Misfire problem with one cylinder bank

I'm still trying to diagnose a misfire problem in all three cylinders on the driver's side, after a valve job (both valve heads rebuilt). An excellent local machine shop did the valve head rebuilds, and I was careful about all of the grounds, the spark plugs, spark plug wires, etc. And I can't imagine that I put the camshaft sprockets together wrong, that would be hard to do. So I'm still stuck on what kind of error I might have made in reassembly that leaves me with a rough running engine and misfire codes from cylinders 2, 4, and 6.

I'm curious whether it might be a fuel problem specific to that fuel rail. How likely is that? This is the fuel rail that has a vacuum actuated regulator of some sort (the passenger side fuel rail just has a banjo bolt). What's the reason for having two separate fuel lines for the different fuel rails? And how could I diagnose this, either as a fuel problem, or a timing problem? My gear is pretty basic.

 

I am thinking that the D/S cam is out of time... a quick compression test could verify this. Compare the P/S cylinders to the D/S cylinders. New cam belt of reuse the old one? A new belt "should" have arrows pointing forwards and paint lines to help in positionong the belt on the pulleys.

 

^^^^ x2^^^^

 

I reused the old timing belt, but it was changed fairly recently and still had the timing marks on it, very clearly. It would be hard to get that wrong. I am 100% positive that the timing belt was installed correctly according to the TDC marking, the line on the timing belt, and the dot on the sprocket. I suppose it might have been *slightly* more likely that I might have been off a tooth when I assembled the camshafts, because I was looking for those dots in the back, with my little mirror. Still, it's pretty easy to line up those markings too, that's another step that would have been hard to get wrong.

OK I think it's time I broke down and bought a compression tester. What would I expect to see if the timing belt or camshafts were off by a tooth?

 

A very noticeable difference in compression from drivers side to passenger side.

 

odd stuff happens ALL the time, lucky she is a non-interference engine, if she wasnt you would KNOW immediatly.

 

OK so I got a compression tester, and as suspected the D.S. cylinder bank is not holding any compression (all three cylinders on the passenger side were around 200 lb/sq.in.).

So it seems this is a valve timing issue. I see three possibilities, #1 would be that I put the camshafts together wrong (not likely), #2 that I put the timing belt on wrong (not likely), and #3 is that the machine shop didn't rebuild the valve head correctly (not likely).

So how do I diagnose what's going on from here? And are there any other options than the three that I listed?

Other question: I *know* for 100% certainty that the camshaft sprockets were lined up correctly to the lines on the timing belt. If somehow I got the timing belt off a tooth on the crankshaft, wouldn't I still get compression in the cylinders? And wouldn't the problem be in both cylinder heads? In order to get no compression, doesn't that mean that the exhaust and intake valves are out of sync?

 

Pull the valve cover and check cam timing. Then pull the t-belt cover and check belt timing.

 

or vise-versa

 

The machine shop bolted the cams in the heads correct?

 

The machine shop had the camshafts in order to adjust the valves. On this engine you need to remove the camshafts to install the head bolts, so I installed the camshafts. Maybe that's my first step, to verify that I didn't make a boneheaded mistake putting the camshafts together. Though it's pretty damn simple, put the two dots together, duh. Anyway pulling off the intake manifold to take the valve cover off is a lot less work than checking the timing belt, so I guess that's my first task today.

 

OK, mystery solved. When I put together the camshafts (exhaust and intake), there are little dots stamped into the sprockets where they mesh together. Well, unbeknownst to me, there are dots, and then there are TWO dots stamped exactly 180º away. So I had matched up one dot on one shaft to two dots on the other shaft. These dots are stamped on the firewall side of the sprockets, so you have to look with a little spot mirror, so it was easy to miss the one dot/two dot thing. So yes, it was my boneheaded mistake (I figured that much), but it was only a semi-boneheaded mistake.

Thanks to all of you who pointed me in the right direction. So it’s all back together and running strong, no misfires and no check engine codes. Next question, however: is it normal to see some smoke coming from the engine for a little while after a valve job?

 

Glad you got it fixed. Yes some smoke is normal.