Here is some information that you might find helpful if you are struggling with passing emissions or down on power w/ no apparent reason:
I picked up my current white 94 atx from a guy that had put in a new/rebuilt transmission but had never figured out how to get the car running again after that. (apparently not a real talented mechanic....) After a few hours of tracing wires and connecting them, and tightening every single hose clamp under the hood (I have no idea why they loosened some of those....) I had the car running again.
But it didn't run right - no codes but it was down on power and ran toward the hot end of the temp range. I took it over to get emissions tested and it failed badly - HC was 1.7 (1.2 allowed), CO was 9.7 (allowed 15.0) and NOx was 4.5 (allowed 3.0) I had a known good Y-pipe, so I changed that and changed the thermostat. Retesting showed virtually no change in emissions.
I found the mafs to be quite dirty (K&N filter w/ too much oil from previous owner) and I changed the O2 sensors. I pulled the SPOUT connector and took it to emissions again. This time it passed at HC 1.0,CO 10.6, NOx 1.7 - which told me it still really wasn't running right, since it should have easily passed with the SPOUT pulled.
However, it still didn't run with the power that it should have and always ran hotter than I thought it should w/ a new thermostat.
After a few weeks, it died on my in typical crank sensor failure mode, and pulling codes did indeed show a 'failure in crank position sensor circuit' code. So I pulled it apart to change the crank sensor.
While I had it apart, I needed to rotate the engine over a little to get the new sensor positioned. As I did this, I noticed that the timing belt was too loose. Inspection revealed that the timing belt tensioner was very weak. Further inspection revealed that the cams were out of time. The rear cam was 2 teeth behind the front cam. Whether this timing error was due to the bad tensioner (maybe) or due to the clueless prior owner (likely), I don't know, but I reinstalled the timing belt with the cams timed properly and adjusted the tensioner so that it would keep the belt reasonably tight. (I won't bore you with all the other little things I found wrong while I had the timing covers off...)
Viola! now it has the power it was lacking previously and it runs w/ the temp gauge where I would expect it to with a new thermostat (at the lower end of the 'normal' range). Mileage is much improved as well. I'm willing to bet that it would now pass emissions without having to pull the SPOUT connector.
The moral of the story is that if you are having trouble passing emissions or down on power for no apparent reason, it might be worth checking to confirm that cams are timed properly, because that makes a big difference on power and emissions.
I picked up my current white 94 atx from a guy that had put in a new/rebuilt transmission but had never figured out how to get the car running again after that. (apparently not a real talented mechanic....) After a few hours of tracing wires and connecting them, and tightening every single hose clamp under the hood (I have no idea why they loosened some of those....) I had the car running again.
But it didn't run right - no codes but it was down on power and ran toward the hot end of the temp range. I took it over to get emissions tested and it failed badly - HC was 1.7 (1.2 allowed), CO was 9.7 (allowed 15.0) and NOx was 4.5 (allowed 3.0) I had a known good Y-pipe, so I changed that and changed the thermostat. Retesting showed virtually no change in emissions.
I found the mafs to be quite dirty (K&N filter w/ too much oil from previous owner) and I changed the O2 sensors. I pulled the SPOUT connector and took it to emissions again. This time it passed at HC 1.0,CO 10.6, NOx 1.7 - which told me it still really wasn't running right, since it should have easily passed with the SPOUT pulled.
However, it still didn't run with the power that it should have and always ran hotter than I thought it should w/ a new thermostat.
After a few weeks, it died on my in typical crank sensor failure mode, and pulling codes did indeed show a 'failure in crank position sensor circuit' code. So I pulled it apart to change the crank sensor.
While I had it apart, I needed to rotate the engine over a little to get the new sensor positioned. As I did this, I noticed that the timing belt was too loose. Inspection revealed that the timing belt tensioner was very weak. Further inspection revealed that the cams were out of time. The rear cam was 2 teeth behind the front cam. Whether this timing error was due to the bad tensioner (maybe) or due to the clueless prior owner (likely), I don't know, but I reinstalled the timing belt with the cams timed properly and adjusted the tensioner so that it would keep the belt reasonably tight. (I won't bore you with all the other little things I found wrong while I had the timing covers off...)
Viola! now it has the power it was lacking previously and it runs w/ the temp gauge where I would expect it to with a new thermostat (at the lower end of the 'normal' range). Mileage is much improved as well. I'm willing to bet that it would now pass emissions without having to pull the SPOUT connector.
The moral of the story is that if you are having trouble passing emissions or down on power for no apparent reason, it might be worth checking to confirm that cams are timed properly, because that makes a big difference on power and emissions.
