purplewindworm

............High speed Emission Results...RPM:2311
................Standard...........Curre nt Reading.........Result
HC(ppm)........220.....................4 4.....................Pass
CO(%)..........1.20..................... 0.02...................Pass
CO2(%).................................. 12.5
O2(%)................................... ...2.6
DILUTION: >6.0.......................12.54........ ........Pass

.....................Low Speed Emission Results...RPM:716
................Standard...........Curre nt Reading.........Result
HC(ppm).......220......................3 21....................FAIL
CO(%).........1.20...................... 4.62...................FAIL
CO2(%).................................. 11.4
O2(%)................................... ..0.2
DILUTION:...>6.0.....................16. 02.................Pass



Ok, what is wrong with my car?

toptechx6

The low speed test shows a rich condition and possible misfire. Was the car at operating temperature when tested, do you have a low temp t-stat, is air injection or other emission equipment disconnected, does it idle rough, codes in memory?

purplewindworm

I drove the car for 20 minutes prior to testing, so yes it was at operating temperature. I have a 195 thermostat in the water neck. Nothing is disconnected. I guess if air pump was not working it would have locked-up? There is alot of heat coming from around the air pump, so much that when I put wire loom around my alternator wire that it was beginning to melt after driving it. I have since removed radiator and cleaned it, car was pushing 245 degrees in traffic.

toptechx6

It does sound like it was warm enough, the air pump turning does not guarantee it is functioning properly but at least it is there and seems to be connected. I'd pull the codes to see if that will give you a direction, does the idle seem smooth?

purplewindworm

Idles great. I was getting a code 32 (EGR) and 25 (MAT). I replaced the EGR, mat sensor, spark plugs, and plug wires. Tested Emission and failed. I put a new O2 sensor and a catalytic converter on it yesterday and was planning on trying the emission test again today. However, I did have engine light come on briefly on the way to work this morning. Light came on as I was approaching a red light, I suspect it set code 32 again, will pull codes after work.

toptechx6

Okay Purplewindworm, I will be busy most of the day myself but will check back to see what you found.

CFI-EFI

It is running way rich at idle. The CO tells you it is rich and the HCs tells you that not all of the fuel is being consumed. I would suspect a small vacuum leak that doesn't effect the high speed test. Also, both COs and HCs are effected by a malfunctioning air pump. The very first thing I would do is to check, trouble shoot, and correct your trouble code(s). A code can cause the diverter valve to dump the output of the pump, rather than send it to the converter, where it is used to keep the COs and HCs down. Then, you can check for the proper operation of the A.I.R. check and diverter valves. A defective check valve could explain all the heat you are getting at the air pump. Interestingly, that is the same test my '84 has to pass. If you can get the operator to hold the engine speed at the highest allowed (1200 rpms for my test) for the idle test, the results will look better. My last test showed the "idle" test at 1187 rpms, where your shows to be 716 rpms.

RACE ON!!!

purplewindworm

Sorry, i dont quite follow you on "why the air pump" is getting hot. And what is the purpose of the diverter valve? I have a black plastic cluster with several hoses connected to it next to the A/C compressor, i assume this is my diverter valve. Or is there another one somewhere?
1990 L98 Thanks Tommy

edcmat-l1

The 02 at cruise being 2.6 means the air pump is pumping out the exhaustat cruise. Th 02 at idle tells me that its NOT pumping out the exhaust at idle. I would look for a small vacuum leak at the diverter valve assembly, the black thing you are refering to. The small hoses going to it are what controls it. Find the vacuum leak and your problem will probably be cured

CFI-EFI

One of the places the pump can pump air to, is the ports in the exhaust manifold. There is a check valve on either side of the engine to prevent exhaust back flow to the pump when the pump is directing air elsewhere. If there is a problem with the check valve(s), the pump could become over heated.

Between your air control valve and your air switching valve, there are three places the A.I.R. air can be directed. One is to the exhaust manifolds, another is to the cat, and the third is a dump. Your FSM will outline how and when the pump output will be directed to each destination. If the cat has the A.I.R. air directed to it, the HCs and COs should come down. The proper repair of the cause of the code could solve the whole problem. Again, after everything else is properly repaired, look for a vacuum leak. My poor old, high mileage, worn out, oil burning, 1984, passes to those same standards, with no cat. I don't even DARE to mention my truck.

RACE ON!!!

purplewindworm

You pass emissions with NO CAT???

toptechx6

CFI-EFI can not only tune the hell out of these Vettes he has to be a silver tongued devil to talk the testing tech into running that idle up to 1187, way to go I'm impressed.
Lots of great suggestions, edcmat-l1 makes a good point on the high O2 content at cruise compared to the idle, I didn't spot that but it could very well indicate A.I.R is not working properly at idle.

purplewindworm

Here is a little something else that may be totally inrelevant to may problem. But let me know if you think it is.

In mornings when outside temp is cool, my A/C clutch relay energizes and de-energizes as I hit bumps. After running the car for about 5 minutes it seems to quit. When I crank my car up after work (outside temp 100+ degrees) I never notice it clicking. When I took the car for Emission, he said the clutch engaged a couple times, so I disconnected the plug for the clutch and he retested it and it still failed. In another post i read someone say that the A/C is exempt from emission because it adds more fuel. This just does not sound logical.

purplewindworm

SUNCR wrote the message in another thread, but may have been talking about a different application. Does this apply to me?

Generally, cars that overheat with a/c on but not with it off don't have a problem with the cooling system. A/c is designed to run cooler (it has to) with the fans (on the LT's) geared to come on when the gas hits about 90 degrees at the condensor. The first thing you check is that the fans are coming on at idle (there's no way to add extra coolant or capacity when you hit the a/c switch, so the only thing the engineers could do was turn the fans on sooner and add a little more fuel - which is why a/c is exempt from emissions law). The signal is from the pressure sensor on the high pressure line, a thermistor with a 5volt reference from the ECM. Once the return signal hits 1.5 volts (about 150 psi), the fans should crank on. Easiest to check with a scanner as it will show the voltage and the pressure. Assuming the fans are working within specs (if not, you may need to put a new sensor in it), and if it's overheating at cruise, then the system has probably plugged up - compressors shed metal and that gets trapped in the orifice screen - or someone added too much juice - or the Accumulator/Dryer is falling apart (which they'll do if you dump a different gas in it and didn't swap it out). With flow restricted or too much gas, the pressure rises and it overheats. Putting a manifold gage set on it will tell you what's going on - try Pep Boys for their $29.95 a/c system checkup or invest 80 Bucks for a set of gages so that you can diagnose it.

black_89_vette

Disconnect your EST wire by your brake booster. It is a brown/black wire connector that will allow your engine to run at base timing of like 6 or 8 degrees.

This helps a lot when dealing with emissions.

purplewindworm

Just got home from work (20 minute drive) and code 25 has been set. I have changed the Mat sensor, O2 sensor, spark plugs, plug wires, and catalytic convertor. I just noticed that the wire loom is melted on the alt wire but the other wire loom is unaffected. maybe my alt wire is just hot and the heat is not coming from the air pump.

purplewindworm

No small hoses on mine I got one big hose (1/2" diameter) going in from air pump, 3 big going out, one to dump, one to spliter then to exhaust and one to cat. There are some wires going to a solenoid in there.

toptechx6

If you don't see any obvious vacuum hoses disconected near the air pump or distribution valves I'd start by running the diagnostic procedure for the code 25 using the FSM. I don't have one for a 1990 so I can't help but I'd try to make that code go away first.

Benny42

Hi. My '86 failed that test in march. The vacuum source for the fuel pressure regulator and the diverter are the same (on my '86). This line was split under the plenum. I replaced it, this brought the idle fuel pressure down and a.i.r. began working too. Passed with flying colors on next try. Good luck.

purplewindworm

I just disconnected the two hose from my A.I.R. diverter that go to the exhaust amnifold and the cat, there is very little air coming out. Is this normal? What engages the solenoid inside the air diverter? I dont have a 1990 FSM, I got a 1991 electrical (skinny red book) and a 1992 FSM (the big red book) but cant find nothing in either about ECM codes. I guess there are 3 books to the collection.