Whats wrong with my Renix.

[DansGreyMj]

It has a new TPS, CPS, fuel pump, fuel filter, vacuum lines, coil, cap/rotor/plugs/wires, it also has 5.0 4 hole injectors; and none of this has helped, it still "stumbles" around 2k and makes cruising on the highway a chore.



Here is a short vid of what it does. I also took a vid of the actual motor doing it but my camera is not to great so it looks like nothing is going on.

 

[bigalpha]

Did you clean or replace your IACV?

Wait, that's a retarded suggestion.

 

[tugalo]

My MJ did the same thing.....I replaced the Manifold Air Temp sensor, added an extra ground from the battery to the front sheetmetal, and cleaned all the other grounds really well. Don't know which one fixed it, but now it works fine........

 

[ehall]

yeah, either the map or mat sensors would explain it

grab a couple from the jy and see if they do anything

 

[DansGreyMj]

MAT sensor is the one on the side of the block under the headers, right?

 

[Slip Kid]

MAT would be in the manifold. Coolant temp sensor(one of them) is on the block.

 

[DansGreyMj]

MAT would be in the manifold. Coolant temp sensor(one of them) is on the block.

Whats it look like?

 

[ehall]

Look for something that is screwed into the manifold (or maybe the TB) that has a pair of wires going to it. The connector should be one of the GM weatherproof things with the tab.

 

[garyindiane]

Check this out...

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm


-Gary

 

[DansGreyMj]

IS this mod worth it?
http://www.angelfire.com/my/fan/IAT_sensor.html

Also if anyone know wher i can get a new one? The only one I found was on Autozones website and it has to be mailordered. I may just try and snag a few from the jy next time.

 

[ehall]

Impossible to say without actual data like dyno numbers. The principle of the MAP and MAT is so that the computer can determine the density of the air entering the combustion chamber (see this table http://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html). As long as the MAT is measuring the air temperature in the manifold (which is the air that gets combusted) and is not measuring something like the temperature of the manifold itself, then it is doing what it should do.

ps--lots of sites recommend relocating the MAT/IAT but I've never seen dyno numbers

 

[88 Wagonman]

Have you ever replaced the cam position sensor? If so, you might need to index your distributor. If that's not it I would definately check the MAP sensor.

 

[DansGreyMj]

Have you ever replaced the cam position sensor? If so, you might need to index your distributor. If that's not it I would definately check the MAP sensor.

Yes i have replaced the CPS, How do you index the distributor?

 

[88 Wagonman]

Yes i have replaced the CPS, How do you index the distributor?

The one in the distributor (Cam position sensor) or the one on the bellhousing (crank position sensor)? If you haven't replaced the one on the bellhousing then I would highly suggest that you do, but it sounds like you probably already have.

I will try to find a link on indexing, but I will give you what I remember.
1) find an old distributor cap and cut it open to view where the rotor meets the #1 post in the cap.
2)Remove the distributor (after marking it's position for reassembly)
3) Cut the locating tab off.
4) Reinstall the distributor
5) Rotate the distributor until it lines up with the rotor at the specified point (Like I said, I will try to post a link)

It's really not that hard to do.

 

[DansGreyMj]

I replaced the one on the bellhousing.

 

[88 Wagonman]

Links:
http://www.asashop.org/autoinc/feb99/techtotech.htm
http://blog.hemmings.com/index.php/2007/11/28/hmx-countdown-to-ignition-indexing-the-distributor/
http://ezinearticles.com/?How-to-Index-the-Jeep-4.0-Distributor&id=1357018
http://www.angelfire.com/my/fan/dist_index.html

 

[88 Wagonman]

I replaced the one on the bellhousing.

If you still have the old cap, I would try it anyway, what have you got to lose?

 

[old_man]

My thought would be that your injectors are too large. Pull the plugs, take a picture and post it up.

 

[Ecomike]

I know the parts are new, but have you bothered to check the new parts running (volts) or off (Ohms) with a multi meter? See if the TPS signal is smooth for instance. That verifies the new part, and the wiring and computer (when hot).

Just because a part is new, does not mean there is no problem in that circuit, or that the new part is good.

 

[DansGreyMj]

I know the parts are new, but have you bothered to check the new parts running (volts) or off (Ohms) with a multi meter? See if the TPS signal is smooth for instance. That verifies the new part, and the wiring and computer (when hot).

Just because a part is new, does not mean there is no problem in that circuit, or that the new part is good.

I've already checked the TPS with an analog volt meter and its within spec and works smoothly.