missing in fourth

[DHolmes]

My car's missing in 4th and 5th in the low and mid rpm's,high rpm's it doesnt,Plugs are changed,the car hesitates to give power,help please any one?????????????

[DHolmes]

Very weird ,I capped my exhaust and the problem went away,the car also seems faster and is getting better mpg,(but sounds sissy)why would my cutout cause this problem,It's been uncapped for about 3 months

[BrdWAtti2d]

This sounds stupid but does the cutout somehow bypass the O2 sensor? If it does that might casue the issue you mentioned. But I would think it would have happend right away and not 3 months down the road. Could be another issue with the cutout and the sensor, something in the wiring maybe.

[DHolmes]

This sounds stupid but does the cutout somehow bypass the O2 sensor? If it does that might casue the issue you mentioned. But I would think it would have happend right away and not 3 months down the road. Could be another issue with the cutout and the sensor, something in the wiring maybe.

I dont no,the cutout is right after my cat,The problem would happen, but on and off,yesterday it was the only time it was real bad,and thats when I was really using 4th and 5th on the freeway,I usually dont use the freeway and dont even go into 5th gear or speed cause I live less then 2 miles from work,store,taekwondo and the gym,My car's not even warm by time I get to most of those places so I could have not noticed

[BrdWAtti2d]

If the cutout is past the cat then it's way past the O2 sensor. Might just be a coincidence with the cutout. I assume you capped the cutout after the car cooled off. Did you try it uncapped when it was cool?

The reason I ask is when my optispark started going it only seemed to act up at low rpm under load and when hot. Once I got to crusing speed the car ran fine, or at least fine enough so I couldn't notice. Not sure how the car's temp effects the opti but it did. On cold days the car would run fine, or let's say much better. Once it started going it was only a couple months and the car would barely run and a bad opti is a common performance issue. Have you replaced the water pump within the last year? All that water leaking is an opti killer. Are you getting engine codes? (check engine light on) If so, buy, borrow, steal an OBDII scan tool and check the codes.

[DHolmes]

when the car is cold and ucapped it back fires,makes popping sounds till it's warm,but no I havent ,I usaully drive slow till it's warm

[BrdWAtti2d]

Do you feel the backfires? Is it possible it's backfiring with the caps on and you just don't hear them because they are going through the stock exhaust and being muffled? I don't think the caps would effect the way the engine is performing or at least make it perform worse.

[DHolmes]

well in the mourning it doesnt affect the performance it just pops when I shift gears,Conelite said thats normal and his car does it to,but in fourth there's no sound when it misses,Just hesition in power,But the cap on and now it's not happening ???

[00 Ragtop Z]

You might also consider cleaning your MAF sensor. I recently did that on my ragtop, using MAF cleaner spray form Orielly's auto parts, and it's like driving a different car. I was having power loss problems and throwing all kinds of 02 sensor codes, and after I cleaned the MAF full power and no codes. Might take a look-a good $7 investment.

[DHolmes]

You might also consider cleaning your MAF sensor. I recently did that on my ragtop, using MAF cleaner spray form Orielly's auto parts, and it's like driving a different car. I was having power loss problems and throwing all kinds of 02 sensor codes, and after I cleaned the MAF full power and no codes. Might take a look-a good $7 investment.

where;s the maf and how do I clean it ,

[Jeff_in_Atl]

A guy where I work has a 2003 Z06 and he was doing the same thing. It was caused by a dirty MAF. I think it may have been caused by a K&N filter to.

[Jeff_in_Atl]

where;s the maf and how do I clean it ,

You are a lucky dog with your car. Everything you could ever want to know is on Rob's web site. http://shbox.com/

[DHolmes]

that looks like my car,but isnt that were my holley throttle body is ,

[sneitzel]

That pic is of a car without RamAir. So yes, where you see the black rubber elbow in the top edge of the pic is where your throttle body is.

[DHolmes]

so where's the MAF right next to it on the right