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Discussion Starter · #1 ·
I have an 04 XG350 that cant get out of its own way(2500-3000 rpm no more)no power.been scanned with my sapon scanner and also by hyundai dealership and got same thing,NO CODES!
So i changed the apps and tpsalso ets motor and throttle body no change.cleaned maf just because,no change .today changed ecmand reinitialized still no change .not sure what else to do and hyundai doesnt have a clue either.maybe its just time for it to have an unfortunate electrical fire.
 

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I have an 04 XG350 that cant get out of its own way(2500-3000 rpm no more)no power.been scanned with my sapon scanner and also by hyundai dealership and got same thing,NO CODES!
So i changed the apps and tpsalso ets motor and throttle body no change.cleaned maf just because,no change .today changed ecmand reinitialized still no change .not sure what else to do and hyundai doesnt have a clue either.maybe its just time for it to have an unfortunate electrical fire.
How high will it rev in neutral?
 

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I would check the timing (I think that's fairly easy with a timing light). Here's why:

We had out 2002 XG350's timing belt replaced at 120 k miles AT A DEALER. The car ran FINE for over a MONTH (1500 miles). Then one morning it started fine, but wouldn't idle worth a ****. Driveability was ok, but very rough idle - almost stalling. Drove it that way for another month (500 miles) while trying everything I could think of, including swapping entire plenium with another 2002 XG350. Finally brought it back to the dealer and the timing belt had skipped a tooth because they "didn't install it quite right".

Good luck, hope this helps.
 

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Discussion Starter · #7 ·
thank you for the intel,i will check that out,the car only has 60k on the clock and other than throttle problems the car is for lack of a better work perfect inside and out.have only put 3500 miles on it since buying it.would be a shame to see it go up in smoke.
 

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Discussion Starter · #8 ·
well timing isnt the problem .all marks line up and timing light and scanner data agree its at 9before at an idle and advances accordingly when throttled.have a pcm known to be good just have to access the old one and try replacing that.aint appening tomorrow as high for the day isnt supposed toget above zero degrees.
 

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Discussion Starter · #9 ·
It has occured to me that there is a possibility that the fuel pressure regulator could be bypassing and not allowing pressure to rise to optimum when throttled .has anyone had this happen or have an opinion on this possibilty.the manual i downloaded doesnt show how to test the pressures and is kind of vague as to what they should be at idle and at wot.
 

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If you have an android smart phone I would suggest getting the Torque app and the Hyundai advantage plug in. Along with an ELM Bluetooth OBDII adapter this can monitor and log all kinds of OBDII parameters. Total cost should be under $50 to get everything.
 

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Discussion Starter · #11 ·
Good thought on the tech,however my snapon m 2500 scanner running full streaming data still doesnt show actual fuel pressure and i have yet to locate any kind of sensor on the fuel rail that would read it.so the question remains what is the process for testing fuel pressure.I am a heavy diesel mechanic and am used to having actual test ports .I have little experience with these light duty fly by wire systems.
 

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If there is no port or schrader valve you will either have to put in a temporary port for a gauge or unhook the line and do a timed test to measure how much fuel it pumps is say 15 seconds or so.

The temp pressure fittings are around $20.
 

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You should verify that your maf is putting out enough voltage when you give it throttle. cleaning these wont work and you have to get the $700 hyundai sensor the aftermarket ones usually wont work. The dealer looked at mine and the maf wouldnt put out more than 2mv and they should go over 4.
 

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Discussion Starter · #17 ·
no problem withMAF sensor, but am discharging more exhaust @ the flex joints on the "Y" pipe whats coming out the tail pipe ,and what is coming out the tail pipe is so hot you can put your hand in the stream.sounds to me like i have astuffed secondary cat. convertor.
 
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