Rough Idle/apparant misfire during high alternator load

[MichaelOverfield]

Ok, I did some testing, and got mixed results.. but did find and correct one problem.

One of the connectors (field and sense) to the 2nd alternator is loosening up and causing it to shut off.. it's now fixed, but that had nothing to do with is issue, it seems.

I first did the AC voltage check with a digital multi-meter.. you can say I was shocked to see 30V AC.. but that seemed so crazy, I did same on another vehicle and got 28V AC.. then noted if I reverse the leads I got ZERO.. so that meter was just giving bad data, later I got my much better meter and did the check and got about 0.3V AC under heavy load, and about 0.2V AC under normal load.

I also hooked up the O-scope and saw no smoking gun there, normal ripple all about 0.2 to 0.3Vpp.

Also I did ground check, alternator case to battery negative terminal, about 0.01V normal load, heavy load, 0.02V. Both alternators.

I used a heavy set of jumper cables to route addition ground from the alternator case to the battery negative terminals.. no change (with the very low voltage drop that was not a surprise).

That said, it was still doing the stutter under load. Having swapped the ECU for a different issue, and found it not the problem, I decided to put the original ECU back in, and double check the ECU grounds while I was at it.

With the ECU out, I took the mounting plate adapter off and inspected it for issues, it has it's own ground strap for the ECU. Nothing seemed off, but ensured it was clean and put it back on. Installed the original ECU. Part of this was due to another issue I've been chasing on another thread, where I was setting up to swap the WCM for it's having had multiple past communication codes, but I digress..

In any case, after an WCM adventure, I went to check my AC with the good meter, the results I mentioned earlier, and oddly, NO STUTTER. No rough idle, and yep, well over 120Amps draw. Could the ECU ground/mounting adapter been an issue? Perhaps, but generally I don't get that lucky, I'm expecting it will come back, but for now it appears to have been corrected.

 

[MichaelOverfield]

Is there an amp draw test for the grid heaters in case one is shorting out or suffering from that loose engine killing bolt issue?

Tell me more about this issue! I have what I think is excessive draw on the grid heaters, like close to 200AMPS. I have them disconnected right now because I'm concerned it is a sign of some kind of grid heater short. I have planned new intake with the Duramax style plug type heaters planned to install at a later date, just have not got to it yet.

 

[MichaelOverfield]

What wires have you added and where? Was the 2nd alt a factory installed option and have you routed the wires exactly as the factory would?

Ok, well sort of.. there was no 2009 factory option for the second alternator, that began in 2013, if I recall correctly, but I did route similar to the 2013, it's a straight shot to the battery, with a 250A fuse in line, and I have a hall effect current sensor on the output of each alternator, which is how I can monitor the current draw and see the correlation to the rough idle issue. There is a longer thread on my Dual Alternator install on another thread if you want the details.

 

[petersonj]

I have what I think is excessive draw on the grid heaters, like close to 200AMPS.

I think your current draw on the grid heaters is normal. Although my truck is a '02, each intake manifold heater draws 95 amps - 190 amps total. This is from the factory service manual. I don't think the intake manifold heater operation has changed much over the years.

- John

 

[Tuesdak]

Tell me more about this issue! I have what I think is excessive draw on the grid heaters, like close to 200AMPS. I have them disconnected right now because I'm concerned it is a sign of some kind of grid heater short. I have planned new intake with the Duramax style plug type heaters planned to install at a later date, just have not got to it yet.

https://www.turbodieselregister.com/threads/grid-heater-bolt-came-loose.265513/

 

[DavidC]

Tell me more about this issue! I have what I think is excessive draw on the grid heaters, like close to 200AMPS. I have them disconnected right now because I'm concerned it is a sign of some kind of grid heater short. I have planned new intake with the Duramax style plug type heaters planned to install at a later date, just have not got to it yet.

Normal operation. That's why you have 2 batteries. If you could find something defective why would you try to replace the system ?, instaed of the component.

 

[MichaelOverfield]

https://www.turbodieselregister.com/threads/grid-heater-bolt-came-loose.265513/

Excellent.. I missed that one, but it moves up my schedule to get mine replaced. When I get all that together I'll have to put up a thread on that process. The way I simulated load to troubleshoot was to use one of the 2 GM Duramax style heaters, it draws about 60Amps, so 2 is pretty close to the original, and slightly less. I can tell you that thing made PLENTY of heat. I had to keep it away from things, and even still the clamp holding it at a some distance had it's paint getting cooked off. I'm sure 2 of them will suffice in place of that grid.

 

[MichaelOverfield]

Normal operation. That's why you have 2 batteries. If you could find something defective why would you try to replace the system ?, instaed of the component.

I'll use the existing system with a better heater in a new stainless intake horn (still have to locate and weld the bungs for these heaters, but I'll need to fit check it on the truck first to get the location correct), as seen in the post above about the failed grid heater that wiped out an engine. The GM style is like a sensor plug, easy to replace and inspect, and about 60A each, so 2 will be close enough to add heat (which I really don't need much where I live, but the system cycles these things for emissions reasons). Another reason, the massive cycling on the alternators and batteries.. which puts that system under considerable stress. When I see the grid pulling down dual 220A alternators (they can keep up, but work to do so), that seems excessive. I'd have to do another test to verify, I could be well over 200A on the grids, I see about 130A+ on EACH alternator when they energize, the truck uses about 30-40 Amps steady state, so depending on the battery charge state, the grids could be 230A+. It boggles the mind that the truck's original alternator was 136Amps.. my 1996 Saturn has a 140Amp alternator, and no massive grid heaters and dual batteries to charge. No way that 136Amp was a good size for these trucks.

 

[MichaelOverfield]

Normal operation. That's why you have 2 batteries. If you could find something defective why would you try to replace the system ?, instaed of the component.

Here's what the GM style heater looks like:
Amazon product ASIN B00GV8UKCI
I have 2, one for each side of the new SS intake horn.. (ahh, no longer available on Amazon.. interesting.. I've attached a picture of that instead)..

The replacement part to take out the grids:
Amazon product ASIN B0799NL7LF

 

[DavidC]

Are you going to install the glow plug controller also. I am sure the glow plugs need to operate quite differently than a grid heater. If left on for to long it could burn off at the stem leaving the coil rattling around in the intake and maybe eventually finding it's way to an intake valve. I'm not trying to persuade you one way or the other as it is your truck. Just thinking of the drawbacks of glow plugs. You could disconnect one of the grids and only have a 90ish load. Ford had a real problem years ago of glow plugs burning/breaking and landing in cylinders, I do not keep up with other brands but chevy had problems and had to re-program or change their controller.

 

[MichaelOverfield]

Are you going to install the glow plug controller also. I am sure the glow plugs need to operate quite differently than a grid heater. If left on for to long it could burn off at the stem leaving the coil rattling around in the intake and maybe eventually finding it's way to an intake valve. I'm not trying to persuade you one way or the other as it is your truck. Just thinking of the drawbacks of glow plugs. You could disconnect one of the grids and only have a 90ish load. Ford had a real problem years ago of glow plugs burning/breaking and landing in cylinders, I do not keep up with other brands but chevy had problems and had to re-program or change their controller.

It is an intake heater, not a glow plug. Actual glow plugs install in the cylinder, not the intake. The on cycle pattern is similar, there are pre-made aftermarket intake horns available for the Cummins (can't recall for sure, might have been a BANKS horn I saw that used one, but it was a major name in the aftermarket of some kind for sure) that use this heater in place of the original grids, so I'm not doing something that has not been done before. Those come with a single heater, I'm going with 2, one for each pipe bend. One might be sufficient also. The OEM grid is still flow restrictive and given those that have had them fail I'm looking to get rid of it (Cummins is a great engine, but seems they had the KDP and now the grid heater failures.. best to eliminate a known weak point) I I have to admit, I have searched on whether the other style has a failure history, if so, I have not seen it, I believe the Ford 7.3L at one point used a similar intake heater as well.. come to think of it).
Now that I think of it, I might be able to locate the heaters such that in the unlikely event one comes apart, it will not fall be gravity into the intake, but rather go the other way and cause no harm. Generally not going to be massive air flow when these light off, as it's basically used during idle warm up and pre-start conditions.

 

[MichaelOverfield]

Actually, it was BD, not Banks.. Found it. This is the same heater I got for HALF the price on Amazon. It pays to cross check and shop around. BD intakes have the threads for this heater. I have the stainless bungs to weld on to my intake.

https://www.xtremediesel.com/bd-power-1041563-x-flow-air-intake-heater

Here's the BD intake elbow set up for the above heater..

https://www.xtremediesel.com/bd-power-1041560-x-intake-elbow

since I have a welder and some stainless wire/gas.. to make my own saving over $300 was the way to go.. Now if I can find the time!

 

[Ozymandias]

I don't know where you life, but, most places the grid heater is an useless add on.
So, maybe it's just smarter to disconnect it and leave it alone instead of doin a lot of work and fab for something thats actually useless*.
....*aside from killing batterys.

 

[MichaelOverfield]

I don't know where you life, but, most places the grid heater is an useless add on.
So, maybe it's just smarter to disconnect it and leave it alone instead of doin a lot of work and fab for something thats actually useless*.
....*aside from killing batterys.

That is a great point, It's rarely below freezing (Western, WA, but might not always be..), and I could likely just get rid of it completely. Though, since I have the parts already, and a strange habit of making custom modifications to just about everything I own, I'll probably install them. After all I did the dual 220A alternators, just because.. though I did find them useful to run the AC in my RV TT via the inverter... I might some day add a big inverter to the truck to make it a portable generator... which the dual 220s could support. Too hard to do a PTO driven on the 4x4 version because the transfer case is in the way, but I did look into that as well.

 

[AH64ID]

On my 05 I was able to start, unhappily, at -20°F without my grid heaters on weak batteries.

It was often removed, but I did generally re-install it in the winter, but altered the programming so that it rarely came on.

On my 18 about the only time the WTS runs its course is with remote start.

In W. WA it's doubtful you would ever need it.

 

[Ozymandias]

I second this, the CDI starts always.
I never "needed" the aid of the grid heaters through all our winter trips to the polar circle and beyond.

But if one wants to modify as his hobby, well, that's another story.

 

[MichaelOverfield]

I second this, the CDI starts always.
I never "needed" the aid of the grid heaters through all our winter trips to the polar circle and beyond.

But if one wants to modify as his hobby, well, that's another story.

yeah, modifications and making various contraptions.. might be an addiction for which there is no known cure! But I do appreciate the great feedback on the utter uselessness of that grid heater.. It's also something to do with emissions in addition to supposed start aid, that darn thing cycles some times even in mild temperatures for no apparent reason, I suppose it is trying to get EGTs up for the DPF and beyond.. but that seems a bit futile, and certainly strains the electrical system.

 

[AH64ID]

yeah, modifications and making various contraptions.. might be an addiction for which there is no known cure! But I do appreciate the great feedback on the utter uselessness of that grid heater.. It's also something to do with emissions in addition to supposed start aid, that darn thing cycles some times even in mild temperatures for no apparent reason, I suppose it is trying to get EGTs up for the DPF and beyond.. but that seems a bit futile, and certainly strains the electrical system.

Even the 5.9 did that. The intake temp has to be above 66°F for them to not be used. It is for emissions.

 

[cerberusiam]

I never "needed" the aid of the grid heaters through all our winter trips to the polar circle and beyond.

I don't know where you went to the arctic circle in winter time and not needed the grid heaters on overnight cold soak, that is stretching things just a bit. That far north they build houses around equipment and heat them for a week to even attempt a startup procedure.

Cannot even do that in the lower 48 in the high plains most winters. At -20 to -30 F better have good batteries, light oil, and #1 diesel or it ain't happening. It will take 2 to 3 cycles of the grids to get a fire going the cold air won't quench and if doesn't fire by that time the batteries are done. At -40 F overnight with no oil heater or block heater it ain't gonna happen at all.

We ran oil heaters, block heaters, straight #1 diesel, insulated sideboards and pan wrap, then wrapped everything in a heavy tarp to get tractors to start and even drive them out of the barns in those temps. Western WA any time, just delete the grid heater. If it ever got cold enough to need the grids you would be living in your truck or headed somewhere else as the whole area would freeze into a big icicle. If you were spending time in eastern WA or Montana or northern Idaho THEN you would need the grids.

Note there is also a 5.9 style grid that will mount inline in the intake pipes also. If those coils ever burn off they will be embedded in a piston just like the bolt head. The grids will give more heat with less chances of FOD than anything.

 

[MichaelOverfield]

I don't know where you went to the arctic circle in winter time and not needed the grid heaters on overnight cold soak, that is stretching things just a bit. That far north they build houses around equipment and heat them for a week to even attempt a startup procedure.

Cannot even do that in the lower 48 in the high plains most winters. At -20 to -30 F better have good batteries, light oil, and #1 diesel or it ain't happening. It will take 2 to 3 cycles of the grids to get a fire going the cold air won't quench and if doesn't fire by that time the batteries are done. At -40 F overnight with no oil heater or block heater it ain't gonna happen at all.

We ran oil heaters, block heaters, straight #1 diesel, insulated sideboards and pan wrap, then wrapped everything in a heavy tarp to get tractors to start and even drive them out of the barns in those temps. Western WA any time, just delete the grid heater. If it ever got cold enough to need the grids you would be living in your truck or headed somewhere else as the whole area would freeze into a big icicle. If you were spending time in eastern WA or Montana or northern Idaho THEN you would need the grids.

Note there is also a 5.9 style grid that will mount inline in the intake pipes also. If those coils ever burn off they will be embedded in a piston just like the bolt head. The grids will give more heat with less chances of FOD than anything.

Thanks, all great points. I do like the flexibility to travel (also have some land in Idaho), so some type of pre-heater seems prudent. Might locate the heaters in the horn on the "up-hill" side, which should mitigate FOD concerns. Also, these are easy to pull and inspect, which can be periodic maintenance, something not so easy to do with a grid.