I have an 88 nissan truck with a Z24 engine that blew a head gasket between #3 and #4 cylinder. I had the head shaved, laped the valves in, new gaskets and put her back together. I started her up and it is now not running on #1 and #2 cylinder. Compression is good, I have spark to all cylinders, timing is set right, I cant see any loose connections anywhere, wires or vacuum lines. Anyone know what could be the problem? I was thinking a fuel problem but it is a TBI, it should be feeding all 4 cylinders together, right?

Firing order correct?

yes, according to my repair manual anyway.

I have to ask....New or used plugs in the engine?

I wouldn't think it would even start if 2 of the 4 cylinders are not firing. Are you sure that's what is really going on?

zlathim said:

It may start, but it's going to run like crap, if at all...rattle and shudder worse than a mis-timed Harley with a rigid mounted engine. Probably slam the door for you if you leave it open.

With TBI, it should feed all four cylinders equally. Well, as long as there is nothing blocking the intake ports, such as rags stuffed in there (seen that before).

What is your compression readings per cylinder?

It does idle very rough, though seems to smooth out when revved up. This engine has two plugs per cylinder, I can pull all the wires for #1 and 2 and no change in idle, but when I pull the wires for either #3 or 4 it will almost die out. I did not put new plugs in, but I did switch them around to see if that's what was causing the problem and no change. Each plug is sparking when I grounded them to the block. I checked compression on #1, it was about 135, didn't check the others. Is there something that links #1 and 2 cylinders that does not control 3 and 4?

Valves too tight? Run compression and check valve clearances.