doublechaz

I was looking at a new CAT for my 88 and it seems to have an air pump inlet fitting, but I can't find any reference to an air pump for that year. Anyone know what I'm doing wrong? There isn't an electric air pump somewhere, right? I also don't see any room on the front of the engine for a pump, or any evidence of lines going down to where the CAT should be. I want to put this system right, but I'm not going to wrack my brain cell retrofitting emissions gear it didn't have OE.

If the CAT I'm looking at is a multi year "direct" fit, then I have the TIG to close off that inlet if needed.

doublechaz

Turns out my FSM for 1988 doesn't really match my vehicle. My manual shows a passive air injection system, but all the diagrams are for a carburetor looking round air cleaner, but I have a modern fuel injection style remote air box with panel filter.

Do I need a manual for an 89? Did Jeep have major changes mid year like some other auto companies?

Looks like I can figure out how to restore this with some more research. But not until it gets below 110F out there.

MaskedMallard

Counting from left to right, what is the 4th VIN digit? What is the 10th digit on your VIN? This will tell you what engine you should have & what year of a vehicle you have. Post up what you find.

Do you live where they do the exhaust gas testing?

doublechaz

Fourth is M
10th is J

It's the straight 6, but I'm having trouble matching up 88 manuals to this thing titled as an 88. OTOH, I've seen AZ title a Mopar model that ran from 76 to 80 as a 74, so there's that...

We don't have testing here, which I'm sure is how some PO justified hacking away at it. Some of the exhaust is just gone and I'm not excited about going to an exhaust shop with such a mess and I don't want to take the time to build it myself. If I do build it, then I want to get quality parts and put together a top notch system. It's a problem I have along with a serious case of 'while I'm in there'...

ajpulley

Yes, 1988 and 4.0L I6.

On your XJ, at the end of the exhaust manifold, after it collects and crosses under/behind the engine, should be a square flange with four bolt holes, one in each corner, facing rearwards and supported by the transmission cross brace. If that is still there, you can order all the parts you need, including a catalytic converter (CA or non-CA versions).

Your converter need not have a port on it as your engine does not utilize an air pump of any kind. Part number 15634 is Walkers’s version of a direct replacement for federal applications.

MaskedMallard

Okay, I understanding they don't do the tail pipe test, do they do a physical inspection?

Hypothetically, if this was an "off road" vehicle only, a cataltic converters would not be needed. There is no sensor for the cataltic converter, therefore no check engine light would set. You have an OBD-I system (On Board Diagnostic 1st Generation System). A slight gain of power might be noticed, due to the exhaust not being restricted. I have seen people run a test pipe in place of a cataltic converter. I have seen people remove the cataltic converter from the car & either knock the catalyst out with a long screw driver or cut open the cataltic converter, remove the catalyst as a whole piece & weld the cataltic converter back together. The people that have cut open the cataltic converter, cut the top open so it would be less visible when it was welded back together. Then they took the catalyst to a recycling center & got cash for the precious metal inside.

To make sure your engine is running at optimum efficiency, make sure you have a good name brand oxygen sensor installed. On my 1987 XJ, I got a large grounding strap, drilled one of the ends more open so an O2 sensor would fit into it & installed the grounding strap so it was held in by the O2 sensor. Then I grounded the other end, some where solid (don't ground it back on the engine).

doublechaz

I have the square flange. My main confusion was the cat listing I found had an air pump input, but the vehicle and my FSM didn't.

My manual lists a two stage passive air injection, but since my engine doesn't match the manual I don't know if I have the wires for those two solenoids.

O2 sensor is on the short list of tasks as is coolant temp sensor. The exhaust is pretty sooty, power seems low, and the mpg is around 11. I can't really replace the cat until I know it's running right or it'll just carbon up or melt.

MaskedMallard

I would recommend to buy a code reader for your Jeep that will display live data. The Snap-On MT2500 is a great OBD-I scanner, if it's in your budget. As a thought, your coolant temperature sensor that the computer see (might be different from the dash display), could have failed & could be indicating -40*F. This would cause the computer to dump extra fuel. Same for the O2 sensor, if it's failed, the computer could think the engine isn't fully warmed up yet & the computer would be looking for the O2 signal.

doublechaz

Exactly why I mentioned them. I was under the impression that 88 was a Renex system rather than OBDI. Either way, with 400k and dubious prior maintenance I'm willing to fire the parts canon at O2 and CTS given the obvious symptoms.

ajpulley

Renix, not Renex. Bendix + Renault = Renix. Otherwise, you are correct; 1987-1990 model years had these computers. There is no standard OBD diagnostic port. Live data, and live data only, can be read by either the tool he mentioned or a DRBII tool made by AMC or Chrysler of the time.

If you're so inclined, you can still buy the square flanges and weld your own tubing to suite your needs.

doublechaz

I'm supposed to be spending as little as possible on this Vehicle, but that's a problem for me.

I was looking at https://nickintimedesign.com/product...ack-adapter=No
but I don't strictly speaking need it as I've learned enough from my other vehicles to do a decent job from smells, sounds, multimeter, etc. I guess I should mention in the build thread what I've found so far and what is in the upcoming budget.

Saudade

If the CAT has the air pump inlet, it's typically already capped off. You can look at RockAuto and see both types available. CARB Cats are CA Compliant which explains the enormous price.

Two sites you should bookmark.

First: http://cruiser54.com. All things Renix.

Next; http://www.lunghd.com/Tech_Articles/...iagnostics.htm Specifically looks at sensor testing using only a multimeter.

I have an '88 Laredo.

doublechaz

Thanks! I'll check those out.