sorry, no your too far away and were too bussy' when I contacted the other nearest dealers (Conwy and Anglsey) some time ago the stated I was too far away.

The boat is in Fleetwood Marina, Lancashire, but can only be tested (under load) one hour either side of high water, which just makes things even more frustration.

I took the time to take some readings of the Rinda tool today whilst under load at 2500rpm and these are as follows

ECM REF 2.49 VDC
TPS SUPPLY 4.98 VDC
TPS VOLT 3.06
MAP 4.96
MANIFOLD 27 HG
MAX INJECTION QTY 35.5 MG
ACCELERATION INJ QTY 75 MG

Does anyone have any ideas, as I have run out??

I have removed the ECM/ECU which I have sent to a guy up north to test on his 300 D Tronic, and to speed things up, he is sending me a spare 250hp ecu to try, failing that with no Cummins engineers to help, he has also offered to come to the boat to strip the timing cover of and check the timing and get the diesel injector checked as well, has anyone got any idea?
also, has anyone experienced any engine running issues with split charge relays fitted?

 

[spannerman]

I am suprised at Mercruisers response as there are lots of these engines out there and its the same basic motor as the new common rail units.
Have you had the injection pump off?, if so is it timed up correctly.
Next have you checked the boost pressure while running at full throttle, it should be 1.1 bar.
It could be too low, which is easy to adjust with the hex screw on the end of waste gate housing , we had the same motor with the same problem straight from the factory, and another workshop spent hours checking for blocked intercoolers and exhaust etc and all it needed was a trip on the sea with a manometer connected to the tapping on the inlet manifold and I sat in the engine room and adjusted the screw till it read correctly and the boat flew after that.

 

[Latestarter1]

Wetspot,

A very comprehensive posting, however I have may have missed any report of a 'High idle' test. You mention under load a number of times, but nothing I can see at no load.

Do you have access to a Rinda tool for a high idle test? Spec is 3,875 plus minus 50 rpm.

I see you have already replaced #1 injector which has the needle lift sensor, not sure why. The test for a failed needle lift sensor is engine revs limited to 1,500 rpm out of gear however Rinda tool does not always flag this fault, but obviously stands out a mile. This coupled with switching ECU's is not symtomatic of disiplined approach to trouble shooting. I do not think that the 250 used the needle lift sensor therefore pointless trying another.

Sadly Barrus technical support was at best poor and Cummins had nothing to do with early VM D Tronics.

The turbo problems give me a small clue. However post your high idle figures before you rip into anything else.

 

[wetspot]

Hi, yes I have a Rinda tool, but what is the high idle test?, the engine will rev in neutral all the way, but when in gear flys upto 2500rpm them wont go any further

as for checking the ecu, I have to cross it of the list, as the next job is to strip the timing cover and check timing (and test injector pump)

 

[kdtran]

Hello!

Have you checked the MAP sensor temperature readings?
A few years ago, whilst working as an employee of Brunswick Norway, one of my customers experienced the same behavior on his 4.2ES250.
Engine would not rev over 2500rpm when under load, but reved freely to 3900rpm in neutral.
It turned out that the map sensor temperature readings were way out, showing values that were no way near the actual intake manifold air temp, thus confusing the ECM.
This fault gave no alarms.
Worth checking at least, as it is easy to check using RINDA.

Good luck! /forums/images/graemlins/ooo.gif

 

[wetspot]

[ QUOTE ]
Hello!

Have you checked the MAP sensor temperature readings?
A few years ago, whilst working as an employee of Brunswick Norway, one of my customers experienced the same behavior on his 4.2ES250.
Engine would not rev over 2500rpm when under load, but reved freely to 3900rpm in neutral.
It turned out that the map sensor temperature readings were way out, showing values that were no way near the actual intake manifold air temp, thus confusing the ECM.
This fault gave no alarms.
Worth checking at least, as it is easy to check using RINDA.

Good luck! /forums/images/graemlins/ooo.gif

[/ QUOTE ]

what was the solution? it's had a new map sensor fitted

 

[wetspot]

how far out were the readings?

 

[kdtran]

Solution was to change the map sensor.
Readings were out by 40 - 50 deg C and fluctuating as far as I can recall.
These engines are in my experience very reliable, but as their electronics are relatively "simple" in comparison with e.g a common rail engine, fault finding can be a bit of a challenge as not all sensor faults give alarms in the ECM.
Also struggled with similar fault on an 4.2ES320 once.
Rinda gave normal readings of all values, incl 100% throttle.
I did not manage to find the fault, but was told that the boat dealer had adjusted the throttle cable after after my visit, which apparently rectified the problem.
Suspect that he did something else as well, but "forgot" to tell me what, the tw*t..
/forums/images/graemlins/grin.gif

My suspicion is that he followed my recommendations and changed the engine mounted fuel filter, and cleaned the fuel lines and the metal mesh inside the fuel pump (on top of the fuel pump, under the round black lid held in plase by a single 10mm bolt).

Again, these are reliable engines with simple electronics and few sensors, meaning that as long as the engine gets sufficient fuel and air they normally will keep on running for ages without problems.

 

[Latestarter1]

Wetspot,

OK, lets get down to basics.

Low idle, that self explanitory. High idle is rated speed I.E. maximum power producing rpm, plus the governor droop (rpm increase with reducing power) specified as 3,875 plus or minus 50 rpm. 'Rev all the way' is not sufficient.

Unless you can confirm throttle connection is set to give 'high idle' to the correct specification there is no point in going down any other route.

I have dealt with a number of turbo issues on these engines, however until you can confirm step #1 pointless taking a scatter gun to the job, let alone ripping into the timing gear.

Do you have a Mercruiser installation manual? If not send me your email address and I can mail it to you.

 

[DAKA]

You have some experts giving excellent advice here, and I am no expert my only input is to guess you have replaced a 230hp petrol or a 180 hp diesel for a 300 hp diesel.
If you have not added extra air vents then you could be starving the engine of air.
Have you tried running with the engine hatch open ?

 

[gingie]

if you had rebuilt the long block to the manufaturers spec there is a mis print regarding the setting up of the fuel pump timing.

unfortunatly if you look or ask about it there is no information.

i do have the details what was it set up to

 

[wetspot]

[ QUOTE ]
You have some experts giving excellent advice here, and I am no expert my only input is to guess you have replaced a 230hp petrol or a 180 hp diesel for a 300 hp diesel.
If you have not added extra air vents then you could be starving the engine of air.
Have you tried running with the engine hatch open ?

[/ QUOTE ]

The diesel replaced a 300hp 7.4 big block petrol, and the engine bay has some quite big air intake ports, so I doubt that is the problem, but it is food for thought !

 

[Divemaster1]

If it was too little air, the engine would have over fuelled and excessive black smoke is a good indication of this..

 

[DAKA]

On an old volvo penta I agree but the new Cummins-Mercruisers are supposed to monitor this.

I havent seen any black smoke or muck on the stern/tender since I have had cummins-mercruiser engines. /forums/images/graemlins/cool.gif

 

[wetspot]

[ QUOTE ]
Wetspot,

OK, lets get down to basics.

Low idle, that self explanitory. High idle is rated speed I.E. maximum power producing rpm, plus the governor droop (rpm increase with reducing power) specified as 3,875 plus or minus 50 rpm. 'Rev all the way' is not sufficient.

Unless you can confirm throttle connection is set to give 'high idle' to the correct specification there is no point in going down any other route.

I have dealt with a number of turbo issues on these engines, however until you can confirm step #1 pointless taking a scatter gun to the job, let alone ripping into the timing gear.

Do you have a Mercruiser installation manual? If not send me your email address and I can mail it to you.

[/ QUOTE ]

Hi, thanks for taking the time to help me, in neutral the engine will rev all the way up past 3800 rpm, as the engine is free flowing as with any large engine in neutral it will exceed its maximum as no resistance will allow it to do so, only lack of fuel at this point will actually reduce the rpm, it is only when an engine is under load will a rpm restrictor/limitor work effectivly , as for the high idle, I assume you mean position of the throttle in relation to the throttle position sensor? if so, yes its right, the position of the throttle in relation to the sensor apears to be correct until engine revs get to around 2500rpm, at which stage the Rinda shows that any further increase in the throttle position is correct in relation to the position sensor all the way upto 100% but the engine rpm remains unaltered.
what do you believe the problem was with the turbo? as from my understanding the engine was origionaly fitted into a large show rib, which was trailerd in and out of the water, and as the turbo and wastegate are in the line of fire (as far as water leaking back through the exhaust elbow), thus corroding the wastegate shut and allowing the turbo to overboost and dammage the bearings, this to me makes senses, but what is your view?
As for the engine, apparently it was then sold to the end user, at which time, they were unable to get it to run right, so it was replaced under the warenty, the engine was then returned to Barrus, where it sat for a few years, to confirm this the Mercruiser dealer I purchased it from (as a complete working unit in 2006) is on with contacting Barrus to confirm its exact history, which should shed some light on it, but please let me know your views on turbo/ problems

 

[wetspot]

[ QUOTE ]
if you had rebuilt the long block to the manufaturers spec there is a mis print regarding the setting up of the fuel pump timing.

unfortunatly if you look or ask about it there is no information.

i do have the details what was it set up to

[/ QUOTE ]

Could you let me have the correct details?
it might help

 

[Latestarter1]

Wetspot,

Just a simple request 'what is your high idle number EXACTLY.

I has total relavance to everything else.

Please please try to conform to a disiplined trouble shooting tree.

 

[wetspot]

[ QUOTE ]
Wetspot,

Just a simple request 'what is your high idle number EXACTLY.

I has total relavance to everything else.

Please please try to conform to a disiplined trouble shooting tree.

[/ QUOTE ]

Hi , I dont mean to be rude, but you keep refering to "high Idle", I have been in and out of forums about this engine for 2 years, and I have spoke to a lot of marine mechanics around the world, and no one has ever mentioned anything about high idle, as far as I am aware, high idle is when the engine is cold (choke), has nothing to do with max power, so why has this got everything to do with the problem I have got, perhaps if you explained your reasoning better, I might understand better?
yes I have a workshop manual including the 300hp supliment, if you know the page number, let me know, so I dont spend hours trying to find it.

as for disiplined trouble shooting tree, I have been trying to get information out of Mercruiser and Cummins for the last few years, what troubleshooting tree?, even Rinda technoligies stated "go to the manufacturer for diagnostics info", Cummins wont come to the boat as its too far and not worth while, but that said, they dont even know anything about the engine anyway!
So if you have any info that might help, please let me know

 

[wetspot]

What you all should know is this engine has only 9 hours on it since it was fitted over 2 years ago, so you can all see why I am getting annoyed and all of this time has been spent trouble shooting!!!, mercruiser dont want to know, Cummins say they want to know but wont visit (and have no knowledge anyway), from what I can gather, these engines are very reliable, but when they go wrong theygo very wrong!!,
please keep coming with the ideas
and thank you all for your help so far

 

[AndieMac]

[ QUOTE ]
[ QUOTE ]
Wetspot,
a large show rib, which was trailerd in and out of the water, and as the turbo and wastegate are in the line of fire (as far as water leaking back through the exhaust elbow), thus corroding the wastegate shut and allowing the turbo to overboost and dammage the bearings, this to me makes senses, but what is your view?
As for the engine, apparently it was then sold to the end user, at which time, they were unable to get it to run right, so it was replaced under the warenty, the engine was then returned to Barrus, where it sat for a few years, to confirm this the Mercruiser dealer I purchased it from (as a complete working unit in 2006) is on with contacting Barrus to confirm its exact history, which should shed some light on it, but please let me know your views on turbo/ problems

[/ QUOTE ]

Wetspot..... I sincerely hope you do indeed source a solution for your problem/s, you have some very clever people offering suggestions, and I'm sure you are all ears.

The above quote has me concerned. Are you inferring there has been water ingress to the motor due to back flooding, then the motor was left standing for a couple of years! That's a concerning issue in itself.

Good luck.