2014 Grand Caravan 3.6L P0304

Just looking for suggestions on how to verify that the ignition coil and fuel injector are not the culprit of this misfire on cylinder 4. Since you have to remove the intake assembly to access the plugs (be first time doing this, so should be fun), was just wondering about ways to check things first before pulling it apart. Would like to be able to simply shift the COP to a different cylinder to see if the miss follows the coil or not but would have to reassemble the intake etc and that is just way more fun than I would like..lol.
I was planning on new plugs for this van, its at 170 K (km) now, so its due (runs all the time..a conversion to a wheel chair access taxi), but like I say, just wanted a way to verify COP and injector integrity.
We have a Mitchell DIY subscription for this vehicle (since our old Alldata program does not cover the newer years) and its a real PITA to find any info on that Mitchell..ok if you have all day to click a hundred links to finally get something useful I guess.

Do you have a scope? That is going to be key here. Not a whole lot of basic tests you can do to a fuel injector and ignition coil that lives under the intake manifold.

Yes, I have a Hantek pc scope, sorry for not replying sooner, was just watching your video on testing a COP on toyota lexus to pick up some good basic info (the air hammer interruptions..lol) I can't seem to get a decent schematic on the ignition system of this caravan, so can't tell how many wires go to the coil at this time..I will be tackling this job on Monday morning and just arming myself with as much knowledge and info as I can ahead of time, thanks for taking the time Paul!

they are 2 wire coils. the power feed comes from the asd relay for all of them. you can use an amp clamp around the feed wire for all the coils. and look for a pattern that is different from the rest. (paul has videos on how to set it up) specifically on a ford expedition... also I would do a clear flood mode crank first thing. (foot all the way down on gas pedal while cranking) and listen for a consistant crank.

Hey Chris! I was able to dig up a ignition system diagram, for reference:



Here's the injectors, too, just because:



Good ol' two-wire coils on this one, nothing fancy. Second thing I see is an 'Inline-Engine/Injector' bulk connector in both diagrams. I think that'd be an ideal place to connect up for all six cylinders, assuming that the connector is easily accessible. Easy ignition primary voltage and injector voltage testing.

Not trying to color your diagnosis at all here, but there is a recall/campaign/TSB/whatever out for cylinder heads on these engines. Or, are you already going in that direction?

cheryl hartkorn wrote: also I would do a clear flood mode crank first thing. (foot all the way down on gas pedal while cranking) and listen for a consistant crank.

Hahaha YES, exactly what I was thinking.

Tyler wrote:

cheryl hartkorn wrote: also I would do a clear flood mode crank first thing. (foot all the way down on gas pedal while cranking) and listen for a consistant crank.

Hahaha YES, exactly what I was thinking.

Will do, but don't have a lot of faith in that, or anything requiring hearing (too much loud music in college and a sheetmetal apprenticeship after that) for I have tried before to hear changes in the sound of an engine while cranking and can't detect anything, even though the old mechanic I work with is saying 'can't you hear that' or 'thats what a good one sounds like'..they all sounded the same to me..lol. I prefer methods I can either see or measure in some way. Ahh if could only go back in time to give yourself a smack upside the head and turn that noise DOWN..lol

Ah, sorry about that sir I had to start keeping a set of earmuffs on my tool cart after I got my cordless impact wrenches, which are somehow LOUDER than the air ones. Still not as careful about it as I should be...

If you're interested, relative compression is still an option with your scope. No low amp probe required. Here's a shot of a relative compression test I did on my car recently:



Settings are in the lower left, 1V scale with AC coupling and filtering on. The scope leads are connected to battery positive and negative. Not sure how the Hantek works exactly, but it may be worth a try?

Well, changed all the spark plugs (they needed changing..tips were mostly burnt off) and of course the old mechanic I'm apprenticed under had me throw a new coil on number 4..'since your already there' Turns out, still have the misfire on #4, this time I was allowed time to actually study the waveforms I had pulled up on my scope..I had the current clamp on the power feed and t pin on #4's wire at the fuel injector/ignition connector at rear..easy enough to find it since it was pin 4. It looked pretty much like a few others that I tested (couldn't do that before the plugs went in, for he didn't want the engine to get too hot...whatever..just let darn thing cool down again..no biggie, but anyways..lol
Now we are at the point of checking the fuel injector operation, but I can't seem to find a connector diagram/pin layout anywheres in Mitchell DIY or even our old Alldata, which has some coverage for the 2013 model 3.6L (presumably the same) has next to nothing in the way of diagrams.
It is super frustrating to need info to do some tests and keep running into brick walls..why does it have to be so difficult to pull up info like connector views and pin layouts etc! Hopefully the dealership will be able to send me over the diagram after lunch, had to send the van back into service, since could only have it until noon today.

Not too familiar with your engine been a Euro boy but going back to circuit basics will be the way to tackle this. Did you take note of the wire colors to injector 4 when the intake was off? Current ramping these will be the next step. If no current clamp is available this could get abit messy with using the scope as an in-line amp meter. May be easier for direction to do a quick relative compression test. Just to eliminate the possibility of internal engine damage.

If your not sure on the wiring I'd hazard a guess that you'll have a thicker gauge wire on the connector mentioned earlier that will be the shared earth for the injectors, you could read the current on this wire and you should see the current for all the injectors, then just look to see if one stands out as different to the rest, this will show your duff injector. That been said this been a modren engine harness it could be a multi plug full of wires for all sorts, again not been families with the engine it's hard to say.

Good luck!

Chris_In_North_Bay wrote: Well, changed all the spark plugs (they needed changing..tips were mostly burnt off) and of course the old mechanic I'm apprenticed under had me throw a new coil on number 4..'since your already there' Turns out, still have the misfire on #4, this time I was allowed time to actually study the waveforms I had pulled up on my scope..I had the current clamp on the power feed and t pin on #4's wire at the fuel injector/ignition connector at rear..easy enough to find it since it was pin 4. It looked pretty much like a few others that I tested (couldn't do that before the plugs went in, for he didn't want the engine to get too hot...whatever..just let darn thing cool down again..no biggie, but anyways..lol
Now we are at the point of checking the fuel injector operation, but I can't seem to find a connector diagram/pin layout anywheres in Mitchell DIY or even our old Alldata, which has some coverage for the 2013 model 3.6L (presumably the same) has next to nothing in the way of diagrams.
It is super frustrating to need info to do some tests and keep running into brick walls..why does it have to be so difficult to pull up info like connector views and pin layouts etc! Hopefully the dealership will be able to send me over the diagram after lunch, had to send the van back into service, since could only have it until noon today.

Sorry to hear you got overruled about testing first Some guys are just set in their ways...

I'm not sure if you saw the injector diagram I posted earlier? Pin 14 is the #4 injector control wire, brown/yellow on the engine side, and brown/tan on the computer side. The #3 injector control wire is right next to it, pin #13 brown, for waveform comparison.

Are you feeling a miss, or is it just the code? When and how badly it misses may help us get a better idea of what's going on.

Yep, finally identified the right pin and got a waveform from it, which looked fine, (I think I can make out the pintle hump). I attached images of the waveform as well as one I got from the control pin of the #4 coil. Both of these waveforms look to be the same as others I looked at.

It is still a definite misfire, still has the shake and the trouble code came right back after clearing the codes after changing plugs. Did a relative compression test and all the humps look to be the same height, none are missing. So if I got compression, got pcm control for the coil, new oem coil installed, as well as plugs, the injector looks to be working. Only thing I can think now would be a dirty injector? Could run cleaner thru it (the one that connects to the fuel rail and engine runs off it) but really that is not 100% successful either. We have an OEM injector on the bench from the dealer, so can put it in, would like to have a confirmation that it is faulty tho, but at this point what else could it be?


Coil control signal with the upside down current ramps


Injector 4

Indeed a pintle hump of some description there, may well be worth getting a current ramp for the injector to confirm your diagnosis. I'd be careful with the injector cleaner I don't trust them too much as I've seen a fuel pump fail on a vehicle as a direct result of the stuff and a diesel injector on another.

It sounds like your satisfied with ruling out spark and compression, might be a case of looking at timing or possible exhaust or intake blockage however you would expect this to affect multiple cylinders

I understand that this is an older thread, but I have a 2014 Caravan with a similar issue. I was wondering what the outcome was please. I too have changed the plugs and swapped coils but the misfire is still detected on the same cylinder. Also I cleared the engine codes with my scanner and without cranking the engine the codes still return. Possible bad wire??

Any help would be appreciated.

Jeff