Need help getting 1991 back in operation

[dmaclennan]

History:
Original owner, un-modified 1991 with 85k miles - been stored for last 10 years. Trying to get it back on the road.

Issue:
Failing smog test for nitrous oxides [697 ppm vs max 545 ppm at 15 mph. OK, but only just at 25 mph] - CO percentage is twice the max at both speeds and hydrocarbons [103 ppm vs 78 max at 15mph, again just OK at 25 mph]
I sense a very slight occasional surging around 2000+ rpm cycling at around 50 Hz. Don't get anything unusual on the tech 1 using snapshot.

Recent maintenance:
New fuel pumps & filter
New plugs
Repaired vacuum line that was disconnected
New fuel injectors

No codes

Diagnostic Circuit Check with Tech 1
All items in range except:
Blk Learn Enable has value YES and should be NO
Spark advance is 11 degrees and should be 0 degrees

Checked fuel pump operation:
Intial pressure peaks at 58psi and immediately drops to a steady 50 psi and holds. [I assume this means the pump is generating plenty pressure and the regulator valve is also working]
At idle get around 45-46 psi. [I think it's supposed to drop 3-5 psi but not certain]

To do's:
Check spark
Check A.I.R.
Replace O2 sensors - maybe?

Any suggestions? [Other than CA smog test sucks ]

Appreciate any help.

Cheers,
Don MacLennan

[Paul Workman]

I would give Marc Haibeck a call and discuss it with him. Marc has put together some calibrations along with a few other tricks to get California cars compliant, so I'd start with Marc, the ZR-1 Specialist.

[XfireZ51]

Is this in Closed Loop? What do the O2 sensors say?

[dmaclennan]

Originally Posted by XfireZ51

Is this in Closed Loop? What do the O2 sensors say?

Yes. Closed loop.

O2 sensors are reading from about 100 mV up to 700 mV or so. Hard to say precise numbers. Snapshot gave mid 300 mV on both.

Thanks

[XfireZ51]

Originally Posted by dmaclennan

Yes. Closed loop.

O2 sensors are reading from about 100 mV up to 700 mV or so. Hard to say precise numbers. Snapshot gave mid 300 mV on both.

Thanks

Ok, so if its C/L, then what are the BLMs like?

[dmaclennan]

Originally Posted by XfireZ51

Ok, so if its C/L, then what are the BLMs like?

L. INT 127; R. INT 126
L. BLM 122; R. BLM 125

Thanks

[dmaclennan]

Originally Posted by Paul Workman

I would give Marc Haibeck a call and discuss it with him. Marc has put together some calibrations along with a few other tricks to get California cars compliant, so I'd start with Marc, the ZR-1 Specialist.

Absoluteley. Used his video to do the injectors. Want to make sure all the obvious stuff is done first.

[Jagdpanzer]

Imagine it will be tough to get through current Cal emissions test without EGR. That was my experience in Northern VA which has the same limit values

[tpepmeie]

Bfxb was not specifically different for emissions. That likely won’t make a difference for you. Save the money.


Sent from my iPhone using ZR-1 Net Registry

[Ccmano]

Yes, the nut has to come off. While it is the nut for the engine mount, it and the “K” member do not support the engine. After you have the O2 sensors in take it for a long hard drive to get the cats good and hot. Its likely the cats got a bit contaminated from that old gas, long inactivity and frequent startups without really driving it. When I still lived I CA I found that a few good full throttle runs to redline immediately before taking to the smog station brought the numbers down somewhat.
H