SO, I couldn't find much on this problem while searching... My '02 Cav is now at 123,xxx km and for about the last 3,000k it has been running rich 3 of the worst tanks of fuel were... 79km to a tank, 106km and 200 km... then about a week ago it stopped doing that, great milage and tonight it burned 1/4 of a tank in 23 km and actually sounded rough, and was smoking. any other time you could start it and never know it was going through that much fuel. Anyone ever see this before? BTW, the exhaust consists of 2 glasspacks end to end under the car and exiting behind the left rear tire. So I know it isn't a cat problem, even the plugs look fine which I find weird.
try the o2 sensor....when was that replaced if at all?
this would be easier to diagnose with a cat and second 02 sensor that comes stock on the car......
I have never done the o2, it looked to be new when I got the car(55,xxx km). As for the cat and rear o2, they have no affect on the way the car runs. Lack of a cat, and rear O2 does not affect the fuel mixture of the car. The front O2 controls the A/F. It has been running fine this way up until about a month or so ago.
i just had a very similar prob with mine but the system was too lean not rich to where my car wood not run at all
your best bets wood be the o2 sensor, fuel presser regulator , or the fuel pump which was my prob
IF YOUR GONNA GO DOWN ... THEN GO DOWN IN FLAMES
Ryan wrote:I have never done the o2, it looked to be new when I got the car(55,xxx km). As for the cat and rear o2, they have no affect on the way the car runs. Lack of a cat, and rear O2 does not affect the fuel mixture of the car. The front O2 controls the A/F. It has been running fine this way up until about a month or so ago.
front controls the a/f, no one said it didnt. however the rear monitors what happens between the front and the cat.... kinda like a check system. it keeps the first one in check and monitors the total output.
so as said, it would be easier to diagnose, as if you were running rich or lean, you would have thrown a code by now.
at 100K the front o2 should have been replaced. i usually do em at 60K as they only cost around 20-40$ at most places.
trust me, i'm not a rookie to these forums or this particular problem. plenty of the people since jbo have started have had this problem with the deleted second o2 sensor.
is there any way 2 delete the cat and position the second 02 sensor further down the exhaust ?
james gilk wrote:is there any way 2 delete the cat and position the second 02 sensor further down the exhaust ?
virtually no point. the point of the cat is to get rid of the hydrocarbons and bad stuff in the exhaust from combustion..... if you remove the cat, the second o2 will then read the "raw exhaust" that hasnt been through the cat as if something is wrong, aka the cat isnt working correctly, and will throw a code.
thats why when cats go bad, the codes in the range of DTC P0420, which is if i remember right, low efficiency catalyst. theres a few more codes that deal with the heater circuit of the second 02, and theres maybe a few more than deal with the cat itself.
I did the mechanical O2 simm and it worked fine untill the moisture build up in it(condensate wouldn't evaporate) took out the rear O2.
UPDATE:
The car has now started to run on 3 cyls at times, (totally random) and between 2000 and 4500 Rpm and it surges at any throttle position while smoking black as hell off and on... Puts some diesels to shame, if I pull the ecm fuse and reset it, the car runs fine for awhile. This is starting to look like ECM failure.
If I had been able to get my hands on a 95 Grand am upper mount I would be swapping the Gen 2 2.8MPFI from my '87 Celebrity into it. At least that engine has never let me down.
82+ GM A / X Body cars... Best ever...