01' MCM5.0 EFI runs rough

[waterone1@aol.com]

Re: 01' MCM5.0 EFI runs rough

If the coil was breaking down due to heat, that could be duplicated by heating the coil with a hair blow dryer prior to starting the engine (use all safety precautions, make sure engine room is free of gas vapors first, etc.) Then start engine. If it acts up right away.....it's a coil that is breaking down when hot. If it still takes the engine to warm up before it starts acting up, we have eliminated the coil.

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

hello<br /> I still agree with Dons. I will bet the laptop will show you there is nothing wrong. usually when the iac starts screaming its due to lack of fuel or proper spark. as the engine speed slows down the iac and pulsewidth increases. did you look for a basic EFI manual? the first step in trouble shooting a TBI setup is understanding how the fuel dribbler works. so far there are no O2 sensors on marine engines. however the last 3 sets of risers I replaced had a hole drilled,tapped and plugged that went directly into the exhaust cavity. the next step is to study how the system works. and to check the systems will require a laptop/pc with the correct software or the scan tool. but its very rare to see an ECM failure or a sensor failure. usually its a coil arcover or fuel pressure and the occasinal injector. whiles the TBI is idleing nasty and while its idling well remove the flame arrestor and observe the spray pattern. it should be a fine cone shaped spray with no large droplets or steady streams.<br /> good luck and keep posting

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

Good evening once again. Thanks again to all who posted. MUC- you mentioned the ignition sensor having been replaced under warranty in 2001. The Merc shop I spoke to also ran a check and saw the same thing. The original GRAY sensor was replaced with a new BLACK sensor at that time, this was bulletin 99-4. DON S- you referenced bulletin 2000-14, which I printed out. Our engines' serial number is referenced. This referenced the problem with the BLACK units. The new one is p/n 87-892150A 02, and has a ground wire, as mentioned. This makes sense, as in bulletin 2000-14, they state that most of the problems with these are caused by voltage spikes as a result of loose/dirty battery cables. The new part is $49.95 and the Merc shop has them in stock. I am NOT one to typically just replace parts and hope to hit the problem, but would prefer to have the new unit with ground wire, if there is a chance it could leave me stranded later. Also, since we do not have a trailer, the shops are busy with winterizations,etc... I'm seriously considering throwing one in and see what happens. I know from the posts here that some of you think I should do it, and some not.<br /> Can someone forward a copy of the service bulletin that pertains to the new p/n? Would like to see it since the new one has a ground wire so that I can be sure to install correctly. I also will pickup a new rotor since they can be damaged when removing. THANKS again, all, and feel free to tell me what you think.

 

[Dunaruna]

Re: 01' MCM5.0 EFI runs rough

Rodbolt, I believe holley is selling an aftermarket TBI for marine engines that has an 02 sensor incorporated - interesting to see how its plumbed in. Bommyal may have more details, he looked into it a while back.<br /><br />Aldo

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

The newest, latest and greatest part number is 87-892150Q02, which is actually 1 newer suppersesion than the A 02 version you mentioned.<br />They aren't hard to change, and if you want, change it. Don't throw the other one away either. You never know when the new one could fail and give you a no start.

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

Don S.- Thanks for the reply. Once again, your timing is great, as I havn't yet had a chance to pick up the new part, and it would have been an older version. Can you tell me if there is anything special about replacement? The old one does not have a ground wire as (I think) the new one will. Where does the ground wire connect? Is it self explanatory? I will pick up (hopefully) tomorrow, and hope to be able to determine if this is the fix before she is hauled on Sunday. Thanks also for the advice about keeping the old unit. One of my winter projects is to assemble a good set of tools to keep on board, and I will keep the old unit with spare bulbs, spark plugs, drain plugs, etc... Thanks again, Eric

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

Don S.- Thanks for the reply. Once again, your timing is great, as I havn't yet had a chance to pick up the new part, and it would have been an older version. Can you tell me if there is anything special about replacement? The old one does not have a ground wire as (I think) the new one will. Where does the ground wire connect? Is it self explanatory? I will pick up (hopefully) tomorrow, and hope to be able to determine if this is the fix before she is hauled on Sunday. Thanks also for the advice about keeping the old unit. One of my winter projects is to assemble a good set of tools to keep on board, and I will keep the old unit with spare bulbs, spark plugs, drain plugs, etc... Thanks again, Eric

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

Dunaruna<br /> that is why I wrote about the last 3 sets of risers. I can see O2 sensors coming cause there is no other reason to drill and tap a pot into the exhaust cavity. I think they are waiting for the 2008 emission standards as most all have met 2006.<br /> just more stuff to fail I am thinking<br />I just hope the ECM mapping will allow for a contaminated sensor at or near WOT without smoking a valve or holing a piston

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

Those are not O2 sensors rodbolt, they are temp senders. Volvo uses them on the new MPI engines. One on each riser.<br />It's #8 in the picture below.<br /><br />

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

Eric.<br />After you make a post and the forum brings you back to the thread you just posted in, scroll down near the bottom to a section that say says Move to other topic and click the GO button. And stop using the back button, all you are doing is makeing the treads longer.<br />Here is what the button looks like.<br /><br />

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

Dons<br /> I know about the temp senders. next set you do look for the hole that is drilled and tapped then plugged that goes into the exhaust cavity. the temp sender cavities arte blind holes. the temp senders have been out for 3 years that I am aware of. they had them on the TBI 5.7 that we prototyped. we had them when prototyping the composite drive for volvo in chesapeake VA. we also ran the composite drive behind a 5.7 to see if it would last a crabbing season. <br /> but look close at the new merc and volvo risers and I can see O2 sensors in the future. I think its the cavity that #2 is now plugging

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

I really hadn't thought about that hole like that, suppose it could be. I worked in a foundry many moons ago and used plugs to fill holes when we needed to keep cores from moving around. But with all the enviornmental regulations, it wouldn't surprise me if it was for the O2 sensors.<br />Have only had contact with one of those coposite drives, and I don't like anything about them (except maybe the corrosion resistance if it works), but what a royal pain to work on.

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

Dons<br /> the pain of the composite is a whole nother thread. I have a few tricks on them that the school dont teach. <br /> as far as the machined and tapped hole entering the exhast cavity the only thing I could think of that would justify the cost of the die change and the extra machine work is the sensor is coming. I also keep hearing romours of catalytic converters.<br /> going back to the rough running EFI. I still think it will be a simple problem. but you need to test fuel rail pressure and spark while its running rough. you must isolate which subsystem is failing. the other systems will try to compensate. <br /> good luck and keep posting

 

[muc]

Re: 01' MCM5.0 EFI runs rough

Shmart2, 2000-14 is the newest bulletin and covers installation.<br />As close as I can tell the A 02 sensor is a Mercury Precision part that is available to Mercruiser dealers and the Q 02 is a Quicksilver part that is available to most everybody else. No difference in the part just a different box. Good Luck. MUC

 

[bigbrownbuku]

Re: 01' MCM5.0 EFI runs rough

the electronic unit in the distributor was updated twice. once from grey to black, then again black mk2. when you get the manwell use the flow chart, dont just start testing stuff left and right. the flow chart works. some other simple checks. fuel system vacuum check, negative ground at the back of the block, distributor ground. also disconnect your shift interupt and try again.

 

[waterone1@aol.com]

Re: 01' MCM5.0 EFI runs rough

Rodbolt- Gm's latest generation of marine EFI ECM's are set up with inputs for O2 sensors and believe it or not catalytic converter temperature sensors. I think you're right...it's on the horizon.

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

and they wonder why I am ready to retire <br /> sometimes I think the engineers that design the stuff with the expectations that it wont get wet should have to explain to the customer why it cost 700 dollars to service parts.

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

The latest: I replaced the ignition sensor yesterday with the newest version- has a ground wire. Boat started easilly and ran at idle in slip for over an hour. I monitored oil pressure and temp, just to be on the safe side, and kept engine cover closed most of the time to build up some heat. I occasionally revved up to 3500 or so RPM to check responsiveness. At first, she would hesitate slightly if I didn't throttle up all the way but I believe this was due to wet plugs from the last time I shut down after running rough. Generally, after a few minutes, she ran great, idling at 650RPM and returning to a smooth idle after throttling down, not even a hiccup. I did observe a small amount of light blue smoke if I revved her up, but this seemed to clear up after she ran for awhile. I believe the ECM may have been resetting mixture after trying to compensate for problem last time. Overall, ran great. I did not have time to take her down the no-wake zone (damn standard time,) to test under load, but plan to bundle up and give it a try tomorrow. Weather is predicted to be better on Sunday, and will try again then if all goes well tomorrow.I have an appointment to have her hauled out at 3:00 Sunday. Also plan to check all connections, grounds and others, first. It seems like I always find something that is not as tight as it should be. Thanks again for all of the help, I will post tomorrow night. Eric

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

We took her out Sunday, ran out of time on Saturday, only ran her at idle and took batteries home to fully charge. On Sunday, I put the batteries back in and we went further up the no wake to pump out, then past our marina and out into the river. She ran GREAT, got up on plane faster than ever, even with 3 aboard, almost a full tank of gas, and fairly-stocked cooler. Made a big 3 or 4 mile loop, then back to the local party cove for a couple of beers before taking her back in to be hauled. Went from idle to up on plane a couple of times to really put her to the test, no hesitation to full speed (about 43 MPH,) in NO time. I am 90% confident that she is fixed. Will feel 100% after we take her out a couple of times next spring. The tune up seems to have improved her performance, and the grounded ignition sensor seems to have improved her attitude. A HUGE THANKS TO ALL WHO POSTED. I realize this was something I may not have been able to have correct myself, and by no means would say that a qualified EFI tech would not have been a good source to check her out, but the logistics made it worth my own effort to correct the problem. I really feel like I know the engine much better as a result. THANKS again, I will keep reading posts here to keep up. All the best, Eric

 

[muc]

Re: 01' MCM5.0 EFI runs rough

Eric, Happy that it worked out for you. PLEASE tell your friends and family to get into boating.