Papamurphdog

Good luck. Hopefuly you will be able to adjust and tune. Keep us posted on the results. BTW, just re-checked with my inspection station/PCA member operator and he confirms that emissions testing is dialed specificly to be certain that an operational CAT is present and working. Tune the thing fer sure, but your CAT may simply be old and disfunctional. Not supposed to happen, but...

Techno Duck

I just adjusted the idle and it was off by quiet a bit. Disabled the ISV with the test port and idle dropped to about 600rpm. I still need to put in the new O2 sensor so i can tune the AFR back into spec...as i dont want to tune the AFR with a bad O2 sensor.

Now i think i should be able to tune this without even using a multimeter by just going off the wideband, but im not certain. So i would appreciate if anyone can comment on that. When i disconnect the O2 sensor, my AFR goes from a dithering 14.7 AFR to around 11.5 AFR.. which as i understand is correct according to the post on Pelican im reading off, as the DME goes into open loop and runs off preset fuel maps. Now i should be able to adjust the AFM to get my AFR down to 14.7 (reading off my wideband) during this period with the O2 sensor disconnected. This can be double checked using a multimeter hooked up to the stock O2 sensor. A 14.7 or Lambda reading of 1.0 on the stock O2 sensor is around .5v . So i can lean out the AFM settings to achieve to .5v on the multimeter and 14.7 on my wideband (it should correspond).

Now the fact it goes down to 11.5AFR could also be because i put my APE Stage II chips back in last night..as the car was running like crap on the stock chips. Once i change the O2 sensor and dial the AFM back in ill put the stock chips back in and see what happens.

These are the directions i am reading off from Pelican...

http://forums.pelicanparts.com/showp...72&postcount=9

Now if you see anything wrong with my logic please correct me, as i am not exactly an expert on 80's fuel injection technology.

marky522

Your completely missing my point, maybe you find it acceptable for your car to run like crap, and let the cat clean it up but i would rather have the car running the best it can for fuel economy/power. Chances are if your car was THAT bad and your cat had failed, it was due to being overloaded with fuel and thats what caused it to fail. This is why there is a test port on the exhaust BEFORE the cat, so you can make sure your car is tuned properly and not relying on the cat to clean it up.

Mark

Papamurphdog

OOOOOuch Mark! Wasn't trying to be a *****, or call you out bud. My car is rich because it is tuned that way fer criss sakes. I've had it on the track for the last 5 years and it hasn't done anythiung to **** me off on the track and makes plenty of power with the headroom I desire to keep from popping the #4 valve, a head gasket, or all the other stuff I see happening to "tweeked" cars at the track. I am sure the CAT failed from rich use...or more likely the leaded race gas I used a few times! The '90 was an age issue. The reason I posted here was it took me MANY HOURS to track down and research CATS for the my two 944's and it was a bitch getting rejected for emissions repeatedly AFTER TUNING both my cars twice. After tuning, they were just over the limit, barely. The point is, the CAT made a huge difference in the emissions, regardless of the tune. Went from well tuned and still illegal, to barely registering emission at all; with RACE CATS on both cars (so very little restriction) Which I thought would save you time and money. BTW, I would NEVER tune my cars just to pass emissions and leave it that way. The emissions test is NOT a peak performance test or a tuning test. Tune away. Certainly a good idea to have a well tuned car with all the bits working properly; tuned for the way you drive it though, not jsut to pass emissions. Then, when that is done, you can write me and tell me how much your new race cat reduced the emissions when you finally passed the emissions test, after having to replace the cat anyway! good luck. I'm outta here...

Techno Duck

Did a bunch of reading through old posts last night, the general consensus is that the CO adjustment screw should be set anywhere from 6-8 turns from bottomed out. I checked my AFM and it was set 1.5 turns from bottomed out. This means it was set around 5-6 turns richer than what is close to the factory setting. I adjusted mine to 6.5 turns from bottomed out to be on the safe side. After i did this, i disabled the ISV again and the idle was around 600rpm so i adjusted that back to spec as well. I disconnected the O2 sensor with the car was running and now get low 14's AFR's.. before it was in the mid 11's.

I woke up to late this morning to put the new O2 sensor in and its about 95 degrees out right now..so it will have to wait until tomorrow morning. Im going to double check the CO setting with the new one just to verify i have it set correctly.

Im wondering if this is even going to have much effect on the actual emissions while at anything other than idle. There were various remarks in older posts stating that the CO adjustment only really makes a difference at idle.

What a pain in the butt.. sometimes i just wish i bough a factory fresh car to mess around with so i didnt have to deal with those weird previous owner charades. Instead i would just be worried about if i voided my warranty or not.

Techno Duck

On a whim decided to try taking the O2 sensor out..amazingly it came out without a hitch. Took it off and after some struggling managed to fish it out. Getting the new one in was a pain but just took some luck trying to fish it through a spot i could reach from above. Wired everything up and took a short ride.. car runs smooth. Going to take it down to my friends place for reinspection in about 10 minutes..said he might be able to squeeze me in before they close. Wish me luck.. .

Less than an hour and a half.. not to bad. The O2 sensor on my '87 n/a was so badly frozen i had to drop the Y-pipe to get it out.

marky522

Ok, didnt mean to come across as a *****... I understand the reasoning for your tune, its a safe tune. My point is you CAN tune these cars to pass a emissions test WITHOUT a cat, which would suggest that there obviously are problems with his car.

Mark

fast951

Tecno Duck, Make sure the O2 sensor is working properly before you test, you will have a better chance passing a test with the stock DME chip. MAKE SURE you drive the car at cruising speed for at least 30-40 minutes and don't turn the engine off before the test. It takes lots of time to bring the factory cat to life.
I just experimented with this on a car with a few mods, but has the cat. The first try, after a 10 minutes drive prior to the test, it failed badly. The only change was to drive the car for 40 minutes (no boost, just cruising 60-70mph), then test; it passed with ease. The test was done on a rollers 1500 & 2500rpm.

Techno Duck

Thanks for the suggestions John. I tried to have it done yesterday afternoon but my friend wasnt able to squeeze me in. Hopefully come next year when its time for reinspection with the MAF and everything hooked up it wont be such a hassle. Right now there are just to many darn variables to try and sort out with this original stuff.

I ended up making an appointment at the place this car used to be inspected at by the previous owner (S&M, mentioned earlier in the post by a few guys) and im going to bring it in first thing monday morning..its a good 30 minute drive from me so a good time to get it warmed up. I was going to leave the APE chips in but as per John's suggestion will but the stock stuff back in. This will mark the 3rd time im changing the chips in a one week period... atleast im getting good at it now . If the car fails again its not the end of the world, im just going to bring it down to a place where i know for a fact it will 'pass'.

Techno Duck

Just wanted to follow up on this. I just got back from reinspection at S&M and it passed without a problem. Here are some of the 'variables' that changed from the original test.

-Car driven 20 miles to shop and tested on dyno within 30 minutes, car was never shut off
-O2 sensor replaced, age of the one removed is unknown but it didnt look to old (but who knows).
-AFM CO adjustment screw moved to 7 turns from bottomed out, originally at 1.5 turns from bottom. This was set based on old postings where people said theres was on unaltered AFM's.
-Car run in 1st and 2nd gear rather than 2nd and 3rd

So in short here were the original test results..

Test Limit
HC: .8 GPM
CO: 15.00 GPM
NOx: 2.0 GPM

First test
HC: 7.41 GPM
CO: 94.93 GPM
NOx: 5.18 GPM

Second test after changes
HC: .46 GPM
CO: 5.2 GPM
NOx: 1.13 GPM

Papamurphdog

Thanks Mark. Just trying to help here... Jon, congratulations on passing. Now, be sure to rdouble check you mixture settings if you are going to track the car. See ya! :-)

Techno Duck

Everything is going to be staying the way i left it until atleast the weekend. Ordered a Vitesse MAF on friday, so its all getting replaced anyhow.. . Getting the good gas mileage anyhow isnt to bad either! With the way things are going i should be able to do about 350 miles on a tank.. used to be just barely 300 miles.

MM951

Congrats, huge improvement!