MBMB

I didn't pay attention to my fuel pressure earlier in this saga.

I'd better try another gauge -- this one could be off. That hadn't occurred to me.

40 cm Hg to one damper and the regulator. Haven't checked the back left damper yet.

MBMB

Fuel pressure gauge was busted. With new gauge pressure is 48 / 55.

TRUESCOTSMAN

You seem to have a tighter test in the U.S than we have here in the UK. Over here they only test for C.O and H.C with 3.5% and 1200 ppm the max limits respectivly. What is the max values you have to work to?

TRUESCOTSMAN

HAD MINE TESTED TODAY. Here are the test results

MBMB

The max values are the "standard" values in the table I posted 5/19. Currently 148 HC, 0.94 CO at "low speed," 152 HC and 0.86 CO at "high speed." Maybe I need to get inspected in Scotland.

worf928

Mark, is there anything at this point in the o2/fuel/spark loop that you haven't touched other than the cats? (And I think bad cats would result in high NOx not your wildly out-of-spec numbers on HC, CO and NOx - somebody correct me if I'm wrong.) Is there anything about your car's operation that might provide additional information? Still smooth? Good power? No funny-smelling exhaust?

These scores - after all that you have done - do not make sense. It's like you have one or two cylinders that are just not combusting the fuel-air charge properly or are burning something other than gas. Have you pulled plugs recently to see if there's any difference between cylinders?

Has your LH been rebuilt? I have no idea if your scores are a possible failure mode of the LH, but you could ask John Speake or Rich Andrede.

MBMB

Dave,

I don't think there's anything I haven't touched other than the cats.

I have noticed more idle fluctuation (and a higher idle) now that a few months ago.

Diagnosis has been slow going because of the garage construction; once I get home to Houston (I'm in Dallas right now -- hi Dallas people!) and get the batcave done, I'll have more time to dedicate to the problem. I haven't gone through the system looking for vacuum leaks; I'm hoping I can blame this on a vacuum leak but I really don't think so. Incidentally, my fuel/air ratio hovers around 14.7 when I'm driving.

Spark plugs all looked alike, with a light to medium gray dry coating, when I replaced them after my first bad emissions test.

My LH has been rebuilt recently.

douvillier

When both HC and CO are excessive, this often indicates a problem with the emission control system. Since you indicated earlier that you had an ECU problem that dumped raw fuel into the cats, that would explain the cats failing. Also I believe that your 89 has a three-way catalytic converter(anybody please correct me if I'm wrong). This type of converter reduces NOx as well as HC and CO. Of course if I'm wrong my lawyer is standing by.

WICruiser

Three way cats do reduce HC, CO and NOx, not sure if this model year utilizes three ways but I would not be surprised if that was the case. Three ways work in conjuction with the A/F ratio control to cycle slightly rich then slightly lean of stoichiometric. The switching is controlled by the O2 sensor. Given that I believe you have touched all of the control end, spark plugs look good, and the history I would suspect that the cats have seen better days.

MBMB

Final update: new cats made all the difference in the world, cleaned everything up.

StewartT

I had the same exact issues and based on this thread and a few others, I bought new cats. It fixed the problem of the failed emissions tests.
I also believe the car started performing better with the new cats. As a couple of people mentioned, it did , indeed, register on the ***-o-meter!

Speedtoys

I just recently passed by an inch at low speed, and failed by an inch at high speed.

New plugs, wires, caps, rotors, injectors, and o2 sensor.

Before all that, it poured fuel down the gullet.


New exhaust/xpipe/cats on the way and retest soon.