98-tj

my 88 Cherokee 4.0l is running extremely rich, I failed CA smog as a GROSS POLLUTER here are the #'s

[ RPM ][ %CO2 ][ %O2 ] [ HC(PPM) ] [ CO(%) ]
[MEAS ][ MEAS ][MEAS ] [ MAX][ GP ][ MEAS] [MAX][ GP ][ MEAS]
[952 ][ 11.4 ][ 0.0 ] [ 120 ][270][ 223 ] [1.00][2.50][ 5.96 ]
[2339 ][ 11.0 ][ 0.1 ] [ 180 ][330][ 127 ] [1.00][2.50][ 6.48 ]

I have replaced, fuel pump, fuel filter, spark plugs, cat., O2 sensor, upgraded injectors with (#0280155703) injectors, replaced intake gasket, all vacuum lines are connected and not leaking, have borola header, running stock air box with clean filter, when I unplug the vacuum to the MAP sensor, it idles down, un plug MAP, sensor it dies, the motor back-fires through the intake when you slam on the throttle, revvs fine when you are easy on the gas, idles fine, every 10 seconds RPM's suddenly drop and goes back, no change when I unplug the CTS coolant temp. sensor, I am going to swap out cap/rotor/wires and see if there is any change

cruiser54

TPS is not on the list of replaced parts, Cap, rotor, and wires are an excellent idea. What spark plugs are you using?

98-tj

I am running champions RC12YC

cruiser54

Okay. Wanted to make sure you weren't running some "miracle" plug.

98-tj

here is what I have checked with an multimeter using RENIX(ono-ho) engine sensor diagnostic and all turned out good

02 sensor
CTS - coolant temp. sensor
MAT - manifold air temp. sensor
MAP - man. absolute pressure sensor
TPS - throttle position sensor

I also checked timing...still doing the same stuff

67 GMC

Did you adjust the TPS as well? I had the same issue on my '87 with the backfiring through the intake when you put it to the floor. Solved when I adjusted the TPS and changed the fuel pump.

98-tj

I adjusted the TPS correctly, adjusting it at idle and reving up did not effect a thing, then I adjusted it per spec. still same problem

cruiser54

When you adjusted the TPS, did you use the flat connector or the square connector?

Get the tune up parts on next. That may fix it.

98-tj

I used the only connector on the TPS per this article:

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

I did not touch the idle speed stepper motor/idle air controller (IAC) (located next to the TPS), I also sea fomed fuel and intake, new oil, do you think it would be the fuel injectors?, I cannot test the fuel pressure, but I would assume that would be related to a LEAN condition although it back-fires through the intake with a hard throttle....???

I pulled the distributor, it has a little up and down play (1/8"), but solid side to side, spins smooth

98-tj

I cleaned the IAC - Idle Air Control and installed it, with no change, then I disconnected it and ran it, runs the same with it plugged or un-plugged, it might be this, but I have no way to check if it i, I am going to check the fuel pressure today

cruiser54

Is your Jeep an auto trans?

Anyway, the link you supplied is for the auto trans connector on the TPS, not the engine connecotr. Try these instructions and do yourself a favor and check the sensor ground circuit as described in the beginning.

How about the tune-up parts?


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 a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS 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. Adjust the TPS until you
have achieved this percentage. If you can't achieve the correct output voltage replace the TPS and start over.
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—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. 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 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 08-27-2012

98-tj

I have an automatic with the flat 3 connection, all stock...I will try this out today

cruiser54

The instructions you used have you checking the trans side of the TPS. No bueno for engine issues.

98-tj

I replaced the plug wires, cap & rotor, still did the same thing with no change, I checked the TPS by your guidelines and the ground is in the 8-14 ohms and fluctuates depending on what you wiggle around, the map sensor connection and the main wiring connection, it is intermittent though and sometimes changes the ohms, I checked terminal A & B and got 4.8v X .17 = .816v (terminal B & C using paper clips jammed in the connection to test, .816v was unachievable by moving the TPS, the TPS is about -0.1 to -0.4, so I determined it is bad, I sold the Cherokee last night and told the new owner about it...Thanks A lot

cruiser54

LOL. Good job and you can have a clear conscience selling it.

Here's something you should provide to the new owner also:
Find your Intake Air Temp sensor. It's the sensor just to the rear of the throttle body, has 2 wires, and screws into the intake manifold.
Where it's connector plugs into the harness you will see that one of the wires on the harness side　is brown with a white stripe. Follow the brown with white stripe wire back into the harness. You'll have to open up the split-loom plastic sheathing to follow it. It will come to a splice with 2 other brown with white wires with duct tape over them. They're from the TPS and the CTS. The 3 wires will be　 spliced to a single wire headed toward the C101 connector if you have an 87 or 88. If you have an 89 or 90, you do not have the C101 bulkhead connector.
　
Now go to the MAP sensor. Follow the brown with white wire into the harness from there. You will find a splice with 2 more brown with white wires with duct tape over them. At the splice you will find the 3 wires connected to a single brown with white wire going toward the C101, or just along the firewall towards the engine if you have an 89 or 90. Along with the MAP sensor that you traced, they are the ECU sensor ground port and the diagnostic connector on the passenger inner fender.
　
You now have 2 sets of 3 brown with white wires, one near the firewall and one near the engine.
　
Cut the splices out of each set of wires eliminating not only the crappy factory splices, but also the single wire between them. Bring both sets of 3 wires together. Solder the 2 sets of wires together and insulate them properly with tape or shrink tubing.
　
Zip-tie up your new sensor loom to allow for engine movement.　I prefer to cover it with some new split-loom or wrap it neatly with electrical tape when done.
　
　
Revised 03-09-12