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Cruiser's RENIX diagnostics thread

Thanks to you, Rags, for posting that info up.

I'm working on a few more. Hard to do this time of year as I work in the propane business. We're real busy as you can imagine.
 
I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals, and adding dielectric grease before plugging it back together. Be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else.
Revised 03/15/2012
 
Cruiser’s Renix Sensor Ground Test
Set your meter to measure Ohms. Be sure the key is in the OFF position. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
You want to see as close to 0 ohms of resistance as possible. And when wiggling the harnesses/connectors the resistance value should stay low. If there is a variance in the values when wiggling the wires, you have a poor crimp/connection in the wiring harness or a poor ground at the engine dipstick tube stud. On 87 and 88 models, you could have a poor connection at the C101 connector as well.
Revised 05/03/2012
 
Cruiser’s Trans Plug Refreshing

Over near the trans dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and trans solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.
Revised 3-28-2012


 
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
 
Cruiser’s Valve Cover Mod
Most early and even later Renix 4.0s could be bothered by excessive oil in the air cleaner box. A fix from my old days as Service Manager at a Jeep dealership follows. Information was provided to me from a buddy at JeepTech during those days. I don’t believe it ever came out in a Technical Service Bulletin.
　
Remove the valve cover and turn it over. Next, remove the fluted tubes that are now facing you by removing three screws on each. Chop 1 inch off each of them. Then, about a half inch up from the area where you just sawed them off, drill a half inch hole in the tubes so the holes will face the rear of the valve cover. Clean and de-burr/sand all rough edges nicely, clean with solvent, and reinstall. Don’t be concerned about the chintzy gaskets that will probably crumble into oblivion when you remove the fluted tubes. They can go back together without gaskets.
 
Very good advise!!!
 
I've been pretty busy. Here's my outline of what I've done and what I plan to do as far as write-ups:

　
Revised 04-18-2012
* means instructions have been written.
　
1-Ground refreshing, adding engine bay grounds, link to Kelleys WIP*
1a-Improving the instrument panel ground*
2- Checking sensor grounds*
2a- Repairing sensor grounds*

3-C101 Connector Refreshing*
4-Connector and relay /receptacle refreshing*
5-Coil/ICM contacts*

6- Snugging up intake manifold bolts
7-Throttle body and IAC cleaning
8-TPS testing and adjusting*
9-CPS testing and adjusting*
10-CPS wiring bypass
11-ECU connector refreshing
12-Distributor indexing
13-O2 sensor diagnostics
14-Setting base idle
15-Valve cover mod*
16-Sensor ground upgrade*
17-CPS Timing Advance Mod*
18-Headlight Harness Installation*
19-Trans Plug Connector Refreshing*
20- Rear Main Seal Diagnosis*
21-Vacuum Test For Exhaust Restriction*
22-Restoring Throttle Butterfly Adjustment
　

 
id like to see one on dizzy indexing over the renix
 
Remove the distributor cap and cut a "window" into the side of the distributor cap at the #1 spark plug wire post . The "window" should be large enough to allow easy visual inspection of the position of the distributor rotor at the #1 spark plug wire post. Reinstall the distributor cap.

Install a ¾" wrench or socket onto the vibration damper retaining bolt. Rotate the engine in a clockwise direction until the #1 cylinder is at top dead center. Align the timing mark on the vibration damper with the "0" degree mark on the front cover timing scale. The tip of the distributor rotor should be near the #1 spark plug wire post.

Disconnect the distributor electrical connection. Remove the distributor holddown clamp, holddown bolt and distributor. Remove the distributor cap and rotor.

Place the distributor housing upside down in a soft jaw vise. Scribe a line 1/2 inch from the end of the distributor locating tab. Cut the distributor locating tab at the scribed line with a saw.

Remove any burrs and metal filings from the distributor. Reinstall rotor.

If necessary, using a flat blade screwdriver, turn the oil pump gear drive shaft until the slot is slightly past the 11 o'clock position. The oil pump gear drive shaft is accessible through the distributor mounting bore in the engine block.

Visually align the modified locating tab area of the distributor housing with the holddown clamp bolt hole.

Turn the rotor to the 4 o'clock position.
Lower the distributor into the engine block until it seats. The rotor should now be very close to the 5 o'clock position.

Reinstall the distributor cap with the cutout "window". Rotate the distributor housing until the trailing edge of the distributor rotor tip is just departing from the #1 spark plug wire post terminal .

Reinstall the distributor holddown clamp and bolt.. Reinspect the position of the rotor to the #1 spark plug wire post to insure that it has not moved.

Install the new distributor cap, reconnect the distributor electrical connections.
Revised 07/03/2012
 
Here's an updated list of my write-ups:
　
Revised 07-20-2012
* means instructions have been written.
　
1-Ground refreshing, adding engine bay grounds, link to Kelleys WIP*
1a-Improving the instrument panel ground*
2- Checking sensor grounds*
2a- Repairing sensor grounds*

3-C101 Connector Refreshing*
4-Connector and relay /receptacle refreshing*
5-Coil/ICM contacts*

6- Snugging up intake manifold bolts
7-Throttle body and IAC cleaning
8-TPS testing and adjusting*
9-CPS testing and adjusting*
10-CPS wiring bypass
11-ECU connector refreshing*
12-Distributor indexing*
13-O2 sensor diagnostics
14-Setting base idle
15-Valve cover mod*
16-Sensor ground upgrade*
17-CPS Timing Advance Mod*
18-Headlight Harness Installation*
19-Trans Plug Connector Refreshing*
20- Rear Main Seal Diagnosis*
21-Vacuum Test For Exhaust Restriction*
22-Restoring Throttle Butterfly Adjustment*
23-HO Engine into Renix*
　

 
Reinstall the distributor cap with the cutout "window". Rotate the distributor housing until the trailing edge of the distributor rotor tip is just departing from the #1 spark plug wire post terminal .

departing clockwise or counter clockwise?
 
Your information has been a huge help! I am trying to fix a high idle in Park that has recently developed.

Idles fine when cold, but as engine temp increases, so does the RPMs. Starts around 800rpm but then goes as high as 1800rpm. I replaced my IAC before finding this thread. Problem still there - worse even after replacement. I did scrub the carbon off the butterfly before the readings I just took, but have not let the XJ warm up to temp to see if it helped yet. Will do that shortly.

TPS measurements:

Reference: 4.65v
Output: 3.88v

So I am off by 0.02v - is that enough to make a difference?
TPS resistance: 1.002ohm

Any ideas? I do happen to have an old school Snap On MT2500 here at the shop so I can look at real-time info.
 
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