troubleshooting engine pulsation

Hi All,

I'm hoping for some more of the usual great advice that I get from this group.

I have just finished the engine swap to get my 99 Montana running. The engine doner was an identical Montana 3.4. During the swap, I pretty much disturbed everything so I can't narrow the problem down.

I haven't driven it yet but when I start it there is a good idle and I can rev it to 3700 then it starts to pulsate between 3700 and 3500 at an even rate. It does not pulsate at 3600. It will not go above 3700. There is no CEL. The problem is repeatable, it acts the same way each time.

I have 2 of everything (sensors engine part etc.) to swap out to try to eliminate. Does this sound familiar to any of you?

Thanks in advance for any ideas.

Kevin.

Most late model cars will not let you rev past 3500rpm in park/neutral. Have you driven it yet?

In reply to John Brown:

Hi John,

I have not driven it. I have it up on jack stands to go over the engine checking for leaks etc. I did not know that it was limited rpm in park/neutral.

That would be fantastic if that is what is going on. I have put a lot of time into this swap and did everything very carefully and by the book. I was disappointed to see it act this way.

I will get onto the ground tomorrow morning and try it in drive. Thanks for the tip!