HELP!What did I fudge up....? Misfiring entire left bank after removing exhaust cam.

[robb1887]

:roadkill:

I seem to never be able to do anything to this truck without something flipping up.

I was doing VCG's and the such... passenger side went well enough and everything got back together easily. I go to do the driver side and when removing the VC the engine harness 16 y/o plastic cover decides to explode sending small/large shards into my now exposed head...

I find that two have fallen into oil returns and the only way to get into those is to remove the exhaust cam. FML. I mark three teeth on the cam gears so that I can replace it in the same timing that I removed it with.

I get all the pieces of plastic out with a long flat head screw driver and some FPIG. I replace the cam and finish the job.

I turn the truck on to check to make sure everything is running... as I clean up I am not in the truck obviously to feel it running funny. When I come back I have a check engine light and I hop in and feel the misfire.

I was hoping it was just from the MAF that I cleaned and it need to be ran, I took it to the closest autoparts store and low and behold my entire left bank is misfiring.

AWESOME...

What'd I do? I'm at a loss.

And pictures since everyone loves them:

Pieces in the drains:



Piece that were extracted:



Match marks two teeth on cam that was removed, one on cam that stayed to make sure it was the exact toothing:


Help please

 

[robb1887]

I have this on instant email notification I will give real time feed back for any other questions you guys might have.

 

[Pmcmasters]

Sounds like timing is off

How did you remove the camshaft? Did you line up all of the timing marks on all camshafts and crankshaft pulley before pulling the camshaft? The first thing I would do right now is verify all of your timing marks line up. Did you remove or reset the timing belt tensioner before you removed the cam gear? My shoot-from-the-hip diagnosis is that your timing is off by one or two teeth.

 

[robb1887]

Nothing else was removed. Just the one camshaft. I didn't remove the other cam shaft so to my understanding the timing shouldn't have moved with the rest of the shafts. I could be wrong though. This is definitely not my forte.

 

[Pmcmasters]

The quickest and easiest way to rule out incorrect timing would be to pull the plastic trim covering the camshaft timing belt sprockets so you can see the timing hash marks. Roll the engine over with a socket/ratchet clockwise at the crankshaft bolt until you line up the TDC mark on the crankshaft pulley to the pointer. Then check the timing marks on all four camshafts. If none of them line up to their pointers then roll the engine over one time and recheck. My guess is that the exhaust cam on the driver side is going to off by a tooth. The engine will still run with the timing off by one, maybe two teeth but it won't run well. Is the check engine light on?

 

[robb1887]

Yes the light is on. Throwing a P0300 multople misfire code and its for 2-4-6 cylinders.I guess I'd have to pull the VCs again to see the exhaust cam TDC marks? What's size socket is required to roll the engine?

And yes it seems to run fine, it just idles rough as hell.

 

[Pmcmasters]

I apologize for some of the mis-information I said about the timing belt sprockets. I just ran out to my 4Runner to take a look at the bolt size and realized I was thinking of a different engine. Anyway, regardless of that you're still most likely off by 1 or 2 teeth and will need to pull the valve covers back off. Once the VC's are off, roll the motor and check the factory marks before going any further. Rule of thumb is whenever you mess with camshafts, timing belts etc. you always roll the motor over manually at least 3 times and verify all of the timing marks line up every revolution before finishing reassembly. The bolt for the crankshaft pulley feels like a 17mm or 19mm.

Just out of curiosity, what wiring harness exploded? Does it have anything to do with the coil packs on the other side of the engine or any other part of the ignition? It most likely has nothing to do with the misfire but it doesn't hurt to trace the harness to make sure there aren't any exposed wiring shorting out on the engine.

 

[robb1887]

It was the plastic cover over the wiring harness o. The driver side. It was super brittle from the years if great I guess. I broke the rest of it off and removed it matter putting the VC back on.

 

[iowajosh]

I will bet it is electrical. The engine knows if it fires the plug or not. It doesn't know if it actually combusts. At least I don't think so. Put my cam in wrong and no CEL but I didn't exactly take it for a road trip, either.

About the cams, there is a single dimple on one side of the gear and a double dimple opposite. Align either the single dimples or the double dimples with a twin. I can't see it in your pic. On one side they are facing rearward and are really hard to see. On the other side they face forward and are easy to see.

A loose ground by the diagnostic plug will make it run terrible also.

 

[robb1887]

I'm pretty OCD about putting everything back together. I will double check the ground but it should be tight. I just don't want to have to break it all the way down again. Its a PITA to do it once in a weekend let alone twice.

 

[TheDurk]

I will bet it is electrical. The engine knows if it fires the plug or not. It doesn't know if it actually combusts. At least I don't think so. Put my cam in wrong and no CEL but I didn't exactly take it for a road trip, either.

About the cams, there is a single dimple on one side of the gear and a double dimple opposite. Align either the single dimples or the double dimples with a twin. I can't see it in your pic. On one side they are facing rearward and are really hard to see. On the other side they face forward and are easy to see.

A loose ground by the diagnostic plug will make it run terrible also.

Actually, it does know. The crank position sensor lets the ECU 'feel' the misfire in the change in speed--or the lack thereof--in the rotation of the crank. That's what sets the P030x codes. I also doubt that one entire bank could have an electrical failure and no problem on the other one--unless the plug wires were completely scrambled causing sparks, but in the wrong places. The waste-spark setup is a series circuit, so an open-circuit kills the plugs on both sides. It would take three separate shorts to ground to kill the three even plugs while leaving the odd ones firing.

So I would triple check the plug wiring (always a difference of three: 1-4, 2-5, and 3-6). Then concentrate on the cam shafts as described above. Crank bolt is 19mm.

 

[robb1887]

Welp the cam was the culprit. I ended up breaking it back down and turning the motor over. The factory cam marks were out 4-5 teeth. How that happened still puzzles me but it is running well now. Makes me wonder if it didn't start a tooth or two off before I opened it up. And when I aligned the factory marks the sharpie I had done the day before was out too.... its weird. Nevertheless the truck is back up and running it seems.

Thanks for the help fellas

 

[robb1887]

Update:

So found out that the follow(exhaust) cam has a clock spring gear in it that keeps the gears tight. I found this out later and took it apart again and reclocked the gear and reassembled and everything is quiet again. This can be prevented during disassembly by installing a bolt into the hole in the cap gear (I hear one from the VC fits) to hold the spring tension.

In case anyone digs this up looking for info on it.