90xjnewbie

I have a 90 xj stock except I modified the coolant system and aftermarket exhaust. It was sitting for 18 years when I got it. 78,000 miles. I have replaced a lot of stock parts. Fuel injectors, radiator, o2 sensor, New Cat, plugs and wires. map sensor. It has failed smog 5 times. Looking for any suggestions. My last option is to check exhaust manifold for cracks and a new gasket. I have checked all other emissions equipment.

aroundincircles

can you be more specific on how it is failing? Is it running too rich? too lean?
Does it have the 4.0?

tech

We need to know what it is failing ?

Camaroboi13

Post a picture of your failed smog readings, I had my smog license many moons ago and still remember some of the basics. Might be of some help but gotta see what it's doing first.

Saudade

I struggle every other year with my '88 but always end up passing so it can be done.

As others said, post the results.

You said you checked all other emissions equipment. How exactly?

Meanwhile, go read: http://cruiser54.com/

90xjnewbie

So it is 1990 4.0 the technician told me that before I changed the manifold I could have already smoked the new cat. What do you guys think.


This is from before I changed the exhaust manifold

This is most recent after changing manifold

Camaroboi13

These are the most common issues when dealing with smog equipment. This is not an end all be all list, but 90% of the time your issue will be on this list.

High HC Emissions

• Inoperative/missing catalytic converter
• O2 sensor malfunction
• Internal engine problem
• Vacuum leaks (hoses, vacuum operated devices, intake manifold, carburetor)
• Ignition system malfunction (plugs, plug wires, points, dwell, etc.)
• Improper fuel injector operation
• Incorrect ignition timing and/or idle speed
• Incorrect carburetor air/fuel mixture
• Defective EGR valve or air injection system failure

High CO Emissions

• Excessively rich air/fuel mixture
• O2 sensor malfunction
• Faulty computer control(s)
• Malfunctioning fuel injection system
• Inoperative/missing catalytic converter
• Carburetor float level maladjusted
• Air cleaner, choke or carburetor
• Defective canister purge system

90xjnewbie

Also Would four hole fuel injectors be a cause of the problem? Just realized the OEM one are single hole.

4.3L XJ

What O2 sensor did you use? Is there a crack in your exhaust manifold? What catalytic converter did you use? Of hand, it is the cat or the O2 sensor or possibly faulty coolant temp sensor

90xjnewbie

O2 sensor was an autozone one not the best but not the worst. It is under warranty so going to take it back. The manifold was cracked. so replaced it with new gasket of course.. Cat is walker cal cat d-182-55 80945 the direct fit.

Camaroboi13

I'm just curious... what does the smog tech say about it? If he's gonna keep taking your money he should atleast let you know where to throw it. I don't think the before and after really shows a blown cat, but it's been awhile since I've sat in on a smog run. One thing to note, a bad cat will smell like rotten eggs, so if you take it for a freeway run and get the cat nice and warm, you should be able to tell if it's bad or not by pulling over and giving the exhaust a whiff. It's not THE way to figure things out, but it is A way to figure things out.

4.3L XJ

Since it is running rich, I am guessing the O2 sensor might be giving the wrong data, however you said the manifold is cracked. That is a notorious cause of running rich. However the other gasses present lead me to believe that cat is not working well. But have you verified the coolant temp sensor is sending the proper data to the ECM? If it isn't, that can cause you to run rich because the ECM thinks the engine is cold

Saudade

Here's a link with details to test each sensor.

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