1991 Corvette failed emissions. Test results inside...
#1
TheCorvetteBen
Thread Starter
1991 Corvette failed emissions. Test results inside...
My brother in law has a 1991 Corvette with 140K on it and it recently failed emissions in TX. Here is a list of things that have been done on the car in the last 6 months:
New spark plugs/wires
New Cap/Rotor
New Fuel Pump/Filter
New Bosch III 24lb injectors two days ago (LINK BELOW)
http://fuelinjectorconnection.com/sh...p?productid=57
Here are the results of the failed emissions test:
He passed the high speed emission test at 2598 RPM, it is the low speed emission test that is the issue at 700 RPM. Here are his numbers:
HC(PPM) 512
CO(%) 6.50
CO2(%) 9.9
O2(%) 0.4
NOx(ppm) 0.00
DILUTION (%) 16.4
Any help would be appreciated!
New spark plugs/wires
New Cap/Rotor
New Fuel Pump/Filter
New Bosch III 24lb injectors two days ago (LINK BELOW)
http://fuelinjectorconnection.com/sh...p?productid=57
Here are the results of the failed emissions test:
He passed the high speed emission test at 2598 RPM, it is the low speed emission test that is the issue at 700 RPM. Here are his numbers:
HC(PPM) 512
CO(%) 6.50
CO2(%) 9.9
O2(%) 0.4
NOx(ppm) 0.00
DILUTION (%) 16.4
Any help would be appreciated!
Last edited by chstitans42; 07-15-2014 at 06:35 PM.
#2
Melting Slicks
My brother in law has a 1991 Corvette with 140K on it and it recently failed emissions in TX. Here is a list of things that have been done on the car in the last 6 months:
New spark plugs/wires
New Cap/Rotor
New Fuel Pump/Filter
New Bosch III 24lb injectors two days ago
Here are the results of the failed emissions test:
He passed the high speed emission test at 2598 RPM, it is the low speed emission test that is the issue at 700 RPM. Here are his numbers:
HC(PPM) 512
CO(%) 6.50
CO2(%) 9.9
O2(%) 0.4
NOx(ppm) 0.00
DILUTION (%) 16.4
Any help would be appreciated!
New spark plugs/wires
New Cap/Rotor
New Fuel Pump/Filter
New Bosch III 24lb injectors two days ago
Here are the results of the failed emissions test:
He passed the high speed emission test at 2598 RPM, it is the low speed emission test that is the issue at 700 RPM. Here are his numbers:
HC(PPM) 512
CO(%) 6.50
CO2(%) 9.9
O2(%) 0.4
NOx(ppm) 0.00
DILUTION (%) 16.4
Any help would be appreciated!
#3
TheCorvetteBen
Thread Starter
I have seen from he search option people have been driving thier cars for twenty minutes before they go in for a test... I bet that will help but his numbers are crazy high.
#4
I think you may be running too rich. Isn't the 1991 Corvette supposed to have 19 lb injectors, not 24 lb? Not sure what the okay test result range is but it looks like you may be a little rich.
#5
TheCorvetteBen
Thread Starter
I bought the ones from fuelinjectorconnection.com for the car. They are the ones that were recommended for the L98 Corvettes...
#6
Drifting
#7
TheCorvetteBen
Thread Starter
#9
TheCorvetteBen
Thread Starter
#10
Drifting
If you can't borrow one and have a windows 7 or older laptop this works good.
http://www.moates.net/aldu1-and-cabl1-p-127.html
Free software for 20 datalogs
http://www.ttspowersystems.com/DataM...ownloads2.html
http://www.moates.net/aldu1-and-cabl1-p-127.html
Free software for 20 datalogs
http://www.ttspowersystems.com/DataM...ownloads2.html
#11
Drifting
HC is high, CO is high, and NOx is 0. Its way rich and the EGR seems to be working fine.
#12
Melting Slicks
When my HC at idle were high, I was allowed to run the idle up to 1400 RPM and although it was out of the "window" for the test, the test continued which meant it accepted the high idle.
Passed with flying colors.
Passed with flying colors.
#13
Le Mans Master
my 89 failed emissions a few years ago, it also was running rich and i also had 24 lb injectors. ended up replacing the fuel regulator and the fuel pump to correct the issue.
#14
Drifting
This is a great idea^. Turning pressure down to 38, or 39 psi should bring operation back into the programmed parameters.
#15
Le Mans Master
Yes, stock injectors are 22 lbs. If you do have an adjustable fuel pressure regulator, then back off on the pressure.
High hydrocarbon (HC) readings usually indicate excessive unburned fuel caused by a lack of ignition or by incomplete combustion. Concentrations are measured in parts per million (PPM). Common causes include a faulty ignition system, vacuum leaks, and fuel mixture problems. Circumstances that can lead to a high HC emissions are:
* Incomplete combustion due to fouled spark plugs.
* Improper timing or dwell
* Damaged ignition wires
* Poor compression
* Vacuum leak
* Ineffective or faulty air management system (ECM control of air/fuel ratios) -O2 sensors
* Catalytic converter intervention and HC concentrations
High HC readings at the tailpipe are a clear indication that there is a problem in at least one part of the system, but an HC reading that appears within "normal" ranges or is only modestly elevated is not necessarily a reliable indicator of proper or even acceptable system performance. HC readings at or near "normal" are possible, and not uncommon. From a malfunctioning engine equipped with a properly functioning catalytic converter. In such circumstances, truly elevated pre-catalytic converter HC levels will be masked by the catalytic converter and the potential for an HC problem must be further evaluated in the context of other readings of abnormal gas concentrations and AFR / Lambda readings.
High hydrocarbon (HC) readings usually indicate excessive unburned fuel caused by a lack of ignition or by incomplete combustion. Concentrations are measured in parts per million (PPM). Common causes include a faulty ignition system, vacuum leaks, and fuel mixture problems. Circumstances that can lead to a high HC emissions are:
* Incomplete combustion due to fouled spark plugs.
* Improper timing or dwell
* Damaged ignition wires
* Poor compression
* Vacuum leak
* Ineffective or faulty air management system (ECM control of air/fuel ratios) -O2 sensors
* Catalytic converter intervention and HC concentrations
High HC readings at the tailpipe are a clear indication that there is a problem in at least one part of the system, but an HC reading that appears within "normal" ranges or is only modestly elevated is not necessarily a reliable indicator of proper or even acceptable system performance. HC readings at or near "normal" are possible, and not uncommon. From a malfunctioning engine equipped with a properly functioning catalytic converter. In such circumstances, truly elevated pre-catalytic converter HC levels will be masked by the catalytic converter and the potential for an HC problem must be further evaluated in the context of other readings of abnormal gas concentrations and AFR / Lambda readings.
#18
TheCorvetteBen
Thread Starter
As mentioned above, I am not going to do the whole fuel injector job again to put in the crappy multecs again. not worth the trouble or work. I have already replaced the fuel pump, but did not touch the fuel regulator. Does any one know of which one I can buy that will fix the problem.?
#19
Pro
On my cars in the past I used to put a bottle of cat cleaner in about a half a tank of gas, then drive it around for half an hour before the test, high revs in a low gear, get some real heat in it, we used to call it an "Italian tune up" it does the trick though if your concerned about emissions...
#20
As mentioned above, I am not going to do the whole fuel injector job again to put in the crappy multecs again. not worth the trouble or work. I have already replaced the fuel pump, but did not touch the fuel regulator. Does any one know of which one I can buy that will fix the problem.?