2.5 swap issues

[amishmonk]

Hey all,

 

I am a brand new user to this site and i have had my comanche for about 6 months.

 

It is a 89 Sportruck 2.5 2wd w/ ax4 4speed. I did a engine swap and the new (to me) motor won't run right. We have all the vacuum lines hooked up correctly to the throttle body, map sensor, and everywhere else they go. I thought the issue was in the timing, but this motor does the strangest thing i have ever seen. We hooked a timing gun to it and it stays at 10 deg before or after tdc (i can't remember the spec but i think it is right) no matter where the distributor is. This absoultely boggled me because it has points and a rotor. How can the spark be whenever when the rotor has to be near the points? It has no power and from what i know about engines, it sounds like the timing is off. It will run and drive, but it has no power and will occasionally fire out the top of the throttle body.

 

The motor didnt come with a throttle body, distributor, or cps. From what i understand from this site and others, this motor uses the renix ignition control system. The motor that was in it (which i don't think was original bacause it had XJ on the intake manifold) had the renix system as well so the cps that was on my bellhousing would be renix and my flywheel flexplate has the big notches in it which is also indicative of the renix system.

 

All i did to the motor is re seal all the gaskets. The only critical parts i removed were the pushrods, valves (hand grinded), and the rocker arms. Everything was labeled and put back exactly as it came out. I didnt touch the crank, cam, or pistons because that is beyond my expertise.

 

I am at the end of my knowledge with this so any help would be much appreciated.

[Jeep Driver]

If you have a points distributor.........>you have the WRONG distributor.

 

XJ on the intake is correct to the MJ.

 

 

You need a Renix distributor. The points dist would have come in a '86 2.5 or earlier that was carbed, not injected.

[dasbulliwagen]

I agree. You shouldn't have any points. I'm surprised it runs at all. It also makes me wonder what else might be wrong.

[amishmonk]

Thanks for the replies. And that is what i don't understand. The same motor that it had in it before i swapped was running with this distributor. Did they change distributors at some point during the 2.5's lifespan? And if so, why would the engine behave differently if the throttle body, sensors, and ignition system is all the same?

 

Btw, i may have mispoken when i said it is a points distributor. I'm actually not sure what kind it is, but it has the drive for the oil pump on the end like it is supposed to and it was on the other engine when it was running.

 

I would post pics, but the jeep is back in the woods covered in snow. If you need to see something specifically, i can get pics.

[amishmonk]

Hey. Dragging this back to the top because the snow melted and i was able to haul the jeep out of the woods.

 

I cleaned the cps which is certainly not overstated on this site. It did considerably improve how it was running but it is still not up to snuff. I have a question. Where is the o2 sensor supposed to go? There is a connector behind the throttle body that looks like it should recieve the o2 sensor connector but it won't. I can hard-splice them together to get it running right, but since the connectors didnt fit, i wasn't sure.

 

Also, were there any sensors in the airbox that i got rid of that i shouldnt have? Air intake temperature or pressure sensors? I got rid of it and replaced it with one of those spectre cold air intakes.

 

I will get pictures tomorrow if i can remember to give y'all a better idea of what the hell I'm talking about.

[gogmorgo]

I can't tell you for sure where the O2 sensor plugs in on a 2.5, but I can say that splicing the wires in won't work out for you. O2 sensors take an atmospheric O2 reference through the harness, so if you cut and splice, you'll be interfering with that.

[amishmonk]

Boy am i glad i didn't start cutting wires. I just started to make a video to show y'all whats what when i noticed three things.

One, i am an idiot.

Two, the connectors i was concerned about werent even the o2 sensor. There were two. Both behind the throttle body. One was the water temp sensor and the other was, i assume, intake air temperature sensor. What i had done was i connected the two harness-side connectors together. One was male and the other was female. Both two-pronged. I thought birds and bees and put them together. Turns out the two sensors went into these harness connectors that i had connected without thinking. Oops.

And three, i reinstalled the tps wrong. The piece on the throttle that is supposed to push down on the tps to, you know, work it, was below the sensor lever and was doing nothing. No friking wonder my throttle response time was terrible.

 

Now it idles nice and low. About 800rpm or so, but it is still a little shaky. Maybe it just needs to be broke in a bit, to my setup anyhow.

 

Don't fret though, i am sure something will go wrong again once i start messing with stuff so i can come here and complai... i mean contribute more.

 

Thanks for the help and if anyone knows how i can get rid of the shakiness some, i would be happy to hear.