Emission sensor on, engine hesitation

[higear4]

Im just started having a new problem with my '03 turbo yesterday. My emission light came on (on the lefthand side of the console), and then the car almost jumps backward in 1st through 3rd gear at about 2500 rpm and then returns to normal. I have had problems twice before and I have changed my plugs once and my plug wires once to solve a different type of hesitation problem. It almost feels like im missing a whole cylinder when it hesitates, which would be the worst case senerio. At the same time, once I hit fourth gear tonite, it seemed to not happen. I check the fluids and other major components regularly, and I am going to check the plugs and wires tomorrow. I have had problems with faulty plugs and wires which caused the same warning light to come on because of unburned fuel being dumped into the exhaust but this seems different. It is almost a total stall for a split second. Please any insight would be appreciated.

[MX-5]

Since the MIL is lit, maybe reading the codes would give a path for diagnosis.

[quicksilverdon]

Stop by an autozone, Advance Auto, etc - they'll read your error codes for free.
Why guess? Codes will steer you to problem.

[Wicked_PT]

I had this same problem with my Supercharged PT. I had to reaplce one of the O2 sensors on the Cat. They can go bad from time to time. Plus the amount of heat generated by the Turbos and Superchargers sometimes burns them out. There are 2 Oxegen sensors, one on the Exhaust Headers, and one on the Catalitic Converter. It is most likely the Cat one that needs to be replaced. But check your engine codes FIRST. I bet it will give you an error saying the O2 sensor is reading the car is runing to lean and needs to be richened up. But as you know, the CPU is suposed to take care of that. That is the first sign that your O2 sensor is going bad. Hope this helps.

By the way, I had an AEM air/fuel ratio gauge installed in my PT so I could monitor this better. It helps to see if you are running to rich or lean. The new ones that are out there are VERY expensive ($345), but it they are more accurate with an anolog L.E.D reading instead of the usual needle reading. They also come with a new O2 sensor which replaces the stock one instead of just splicing into the stock O2.

[Fodder4U]

Could be a cam or crank sensor too.

[Wicked_PT]

quote:Originally posted by Fodder4U

Could be a cam or crank sensor too.

Dam sensors!

[bobs turbo pt]

wow !! sound s like the same problem i had with my first 03 turbo dealership had car for 47 days could never fix it !! gave me a new car!! keep us posted !!