YELLOWGSLSE

iTrader: (7)

Here's the deal, I recently had my engine rebuilt by a very reputable builder. The install however was not so good; misplaced vaccum hoses, spliced harness (since been replaced), and TPS put on BACKWARDS (now within spec). Long story short, the car has run like crap since getting it back a month ago. It's running rich as hell, knock sensor code for the first 15 or so mins. of operation, idles at 1500, and, naturally, failed emissions pretty badly.

Now, since failing the first time, I have;
Changed spark plugs
replaced bad original cat with bonez high flow
changed oil
corrected mis-routed hoses

I dont have the results of my first test, but the results of the second test are as follows;

reading allowed
HC 137 132 fail (barely)
CO% 4.92 .073 <----FAIL---------WHY??
NO ppm 28 945 PASS
CO+CO2% 16.7 6.0 min PASS

So, as you can see, the allowable limit for CO% is .73, whereas I measured 4.92. Question is, what would cause the CO% to be so far off?

I've searched the other "failed emissions" threads, but usually the HC number is high. Mine is ok. But I havent been able to find a situation like mine. It seems like it has to be something majorly off. Any ideas??

wstrohm

Have you checked for stored fault codes (assuming you have a stock PCME)?

Are you sure it's running rich and not lean? The high idle sounds like you might have a vacuum leak. A vacuum leak will cause lean running, which causes misses, which dumps unburned fuel into the cat that it can't necessarily handle, causing high CO and high HC. (Yes I know your HC is not all that terrible but still...) Do you actually see black smoke coming out the tailpipe when the engine is warm? Is the lower LIM gasket of the newer stainless steel type, or of the older, fiberboard type (that blows out)?

FYI, I have attached our '94 FD's test results for this year's CA smog test... just a data point. Note that this car also has a Bonez downpipe, and a few other minor mods like no EGR system.

YELLOWGSLSE

iTrader: (7)

Thanks for responding wstrohm. I am just about positive it's running rich. For instance, I can clean off my tailpipes, then start the car. After about 5 mins, they're black. And yes, I can see a faint hint of greyish brownish blackish smoke. Very faint. It also smells rich, and this has been noticed and commented on by random people. It can bring tears to your eyes.

The only code I get is the knock sensor code. LIM gasket is the original as far as I know. I've tried spraying to check for leaks. Nothing.

Thing is, I had NONE of this before the rebuild. It has always passed with flying colors. This is why I'm thinking a part (but which one) has failed or a misplaced hose, or leak like you mentioned.

wstrohm

A knock sensor code is unusual... are you sure the crankshaft angle detectors at the front pulley are correctly spaced?

Our car was a gross polluter when tested for the first time in 1996. CO = 3.41%, HC = 552 ppm. At that time the car was completely stock, under care of dealer, engine never touched, etc. The dealer's tech found one vacuum hose disconnected, two others interchanged, and a wire (to the ACP valve) pinched under the UIM. As far as we know, those errors were from the factory, since we bought the car new from a CA dealer.

You should ask the engine rebuilder what material the lower LIM gasket is made of... just to be sure you have the upgraded S/S gasket.

wstrohm

Here's a pic of the crankshaft position sensors... be sure they are not too far from the rotating wheel.

ohioredrx7

iTrader: (13)

CO is directly proportional to your A/F ratio. Since it's so high you are definitely running rich as you suspected. Could it be a bad MAP sensor? (thinks it's running WOT all the time), TW sensor broken? (stuck reading very cold so it's getting cold enrichment all the time)

Speed of light

iTrader: (8)

Yes it is.... IIRC, it may also put the ECU into one of its limp modes, which may explain the rich operation.

I once figured out the correct value of resistor to sub in--in place of the knock sensor--it was high, I think it was around 240K ohms, but it would properly bias the ECU for operation/testing with no error code.

YELLOWGSLSE

iTrader: (7)

Once again, thanks for the replies guys.

Speed of light, I'm not familiar with the resistor thing. where would I get one, and exactly where would it go, ECU? And could this limp mode also cause the high idle?

Ohioredrx7, Is there any way to test the MAP sensor and TW sensor? And where exactly is the sensor for the TW?

j9fd3s

iTrader: (3)

doubt it. on the FD vacuum leaks will cause a high idle.

it is weird that the HC's are low and CO is high, i've never seen that before, and ive lived with rotaries in CA since 1993...

wstrohm

See pic below. It's the sensor with the green connector. (Below that is the (black) fan thermoswitch.)