So yesterday I took my 85 to get inspected. Its the last year I need to pass emissions here in NY and I was hoping she'd pass. No such luck. She passed the safety part, but failed the emissions part. Here are the readings:

Vehichle Reading: HC: 0.94 gpm CO: 8.33 gpm NOx: 1.42 gpm
Test Limits: HC: 0.80 gpm CO: 15.00 gpm NOx: 2.00 gpm

As you can see, the HC level is a little high and that's why it failed. The inspector suggested I add some fuel injector cleaner and "blow the car out". I had already blew the car out as it was a 35 mile trip to the station doing 72 mph most of the way with an occasional burst to 95.

Needless to say, I took my readout and left. My regular mechanic suggested that I test the fuel pressure and said it maybe the cat. Here's what has been changed on the car: O2 sensor, Bosch III injectors from FIC, EGR valve and temperature sensor, IAC valve and Air Hog air filter. I also just changed the oil with Royal Purple.

I spoke to John at FIC yesterday and he asked whether the new injectors were leaking. The car starts quick when its hot so I doubt it. He asked what the fuel pressure was and said it should be 36psi at idle with the hose connected. I tested it and its 31psi. That would suggest a lean condition, correct?

From what I know, the HC reading is a measurement of unburned fuel, correct? Any suggestions what could be causing this? Everything seems to be working correctly and within spec with the exception of the FPR. I don't want to start changing parts to experiment.

Any thoughts?

 

When checking the fuel pressure it is importent to check bleed down, thats when the engine is off. Does it hold fuel pressure or drop right down? If it drops you might have a really dirty injector(s) or leaky fuel press. regulator, also poss leak inside tank.
Whats the engine temp going down the road? Should be 190-200*, cooler running engines run alittle richer.
Are the tune up parts good, maybe a tune up is in order, easy to check the parts. Check your ign timing (follow the emission label), & make sure it advances when you rev it.
Make sure the maf sensor is clean, check for vacuum leaks, air pump connctions are good.

 

I did check for leak down. It takes about 2 minutes to leak down to about 12psi. With the car running, its steady at idle and rises when I give it gas. Should it stay a constant psi or rise with idle? I suspected a leaking FPR as the pressure is lower than it was the last time I checked for pressure, right after the new injector install, although I didn't find any fuel in the line when I pulled it off.

The last tune up I did was about 2 years ago, all Delco parts. I will recheck the ignition timing as I went to higher octane last time I filled up. The MAF is cleaner and I hear the burn off relay working when I shut the car off. I did find a possible vacuum leak, when I went to pull the line off the FPR, one of the lines from the back of the plemum just fell apart. Now I have to locate that little plastic diaphram with the 3 ports (any ideas where to get that). Other than that, everything seems in order.

The car runs fairly cool for a C4. It never gets above 225, per the dash gauge readout, and when driving it will hover around 185 - 195, depending on the weather.

 

Yeah that engine off leak down is too fast, should hold 30+psi then slowly drop after hours of sitting. Sometimes those regulators leak slowly so you might have to watch it.
I'm not sure of the diaphram, might need a picture.

 

with ex. Here is a quick FPR test for you.
Clamp return line
Turn key on
Do not start engine
Turn key off
Record and observe fuel pressure reading
If the pressure holds, the FPR is leaking
If the pressure drops like before, the fault is in the supply side of the system, fuel pump, pulse dampener, etc.
Hope this helps,
Bob

 

It was the 2 way check valve, not a diaphram, my bad. I found it at AutoZone for $4.

The leak down stops at 10psi after 4 minutes. I am waiting on it to see if it gets to 0. From everything I've read, a new FPR is in order. An adjustable one is ideal to get the correct match for the Bosch III's, correct?

 

Ok, I did the above test. With the return line open, it goes to 45psi and then drops. With the return line pinched, it goes to 75 then drops quickly. So, should I start with the fuel pump and dampener replacement? I am sure they are the original ones.

 

throw a cheapo cat on it. a new one will cut all numbers in half easily.

 

PM sent

 

I thought of doing that too. Any recommendations for brands or places to buy?

 

just buy a magna flow direct replacement. I've had a gross polluter trans am that a new cat made it pass with ease. Just make sure you drive the car a day before it is tested and make sure cat is nice and hot before the test and I guarantee a pass. You test has to have higher limits then california and new cats always get me through no matter what.

 

When did it last have one put on it?

 

The cat on the car is the original cat, still attached to the original front extension pipe....the car has 151K on it.

 

replace it and you will pass with ease go on that auction site, cost you maybe 125-150

 

Found a few, no real bargains. Rock Auto actually has a better price so I will probably place the order through them and get some other items I need as well.

 

Does your car have it's air injection working?

 

All the components for the system are in place and seem to be working OK. Is there a test to see?

 

was just asking, cats don't work good without air injection is all. Buy a universal one and weld the sucker on. ... I just prefer bolt on and go is all. Misses, plug gap, timing, temperature will up HC though, but either way if you don't want to chase down the culprit a new cat will get you right through.

 

A new cat will be ordered today and hopefully installed before next weekend. I will also plan on replacing the FPR with an adjustable one and the fuel pump to get the fuel pressure to where its supposed to be for the new injectors.

 

Before catalytic converters, the manufacturers reduced HC emissions by retarding the spark.