S-10 Troubles
My '00 S-10 with the 2.2L four-cylinder engine just got a shortened aluminum gas tank from Devious Customs, and in the process, the EVAP canister was mounted closer to the muffler. I had an SES light, took it off, and never really had any problems as the light stayed off. I went to smog the truck, and it didn't pass. I was way too high on the NO gas on the test.

I do have a CGS intake and heard that this may have caused it to not pass. Would that be true, or can it be something else? My other problem is with a misfire in the No. 4 cylinder. Since the failed test, I was told to run the truck on Arco EC premium for a retest because it's supposed to lower the fumes. Then, after a few miles, it started to run funny, and later it just misfired like crazy.

I thought it might be the old spark plugs and wires, so I replaced them. That didn't work, so I tried a fuel-injection cleaner and had no luck again. Then, it was suggested that there could be water in the new gas tank and that I should add some HEET fuel-line dryer. That didn't fix the problem. I even went back to 87 octane gas, and so far nothing has worked.

I was told that it could be a bad coil or a bad injector. Do you know of any similar problems with these issues on my truck, or could you suggest anything else I could do?
via e-mail

Several things could be causing the problems you describe. We'd put a faulty or clogged fuel-injector high on the list of possibilities, but you need to do some elimination work first. It seems you have some overlapping problems-the driveability issues and passing the emissions test. An OBD II code reader is the best way to pinpoint the problem or problems. Without a code reader, you can still use process of elimination.

We doubt that your problems are related to the new gas tank. Although there are a couple things that could be checked. It sounds like you took steps to eliminate excess moisture in the tank. The chances that there is some debris in the system are slight. There could be a problem with the gas cap. An incorrect or poorly sealing gas cap can trigger an EVAP code, and it can cause you to fail the emissions test. The testing station should have tested the cap off the truck and informed you if it was the wrong cap. There could be some type of leak-possibly to do with the fuel filter-that is affecting the ability of the fuel system to be properly pressurized.

Since you have a misfire, it could be caused by an injector problem or a bad coil pack. You can have the coil pack that serves the No. 4 cylinder tested at most auto parts stores.

Our first choice for your problem is injector-related. The scanner should pick up a misfire code. The injector could simply be dirty or clogged. Even though you used a "cleaner in a can" product, that isn't the same as having the injectors professionally cleaned. The injector might have an intermittent malfunction, which can be tougher to diagnose. We suggest that you have the injectors professionally cleaned and inspected. If one is bad, another could be starting to fail, also. If the injectors are fine, the problem could be deeper, such as a bad injector driver in the truck's computer. It's even possible that you could have a burnt valve.