98 4.0L Valve Timing problem?

[jimlas53]

I just finished a complete rebuild of a 1998 4.0L SOHC V6 in my wife's Explorer. I replaced the timing chains, sprockets, guides, rings, bearings, all seals and gaskets, and had the heads surfaced and the valves done. I bought the Valve Timing Tools required to set up the camshafts properly. I've spent time on the Web (and especially on these forums!) to learn all I could about the timing chain/guide/tensioner issues with these engines. When I pulled the engine down, I checked and at #1 TDC, both cams alignment slots were parallel with the heads and below center line.
All through assembly, I followed the Alldata assembly steps, especially observant of the torque requirements, etc.
I also pressurized the oil system before starting to ensure no initial start-up bearing damage.
When I started it for the first time I had most cylinders, but not all of them. It was missing, and it sounded to me like a vacuum leak. I pulled the upper , then the lower manifold off, and found no problem with the o-rings. I started it again, this time noting that pulling spark plug wires on the left bank didn't seem to make much difference. Pulling the #1 plug killed the engine. I also noticed that after 5 minutes running, the left exhaust manifold was somewhat hot to the touch, but much cooler than the right bank. I've pulled the valve covers, and at #1 TDC, both cams slots are parallel to the heads and below center line. The intake and exhaust lobes are properly positioned for #1 cylinder in firing position, and the flag on the left cam is coming up under the Cam Position Sensor in the left valve cover.
I have verified the spark plug wiring (according to Alldata) and all vacuum connections.

WHAT have I missed????

Thanks for the help!

Doug

 

[dogfriend]

I would go to the basics for the cylinders that aren't firing:

Spark, Fuel, Compression

Spark - Verify that you are getting spark with a spark tester

Fuel - Verify that the injectors are working by listening to them with a stethoscope and/or using a "noid" light to see if they are getting a signal.

Compression - Verify that you have a good seal in each cylinder by performing a leakdown test. You can test each cylinder at TDC and listen for where the leak is occuring (intake valve, exhaust valve or somewhere else) if any are leaking. You may be able to rent a leakdown tester, but I bought one from Harbor Freight Tools for $55 because I couldn't find one to rent locally.

If the valve timing is off, it should be apparent during a leakdown test. Remember that you have to follow the firing order to get TDC in each cyl after #1.