Changed 5.7 to 6.2 and got problem

pmp1986

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Hi, friends,
Got a question today. Engine 2A030384 5.7 was damaged and then replaced by 6.2l (6.2 MX MPI 0W starting serial). Drive is Bravo.
Ecu was reprogrammed from 5.7 to 6.2. But now with no viewed signs boat can't get on glisser (plane).
Compression is great, all other things also in great condition, engine is better, but performance is bad.
Where should they take a look? :)
 
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Fun Times

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Hi pmp1986, By chance was the distributor assembly ever disturbed at all between the two engines? There's a good possibility that the distributor was not phased in correctly somewhere along the line and even if it may not have been disturbed then it still may be in your best interest to double check the phase settings....Also just now that the cap and/or rotor can be problematic at any given time including right from new at times so you may eventually want to eliminate that possibility by trying a different cap just to be sure.

Phasing in a distributor isn't quite the same as setting the timing of older engine models as there is a different technique now which the info of how to go about doing that can be found within one or more of the following direct links for you below.

http://forums.iboats.com/forum/engi...ase-timing-on-5-0-mpi?p=10101498#post10101498
http://forums.iboats.com/forum/engi...gi-c-300-p-egc-alarms?p=10243000#post10243000
http://forums.iboats.com/forum/engi...tibutor-proper-clocking?p=5218875#post5218875
http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80cb36d1

If phasing is out/off, the engine will not perform well at all.
Also finding out what the fuel pressure is while underway could be important should this be a fuel issue.

Note:
S/N # 2A030384 = MERCRUISER 350 B 6 Inch Exhaust Risers, 350 MAG BRAVO MPI https://www.perfprotech.com/mercury-marine-parts-catalog/umodel/26740
 

pmp1986

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Also finding out what the fuel pressure is while underway could be important should this be a fuel issue.

Thx. for a reply :) We'll check distributor as explained surely.

Fuel pressure calculated in psi is 42. Is it fine for 6.2l MX?
 

pmp1986

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Another detail. On "full forward" it can't pass 4000 rpm as i's said.
 

pmp1986

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Ayuh,..... Is this a dock boat,..??
I guarantee the cause is in This list,....

Don't know what is dock boat. It's Searay :)

That list:

1. Fuel condition. 2. Propeller pitch or diameter, damaged blades
5. Marine growth on hull and outdrive 6. Wrong gear ratio in outdrive
8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
12. Boat overloaded, improperly loaded, or improperly trimmed.

Nothing changed from 5.7. Everything operated well with that engine.

9. Poor cylinder compression Compression Test
6.2L show not less than 12 (144 psi) on each. Engine has 350 hours of operation.

3. Restricted fuel pickup tube or anti siphon valve Fuel System Test
Fuel pressure is 42 psi.

4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
Will check tomorrow.

7. Restricted carburetor air intake (clogged flame arrestor)
Will check tomorrow.

10. Carburetor defective, or wrong type.
???
11. Fuel pump pressure and vacuum
Fuel pressure is 42 psi.
13. Engine Overheating
No. Engine temperature sensor tell us it's ok. Sensor called "hand" also don't feel painly degrees :) No steam also.

14. Engine timing and ignition system operation
I've checked ignition distributor as shown in previous links. After restetting to #1 cylinder nothing happen, but distributor (complete with shaft and etc.) is from 5.7.
When 6.2L complete distributor inserted engine performance much worse. It can't get over 3500.
I'll get new distributor (complete set) tomorrow and will check whatever happen. Also spare plugs and wires.

15. Remote control cables and linkage for proper travel to open throttle plates fully.
What exactly that might be? Also in main operation mode (by hand) it can't pass 3800-4000 rpm, so don't think problem is in remote control.

Also. Dispatched injectors from fuel bar. Does anyone know at what pressure should i check whether they work fine and send fuel correctly. Also does any one has pictures of how they should look like, 'case several of them are not as others. And i'd check whether it's ok, or they are damaged. And the main question - is there any crossmatch between any auto parts injectors if they are in bad condition :)

P.S. Some oil in water during operation found.
 

alldodge

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A dock boat is one which sits moored at a marina.

15. Remote control cables and linkage for proper travel to open throttle plates fully.

When the throttle is moved full forward, does the cable move the throttle body to full open (wide open throttle)

What company remapped the ECM?
 

pmp1986

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AllDodge, thx. for explanation.

"When the throttle is moved full forward, does the cable move the throttle body to full open (wide open throttle)"
Yeap. It does so. Checked.

"What company remapped the ECM" - As i's said one of local Merc. dealer mechanincs. But we've change ECM with another 6.2MX for partner storage (control unit change, not reprog.) and also no effect.
 

alldodge

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I'm leaning toward a problem with a cylinder or the TPS is not showing full open. If you get a pair of insulated pliers (usually plastic) do a engine drop test. With the engine at idle, remove one plug wire at a time from the distributer. There should be a slight drop in rpm. If one is found which does not drop the rpm, then we need to look at it closer.

Next you need the Diacom software and check the TPS. Should be able to move the throttle to WOT and the software will show it. Can also turn key ON without starting and measure voltage at the TPS and it should show close to 5V. This can also be done with the motor running and your on plane using the Merc scanner by Rinda
 

pmp1986

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I'm leaning toward a problem with a cylinder or the TPS is not showing full open. If you get a pair of insulated pliers (usually plastic) do a engine drop test. With the engine at idle, remove one plug wire at a time from the distributer. There should be a slight drop in rpm. If one is found which does not drop the rpm, then we need to look at it closer.

You might not believe me, but plug wire removed from the distributer do not perform a slight drop (all of them). Might be sensor on panel do not work well, 'cause i see that there is spark between distributer and plug wire if moved closely (checked all). So rotor work fine.

Crankcase oil volume
Not too high, so it's not the problem.
Air intake filter.
Yeap. It's very dirty. Next time i'll change it.

P.S. Another new trouble. Got a very high-frequence sound somewhere from front side of engine. Mostly located near water pump.
 

alldodge

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Ya, know your right. Every time the plug wire is removed the ECM takes it and changes the motor to keep it at rpm. Not sure if it will work in base timing mode. At least the computer will not change the timing.
 

pmp1986

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Now, what've been done and what result we get.

At start we've 4000 rpm wall.
Changing distributor cap to older one (from 5.7) make a 3000 rpm wall. 18 knots top speed.
Next step injectors were cleaned -> a 3500 wall with hard acceleration. 20 knots top speed.
Next step distributor cap was changed to one from 6.2 (as was found old cap had damaged connecting plates - white color) and we get a 4200 wall with nice acceleraion. 21 knots top speed.
Next step distibutor cap was changed to new one from dealer, spark plugs changed also and we get 4600 rmp with great acceleration and 25 knots top speed.
Changing of spark wires reduced top speed to 24 knots.

But problem is that 5.7 (previous engine) top speed was 31 knots...
What should be wrong now?... :)

Also got a problem: oil pressure sensor show drop just after 3500-4000 rpm passed, after some time at 4500 it even try to show 0 level pressure... No beep or etc. Back to neutral and it show 4 (as always). Check oil after cooldown again - it's at high position, no oil leak found also.

Boat - SeaRay 280
 
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alldodge

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The 0 bar has me concerned at high rpm, and then up to 4 bar at idle. The 4 bar at idle in my opinion high for a warmed up motor, I would think more in the 1 bar. Spec for the 6.2 shows 55 kPa (4 psi , .3 bar) minimum at idle and 124 kPa (18 psi , 1.24 bar) minimum at 2000 rpm. That said most will show much more and this is also done with a mechanical gauge.

Don't see how you loose rpm by changing wires and plugs unless things were not put in order. Do not think this is the issue and things just change on a daily basis. Since this is a new install and everything acting flaky, I will suggest recheck every electrical connection and real close attention to the grounds. Cables should be shinny metal and bend the cables around to see if there is corrosion under the jacket.
 

pmp1986

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Next stage of fighting with our problem :)

Mechanical gauge show 3-3.2 bar at idle, higher readings at acceleration, no drop, so it'd be some problem with sensor.
But oil tube before oil filter and oil filter itself checked by digital temperature equipment show near 110*C. Isn't it high reading?

After all electrical checks we have now 4700 rpm max reading at WOT with top speed at 25 miles per hour. So engine show that it works good, but top
speed reached isn't top speed even for 5.7 which had 30 miles per hour.

Hull has great condition. Propellers are Bravo 3 21.

Might be propellers are too light for 6.2L?
 

pmp1986

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alldodge

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Just as you said things do not add up. Motor runs great except for getting up and top end, no back fire or other issues.

With that I'm thinking one of the following:
As Fun Times mentioned, the distributer was not installed correctly
The ECM was not re-programed correctly
Your original drive was not installed when new motor was done (different ratio)
Your original props was not installed (different pitch)
 

pmp1986

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At last after we checked everything twice (distributor and all other things) we started third try and here's a #miracle#:
TPS reading now (by digital meter) show 0.53V at full close throttle, dropdown in area 1.9-2.2V and max reading at WOT is 4.3V.
During last 2 test it was ok, but anyway now it's not in good condition as i understand.
Will change and see what happen :)
 
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