Smog Test Blues

On a 95 there are two coolant temp sensors (CTS), one for the 1-4 bank and one for the 5-8 bank. The driver side fan is controlled by the thermal switch in the driver's side radiator and kicks in around 190. The passenger side fan should kick in at about 200 degrees. It is controlled by the CTS on the 1-4 bank. If the either CTS is bad the bad side will run rich. If the passenger side fan comes on then the 1-4 bank CTS is probably ok. If not it could be because of a bad 1-4 bank CTS (or the engine just isn't hot enough). But even if it does come on the 5-8 bank CTS could still be bad. You can check them by disconnecting them and measuring the resistance. At room temp it should be around 2k ohms.

 

The picture you posted is for a 5.2 monotonic. What I am referring to is basically item 40. On the 2.7 there are two of them, one on the left (like item 40), and one on the right with mirror imaged position to 40. They can be seen from the rear on to each side of the oil filter (blue connectors) down in the valley.. If both fans come on, the one on the right is likely OK, but you could still have a problem with the one on the left.

It may not be the issue with your car, but I found the RH sensor was bad on mine. I'm hoping that was why it failed the CT smog test. Haven't got around to swapping in the new part yet.

By the way, don't run 100 octane for your next test. If anything it would make things worse. At best it would make no difference.

 

You can get a connector with pig taile at NAPA, NAPA AUTO PARTS

Pull off the blue connector, put on the pigtail and check the resistance. It should be around 2k Ohms at 80* F, less when hotter. Buy the pigtail first and you will see how to release the connectors from tne CTS.

 

Passed with flying colors.

 

I had to put on the OEM cats because the junk "Prospeed" cats went to ****. Thank God I saved them.

 

Just went through this ordeal myself. Almost, but not quite a pass with Fabspeed cats. Had to switch back to stock cats, then easy pass.

I just don't think the high flow cats are as effective as I previously thought.

 

My Hyperflows don't quite cut it in CA either, but they are about 8 years and 23,000 miles old. The sound is so good that it's worth the swap every two years.

 

I had the same problem with High CO HC at the smog test in Sweden and fail the test.
I did a smogtest again today and the smog test pass with no problem at all.
The problem was the connector at to one of the o2 sensors (under aircleaner box) , the contacts were loose inside the rubber protection on the cable, no contact at all, fixed that and ofcourse changed oil, and it did pass with no problem at all, everything 0,0 except lamda at 1,0.


Regards Patrik

 

My hyper flows have always passed but usually Ned new o2s on rear. My smog guy knows me and he always runs the car on the dyno for about 5 mins before the test and that's after I take it for a hard drive before arriving. If he does not do this it always fails. Cost me a free lunch and took him for a ride 8 years ago now it always seems to pass. When it was failing it always seemed to fail on the slow speed, idle and higher speed seemed ok. I think it's due to the gearing and the fact that 1800 rpm n most cars or trucks is a lot higher percentage of redline than ours.