SharkSkin

Nothing like an Italian Tune-Up to put the grin back on your face... Even better if it passes smog after that.

MBMB

After the "italian tune-up" (with Techron, then with Berryman's), new plugs, an oil change, and a new O2 sensor (WBO2 with Innovate LC-1), I retested.

Now:
HC 153/148 FAIL 183/152 FAIL
CO .79/.94 PASS .82/.86 PASS
CO2 11.4 11.8
O2 4.7 4.2
Nox 1872/1047 FAIL 1660/1146 FAIL

So, another $40 inspection down the tubes and I'm still all over the board.

Next I'll pull the injectors for professional flushing. Replacement cats should be on their way in a few weeks, along with an x-pipe.

worf928

Mark, so....

A clean up-to-snuff 928 can/should read triple-0 emissions on an 'idle' emission's test. (I don't let the shops dyno my 928s - driver's choice here in MA.) Do you have any 'idle' scores?

The 'scores' you posted? Those are from two successive tests on the same day? Is it the same shop that failed you the first (and second?) time?

You have a new Mass-Air Sensor, new plugs and O2 sensor, and new cat on the way.
You've run a lot of fuel injector cleaner through.

Your idle is in the window for a GT (775 +/- 25) so there are no massive vacuum leaks.

The car run's fine otherwise? Smooth? No missing? No harshness? Good dyno chart? No abnormal fluid usage (oil and/or coolant?)

With a new cat and professionally cleaned and balance injectors if it fails again we're going to have a real conundrum on our hands.

worf928

Also, does Texas have a "max dollars to pass limit?" In MA there is a limit of expenditure to fix the emissions system. If you go above that limit you can get a waiver. (Or so the statute says.)

MBMB

Dave,

The two numbers are "high speed" (25 mph / 2495 rpm) and "low speed" (15 mph / 2220 rpm) numbers. This is the same shop that failed me the second and third times, but not the one that failed me the first time.

Car idles fine, runs great. I don't have a dyno chart, but it goes like a bat out of hell. Occasionally it falters when I come off the throttle and on the brakes, especially right after a hard turn. Feels like it's about to stall out, but then picks up again.

$400 in repairs gets me a waiver. I'm probably close (injector cleaner, plugs, a case of oil, LC-1 with WBO2). DR's replacement cats (with x-pipe) will put me way over the limit.

DonS

Hi, Mark. Just up the road from you and in the same boat.

The law here is 25 years or older gets a pass OR you can get a waiver if you can't afford it to fix it. They'll want proof of cost from a certified mechanic and proof of income. I don't think that's your case. I'm sure you're also aware you have a 15 day window for a free retest.

99% of the problems will be the injectors (as discussed above), faulty fuel pressure regulator, WOT switch, 02, Temp2 sensor, AFM/AFC, or vacuum leak. Take your pick. The car should pass without cats or so I've read on several posts.

I've got an '84 grounded because of a failed emissions in February. Always ran fine but measured too rich; note I've got the LJet system with the AFM versus your newer EKJet(?) AFC with a hot-wire. That's my next (fixit) step - resetting it the AFM. Sherlocked just about all other potential problems out. ViribusUnits there in Houston is the (local) resident expert. I'm following the instructions behind what he did with his.

The Techron treatment gained me a 5mpg gain and good buttmetrics. Of course, the car had been sitting 3 years when the PO died. (Not in it.)

I'm hoping to take it back next month and get re-checked. LOTS of warmup as everyone says and try a different testing station that you get along with. Doing all the minor engine stuff I had to take the battery in to be re-charged (0.00 volts DEAD). Interstate sent me to a local shop and the mechanics were curious about what type of car used the battery. When I said a 928 their eyes lit up. I explained I was trying to bring it up to snuff to pass and they said to bring it to them for the test. They'd be glad to help run a good test on it. I was surprised but they were on the up and up. No slip-by but they want happy customers.

We're all waiting to see pictures of your completed garage, too. All you gave us was a slab pic and our imagination. Oh, and I'll take it off your hands if Viribus can't.

P.S. Last week I got a letter from Texas Commission on Environmental Quality reminding me that I hadn't been retested and the consequences of driving the vehicle. :sigh: Another bureacrat's list I'm on.

worf928

Mark,
Don lists a lot of the possible culprits. On your '89 you should be able to use Speak's Spanner to checkout the WOT/Idle switch and see if there are any stored faults. Do you know of anyone local with a Spanner? Surely someone in the Houston-metro area has one?

AFC - or Air-Flow-Controlled injection is the standard term for both yours and Mark's. On yours Air Flow Measurement (AFM) is the means and mechanism whereby air is measured to match fuel flow. On the S4's LH-Jetronic (w/EZK) systems the hot-wire Mass-Air Sensor is used.

worf928

A hard left turn? On about or less than a 1/3 tank of fuel?

MBMB

I have a Spanner. I'll run it again to double-check, but last time it showed no faults.

MBMB

Under those conditions (actually less than a gallon of fuel in the tank), it looses power even when I don't lift off the gas. Gas sloshing away from the pickup, I've always suspected.

But the falter I'm describing is with a full tank of gas, generally when decelerating hard after coming off the throttle. It's very intermittent -- in fact, I hadn't noticed it for several months before today, and thought that it had gone away for good.

DonS

Deceleration valve/vacuum limiter? Wouldn't that also mess with the A/F ratio (briefly)? I think I read on another thread once that it's also sensitive to ambient temperature? Don't know why but that would explain the intermittency. We've had above average temperatures for the past two weeks here. I don't have my WSM right in front of me and hard memories are difficult since I've had a couple since coming home...

IIRC ViribusUnits also has experience here by pulling the whole system; quite a few people just disconnect it. Maybe try that to start with; find out if it's being faulty and messing with the ECU trying to correct.

worf928

No such thing on LH-Jet AFAIK. Overrun management is handled by the ECUs directly with help from the idle stabilizer (rotary idle actuator in WSM-speak.)

MBMB

Update: "Italian tuneup" didn't cure the emissions problem. Neither did a new oxygen sensor. I sent the injectors off to Marren Fuel Injection (Motto: "Tell us your 'drop-dead' date and we'll say 'no problem' then ignore it.") and got the report back today.

Before cleaning, there was a 6.7% difference between the volume flowing through the most-constricted injector and the volume flowing through the least-constricted injector. After cleaning, the difference is 2.0%. So I'll reinstall the injectors and pay another $40 for another f'ing inspection; if it doesn't pass I'll sit on my hands until my new cats (and x-pipe) come in from 928 Specialists.

Unless someone else has a suggestion?

MBMB

Incidentally, Marren's pre-cleaning report shows "N/G" for the spray pattern for injectors 1, 2, 3, and 7. There's no key, but I'm hoping that a) "N/G" means "No Good"; and b) four "No Good" injectors would cause the screwed up emissions numbers.

worf928

All correct assumptions as far as I know.

You may feel an ***-o-meter difference with the 'new' injectors. I did in my '91.

Good luck.