chstitans42

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!

Cyclonite

SES/CEL light on? Any codes? Mine had an EGR problem, but that was years ago and I don't know what any of the readings were anymore. Do you know how to get/check the codes with OBD I? Best bet is to start with that so you know where to spend your efforts.

chstitans42

From what he is telling me, there are no dash lights on, but I guess that does not rule out any codes. Can the ECM be giving trouble codes without turning on he check engine light?

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.

DanielRicany

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.

chstitans42

I bought the ones from fuelinjectorconnection.com for the car. They are the ones that were recommended for the L98 Corvettes...

MrWillys

What color are they? Stock programming is 22.1 lbs. can you see an number on them?

chstitans42

they were a greenish color, the reciept says 24lbs... I unhooked the batery for 15 mins so th ECM could relearn everything per instructions...

MrWillys

I'm just trying to determine if running rich is why it won't pass. Do you have a scanner? What are the BLM counts at a fully warmed idle in closed loop?

chstitans42

I don't have a scanner but have been toying around with the idea of getting one...

MrWillys

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

Benny42

HC is high, CO is high, and NOx is 0. Its way rich and the EGR seems to be working fine.

black_89_vette

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.

Sleazy Rider

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.

MrWillys

This is a great idea^. Turning pressure down to 38, or 39 psi should bring operation back into the programmed parameters.

John A. Marker

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.

DanielRicany

I think you should get the stock size injectors back in there that way you know you are going to be fixing "stock" conditions.

Race Prepared

Sounds like EGR

chstitans42

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.?

ricasso

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...

DanielRicany

You can try using an adjustable fuel pressure regulator and turn down the fuel pressure. I believe there is a calculator online somewhere of how much the injector will flow per PSI. Other than that, you would have to either get a tune and change the injector offsets, or change the injectors back to the original size which FIC should have.