When you say nothing came up on the diagnostic, do you mean they scanned the computer for fault codes and got nothing?
Check these things first.
1) check fuel pressure at the fuel rail. There should be a schrader valve (like a tire valve) that you can screw a mechanical pressure guage into.
2) check to make sure spark is getting to each and every spark plug. Unscrew the spark plug, plug it back into it's wire and hold the spark plug against a clean bare section of the engine block and crank the engine. You should get a series of sparks. Careful you don't zap yourself.
3) check compression on all cylinders and compare them with each other. All the values should be fairly close to each other.
Fuel delivered in the right ratio at the right time, spark delivered at the right time and good compression are the three things an engine needs to run. Additionally check such things as the fuse panel, relay box, ignition timing, wire connections you think might receive a lot of abuse, etc. I hope this helps.
Tuesday, January 16th, 2007 AT 7:36 PM