AmiableDave

I have been beating my head silly with this. Hope someone can help
I have a immaculate condition 2013 Formula 292 Fastech with a pair of 377-320hp Merc engines. I bought the boat with 29 hrs on it. It now has 80 hrs on it now. I DO NOT know if the problem existed when I bought the boat because I didn't pay much attention to the tach's at first.

I have had the boat to 2 different Merc dealers. Both scanned the engines at sea and both said there is nothing wrong with the engines.

MY PROBLEM.... Both throttles are even at idle to 1500 rpm's. After I bring it on plane, 3200 to 4800 rpm's, I have to bring the port engines throttle back a 1/2 inch to match the RPM of the starboard engine. The difference in the port engine ahead of the starboard if the throttles are left even is 200 rpm's... WOT is 5000 rpm and both throttles are again even.

I have checked the cable adjustment as well as one of the shops. All is good. I removed the flame arrestor and checked the butterflies. Both look to be the same. I had the props looked at twice. I ran another set of 28P 4 blade props. Still have the problem. Both shops have no clue. And I'm now on a diet of aspirin now.

Thank you for your time.

Tinkerer

Reverse the props and run the shifters in reverse and see if the problem goes to the other side. If it does then it is a prop problem.
If it doesn't than it is common for one engine not to put out the same HP at a given RPM. It could also be that the power steering pump could be dragging that engine down a little.

mike tkach

iTrader: (3)

i would say the engine with the lower rpm has an issue and is down on power,engine scan wont show poorly seating valves or weak fuel injector,s.

getrdunn

iTrader: (7)

Many have faced the same problem over the years myself included. So sounds like you have a mechanical background and at least know the basics anyway. You checked the throttle plates at various throttle positions including wide open and does not appear to be the problem. You tried other props and still same issue. Next thing is have you confirmed outdrives are equal according to your gauges. I'm assuming you have the electronic trim sendors.

getrdunn

iTrader: (7)

I was going to mention basically what mike did also but start with basic compression test starboard vs port and right all your numbers down while at it.

As as long as your not doing circles at wide open throttle not to worry. Lol. Just start with basics and work your way up. Could always pull drives quick and make sure they rotate equally also. Last resort put a knife edge on the prop that's on that's down on rpm. Wouldn't be the first time that's been done.

Sydwayz

iTrader: (1)

You can't just visually check the throttle body / butterflies. You need to check them with a scan tool and compare the Throttle Position Sensors. You need to make sure that sticks at all the way back both TPS sensors say 0% and sticks all the way forward is 100% open. This does take a little bit of finesse to get right sometimes.

Rinda Technologies Inc. Marine and Industrial Engine Diagnostic Tools is the best scanner out there for these Mercury/Mercruiser setups. Many of us had/have our own scanners.

Two scanners helps to do this task, but not 100% necessary.

Mbam

Check the tachs, Check the drives are actually trimmed the same.

AmiableDave

Thank you all who have given an opinion so far.

I have the props ONCE AGAIN at another shop. Frank and Jimmies in Fort Lauderdale, Fl. I found that one of the props has a crack on the leading edge. I talked with Scott at Merc Racing and said Mike Eggleston was the go to guy. A call this passed Friday said they would comment on what they found today. I had the props to a local prop shop in Bradenton twice. They said the props where bent and after they fixed them, I lost 5 mph. Sent them back and got back to 60mph, which I was doing with bent props I guess..LOL...

My tachs are working perfectly, so says both Merc shops I had the boat to. I thought the engine scam checked the Injectors. At least the voltages to them. Also they said the engines are not misfiring. That the engines are at 100 %. The working power steering pump is on the Port engine, so no drag there. I'll have to check the compression of both engines. I believe that the engines are fine with the low hours. And at WOT they are at the same RPM;s

The TPS where checked twice and they are fine. But I'm not sure if they measured them in sync. If they are not in sync, is there an adjustment? How could that be fixed?

I did notice when I bought the boat a year ago that the drives where off. I adjusted them to there proper height. I also found that after a day of trimming that the drives go out of sync. This doesn't happen right off, but as the day goes on. The easy fix is to put both drives all the way in, then adjust to suit the conditions. I found several web site that sell a devise that corrects this, but First things first.

getrdunn

iTrader: (7)

When adjusting drives makes sure gimble bolts are tight behind sender/indicators. I always hated those and went to mechanical.

BUP

iTrader: (9)

first and foremost what set up is this - 2013 should be the CATALYST engines and DTS ? If not, I have no idea how that could be different --- plus catalyst engines from 500 hp and down is federal mandated from 2010 to current. Yours is a 2013.. I have never seen a V8 OEM stock Marine engine under 500 hp being model year 2010 and up not a CAT engine with DTS in the USA .

If you do have the app as I mentioned - the trim and systems are a digital set up. The DTS throttles plates is not mechanical adjustable nor one should mess with it.

I would not buy diacom for the Mercruiser CAT apps because one can be lost including marine shops if they are not trained with the EC engines / smartcraft / DTS and so forth. There is over 500 fault codes plus Diacom is not the complete scan tool to have for the Mercruiser EC = Emission Control engines. Merc G3 scan diagnostic tool should be used here so hopefully it was plus the shops have a ton experience with DTS and EC engines. .