Trying to smog it

[Renny_D]

I've got an 86gl Turbo and I have not given up trying to smog it. She runs great but won't pass smog. Essentially it's running too rich. We've swapped the amm but the result is the same. The AMM that is on this is the older vane type one I think and it looks the the set screw on the top was uncovered and someone messed with the mixture. I'm trying to see if it's possible to use the stock O2 sensor, a voltmeter and this set screw to get this thing into stoich. Has anyone done this and if so how. Is it even possible? I have access to a wideband but that means dissassembling the whole thing as it's hard wired into my other car? If picks of the stock amm will help I'll try to get some tonight? Also does anyone know if it's possible to switch over to the hotwire amm used on the later efi systems?

 

Please lemme know

 

Thanks

Renny

[Frank B]

Have you done the usual, tune up, new O2 sensor, air filter, etc??

I can't help with the MAF adjustment, but I know you can't swap the MAF with a hot wire one.

Maybe your catalityc converter is toast???

Also look for exhaust leaks in the uppipe(between the cylinder heads and the turbo) and turbo gasket exhaust leaks as well. If you have a leak, it can actually pull in clean cool air and throw off the reading at the O2, tricking your ECM to run a bit rich to compensate.

[Renny_D]

Have you done the usual, tune up, new O2 sensor, air filter, etc??

I can't help with the MAF adjustment, but I know you can't swap the MAF with a hot wire one.

Maybe your catalityc converter is toast???

Also look for exhaust leaks in the uppipe(between the cylinder heads and the turbo) and turbo gasket exhaust leaks as well. If you have a leak, it can actually pull in clean cool air and throw off the reading at the O2, tricking your ECM to run a bit rich to compensate.

 

Thanks I did the Tuneup, haven't done the 02 but I don't think that's it as it's running too well otherwise. Thanks for the tip on the up pipe, I'll check that. Also I haven't done the cat yet. I did pull another one off at the pick and pull. Was gonna use it and some tubing and just fab up another downpipe with cat. Be nice to go 3" there but I need to get it to pass smog first.

 

Thanks

Renny

[Frank B]

I was just looking at my copy of the 89 FSM and even though it is for the hot wire MAF, it does say " The CO content adjusting screw of the air flow meter need not be adjusted as the air-fuel ratio is feedback controlled". And it shows a chart for troubleshooting if the CO content is outside spec.

The things to check are, the ignition, compression, EGI system, faulty injector, improper fuel pressure, clogged air filter, degraded catalyst, faulty muffler.

 

But if someone did adjust the screw on the MAF, I guess the only way to adjust it, or to check to see if adjusting it helps, is to find a willing shop to test it while you play with that screw. Unless someone that knows which way to turn it to lower the CO will chime in.......

[DaveT]

haven't done the 02 but I don't think that's it as it's running too well otherwise.

 

I have had them run fine with a bad O2. I had one burn out the catalytic converter - the ECU didn't know the sensor was out of spec.

[kayakertom]

I just went through the Oregon DEQ headache and finally passed with my spfi 87 gl; the problem turned out to be the #3 intake valve not seating properly at low rpm. A replacement 1-3 head fixed it.

 

Worth doing a compression test.

[skishop69]

Can you post the actual readings? Did it fail idle or cruise? It's important to know what's been done, how hot was the vehicle when you went down, did you wait in line long, blah, blah, blah. Shoot th info over if you can.

[nipper]

An o2 sensor can do weird things. That is usally the first thing you replace on a failed emissions, especially if it is over 60,000 miles for ealry subarus, 100,00 0 for newer.

 

nipper