Timing question

Can the timing be 180* off on my 2010 4cyl? I bought the truck not running. It tries to start but pops and backfires. I checked compression when I got it home and it had 90psi on cylinder 1 and the other 3 had 0. I had the head checked and resurfaced. Installed new head gasket and put everything back together the way it was. Timing marks are lined up. It started and ran a few seconds but cut off. Now it's doing the same thing it did when I bought it. Pops and backfires. I pulled the codes and it said misfire in cylinder 2 and 4. Any help would be greatly appreciated.
Also, I checked the compression after the head resurfacing and gasket. The tester was bad....
Got a new tester and I have around 150psi on each cylinder. So this makes me wonder if I even needed to take the head off to begin with. But either way I'm still back where I started.

 

I suppose it could be but it wouldn't have ran at all if that was the case.
Popping and backfiring would suggest a lean condition, have you checked fuel pressure?

 

I haven't. I'll check it tomorrow. Thanks

 

It sounds like cam timing might be off. I've never timed that specific motor but when they pop and spit back through the intake its usually firing when a valve is partially open and that shouldn't happen if the cam timing is right. Not sure where the pick up is for ignition timing but usually they're down at the crank and shouldn't be affected by removing the head.

One of the fundamentals I learned over the years working on sohc and dohc motors is once the timing marks are lined up and the belt/chain is on but before putting the covers on, rotate the motor by hand in the direction it runs at least 2 full revolutions, as you do this any slack in the belt/chain should be near the timing belt/chain tensioner, (that tells you you're turning in the right direction). The idea is to rotate it through all 4 cycles watching that everything comes back to line up correctly at the end of the 2 revolutions of the crankshaft.

Turning it by hand is a non destructive way to verify it's all correct. You probably know this but if it's timed wrong and the initial rotation is done with the starter its easy to bend some valves. If it's off a tooth and starting is attempted it may or may not run at all, if it does run it'll be real sluggish, throw codes and run like crap.

https://youtu.be/w0zwWF5MZqA?si=0na_eXC9uNrQ4Qqq

 

I did a write-up of sorts for timing here
https://www.tacomaworld.com/threads/used-tacoma-sludged-engine.808661/

Page 4 near the bottom shows the timing chain and gears all lined up.

If I recall.. It took some 60 and a few more rotations of the crank to go from having everything lined up to lined up again. Think it was 64 rotations. If you go 70 rotations without seeing marks and colored chain links line up, you'll know something's not right I suppose.

You can take just the valve cover off to check timing marks on the cams. The chain should be tight between the cams when at tdc with marks all lined up. The above thread, if you wanna dig through it, has an image of what it should look like.

If you need to get at the chain, you dont have to remove the head!
but.. it's still a lot of work.

I'd expect codes for a timing error. Just throwing misfire makes me think of fuel, vacuum, clogged catalyst. On the missing cylinders, what were the spark plugs like?

 

I'll check it out. The spark plugs didn't look bad but I replaced them. The exhaust cam looks to be half a tooth off. The mark on the cap is lined up in the dip of the sprocket and the dot on sprocket is a little to the left. Mark on crank pulley and intake cam are dead center.

 

Hold the phone. Let me check my pics cuz that may be just fine

Intake


Exhaust


These are freshly set with a new chain and guides. The sprockets actually hold tension on each other, pulling away from each other, that is. They just can't be lined up any better than the above.

So it sounds like your timing is looking good. You said your misfires moved... I know this is dumb, but.. What about swapping coils around?
Coils actually have the potential to cause phantom misfires. They can generate some frequency stuff that can interfere with the ECM. I've only experienced that on a ford though, and it had a separate capacitor for handling those frequency issues, which a previous owner had removed and bypassed. From what I've seen, the capacitor is integrated on our more expensive coils and they have insulation to handle it, but maybe it could fail? playing musical coils should ID that problem.

Were the plugs you pulled wet? Can check on the new ones too. if it's misfiring and they're wet, you know they're at least getting fuel. alright, its off to work with me.

Oh, to the end of checking for a clogged catalyst, you could disconnect the exhaust just after the header, stick some foil in between the header and the firewall to protect any wiring, ect. but if you have a clogged cat, you'd have engine heat issues.

 

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When ever I came across a cam timing configuration that relied on marks on the chain itself I create marks (if there wasn't any) on the shafts (crank and cam) while everything is lined up after assy, they will always line back up in 2 turns of the crankshaft. Waiting for the marks on a chain will take quite a bit longer and isn't realistic for this check. A drop of orange torqueseal does a great job of creating temporary marks on the cam and crank. These are pretty simple motors to time, esp if you've ever done a DOHC V design engine.

 

My marks look exactly like your pictures. I checked the coils with multimeter like a guy on YouTube and they were good according to his video. I dropped the tank this morning and drained all the gas just so I could eliminate bad gas as possible issue. Put everything back together and added 5 gallons of fresh 93 octane with fuel injector cleaner. It started and ran with misfires and eventually cut off. Scanner says cylinder 1 and 3 misfire but was saying cylinder 2 and 4 the day I bought it. I guess I need to buy new coils. I ordered a fuel injector cleaner from Amazon and I'll clean them Tuesday when it comes in. The catalytic converter is gone and there a straight pipe there. I guess someone stole it at some point.

 

Does your truck have a modified intake? Like a K&N filter or something? Anything engine/electrical non-stock
Anything plugged into the OBDII port?
I'm suspicious now that I hear there's a straight pipe.

I dont wanna tell you that you have a bad ECM, but that's how stuff's starting to sound. Per my experience, that typically means something else was mixed up during a service, so I get a second opinion beforehand.. that also typically turns out to be an inaccurate assumption of an ecm failure.

 

It has factory air box and filter.
I went out and started it about an hour ago and connected the scanner again. Only reading misfire at cylinder 3 now.... I swapped ignition coil out with cylinder 1 and now I have misfire at cylinder 1. I ordered new coils and they'll be here Tuesday. I'll update with what happens. Thanks for your help

 

The truck runs now. But I have to fix a coolant leak under the intake and I'm getting P0037 code.

 

Woo!!! Good job!!

Is it that plastic coolant line on the side of the timing cover or somethin else? uh. This guy (the arrows are point to timing cover bolts, but the coolant line is directly between them)


I've heard say that the line fails cuz it's plastic, and so there are metal replacements available on ebay as well as rockauto now. If one were so inclined. https://www.rockauto.com/en/catalog...2969,cooling+system,coolant+hose+/+pipe,11564


My plastic one's holding up!

 

The P0037 is for low current on the O2 heater circuit for the downstream oxygen sensor, easy enough to check the sensor.

 

It is the plastic coolant line.
I pulled the intake and ordered the metal tube. Will I have a check engine light with the catalytic converter missing or issues with the sensor?

 

You will have a CEL and a P0420 if the primary cat is gone once it runs the monitor, if it's the secondary cat (not sure if the 2.7L has one?) It won't trigger a CEL or code.