Just looking for some pointers on what to check. Truck has been sitting for the past 5 years in my garage. Had it tested 2 1/2 years ago where it failed, HC and NO over the max limit for both the 15mph and 25mph test. For the five years its been sitting I've started it and ran it around the block every few months, and its never failed to start and runs fine, only a slight surging at idle which I think is common for these trucks? I pulled the cat just recently to visually inspect and nothing is loose or degraded inside that I can tell. Thoughts?

 

Sugs, I just bought a 95 Montero LS and it passed smog, but was at the limit of 60PPM HC at 15mph and I'm concerned about it not passing next time. I learned that this is a measure of unburnt fuel that makes it out the end of the tailpipe, i.e. incomplete combustion. Now not knowing your numbers, I wouldn't know what specifically to suggest besides the usual.

Make certain that your oil is clean. Make sure your engine is completely warmed up for the test so the cat is well-heated in order to do its conversion thing. New plugs, wires and spot-on timing are all going to help. After that, I'd look at the EGR valve, the PCV valve, the oxygen sensor(s) and the cat, which you said looked fine. Make sure the valves are adjusted properly, and lastly, check for leaks in the hoses that go to your various emissions components.

I believe that a vehicle can seem to run fine but still not be performing cleanly enough to pass smog, especially here in California

Could you post your numbers, and maybe that will narrow our search in where to look? I'm hoping to benefit from anything we might learn...

 

I'd forgotten all about this thread. This project was put on the back burner as the truck was intended to be used by my oldest daughter, but she went off to college and decided she didn't need a car there. We did do a lot of work on it last year though, but it still fails the nox test. I do still want to get this truck back on the road as she will need a vehicle for the summer when she is home. I'll dig up the paperwork sometime in the next few days and post the last numbers I got.

 

Ok, Then maybe we can see what's what.

 

Sorry this took so long, I'd forgotten where I placed the paperwork until now.

Anyway, from a smog test last March 2010.

15mph %CO2 14.2 %O2 1.2 HC 19 CO 0.00 NO 1905
25mph %CO2 13.8 %O2 1.7 HC 14 CO 0.00 NO 1223

My truck fails both NO emissions tests by a wide margin, max allowable is 488 and 741, gross polluter is 1508 and 1558.

Mechanics tell me its because of an intake manifold leak somewhere, but they couldn't be sure where exactly it was.

 

I'd guess from the surging at idle that you mentioned that an air leak is a good guess. You may want to give all your emissions hoses a good going-over for defects. Also check your PCV valve and your EGR valve. Can you access your on-board computer to get a readout of any problem areas? It's under the driver's side if the instrument panel. For a 1994 model, all you need is an analogue meter — there are two rows of contacts in the connector. Hook the ground to the one on the lower left and put the positive connector to the upper rightmost terminal. Turn the key on but don't start the car. You needle should jump a combination of long and short times. This is the code. If you do that let us know what you find and I'll decipher it for you.

Good luck.

Sometimes an intake leak can be heard as a hissing sound; you can use a piece of hose as a stethoscope to listen more closely where it's coming from.

 

OK, did a quick check under the dash and cannot find the connector. Never noticed this before but it seems the owner before me had an aftermarket alarm installed and whoever wired it in did some cutting and splicing. I do see what looks to be a light greay colored OBDII connector(I'm guessing it isn't but thats what it looks like) just to the left of the brake pedal. I checked the Chiltons manual that I have and it says that '94 models can output the code to the dash lights? Doesn't outline the exact procedure though.

I also took it for a quick spin a few times around the block and once it warmed up listened for any hissing but couldn't hear anything. Also noticed it wasn't surging like it used to. And currently there are no check engine lights lit. I wonder if the work the mechanics did to clean things up solved the surging problem.

 

Well that sounds good, or at least better. I must admit that I don't have a manual for your year of Montero and I was going off the info in mine, which covers the years 83-96 but in a pretty general way most of the times. I believe that that ODBII connector is what you should be looking for. Don't know anything about outputting the code to the dash lights (!?). My Haynes only covers an analogue meter's output readings.

If I were you I'd talk to the mechanic who worked on your vehicle and get a complete rundown on the work they did; it may clear up all your mysteries.