So I've spent all day at the shop swapping in a new flex plate. We finished everything up start it up check all the gears, start backing up and the timing was off. It wont reach over 10mph but when I get it over 1000rpm it will miss fire and feels like it's ran out of gas. I pulled it back into the shop popped the hood and it sounds like a vacuum leak. I idles perfectly fine until you give it some gas. I have no idea what could of went wrong, we checked the map sensor, o2 sensor, etc. I'm hoping NAPA didn't give me the wrong flexplate. Does anyone have any experience in this department?



:EDIT: OP, watch your language...

 

Of course you compared the new one with the old to make sure they were the same.

 

^^ yeah...

 

Yeah we did match them up

 

pinch some thing between tranny and block?

 

So why do you blame the flex plate when you matched them up to make sure they were identical?

Obviously it's something else you did.

Did you remove the CPS BEFORE switching flex plates - if not could you have damaged it? There's only about .003" clearance between them - and they are fragile.

 

exactly were both on the same page

 

Let's back up to square one shall we.

Always start your posts with make, model, and year. Is your engine a 4.0L or a 2.5L

Sounds like a vacuum leak....check all you vacuum lines, even the ones you didn't touch.

Did you remove the intake and exhaust? Are you 110% certain you re-installed them correctly? Did you get the correct gasket? There 2 flavors...

 

It's an 89 xj with a 4.0, we check every vacuum line and didn't find anything out of the ordinary. We checked my fuel regulator and drops of gas were coming from the wrong end which is obviously bad but it doesn't explain the state of the jeeps condition. The help I'm receiving is much apreciated by the way!

 

Sounds like you need to put a fuel pressure gauge on and see what's happening with the pressure.

 

Check the intake manifold bolts too. They back out and even though you never touched them the movement may have caused them to allow a vacuum leak. See how much vacuum your engine is pulling at idle.
Leaking fuel regulator can cause a fire, so replace it. The only way it is getting fuel on the vacuum side is a pinhole in the internal diaphragm.

 

Do you mean there is fuel dripping out of the vacuum hose nipple on the pressure regulator? If so, you have a ruptured diaphram in the regulator and unmetered fuel in being sucked through the vacuum hose and into the intake. That would cause a pretty crappy running condition.

 

I went to NAPA got another flex plate, we through it in for the heck of it and it worked. When we pulled the faulty flex plate out, everything seemed like it looked normal until we laid them face down next to each other and one was taller than the other. I don't know if that's enough to make it run like it did, but i'm assuming it was cause everything else matched up.

 

How about the holes around the outside edge? The 2.5L and 4L flexplates looks the same but have different number of holes. These holes are what the crank sensor is reading.

 

Yeah, those matched up also. NAPA had the defective one sent off the the manufacture that they got it from and they should be able to tell me what all is wrong with it. I'm just happy I don't have to drive my fiance's s10 blazer anymore.