3 replies to this topic

[nballard76]

Hi Guys,  I have been working through some issues with my '99.  I'll give the cliffs notes version of this season.  When motor was brand new (two seasons ago) it dynoed at 121/119 out of the box.

 

This season I kept losing power with the timing slipping.  I would go out at 14 and come back at 8 (using a 5x timing wheel)...very strange.  I was also getting some wobble on the crank pulley.  Two events ago the wobble got really bad and I took it to the dyno and it made like 111/108 (unraceable).  We pulled the bottom end apart and low and behold, the crank was bent (likely from a previous accident before I bought the donor).  We put a new crank in and replaced all the bearings, etc. and the wobble went away, but at the dyno I was only making like 116/113...barely enough to hang on!  I'll also mention that the bottom end looked great when apart, nothing of concern was noted.

 

I figured something must be wrong with the head so I did a compression test and a leak down test and got these results - 

 

1.  190  4%

2.  183  4%

3.  178  7%

4.  180  3%

 

All good numbers from what I understand.  Thus far I've tried the following and am still getting a rough idle

-New spark plugs

-Different ignition coil

-Looked all over for a vacuum leak and can't find one.

 

The only other things I can think of that could be the issue are the injectors (rebuilt last year by RC Engineering) or the spark plug wires (I'm currently running newer MSD Super Conductor wires so I doubt it's the wires).

 

Short of the injectors is there anything else I should be looking at?  Are there any weird nuances with the 99 that I'm missing?  It seems like all the numbers check out with the head and we know the bottom end is good, so it has to be fuel delivery or electrical.  What am I missing?

 

Thanks!

[mdavis]

Have it timed correctly with the belt?

[nballard76]

Have it timed correctly with the belt?

Yes, cam timing is right where it should be...thanks though.

[Jonathan Davis]

Have you inspected the green and white vacuum check valve under the upper intake manifold? If it's not working the secondary throttle plates don't open at high RPM and it might cause a bad idle if there's a vacuum leak there.