KJL

Their are no vacuum leaks, idles at 18" of vacuum. Same as my 92 ZR1. As you observed, my EGR was removed by previous owner but just the valve and plumbing (I have this). The headers have a blind boss provision for EGR tube but the intake plenum is older model year and does not have a port for EGR. Apparently 90-93 did not use EGR?

At this point about the only thing I can do (aside from EGR) is replace the cats and possibly the o2 sensors.

My numbers this summer were on 93 Octane:
OLD-25/25: 1255 & 50/15: 1448
New-25/25: 998 & 50/15: 1096

I can only attribute the improvemnt to colder ambient temps and 50/50 water/methanol injection. I used a syringe to meter in a very small amount via the cruise control vacuum port.

Some questions:
-Is there a procedure published for checking the O2 sensors? I am sure Paul or one of the other ZR1 guru's has this somewhere.
-What are the part numbers for the correct O2 sensors?
-Can the headers be removed with engine in car from underneath?
-Could the EGR be plumbed to the cam cover breather port on the right side of the intake plenum horn...just temporarily?

Dominic Sorresso

KJL

Not provided, just the measured values versus published not to exceed values.

20% load at 25MPH: Nox max limit 796ppm
50% load st 15MPH: Nox max limit 897ppm

I have no idea how they figure the loading.

No doubt the 4.10 read gears are not helping.

Paul Workman

U B correct. Brain fart - got cornfoozed

C6_Racer_X

I can field the first two questions. O2 sensors when they are working correctly oscillate between two voltage levels (typically around 100mV for the lower level, and around 800mV or 900mV for the higher level). On 1996 and newer vehicles, you can graph the O2 sensor voltage PID on a scan tool. It should oscillate between ~0.1V and ~0.8V or ~0.9V. The quicker it oscillates, the better it is working. They get slower as they get older, and too slow (more than 3 seconds between peeks), or "stuck" at one voltage level is the symptoms of a bad O2 sensor.

If you don't have a scan tool, you can use a digital multimeter set on a low Volt scale to check the voltage. I'm fairly certain there will be three wires on the O2 sensor on your ZR1. Two white wires go to the heater coil, and the black wire is the signal wire. The red probe from your multimeter goes to the black wire on the o2 sensor plug. Ground the black probe from the multimeter to a solid ground. The voltage should swing back and forth between ~0.1V (100mV) and ~0.8V to ~0.9V (800mV to 900mV). A new sensor will oscillate as quickly as twice per second. Older sensors get slower as the performance degrades. Test with the engine at operating temperature, and be careful, things are hot around that wiring harness connector.

Another test to make sure the sensors are working, create a vacuum leak by pulling a vacuum line loose (the brake booster makes a nice big vacuum leak if you disconnect it). You should see the voltage drop to about 0.1V (100mV) at the O2 sensors with a big vacuum leak. They should go back above 0.5V and start oscillating when you "fix" the vacuum leak by reconnecting whatever vacuum line you disconnected.

You can also check for vacuum leaks with the volt meter or scan tool. While watching the voltage, spray throttle body cleaner around the injectors (to check the injector seals/o-rings) and around the intake manifold gasket. If you hit a leak with the cleaner, the O2 sensor will go to the high voltage end of the scale (over 0.8V) and stay there until the cleaner has been sucked in, burned and clears the system. The O2 sensors are usually more sensitive to leak detection this way than the tachometer.

I'm fairly certain that the OE oxygen sensor is a Bosch 13077 three wire sensor. That one is widely available and not terribly expensive. You can get them online for ~$35 or so. A local parts place will probably have them in the $45-$50 range.

Rkreigh

with headers, the crappy cats that go on the collector don't have enough cells and surface area to do the job so they need to be FRESH

I would like to run a zr-1 on E85 (85% alchy) to see if I can clean up the old LSV

with big cams the HC are high on mine too.

Take a look at those cats, if they are more than a few years old, they aren't likely going too do it and fresh cats make a big difference.

sounds like the car is tuned. a few other tips, I wouldn't run the car cool, in fact a few spirited runs help blow the carbon out which contribute to the high readings.

get some "granny cats" old crappy restrictive cats off a truck or something that are huge and cheap. bolt them up, pass, go home and put the bullet cats back on.

for sure re-enable the EGR, it will be tough to get by and you'd fail the visual here without it.

thank goodness 2020 is right around the corner and I'll no longer be plagued with this foolishness.

Va cut the standard from 98 to 48 on HC a few years back so I was screwed at that point and even the fresh cats and alchy aren't going to do it.

I think an E85 calibration would do it though. Plug in the chip, pass, and drain it, put gas back in and go!!!

because you are running low speed on the dyno you'll never run out of fuel with E85 Should burn WAY cleaner on HC and running around on E85 would clean the old gals pipes out.

KJL

I do have a scan tool, an AutoXray which was considered a high end unit in its day. I guess the company in no longer in business and support/firmware updates are no longer available, that said I did do a scan and found the voltages to oscillate between approx 60-800mV. I will time them today. May replace them regardless while I am pulling the cats.

I tested them in closed loop mode. I compared to my 92ZR1 and peak readings appeared a tad lower. In open the loop the voltages are supposed to be near or at zero. One of the sensors on my 92 was reading 550 mv while all others were about 40. Once they entered closed loop, all appeared to start oscillating and reading as expected.

One bad thing about my scan tool is it seems to only be able to maintain a connection with the ECN for about 30 seconds for some reason then I need to reconfigure and scan again. It does this on both cars so using for vacuum leak detection will not be possible. I am going to mess with it more today. I may post a new thread looking for scan tool recommendations, time to get something new and is supported. I love my AutoXray, shame they are no longer in business.

What about spark plugs?

KJL

Are you saying run 100% E85 with a chip calibrated for that?
Finding a random cat that will fit my 3" exhaust system will not be easy so I am going to just pick up a couple of new units at Summit Racing with metallic substrate. I am willing to try anything within reason.

Just for clarification, my HC numbers are fine. NOx is my problem.

Not worried about mechanical inspections, the guy knows me by name now and doesn't do any mechanical checks. He knows the car is not stock. He opened the hood and saw my bubba water injection tube sticking in my intake and didn't say a thing. I may try increasing the amount of water as well.

Dominic Sorresso

May want t look at ALDLdroid for scan and datalogging w a Bluetooth ALDL adpater.

Also, I would recommend AC Delco O2 sensors over Bosch. Much more stable signal than Bosch. Bosch units I have had would drop signal intermittently.

KJL

That looks pretty cool. I recently swapped to iPhone but still have my old droid. I logged onto the ALDLdroid website but there was oddly not much info regarding the cables. Looks like some hunting will be in order.

Dominic Sorresso

ccmano

Just got mine set up.. very slick.

One word of advice if you go this route. The Bluetooth unit needs a power source. RDR provides a wire to hook to a 12v source that is then clipped into the G or L connection of the ALDL connector of the car. On a ZR-1, G and L are already utilized by the CCM and SIR feeds.

The Bluetooth unit has a 12v input on the box. I simply set up a connector to the cigarette lighter and plugged it in the box input. Works like a champ. This is not documented in the provided RDR documentation.

H

KJL

Thanks for the info! I will deff look into this further.
Looks like I have just run into another issue......apparently I have the only converters that were constructed at 10.5" overall length with a 3" ID inlet and 3" OD outlet ever made. Good grief. I could prob get by with a 10" but they all have what appears to be 3" ID inlet & outlets. Mine slip over the collector but into an expanded 3" pipe. No name on the converters themselves.....of course.

KJL

Looks like I would need a device for my 92 and another for my 95 as they apparently have different number of pins and shape. The 95 looks more like an OBDII regarding tapered ends (not rectangular).

ccmano

One device can do both. You will need a device that handles OBD1 (ALDL) for the 92’ and OBDII for the 95’. The GM (Vetronix) Tech1, Tech1a, Tech2 and MasterTech will do both with the correct cables. Look on eBay. An Android tablet or laptop (windows) running TunerPro RT (free) and the correct respective cable or Bluetooth dongle will do the same thing.
H

KJL

The ALDLDroid site recommends a company called 1320electronics as well. They sell a combo blue tooth cable for both the 12 and 16 pin plugs. The cost makes this an attractive option for me. I will look into all options, thanks for the input!

combatdoc

yea, it varies from pump to pump, rule of thumb the cheaper the E85 the better it is. we have some here 2.20 a gallon tests as 70-5, the cheap pumps it is 1.40, test 85-87.

KJL

I just received the ALDL Bluetooth adapter from 1320electronics. Came with a cigarette lighter power cord for the unit. This version came with plugs for my 92 and 95. I have not used it yet.

KJL

Tried to just log in to the ECM tonight with the ALDL software and the blue tooth cable. Everything soomed to be going well, it found the correct Bluetooth address, I selected it. It then asked me for a pin and said it was usually 1234 or 0000. I entered 1234, then all it did was show 0's for everything and flashed "not yet connected" along the bottom of the screen. I tried to get back to the PIN page to try 0000 but I could not. I will try to contact them for support but I don't have my hopes up with that. I fully expected this to be harder than it seemed as is with just about everything these days.

We...I have my new cats on, new lower heat range plugs and new O2 sensors. Will try to get her to pass later this week. If it does I will likely sell this crap to whoever wants it to recoup some of my loss.

Dominic Sorresso

Did you got to ALDLdroid and select the correct .adx for your vehicle?
Also, sometimes w BT, you will need to disconnect and reconnect ALDLdroid to the ECM. The connection can be a little buggy at first but it works well after that.