Calling all Renix Experts

Ok, I buckled down this morning and printed out the renix manual, got out my trusty multimeter and got to work under the hood.

1. I installed a new (used) throttle body with TPS and IAC. The idle went nuts, like over 2k. So I adjusted the idle stop screw deal and got my idle down nice and low. I then adjusted the TPS to spec. I got 4.63 between the ground and 5v supply, but I understand thats nothing out of the ordinary. I played with it till I got .79 between the postive and ground. However, at wide open throttle the reading between positive and ground was 4.42v. Not sure what to make of that.This was the first Renix sensor I have sucessfully adjusted and was quite pleased so I kept going.

2. Moved on to the MAP sensor. This one is a little odd from what I know, but thats why I'm asking you guys. First tried the dummy test, pulled the vac line and the motor started sputtering and was going to die so I just reconected it. Did the 5v supply to ground test and got 4.79v on a the wiring harness while disconected. Then I backprobed the sensor and a reading on the ground and output terminal with key on and engine off. Got a reading of 4.70v. So I moved on to the last step and fired her up and got a unsteady reading of 1.5v +/- .5v. This is what I'm unsure about as its at the high range of the specs and jumps over a little, but it seems to be functioning to me. What do you think?

3.O2 sensor = junk. The resistence at the sensor between terminals A and B came up as 144.3 ohms. So that wasn't even the ballpark. Then I tried testing the sensor wire and the ground together and got absolutly nothing. Tried it connected, disconected, key on, engine off, engine on, and any combination thereof. So I'm about as sure as i can be that it isnt doing anything.

4. Tested the temp sensors last. The MAT and TSU were within specs, which is odd cause it reads aboput 150 in normal conditions so the guage is probobly behind this one. Now here is the weird one. The sensor in the rad for the elec fan brought up nothing. But somehow the elec fan does come on from time to time.

5. At this point I had covered all the usual suspects so I moved to fixing my leaky tranny line, found a new leak at t-case and rear driveshaft, and cleaned up the ever leaky valve cover.I also found that the lower rad hose doesnt have its spring, and it needs a flush and fill so that says alot about when I overheat. I'm also about to bleed the rear brakes, the compartment in the MC for the rear brakes is murky and looks contaminated, but its raining so I'll have to wait.

So whats wrong, whats not and where should I get to work. I can read the manual fine but i need a little expertise to point me in the right direction.

Edit: BTW, I used to hate my renix but you guys were right, its nice to be able to sit down and figure it all out with a cheap little multimeter. Its def starting to grow on me . . .

Also the report on the EGR will come later on. I dont have a vac pump so I have to wait to test it untill he comes around . . .

Not sure what year your dealing with but if you have a C-101 bulkhead connector (on the firewall mounted above the master cylinder) that can reak all kinds of havoc either clean it (electric toothbrush and radioshack cleaner is what I used) or eliminate it (a little bit of work) hopefully you do not have one.. also make sure EVERY GROUND IS SOLID ... the O2 sensor and TPS both run thru the C-101 connector if I remember right

Sorry bout that, I havent set up my sig cause I'm not here as much but I dropped in because I know tends to have the best advice on renix systems.

89 XJ Wagoneer Limited. 4.0 I6, AW4. Bone stock.

when u installed the tps, did u unplu batt so the computer could learn from new(used) one?

and as for tps test, mine come up near ranges, but i tested mine when running unplug see how engine rev, then plug back in and should rev more crisp, u can do the same for IAC . when u unplud IAC should stall, if not IAC stuck or broken.

Yes, when I finished i removed the negative cable and turned the key on to drain any power for about 5 minutes, then drove around for awhile at a moderate pace to give it some good data to work with. Not too slow, not too fast. I think that was a good bit of the problem before. The previous owner wasn't much for taking care of my baby . . .

OK, refresh me as to the underlying problem you are trying to fix. By the way, do you have a vacuum gauge you can hook up to the manifold? A vacuum gauge is a valuable diagnostic tool that has lost favor with the advent of the computers, but it can tell you a ton about an engine.

another thing as old man said with the vac issues... a vac leak can play with the renix.. perhaps one from changing out the intake... also, the renix box doesnt reemmeber anything so disconnecting the battery will do nothing for him

Couple of random observations:

As far as the sensor in the radiator for the fan, I think it's a simple thermal switch, which means it will show open until it heats up and closes. That would be normal.

If you're having idle problems, probably the last thing you should resort to is readjusting the throttle plate. If you do need to adjust it, it probably means either that someone else mucked up the adjustment, or that it's worn out.

Make sure the gasket at the base of the throttle body is good, because if you have a vacuum leak it won't work worth ****.

My 87 had intermittent high idle symptoms that drove me crazy until I found that rust was causing the pivot of the accelerator pedal to bind. So I fixed that, and it was fine for about two years, and then my daughter, who now owned it, complained of intermittent high idle problems, and this time I found that the pivot on the bell crank that attaches to the manifold was worn out and binding. I couldn't get the bolts off, so I put a big spring on it, and all was well again. So check your idle with and without the throttle cable attached, especially if you're having problems with occasional failure to return to slow idle. We often assume the problem is in the complex high-tech systems when it's just a good old mechanical glitch.

If you have adjusted the throttle plate, make sure it is not closing quite all the way. Especially if the pivots are a little worn, it can close too far and jam. There should be a paper-thin gap between the plate and the throttle body when it is closed. If the system is operating correctly, the ECU should adjust the idle speed consistently. Any time you adjust the throttle plate, you must, of course, readjust the TPS.

Have you checked running vacuum? Remember that the MAP sensor won't do its job right if there's a vacuum leak somewhere else.

On the O2 sensor, you should see a voltage and not an impedance (it acts like a battery that produces voltage in the presence of oxygen). If it's got more than 80k miles on it, I'd replace it. On the fan switch, I think it's just a temp switch that clicks on and not a variable impedance sensor.