HC GPM was 5.3 (limit is 2)
CO GPM was 49 (limit is 20)
CO2 GPM was 470 (Good or bad? Report didnt say
N0x GPM was 2.8 (limited 4) Passed

1) timing +4
2) plugs look pretty good (clean) although didnt pull all due to reach and time.
3) MAF tests ok
4) TPS is .5v
5) New cap and rotor
6) Fuel pressure steay at 42
7) 02 sensor just replaced, but my Datamaster software shows it varying widely from 80-900 at a steady 2400 RPM. Is this right)
8) Cat was checked by Midas (used a rubber mallet is what they said after testing) I just rolled my eyes and left. Could this be it?
9) Injectors ohm at 13 and seem to pulse just fine.

It starts beatifully everytime, runs good, runs stong. Just seems with the reading so far off I would have nailed it by now

Any quidance is appreciate before I have to take it to shop.

 

Also,

1)tested for vacuum leaks and found none so far.
2)It also seem to go from Open Loop to Closed just fine (according to Datamaster).
3) Gas cap replaced a while ago.

It definately has a gasey smell though. Actually has for awhile now, but didn't worry about it too much till emissions came along.

 

You didn't state if the timing was checked with or without the est disconnected and engine warm. The injector ohm is on the low side but would be good to replace them and check the fpr vacuum line for any signs of fuel. You haven't listed the ect reading.

 

est was disconnected. No leaks are detected at the fuel pump regulator that I can see. Fuel pressure holds after shut down so I'm assuming no leaks as well. Datamaster results show ect starting at 47F and ending at about 162.5F. Seems a bit low at 162.5. You thinking it could be the coolent sensor? less than 1v warm? This temp would barely put it into Closed loop right? I'll go back and verify all your questions to be sure.

Thank you for responding. I'll let you know results.

 

You can advance your timing 2 degrees, Closed loop usually occurs around 140* coolant temp.This is the ohm vs temp for the ect , does your car always run this cool ?

 

I'll warm the car up here shortly, but the ect measures 33ohms cold (not Running) I just disconnected it and measured across terminals. Colorado's like 35F so it's pretty cold. Your suggesting that if I warm it all the way up it should read in the high 100's at operating temp right? And I think it's always run a bit cooler, but somewhat hard to tell since I dont drive it everyday and it sits a bit more in the winter. temp gage, although not working now, always showed about 200F. I'll recheck timing after it warms up as well and tweak it a couple of degrees.

By the way, what should these injectors ohm for better performance? Do you have a recommendation for this vehicle? There not really hard to change.

 

I'm not sure if your injectors are dribbling while in there spray . Tpi injectors when new are around 16.5 ohms. I have never used data master so I'm not sure how accurate the $32b read is for the cts.

 

Thanks for the tips. I may have measured the wrong sensor earlier. I have a hand made harness I'll try to measure the coolant temp sensor more accurately. It's a bit tough to get to. I'll also check the injectors when there warm and see what they read. Your dribbling theory could make sense, but can you clarify why this would cause it to run rich?

 

Does it have a gutted cat? Set the timing at 6 degrees. Get the car as hot as you can.. Get it up to 22p. This will get the cats hot and they work better when hot.

 

How old is your cat? Was the car well up to operating temperature before the test or did you start the car & drive 2 blocks to the nearest station to be tested?

 

No. it was pretty hot when I got to Midas. I've never replaced it. I suspect it's pretty old. Seems there should be a temp test before and after cat to really determine good or bad, but I'm not sure what the measurements are and don't have a temp probe. My next step is to get everything up to full operating temp and rerun some of the testing you've suggested. I think it's the right path. Since the emission readings are so far off it's a bit baffling I can't nail it.

Thanks again. Catch-up tomorrow afternoon.

 

 

If you have a gas tank crack it can cause you to fail because gas fumes will be pulled into the test equipment by the tailpipe test equipment. These cars are known to crack around the filler neck and even though they do not leak fuel they can leak enough fumes to fail an emission test.

 

This may sound weird, but many people swear that you should change your oil before going in for an emissions test. I think the theory is that the oil picks up unburned hydrocarbons thru blow-by past the rings. Some of those unburned hydrocarbons get into the exhaust, thus increasing your emissions. One gentlemen posted that he failed the test went home and changed his oil, drove around to get the engine up to operating temp, then passed the emissions test. Maybe worth a try, it will only cost you an oil change.

 

Are you sure the cat isn't hollowed out? My suburban was just as bad, since it has 168k i bought 2 magnaflow universal cats. When i cut the pipes to put them on, the cats were empty! Unbolt your pipe and check to be sure

 

I can second that. I did the same thing once.

If all else is good it is probably your cat; it can get coated with crap over time and reduce efficiency. A rubber mallet is to just see if the honeycomb has come apart.

Does your scanner give BLMs for the 02?

 

This whole engine checks out almost perfectly using my Datamaster software, my trusty meter, timing light, pressure testing equipment, etc... I'm probably not an expert, but everything checks outs. ALL sensors, timing, fuel pressure etc.. checked. I ran it awhile and tested the cat temp in and out. Very little difference in temperature. All measured about 370 degrees. It's almost like it's doing nothing. What should the temperature should be? It was my understanding that you should see 50-100 degree increase in temperature from input to output of cat. No change in temp says it's smoked. Any guidance on this is appreciated.

On the fuel leak in the gas tank filler neck getting picked up by the emission test is something I haven't even considered. Is there easy way to look or just get in there and try to find smell or see it? It doesn't leak anything on the driveway.

Right now I'm leaning towards the cat, but hate to spend several hundred and find it's not bad or spend the same amount getting a second opinion from a mechanic and having him tell me it's bad.

Thanks everyone! Much appreciated.

 

I really dislike states that test emissions on older cars. They want antique cars to pass modern day tests. I removed all my emission stuff several years ago and haven't looked back. I know but barely understand why ODB II 1996 to present have to meet standards to pass, but ODB I should be exempt. It is hard enough to get exact parts like air pumps, air divertors, Cats plus other parts to meet some crazy standard.

 

Yea, it really sucks trying to pass current emissions. The car does smell a bit gassy and I'd like to get that fixed and get it on the road by passing emissions. It is a bit baffling that it failed emissions so miserably, yet I can't find anything under the hood that jumps out and says "I'M BAD"! Methods of testing the cat seem all over the board so I'm not sure if it's good or not. I have high quality infrared thermometer which will give me good readings if I can find out what good or bad readings are.

Thanks,

 

your nox is fine , what were your findings on the ohm of the injectors hot ?

Over rich fuel condition causing both HC and CO failures

 

Only got one tested before my meter lead broke, but it tested low 15.2. It's my plan to retest all tomorrow after getting in all heated up. Your suggesting they should all read 16 or high 15 right? If there 15 or under their suspect? Fuel pressure I know is right on and timing is dead on +6 wtih ect disconnected.

What about the no change in cat temp from input to output? Seems it should be different, but my feedback on this topic is all over the map so I'm not sure what to believe.

 

Your car doesn't have a map it is maf, The ohm test is not a 100% proven test to find a bad injector or injectors hot they should be 15-16.5 and can be even down to 12.5 on there last leg.

 

Yea, it's a MAF. I changed all the injectors a couple of years ago with bosch, but doesn't mean I still dont have one acting up. I guess the only way to know for sure is to take them out and turn them on.

 

mafs bosch too.

 

If everything checks out fine then it is probably the only thing you cannot check with testors, meaning the cat. And if nothing else a new cat can mask some engine condition problems like a leaky injector at least the first year and you will also know that is not it.

For instance if you have a valve seal leak it will slowly eat away at the efficency of the cat by coating the honeycomb. So new cat = peak efficiency. Aren't you still running the factory original cat? I think the reasonable life expectancy of a cat is only 10 years. They degrade over time like anything else.

My personal example. I had, leaky valve seals, a bad computer and leaky injectors on my 88 and put a new cat on and passed because since it was new, it was at peak efficiency. Took me two more years to figure out the computer and save for injectors but they helped too. In between when I was able to change those I would just change the oil and add new AC Delco plugs and would pass as the cat had been broken in by then and couldn't pass on it alone. Now after my engine swap everything is fresh and it passes better than anything I ever owned.

 

with good running motor & a good cat you should see around 100+ degree higher temps on the exit side of the cat.
little to no difference means either a bad cat or its cold & hasn't gotten to light off temp.
an extremely clean running motor can also cause a cat to test weak or bad using inlet/outlet temps.
a better test is using a gas analyzer on a car that has just been driven for at least 15~20 minutes to get it to operating temp & pulled into the shop, then running the motor at high RPM for a few minutes, then shut it off & quickly disable the ignition system & crank the motor while watching CO2 readings. a good cat should produce a noticeable amount of CO2, 5% or more. a really good cat can hit 10+ %.

not all cats are equal, i've seen some that do really good on HC & CO, but bad on NOx, some that do good on NOx, but not so good on HC & CO.