525 EFI Guru's need help!
 

Ok so starboard is not pulling as hard as port when at 4700 and up to 5400 with equal trim settings. Keeping in mind the starboard runs the power steering pump.
Pulled all 8 spark plugs clearly #6 is crappy. Looks like a cold plug would. looked fuely (I made that one up but you get the idea) Other 7 are perfect. First action was to put new Iridium plugs in as a direct replacement from NGK. Put about 45 minutes run time (20% WOT, 40% 4k rpm, rest is idle time) and #6 stood out again as not burnning clean when compared against condition of #4 and #2
Header pressure tested at 47 psi using digital pressure gage capable of indicating to 1/100 psig. Pressurized to 47 psig, hold for 15 minutes to allow heat-of-pressurization to stabilize, close off supply and monitor gage for 30 minutes...zero pressure decay.
Standard compression test yields 140-145 psig.
Cylinder leakdown cyl #6 2 psi drop (3%), #4 2 psi drop (3%), #2 3.5 psi drop (5.8%) didn't bother with #8
Plug wire specs are 1000 ohms per inch max. #6 wire about 30 inches long (30k ohms max allowable) measured 14.7k ohms and #2 17k ohms which is about 36 inches.

Possible contributors left to investigate:
#6 fuel injector (not too keen on having to pull the plenum and fuel rail and at $250 a pop guessing would suck)
Coil pack - any way to test without pulling as mine is right under transom ( others suggested swapping between motors but refuse to mess with port as it's running perfect)
#6 rocker arm wear/adjustment (a friend with 525EFIs has been down that road with rocker nut loosening up. Anybody else see this?) Ordered new header and collector gaskets to investigate this next unless I get a good lead on an alternative path of investigation.
Plug wire although meeting resistance spec might have leakage to ground path and spark is getting blown out at high RPM (course you can't buy a single wire to try it Set is $150ish local MOPAR motor guru at work after reading the plugs believes this is the culprit. He is suggesting I take one of the good used plugs and close the gap to reduce energy need to light the cylinder and see what happens

Maybe swap #6 and #2 plug wires and see if the problem follows the wire. Same with coil.

Yup...that's the kind of logical thinking I want from the group. I'm not gonna just start buying parts without having some logical basis for it. Definitely gonna try that because routing the wires across the back should it prove to be the wire(s) is gonna suck. I have enough slack in 6 to get up to 2 or 4. Thanks additional input welcomed

525 efi
 

After u put new plugs in it and ran it u said u pulled em out and it looked fuely ?? Did it look the same as when u took it outa the box?? Like it never burned?? If it did its probably an injector.

No when I checked it #2 and #4 looked barely used, 6 looked fuely, center ceramic was brown like it had residue on it.

Just went through a similar situation, ended up finding a bad coil. Surprised how well it ran on 7 cylinders, could not really tell- it was only down 200 rpm to the healthy motor but felt sluggish.

Our ignitions are different, but I would swap coil pack from your healthy motor and see if problem follows.

Thanks for the input Kelly. Plan to swap #4 and #6 plug wire at both ends and have clean plugs in both to see if the problem follows the wire. If it doesn't the coil is the next place I'm going. I saw a thread that someone else had a coil pack with small cracks in it. The damn coils are way at the back of the motor directly under the lowest part of the transom edge.so when you see me and the backs of my hands are all chpped up you'll know I decided to change out a coil.

If I'm not rnning along side you this weekend you'll know I haven't solved the problem ;-)

If you need one plug wire let me know the length and I can help you out.

Thanks! After I do the wire swap to see if the problem follows the wire I might take you up on that.

I dont know how much access you have.... but a quick easy check for spark leakage is spraying the suspect high voltage leads with water out of a spray bottle (on a running engine). Works well for finding arcing out plug wires, coils, distributor caps (i know you dont have one in this instance), etc.

Easy cheap and effective, however this will only test for spark leakage and will not totally rule out the suspect/failing internally coil. I would recommend the spray down first then moving on to swapping parts around to see if the issue follows.

I did it using aeresol window cleaner and lightly fogged over the wires. problem is the coil packs are way at the back and the wires flow down the side/back of the motor where you can't see them till they come back up under the headers by the plugs. Couldn't see enough of the overall wire length to rule out that they aren't leaking where I can't see.

Appreciate the ideas and keep'm coming.

Now I want to see it solved, so I have another vee to run with !! Ok with you to cruise around the century mark ?

I have a set of spare wires on board, plus scan tool (incl. injector tester), etc. if you want to investigate Friday afternoon. You will have to get a coil though, the spare coil I carry is different than your pack.

Well for the run I did a trick that I had read on some various threads and was confirmed by a colleague at Moog. I closed down the gap from .035 to .025 on the #6 cyl that was not doing its share and that brought the starboard back up to about 98% healthy when compared to the port at WOT. That gives me the confidence that it's either weak coil pack or wire(s). Original plan to swap the wires for #4 and #6 and see if the 4 plug went crappy but because I wanted the best out of it for our run this weekend I went with the gap change and feeling good about my decision. My transom smut went wayyyy down now too.

Well the saga continues. Finally got time to change out the coil pack that the #6 plug was on and same thing as previously noted. Starboard not pulling as hard as port motor beyond 4800 rpm. Perfect Storm had a rocker arm nut loosen up twice and each time was a subtle loss of power similar to what I'm experiencing. So pulled the valve cover and I'll be damned if I can detect a problem Who can tell me what the correct procedure is for setting up the rocker arm adjustment? Limited experience says to set crank near TDC of ignition stroke, run rocker arm nut down til all slack is out and then another ??? Portion of a turn to preload lifter??? Help a guy out here 525 guys. Right now I can detect no slop whatsoever although you can twist side to side without much resistance Next step will be to pull the injectors to see if #6 is acting up.

4 years and I'm still trying to diagnose a similiar issue. Completely rebuilt the lower, new cams, all new valvetrain, blueprinted injectors, new coils and wires, new distributor / senor thing, only thing left is the high pressure fuel pump which should be here this week. If its not it, I am stumpped.

Mine is cylinder specific as all plugs except #6 look perfect all the time. It's the #6 cyl that I detected either the spark blowing out and leaving deposits or just a rich fuel condition occurring above 4800 rpm and leaving deposits.

I'm just guessing but try swapping the ecu's from one motor to the other.. At least its a cheap and easy test. I heard something about bad ecu's on those motors.

Good idea. Merc says all the software or whatever is in there was up to date but like you said, cheap and easy test. I'm running out of ideas. I used a Moroso spring tester and the springs on that side were all in spec for force at lift-off. If ECU doesn't highlight anything injector test/clean/test is next.

if you are saying # 6 is rich and that plug is fuely it could be a leaking fuel injector or its pattern is off or it can be stuck open. Any fuel in your motor oil as this 4 sure would confirm that.

If anyone who works on their own boats , one the easiest ways to check spark while running the motor is with totally sealed inline spark checkers by a quality maker. A great tool to have as you can watch each for spark or weak spark while the motor runs. These are totally sealed but can see thru them to watch the spark firing or not.

Hoping the injector test/clean/test yields results

Give me the name of the Spark checkers you use ,,,please .All I see are clear plastic as a shield, which wouldn't work for long

Did you ever find the problem?

Coil change-out - same
Swapped #6 and #4 wire to see if plug discoloration (not fouled but browner) - stayed at #6
Checked valve spring preload - all on that head right on spec
Cylinder leak-down test - 8 - 9% and consistent cyl to cyl
Cylinder compression test - all good and consistent
Fuel injectors flowed and tested for pattern and leakage at Kennedy's dyno-tune - all four injectors on that side were perfect

Boat is on the computer to see if any of the sensors from starboard motor are significantly different than port motor sensors

Thanks, going thru the same problem.

We were chasing a 525 issue we thought was fuel/spark related last year and ended up being a cracked header.

Have no idea what anyones engine serial #'s are but when ever working on marine apps especially stock OEM it is very important to post engine serial # or drive serial # if working on the outdrive for help - parts - possible fixes and parts bulletins along with Service bulletins.

Anyways HP525 EFI engine serial 0M950064 and all below had PCM calibration change. The change help a lot with poor running conditions and heavy deposits especially soot on the transom. Also make sure you do not have a bad IAT = Intake air temp and or CTS = coolant temp sensor and or its wiring along with connections. I would look there as well. Next clean flame arrestor and good amount of air flowing into the engine compartment.

You mentioned soot on your AT. Rich air fuel mixture, causes unburn fuel that exits thru the exhaust - hence sooty transom and poor running conditions. Thought maybe before it was your injectors so I went back in my memory bank for a possible cause / fix. Good luck.

The PCM calibration change went out to dealers and is listed in SB 2004-04 to help anyone that falls under the engine serial listed..

Next not knowing if your boats are a fairly new used boat to you - just bought and or had the drives worked on but make sure the gear ratio's are the same set ups in both outdrives especially if the engine checks out 100% with everything. Just saying seen this about a handful of times in the past couple of years. People just slappin what they can on the boats to get rid of them.

Also what are fuel pressures thru out the rpms ? I don't think it was brought up or least didn't see it mentioned.

Pressure tested headers to 50 for over an hr with no pressure loss.

Flame arresters power washed from inside out per Merc recommendations for belt dust build up.
Same call to Merc I gave them my SNs and they said my PCMs were up to date
The boat is at shop and guy is gonna run the full set of tests to verify TPS, MAP, etc. I'm hoping it's one of those.
Drives are like new. I run stuff hard but they get lots of lovin to keep them healthy as could be.

I run dash analog FP gauges that show 38-39 WOT but I also added the Merc monitor to convert the CAN Bus digital engine info to NMEA 2000 so my Garmin 740S chart plotter can display all the engine parameters from both motors on virtual gauges and that shows them closer to 40-41 WOT. I believe they're 43 lb injectors stock.
What I need to do is switch my Merc Monitor to the Starboard motor because the MM can display codes, hrs, etc but for just one of the two even though they're ganged together on the bus. It can convert both motors to NMEA 2000 but only display one engine codes, engine name, hrs, etc.

I had gotten the suggestion to swap PCMs but in the AT I think you'd have to pull the motors the way they're packed in under the transom.

Also had done the test where you pull and block
the vacuum line to the FP regulator at idle and it jumped right up like its supposed to.

Just a guess have you ever tried lifting your engine hatch while running to see if you can gain rpm's - Just asking.

MAP,or IAT or coolant temp sensor out range can / will make your engine run rich. If you do not know your engine serial #, what year do you have or both of that info ?

did you check your throttle cable and throttle plate for WOT. Are you still running rich - 4 sure ? Your spark plug wires in good shape.

If you pulled your header(s) off couldn't you get to the PCM somewhat easier - just asking. Plus it would be another good reason to pressure test them, at least one side anyways.

Well Merc engine scan found nothing. Compared data between the two motors and they look damn near identical.

If you can post your scan results that would be good. Did you test the scan while running WOT ? Next since I see now you have a 2004 year model 525 hp here is the engine serial #s that needed the PCM calibration change.

Engine serial # - 0M950064 and below

I would make sure that this has been completed - triple check because Merc is not always right about it being completed. Another possible thing to try is switch out the 2 coil packs & plug wires from your known good source and see what happens. Weak ignition can make it seem as the motor is running rich when in fact it could be spark / ignition related.

You ran the Buffalo run so maybe you got this fixed - if so what was the problem / fix ? Hopefully it was something simple like prop related. If it could only be that easy & simple everytime out.

SN is OM901186 Did not run scan at WOT just because of the guys available time. He said he would but weather is so so. I had emailed Merc and they said both my motors had all updates. I will scan and post print outs. He scanned cold, at temp. But all on the garden hose.

I did run the BPR (pace boat for 70 group) and if you check out the one video there's only one Cat that could run with me. That said I was still having to lean on starboard throttle more than port and wait for it to play catch up.

Had previously swapped plug wire between 4&6 when I was thinking it was single cyl related. Also put new coil pack on that fed #6 with no change.

Ok had a felling your motor fell under the recalibration. Also I know you were the 70 mph pace boat because at the start we were almost right behind you. I put it together after the fact that your boat and post was this.

On the water hose compared to under load is 2 different stories for these marine engines running. Who is helping you with diagnostics - a repair shop or others. I would look under history from your scan and see if the had any knock sensor faults. At this point I know you said swapping over PCM's was a PITA but maybe is a very good option for testing. .

BUP ur inbox is full Wanted to discuss my 525

you can hit my email

put a title on your email so I know who its from.

I will give U my cell if needed. from one NY er to another

[email protected]

Dave I emailed you back from day one and even Sunday. Seen your email last night if I got yours - I sent another email and sent the original 2 back to you. Did you get them this time out. If not send me your phone # and times to call in a new email and I will get back to you that way. I have no idea why you can not get my emails. Sorry. John