jcorenman

THIS ^^^ !!

danglerb

This is my 85 Euro S, it does have an O2 sensor I think, but I don't know which brain I put in it most recently. OTOH it would be all over the place it if was open loop, but that could still be a US brain with US chips or John Speake's special blend.

One of the things that I was wondering about is that it is a federalized Euro, and the Calif catalog only has US models, but not much point in arguing with "the book".

Immediate concern is to pass the stupid test and get new tags before I get impounded or something.

Longer term, what is making it run so dirty, it should be doing better than this with no cats.

HC as high as it is, pretty sure the cats were hot.

Smog guy is really nice, says I can bring it by anytime he isn't doing a test and check to see if its better., then retest if it looks good. Easy tip off, I could smell the HC during the test, so unless that goes away I doubt if its fixed.

I'm not sure of the exact state of mess under the car, or which exhaust manifolds I have on it, Euro Factory cast iron or US 85, thinking latter, which means nothing else is a bolt up fit, and it does have a "hokey" Y merge before the cat. If its welded in, tweaked for US manifolds, borrowing doesn't seem practical.

Cheap stuff to try, drive it some at cruise speed, get rid of old gas, replace the O2 sensor, check the brains and look at pipe sizes of existing stuff. If I haven't gotten it to pass in a week, then a more aggressive approach.

Lizard928

Again,
If you are not at 14.7:1 AFR the catalytic converter wont work....

Fix that first.

danglerb

I could smell HC though, almost the typical bad cat smell. OTOH if I have the wrong chips or wrong brain, that could be it. Car "runs" fine on any of the three options and I was messing around with it at some point.

AFR was 13.8 and 13.7 from a display screen but not on print out. This was during the test run I "think". I would have written down the numbers, but I thought it would all be on the printout, not just this diagnostic screen.

As mentioned, the aftermarket cats are easy to kill of your AFR goes wonky, and the car did get messed with somewhat.

Everybody seems to have the exact same $179.96 price on the Magnaflow, but Advanced Auto Parts has a $50 coupon code for $140 shipped with tax. One sitting in my cart now, just mulling over shipping time vs now someplace more local.

I'm also thinking a little about what I would "like" to have such as factory dual cats., which I thought I had on my 84 parts car, but may have been toast and tossed.

John Speake

Disconnect the O2 sensor, and then set the idle CO adjuster on the MAF to 14.7:1. Then reconnect O2 sensor.

danglerb

Would that apply to your custom chips in a USA brain, or both those and normal USA chips?

This would be something like the Porkenblinker setup? or would it need to be using a tailpipe sniffer?

Unplugging the O2 will mean no power to it so I can't just put a meter on it?

John Speake

It should apply to all versions, other than stock Euro 16v. And I assume you are running with an O2 sensor...

You could keep the O2 sensor powered with the O2 output disconnected, use a P blinker or a meter, you can't go to the tail pipe as your cats will clean up the CO.

Koenig-Specials 928

I have passed the Ontario emission test 3 times (in 6 years) with an x-pipe and dual hi flow cats. The first two times (4 years) I passed on the first try. 2 months ago I failed and on examination it appeared that the CO was too high at idle. Previous to the test I had changed the oil, new air filters, ign plugs from Roger and installed a set of Colin's custom ignition cables. I searched the forum and read everything written about idle and the WOT switch operation and tested the switch at 60mph and guess what, it was the idle switch that was not set up right. The digi dash consumption indicator did not drop to zero and I also could not hear the click. I set the cables up correctly, redid the road test, went back and redid the emission test and passed without spending a $1.

Now this may not help you but could help someone else.

leperboy

This is probably very true for cars that get driven a lot. However, many of us here are only driving our 928s a couple thousand miles a year. I have aftermarket 300 cell cats and an x-pipe that have passed in 2007, 2009, 2011 and 2013. I put between 1500 and 200 miles on the car each year.

I would like to hear some mileage-based experience on aftermarket cats because I think that is more relevant for us with infrequently-driven cars.

Matt

Imo000

On a DD car (any car) its a well known fact that cheap aftermarket cats with small bricks will get you a pass (numbers will be higher than a new OE) the first time, but two years later it will either fail or be very close to failing. Gregg is right, a cheap conveter doesn't have much in it.....it can't or else it wouldn't be $150.

dr bob

^^^^ This ^^^^

Mike:

Lean misfire in just one or two cylinders will give you the high HC and high NOx numbers. If the cause is weak injector flow on a just a small number of cylinders, the oxy sensor loop will still try to control on the net CO value.

Recommendation: Clean (seriously CLEAN) the injectors and put new plugs in at the same time, then reset CO per John's recommendation above.


Need the on-car injector flush kit? It's idling here in Glendale. I can box and ship it to you. Find some BG injector flush chems to use with it. Else pull the injectors and send them off to your favorite cleaning service.



I'm curious about whether the oxy sensor on your car is connected to anything. Virtually all "federalized" Euro S cars I've seen or heard about have the sensor installed but the cable goes nowhere useful.

dprantl

My GT has been smog tested with the 300cpi aftermarket cats 5 years in a row now, passed every time. It is a daily driver and has been that way for over 50k miles. I also have a wbO2 gauge in the car. If you have a bad AFR for whatever reason, the aftermarket cats will not last long.

Dan
'91 928GT S/C 475hp/460lb.ft

17prospective buyer

Did you consider measuring temps pre and post cat with a temp gun? That can be used to see if cats are working. That's all I have to add. Good luck either way, good that your e-test guy is chill like that. Running that rich will definitely not make the cats operate at peak efficiency, and the car has an O2 sensor??

James Bailey

I wonder if most aftermarket cats get installed BECAUSE the car already killed the original one and still has the same problems which then often quickly destroys the replacement ??

dprantl

Not in this case Jim. The only reason I went with aftermarket cats is because I installed an X-Pipe. The factory cats were still passing smog when taken off and are still in the garage. But this is a good point... and maybe further puts aftermarket cats in a bad light.

Dan
'91 928GT S/C 475hp/460lb.ft