Engine misses at around 2500-3300 RPM
Robs_232
Member Posts: 212 ✭✭✭
My 2004 232 BR with 350 MAG B3 has developed a miss at 2500 to 3000 rpm. It idles fine and WOT seems fine at (4800 rpm). I can see the tach move about 100 rpm when it starts missing. I am going to put a new cap, rotor, and plug wires on to start with. The previous owner (my sister) had a new long block installed 2 yrs ago because of a winterization issue and not sure if these were replaced. I'll also pull the plugs to look at their condition. Just trying to figure out if this is a fuel or electrical issue. I cleaned the flame arrestor at the beginning of the year and it still looks clean.
I want to replace all fuel filters. Can any one tell me what they recommend, besides standard fuel/water separating filter below alternator? This was replaced last fall when I has it winterized and have only put 35 hrs on it this year. Looking at the engine parts guide for this engine it shows a filter in the fuel module (35-866171A01). Where is the fuel module and should I replace this filter and any others that I might not know about? Have put Sea Foam in fuel to see if this helps, but only ran about 15 gallons through it yesterday.
Kind of confusing why it runs fine at rpm's up to 2500 and starts minor miss to about 3300 rpm and if I open it up throttle then miss goes away or don't notice or hear it. I will have dealer read for codes when winterized next month. Any other thoughts (wiring, sensors, valves, etc.)you might have would be welcome.
Thanks Rob
Comments
2004 Rinker 312, 5.0 Merc's, Bravo III, Lake Wheeler, AL
I replaced the cap and rotor last night, but didn't have time to replace plug wires before it got dark. I took the boat to the lake this morning. The engine missed even worse than with old cap and rotor; even backfired/popping. I decided to load up and come home.
Once home I replaced the coil wire and plug wires. The coil wire, inside the boot, had a goo on it that resembled dried silicone. Should I be using di-electric grease on the boots or wires so they keep a good electrical contact like other wiring connection plugs? I am wondering if the goo on the coil wire was dried di-electric grease as I had a hard time getting the boot/wire loose from the coil? Drew and r312 mentioned my coil could be causing the miss and wonder if this dried goo is causing poor contact
On another note my oil pressure gauge was acting up today. The needle started flickering towards zero. Pretty soon the gauge was, like the engine was off or, pegged below zero. I know it is electrical because I backed throttle back to 1500 rpm or below and the gauge would read normal; steady 30+ psi. I would push throttle ahead some, out of gear, and gauge would either flutter or go below zero. Is there anyway oil pressure gauge, wiring, or sending unit could be causing the missing issue? I know there are 2 oil pressure sensors, one for gauge and one for alarm. The alarm didn't go off. I am trying to determine if it is the pressure sending unit, gauge, or wiring causing this issue. Any thoughts? It is like the ignition wire (power) to the gauge is losing power but all of my other gauges are working fine so I doubt it is an ignition,power wire to gauge. My sister (when she owned the boat) had to send the tach in a couple years ago because it quit working right. I had to replace the drive trim gauge before this season because it wasn't working correctly.
I hate electrical stuff as it is so hard to diagnose. Any input would be appreciated. I plan on checking oil pressure with a regular pressure gauge first but truly believe it is not a pressure issue but a wiring, sending unit, or gauge issue.
Rob
PC BYC, Holland, MI
i swapped cap and rotor a month or so ago, and found the new cap was a flat PITA to install, and dang near put the old cap back on until I could find a better new cap... turns out the screws were wrong.. I pulled the screws out of the old cap and put them in the new one and it matched right up... check yours.. you may not have it seated perfectly...
also, the cps lives under there.. make sure you didn't pinch a wire with the cap... it's too easily done.
with the age of your engine, and the end of season approaching, you may want to consider swapping water pumps anyway... and... while you're swapping water pumps, the front cover it right there... pop the cover off, turn engine by hand until you can see the alignment dots, and pull the timing chain and cogs off (!!!!DO NOT MOVE THE SHAFTS DURING OR UNTIL YOU'VE SEATED NEW CHAIN AND GEARS!!!).... here is the deal, and it may explain your issues from top to bottom: timing chains, especially morse style, have nylon bushings in between the links to keep the chain quieter.. those nylon bushing wear out pretty quickly, and leave chain slop in their place, which messes with your timing, and makes the chain louder anyway... Given the age of your engine, I'd wager it's time for a timing chain anyway, and i highly recommend a double roller at the absolute minimum... If it were me, I'd not reinstall a chain at all, but gears instead- yes, they are louder, but, they hold perfect timing and they don't break or get sloppy with age...
PC BYC, Holland, MI
I decided to take the new distributor cap off tonight to check fit compared to old one. The new one does not seat like the old one so I put old one back on for now. Maybe why it ran worse after replacing. While I was messing with the cap I noticed there are no wires plugged into camshaft position sensor port Drew mentioned earlier. I searched everywhere on the harness for a loose set of wires. Nothing! Do all engines use the camshaft position sensor? Again, the engine is a 2004 350 Mag MPI (OW023332) and had a new long block 2 years ago because of a winterization issue by dealer. There are only 64 hours on new engine, but ECM shows around 300 hrs. Drew and BD mentioned timing chain. Wouldn't a new long block have a new chain and gears included? I did start the engine after replacing old cap and used di-electric grease on boots. Haven't taken it out on water to check miss.
I also took gauge panel off and went through testing procedure Babyboomer had in archives "troubleshooting those pesky gauges". I checked ohms at sender, voltage to gauge, etc. I also took the main harness connector apart like TH2 mentioned and sprayed out with electric contact cleaner ( then blew out with compressed air) and put some dielectric grease on it. I also tweaked the pins with a small screw driver to separate them slightly so they fit tightly. I started engine and oil pressure read just under 40 psi at idle and went up slightly over 40 psi when at 1200 rpm. I let the engine run for about 10-15 minutes after temp gauge got to 165 degrees to see if anything changed with readings. Read perfect. Hopefully this was coincidence with miss and pressure gauge reading. Maybe cleaning main harness connection helped too. Will test on the water next to check miss and will watch oil pressure to make sure it reads right.
I may also take the boat to dealer and have them check codes as it won't take long replacing suspected parts that might not be bad to offset cost to hook up diagnostics. I have tried looking for an ignition wiring diagram for my engine in a service manual but too many variations and didn't get definite idea about the wiring to camshaft position sensor. Comments welcome. Thanks guys.
After I posted the previous comments I thought about the fact that I had my, new to me dealer, read diagnostics on the engine this spring so I knew what was stored and if any codes were present and none were present. The engine ran fine until recently. I have attached the printout. I was amazed then and am now about hours and run time hours. This print out shows 30 hrs. but I am sure this is the tach hrs. read by the dealer as the tach was replaced when long block was replaced, since the tach was sent in to Faria and started at zero at that time. I say this because the tach engine hour shows 64 hrs. now. My take is this boat/engine hasn't been abused looking at Run History. Hopefully this helps with my post about engine ID. Any thoughts are welcome.
Thanks,
Rob
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So my issues continue. I had my boat winterized last fall and had them check for codes. None. The shop said they were to busy winterizing boats to look into miss and said to bring it in next (2015) spring.
Since the boat ran worse after the new cap last fall, I bought a new Mercruiser cap and installed it when out of storage. I called (2 weeks ago) the boat repair place to look into miss that winterized the boat, and they tell me a sob story about help and can't get my boat in for 4 weeks. We finally had our first warm day with little wind on a weekend last weekend and my friends were going boating. I decided to take my boat knowing about miss, but we planned to tie together and relax in the water.
Well the boat started just fine. Ran just fine to where we tied up at anchor and all gauges read normal. Then had to go pick up my daughter at the marina, since she couldn't come to the lake when we did. On the way to get her the engine missed as before. Got to marina at no wake zone and engine wanted to stumble and die. It would start right back up and run for a minute or so, in gear or in neutral, and die.
I got my daughter picked up and went to join my friends again. It missed like it had at 2000-3000 RPM. Got in no wake zone by friends and my engine kept dying like before.
I am wondering if now I have 2 issues. The idle thing might be idle air control valve and/or filter in throttle body. I am still dumb founded by miss.
I see Al is back on the forum now, maybe he can shed some light. I know Drew gave me some good pointers last fall, but maybe Al has some insight and I wish I was closer to you Al.
Any thoughts?
Rob
Here's the latest. I checked the things mentioned that I could. So I decided it is time to take to the Rinker Dealer two weeks ago to diagnose now what I think is 2 issues. Well they put the diagnostic computer on it and ran on water and have been talking to Mercruiser. The mechanic said Mercruiser's tech support wanted them to put a loaner ECM on, with my boats programming in the ECM ($1,750). The mechanic said it solved the idle issue, but didn't solve the miss. They have had the diagnostic computer on the lake several times. It still has miss at 1,800, on their computer, to about 3,000 rpm and then runs fine as it should. I asked if there is a chance there is a problem with the distributor causing timing issue as I had a friend that had a similar miss and it was the distributor (gear). The mechanic said he would pull the distributor to look at drive gear, but said it would be odd to have a zone miss if that was the issue. Not sure if he did.
The mechanic called yesterday and said he was grasping at straws. He asked me if I had added any electrical items or done anything prior to the time the miss started. This is what I told him; early in May last year I added a second battery, battery selector switch (Blue Seas 9002E), and Blue Seas ACR (7610) as discussed on this forum. I wired all as directed with marine cables, Blue Seas fuses, wiring, and never had an issue during the spring or summer months. Then I changed the oil late summer to synthetic oil, changed audio head unit from Sony to Kenwood and speakers from the Sony to Infinity so I could use USB and improve sound. The miss started late August or September so that is when I started to replace plugs, wires, cap and rotor. This spring I added Lenco trim tabs and wired as directed and they work fine.
The mechanic is wondering about electrical inference from my wiring with the ECM and is going to check sensor wiring routing. He said Mercruiser wanted him to run diagnostics in graph mode so they could review. The previous owner (my sister), as mentioned in my original post, had to have a new long block and exhaust manifolds replaced 3 years ago because of improper winterization 3 1/2 years ago. Is there a sensor in the engine cooling or fuel system that might impact timing that might have been damaged from the winterization issue? I doubt it would show up this long after.
I know the mechanic is frustrated now as he has spent many hours trying to figure this situation out. I know how he feels as I was down to start replacing parts, but thought it might be cheaper to put it on a diagnostic computer to isolate problem. My thoughts are crank position sensor, MAP/MAF sensor, water sensor on fuel, if he has checked fuel rail pressure and injectors on computer.
Drew and Al any thoughts before I have to mortgage my house? Ha Ha
Rob
You've got a sloppy timing chain.
PC BYC, Holland, MI
Timing chains usually have a little nylon like material, like a washer, in the gear sets. I'm sure it's not nylon, but it feels like it. It keeps chains whisper quiet for the first 5k miles or so... after that, they slop. When a couple dozen loose up it's no big deal, as it will only give a mil or two either direction. When it chews a couple dozen more, it can be degrees that are tossed. generally it tightens up at higher RPM's because tension and harmonics take over, and the sprag bites deeper into the chain at the bottom and the top, while the outside (3 and 9 o'clock) miss the cover only slightly.. at low rpm's the tips of the sprag bites and holds fairly tight... In the middle? It's akin to 'getting on plane', where the chain wants to float to the outside (making a circle) but is still being jerked elliptical almost like a figure eight that doesn't connect via intersection- because the snap back off the cog and it wanting to maintain that direction/shape. we're talking tiny variances, but enough to toss timing enough to cause late fires.
Engines control spark with computers nowadays, but it gfs that data from the cam position sensor, which relates to the crank position sensor... That part is simple and easy to trouble shoot. what complicates this, though,and makes it hard to t/s, is fuel sync for the injectors also time off the cps and ckps. When the thing that maps the crank and cam, making them maintain precision chooses to stop maintaining precision, it can certainly look, and easily, like a fuel problem.
Here's the interestingly humorous part, that you won't find funny at all: computer guys will go straight to the fuel or the computer... Or the pump and injectors... old timers have issues with pcm's and injectors, but they'd likely have went straight to the timing chain on an old point engine.
If this turns out your issue, and it's certainly consistent with that, I failed you by going off all modern, when i should have slowed my roll and thought it through.
PC BYC, Holland, MI
Now, I'm curious.
It's a valve event causing your issue.. either it's an issue with the cam/crank index, be it a chain installed advanced or retarded mechanically, or a sloppy chain, or, the items monitoring the crank or cam malfunctioning due to bad reads and not a faulty sensor, which again, could create fuel sync issues making it appear to be something else. Something else fuel related. Which you said they've already been through. The specific rpm range you mention leads me to believe is a mapping/sync issue, and most likely caused by a sloppy chain... Obviously, opinions vary, but at least I'm not arrogantly shooting down.a potential.cause without explaining why .
I went to the lake, without my boat, this past week. I spoke to mechanic yesterday to see if he has learned anything. I asked about distributor gear. Nope looks like new. Timing and advance appears normal he says. Wouldn't this eliminate timing chain? He said he was going to lake last week and cut injectors but hadn't got it on the water to test this week. Said Mercruiser wants him to run and save tests in graph mode and see if this catches a glimpse of a sensor issue. I am not sure if he has screwed a gauge on to check fuel rail pressure like Al mentioned. I discussed this with him when taking it in several weeks ago, as I don't have a fuel pressure gauge.
Al, I would assume he has the diagnostic computer as you mentioned since he said he was going to shut off injectors to see if that can help isolate. Also, the long block was a Mercruiser long block. Doesn't a long block come with a new timing chain and gears?
The mechanic says the dying at idle has to be the ECM as he puts the original on and it dies, so he replaced ECM with a new one. Says he thinks the ECM is losing power when starting to miss. This is over my head. Says it could be a wire or connection somewhere in wire harness. Says a new harness is $800.
I am starting to get frustrated as nothing was done this past week. Any thoughts?
Rob
Latest Update; New IAC didn't solve dying at idle, so new ECM ($1730). Dealer decided to throw out what I had done previously, plugs (AC 41-993), Mercruiser cap, and (Sierra) wires after looking at number 4 and 6 plugs, they were sootier looking compared to the rest of the plugs. They installed new Mercruiser wires, cap, and Mercruiser plugs, and miss was almost none existent. They wanted me to put 2 bottles of Mercruiser Quickleen injector cleaner in gas and told me to run it over the 4th, but told me to watch engine oil level in case injectors were not spraying correctly and didn't wash down cylinders. The Rinker dealer was very fair with me on costs (they had another boat brought in with 5.0l with same parts, that had ingested sand and took out seawater pump and overheated) so they used these parts as trial and error on my engine. They only charged me for 6 hrs. labor, which was ridiculously low for what they did.
I ran it for about 6 hours over the weekend and not a miss. It ran perfectly and didn't die at idle. I am still suspicious of the injectors (4 & 6) and want to have them all checked for spray pattern and volume, especially with the age of the engine. Anyone have a recommendation on where to send the injectors? What about replacements? Drew, I read you recommend Five O Motor Sports, as Mercruiser wants $2200+ for new injectors and you say the injectors are made by another vendor. I have read bad things about cleaning and rebuild services so I am asking for suggestions. Am I better off replacing versus cleaning?
Thanks Rob
Boat Name: King Kong
"Boat + Water = Fun"