Ziff951

I read a ton of these threads hoping I'd find the magic answer, but they all seem pretty old and they didn't have all the mods done...soooo...

I just failed today with these numbers:

15mph
CO2 - 13.9
02 - 1.2
HC - max 133 Meas 156 fail
C02 - max .82 meas .66 pass
NO - max 1125 meas 1828 FAIL

25mph
C02 - 15.8
02 - .3
HC - max 108 meas 46 pass
C0 - max .62 meas .27 pass
N0 - max 955 meas 1363 FAIL

Okay, I have the LR MAF, 55lb injectors, sport turbo, 3in exhaust, and a new performance cat from LR.

My big concern is obviously the huge N0 numbers. The others seem pretty close...maybe lean out the lower area a bit for the HC and have him test the 15mph in first gear?

Is the new cat to blame? The car was very warmed up and my AFR was right around 14.7 range.. with the 3in exhaust, I can't really swap an old cat in...
thanks for any help. I can't register the car...ugh.

Also, my wastegate dumps to atmosphere, so it's not even in the loop...

The test guy was cool and suggested I retard the timing a bit to bring the N0 down...any thoughts?

schip43

First if the guy never mentioned the MAF you got a break because MAF's will fail the visual. What chips do you have in it, if any? The chips adjust the timing some of them can pass becasue they don't effect idle or PT operation.

So you need to determine what chips the car has in it first. My car passed with MAX 951 chips AFM CAT and 55 lbs injectors. So some chips can pass smog.

docwyte

Sounds like the cat isn't cutting it. What cell count cat is it?

Ziff951

Yeah, I got a break on the MAF...I've been going to this guy for 10 years, he knows I'm not undercover or anything, I guess.... not sure of the chips. So, I can't adjust timing on this thing? Damn...my 74' Land Cruiser is much easier than all this computer mumbo jumbo...;-)..
The cat is the hi perf one that Lindsey sells, don't know a cell count... If the cat is not up for the task, what are my options to lower my N0? Are there heavier duty 3" cats that I can slip on for the test? Two in a row? I don't know...just want to register this stupid thing...

minho78

Ziff I got this info from another forum:
NOx high, possible cause or recommended action: Replace converter and O2 sensor; verify tune-up and correct any faults, check lean AFR, leaking exhaust valves, EGR, lean AFR, leaks, run-in converter.

400hp944

The main problem is your CAT. I know from experience. The little CAT that LR sells does nothing. Go to a muffler shop and get the largest cat they have for a "non EGR" application (jeep cherokee). Next - buy 5 gallons of 109 octane unleaded. Done!

schip43

Do you have gauges, what's your AFR at idle and PT? Actually look at the smog cert it should show both or go back to the guy and have him tell you what your doing at idle if it's not 14.7 higher or lower at idle your going to have problems everywhere.

Yep same guy for 10 years is the way to go! Hmm Co2 13.9 is that the same as an AFR of 13.9? If it is then your running rich at idle so you'd be rich at PT.

Timing is part of the test , so technically it would have to be stock but if he's letting you run it with a MAF, don't think he would care.

I think you can manually retard it 3 to 4 degrees but I think you need to know what your AFR is at idle before you start to screw with things.

Red1

Vacuum leak
Check TPS for correct adjustment

BTDT, ten times over the past nine years.

Ziff951

Yes, I have gauges and, in fact, had my laptop hooked up with realtime tuning and monitoring available. The AFR was at 14.7, give or take a tiny bit...

All vac lines are new, I will check TPS.

How do I manually adjust timing on this thing? I really like being able to twist my distributor around on my old vehicles!

I'll definitely go to a muffler shop and see if I can get a huge cat fabbed up to slip on/off for testing..

Thanks guys... I'll check back in soon...

Don 944 LA

Do our turbos have FQS switches on the DME like the NA's ??
If so, you can change 4 degrees by changing the fuel quality switch.
It won't change fuel amount like ROW, just timing

EDIT: Guess it does http://www.motronic.ws/fqs.htm

schip43

You are correct, it looks like you can retard timing with FQS switches.

These are distributor based cars so you can still adjust the timing by twisting the distributor can't you, is'nt that why the timing marks are on the flywheel?

I tired to search for an answer but all I get is timing belt info.

PEvans

You won't get there without a well-functioning cat, and that might be all you need. Also, our cars go through the aftermarket cats. Now that I'm well past the factory cat I'm getting two years but not four out of the aftermarket cats.

Rogue_Ant

Twisting the distributor will not effect timing, at all. Timing is controlled completely by the DME - the distributor simply sends ignition to the correct cylinder.

OP, two cats or one huge one will probably work, but I doubt is necessary... Are you running in closed-loop? (O2 sensor hooked up). And if so, how old is your O2 sensor? Could also throw in a bit of E85 or denatured alcohol.
Also, the cat needs to be quite hot to work properly. It takes a while to get the exhaust/cat really hot - so you might need to do some spirited driving beforehand


-Rogue

Ziff951

Rogue, thanks for the input.
I don't know how old the 02 sensor is..would that cause the N0 to be that high or more likely the cat? I'm planning to try and get a huge cat tomorrow...since all the other numbers are pretty close, you think the cat could do it?
Also, should I click the DME to #4 for the 2.73 degree retard on the ignition? The smog guy said retarding the timing might take care of it...like to hear your thoughts on that. Thanks again for the help.

Stephen

Rogue_Ant

If you don't know about the O2, then I would replace it.
I do think a large cat would help, but I've passed cars with the low-cell count performance cats before.
Really need to get the exhaust nice and hot.
You could try switching the FQS to #4, that should take out some of NOX, but might raise HC...