Jeep Strokers

I just got my new 4.7L Renix stroker installed yesterday.

I broke in the cam today by driving between 2000rpm and 2500rpm for 30 minutes like the Crane manual says.

Before I pulled the supposed stroker motor for rebuild I tested the TPS. 4.6V reference, .7V between B and D. I bought a new one today to get it within the 83% like cruiser 54 says.

So before I switched the sensors I measured it again. .1ohms to ground on the 4 pin plug. The TPS was .7V and 4.6V reference. This equates to 3.22V. This is with the sensor all the way at it's stop down.

I installed the new one and it measured 3.3V and 0V when wide open. So I installed the old one again and remeasured. 3.3-3.4V! What's going on!

When I drove it to break in the cam it ran like total crap, missed BADLY everytime I touched the throttle, If I applied more throttle it would act right and then into massive misfire and popping out the exhaust. I ran e3 plugs and changed to NGK's, miss still there. Checked dist, locked, checked firing order good.

Any help would be great, I really want to drive this thing!

Thanks all!

You drove it to break in the cam??? Yikes!

When you break in a cam its with no load on the engine, alternating RPM's just as you did. Are you sure you didn't wipe out your cam?

Additionally, you should have fixed the stumbling backfire etc before breaking in the cam.

Whats done is done.

Most likely your distributer is not indexed correctly; probably a tooth off.

Awesome, i tried to ask as many questions as i could before i started the new motor. So who has neighbors that would like a loud engine running at 2000rpm for a half hour!!!

The guy just told me to drive carefully for 500 miles, change the oil and be good. I read the comp cams pamphlet and it says run the engine. It doesn't say don't drive it. Anyway if i lived in the middle of nowhere i could have done that.

I had to ask about what kind of oil was in it and he almost forgot to give me the comp cams engine break in additive!

The stumbeling backfire wasn't there before, i just noticed that it didn't seem to lock up the torque converter because the rpm's were to high. I did have to pull the dist because the builder forgot to install the gasket between the block so oil was squirting out. I marked where it was before and it shouldn't have moved.

If i messed anything up in this motor parts will fly! I am in to deep on this one, long story!

So with that info please give anymore advise i could use. Thanks again.

O, and it doesn't stumble when free reving, just under load part throttle.

Muad'Dib wrote:Most likely your distributer is not indexed correctly; probably a tooth off.

I think it's more likely that the timing set was installed one tooth off.
The voltages of the old TPS seem to be OK, but does the voltage sweep smoothly as you gradually open the throttle blade? Any spikes or troughs will indicate a bad TPS.

Well i changed the oil and looked at the dist rotor. Looks like it is correct. Then i looked closer and the dist was full of oil. This was new? So i bought a new dist and installed it. I will report back after i can run it again.

Cheromaniac wrote:

Muad'Dib wrote:Most likely your distributer is not indexed correctly; probably a tooth off.

I think it's more likely that the timing set was installed one tooth off.
The voltages of the old TPS seem to be OK, but does the voltage sweep smoothly as you gradually open the throttle blade? Any spikes or troughs will indicate a bad TPS.

I will recheck the tps thanks!

I double checked the tps and i'm stumped. It is fluent from 3.4v at closed throttle to 0v at wot. It doesn't drop out. Now, i thought you were supposed to get 83% of the reference?

I also noticed there isn't a wire in pin "C" in the four pin TPS plug. Should there be?

According to a FSM I have found the C position goes to the PCM. http://www.pirate4x4.com/tech/billavist ... manual.pdf page 32.

Also, here are some further info on the Renix system:
http://www.cherokeeforum.com/f51/helpfu ... inks-1397/
http://www.naxja.net/forum/showthread.php?t=1033711
http://www.naxja.org/forum/showthread.php?t=905849
http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm

Ok, I have torn apart the harness in search of wire "C". So far I have not found it. This is the 4 pin plug. I noticed right away that someone spliced two old plugs on the harness. The wires change colors after 3". The wires I have are Red, Tan/Orange, and Gray/Black. Can someone tell me what color wire I'm missing? The harness came from a '90 Cherokee, automatic with A/C 4.0L 4wd.

As far as I have traced the 4 pin plug wires they go over to the right side of the Jeep, you mention that wire C should go to the PCM. Unless the wire is still in the harness taped up going through the firewall. It would also help if I knew the wire existed in the PCM. It looks like the PCM is under the glove box. I will keep removing the tape and flex loom until I will find it.

Thanks for the help!!

It's hard to believe this would run this way.

The box under the glove box is the TCU for the AW4.

The ECU on a RENIX XJ is mounted vertical, just above the driver's right foot, IIRC. You can verify it with the part number on the tag.

FOR ENGINE MANAGEMENT RELATED ISSUES. However, the automatic TPS also has a square four-wire connector clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES. Check the four-wire connector side of the TPS.
If you have ENGINE issues check the three-wire connector side of the TPS. For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 04-30-2012


It looks like this was a dead end, in this reading it states "it only uses three wires". So that means the fourth wire is not used in the plug. So onto other ideas unless anyone else has an objection or can find the wiring scematic for the 4 pin square plug. If anyone can verify that they indeed have only three wires on this square plug running into your harness that would certainly help!!!!

My renix tps only has 3 wires in the 4 connector plug.

Ok, that's what I have found in my search. I guess I'll just have to do some upgrades to the engine harness since I've got it pulled apart. Maybe if I have time tonight after work I will try to see how it runs.

I drove it for a few miles last night, the miss was gone and it ran good. It must have been off one tooth and since I installed the new distributor it runs good.

The next issue I have is the torque convertor doesn't lock up or it doesn't go into overdrive. I'm thinking it's just a adjustment issue? At 55mph I tach just over 2000 rpm's. In my '99 Cherokee with the same axle ratio 3.55 and tire size 235/70's I run at 1800 rpm at 60mph.

What should I check to adjust and how do I know if the torque converter is locked up and what gear its in?

Thanks for all the help guys.

yuppiexj wrote:My renix tps only has 3 wires in the 4 connector plug.

Correct. Normal.