cruiser54

I've actually got that square plug on the harness, could it just be plugged in even with a manual tranny? Figure I could get 2 birds with one stone and water proof both connectors. Have any brands you'd recommend? Napa or any parts store's "Premium " brand. Well, maybe except Vatozone.

LOL.

Not normal. Every 30,000 miles it's due for plugs, wires, cap and rotor. How long has it been?

It's usually bad sensor grounds or bad TPS.

Use a good quality "auto" TPS.

They did. Are you certain it's a 1991 model? Is there a computer mounted to the left inner fender, next to the air intake box? Yeah. Something isn't right here. Year is wrong. Maybe had a motor change.

October of what year?

Fuel pump is dying. You need to set the TPS with my instructions using the flat 3 wire connector. RENIX TPS ADJUSTMENT Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up. IMPORTANT NOTE: With the Key OFF, and 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 parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed. MANUAL TRANSMISSION: RENIX manual transmission equipped XJs have only a flat three-wire TPS mounted on the throttle body and it provides data input to the ECU. It has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over. Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage. AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles, as outlined above—FOR ALL 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. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. 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 square four-wire connector side of the TPS. If you have ENGINE ISSUES check the flat 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 09-22-2012

Send your contributions to www.beerforcruiser.com. LOL.

Use the Renix flywheel!!

It was so common when the Jeeps were new that we adopted the practice of tightening those bolts up during the PreDelivery Inspection.

Now check fuel pressure.

Chuck, did you adjust the new TPS? Click on the link in my signature and do the ground refreshing, TPS adjusting if it hasn't been done, the C101 cleaning and the connector/relay refreshing. Known issues and a good dirty job for the daughter. Win-win.

Well, I would like to do my own repairs but if it gets too complicated and needs specialty tools to do then that's is the only time I probably won't try to fix it myself. Yea, I'll have to invest in one of those.. probably order one tomorrow lol.. The things mentioned are easy and rquire basic tools.

battery died a few days ago because I was running the radio without starting it.. could that do it too? Yep. But since this is new to you, do yourself a favor and get new tuneup parts on it, check every gearbox level and grease the chassis and drivetrain.

And, as already suggested by mvusse, check the track bar bracket to frame bolts. Put a wrench/socket on them and tighten them down just because it's a common problem and you won't necessarily "see" that they're loose.

Plugs, wires, cap and rotor are due to be replaced every 30,000 miles. make sure your intake manifold bolts haven't loosened up. Clean your throttle body and IAC. Courtesy of TJWalker: -------------------------------------------------------------------- The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea. CLEANING THE JEEP 4.0 IDLE AIR CONTROL Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to) “Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it. Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Either convert to an open system now, or get a new bottle and use a 703-1396 cap on it from Napa.

Well, what the hell was it?

TEST the CPS. And, inspect the wiring while you're at it. It could be melted on the exhaust manifold because it was installed without routing the harness properly. Click on the link in my signature and scroll down to about the 8th write-up to see how the harness is supposed to be routed. Renix CPS Testing and Adjusting 　 　 Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark. Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad. The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark. Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected. You should get a reading of .5 AC volts. If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer. Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off. A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts. 　 　 Revised 01-26-2013

Never seen one yet since 1987 that you can't unplug the dizzy harness and it runs fine. The sync generator inside the dizzy has absolutley NO effect on spark. Only sequential firing of the injectors. Try it. I challenge any others on CC to unplug the dizzies on their Renix 4.0s and see if they still run. Please report back.

Really? Did you know you can disconnect the harness to that sync generator in the distributor and a REnix Jeep will still run?

IAT/MAT will not cause a no spark condition.

They don't. That's why most, all?, of the big rigs have engine driven vacuum pumps. Big rigs don't have vacuum pumps. Mostly passenger vehicles do. Big rigs use air pressure operated accessories rather than vacuum as they are equipped with air brakes already.

A fuel pressure test is in order.