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Discussion Starter · #1 ·
so my 04 accent runs pretty good till it gets to 3500 rpms or higher and it will randomly pull back some then go again, and pull back again. its really annoying going up on highways and getting to speed or passing. think it could be dirty injectors and its getting leaned out to much or think it's tranny problems? any suggestions?
 

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yeah thats strange...get it on a dyno to see whats up.
 

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Discussion Starter · #5 ·
i cant find any dynos here in maryland. but how much does it usually cost?
 

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If you can find a "dyno day" and tag along probably less than $50 for a couple of runs, maybe $20 extra for the wideband hookup. Probably around $125 if you just have them do your car.

You could also install a wideband O2 sensor and gauge to see it all the time.
 

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well if it was going to lean or too rich you should be getting some sort of stored code and check engine light. First i'd make sure you have all your maitenance up to date. That includes fuel filter, plugs, wires, air filter, throttle body clean.... run some dry gas in your tank just to make sure you don't have any water or contaminents in there.

i'm not sure of your idle quality or other drivability problems but check for vacuum leaks as well.

If you are still having problems after that try to find someone with a scanner to be able to look at your fuel trims, o2 sensor readings, and injector duty cycles. If one of these looks out place it will give you some direction. A wideband is a good tool but unless you have another spare o2 bung in your exhaust it won't work.

its hard trying to diagnose problems without being able to drive the car or work my magic on them but hopefully this will give you some ideas.
 

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if it was a a/f ratio problem it should be rpm and load dependent, being in a higher gear will put more load on the engine making the problem seem worse. If it only does it in 3rd and not say 5th then i'm not sure what problems your having. Without a proper wideband or some sort of scanner your not going to be able to tell what the engine is doing(injector duty cycle, engine load, o2 voltage, maf voltage, fuel trims....). The only thing you can try is to check your plugs and see what they tell you. Depending on the year accent you have you might not be able to check your fuel pressureA(x3 models can lc+ can't), if it was too high or too low it could cause rich/lean conditions. A bad maf sensor could cause major problems with the a/f ratio. A bad coolant temp sensor could cause overly rich a/f ratios in the first few minutes of warm up. Also when does the problem happen, when the car has been warmed up or when its cold. Maf sensor equipped cars will run completely different when cold vs when fully warm. I get extremely inaccurate a/f ratios when my car is cold, it usually takes 4-5 minutes before everything settles down.

A lot of misfires will happen more in high gear under a load, like going up a steep incline in high gear. This is where the engine is under the most load so it will put more strain on an ignition system and fuel system.

there is some info on things you can check out to solve your problems. hope it helps.
 
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