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Does it only happen to you between gears if you let off a bit?
Me?
All around the place. Mainly under WOT it would climb to about 2200 PSI, but when at steady speed, say 30% TPS, pressure drops to 580 PSI or so.

Gosh, I wish there was some exhaustive specification for the car. Such as fuel rail pressure vs. RPM, temp, TPS, load and such. Also, same with Turbo pressure - how ECU adjusts it.
Does anyone have access to it?
Tork? 6th Eng? Anyone?

I thought of paying for access to KGIS, but I am not sure if the system would have tables specifying what does what and where and how and why...
 

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All around the place. Mainly under WOT it would climb to about 2200 PSI, but when at steady speed, say 30% TPS, pressure drops to 580 PSI or so....
This is normal

Gosh, I wish there was some exhaustive specification for the car. Such as fuel rail pressure vs. RPM, temp, TPS, load and such. Also, same with Turbo pressure - how ECU adjusts it.
Does anyone have access to it?
Tork? 6th Eng? Anyone?...
You would need to cross reference 10 tables and do hours of math just to come up with the pressure need at one specific point which 2 seconds later will be different. On the high pressure pump there is a solenoid that the ECU uses to regulate pressure. Pretty sure there is some form of knowing or setting what fuel rail pressure is or should be if you happen to spend the money for the tuning software or pick up a Kia GDS system. The GDS will give you the live calculated specification of what pressure should be and graph that along with actual pressure. If the ECU sees to much of a variance and is not able to compensate with the throttle it will just put the car in limp mode.

As far as specific charts from KGIS good luck, most useful info there is TSbs and even those are limited to what they tell you.

There is a link on the forum for the full service manual with most of the test procedures and what the specs are but not specifics on fuel pressures at specific points. Since RPM, coolant temp, ambient temp, intake pressure, intake temp, cam position/timing, afr/lambda (wideband O2 sensor), knock sensor, TPS, throttle demand position sensor and current fuel rail pressure could all be used to determine whether pressure needs to go up or down and calculated 100s of times a second is a little beyond my skills without software to lend a hand.

Sorry for jumping around from one topic to another and back again in the post, just multitasking at work and keep getting pulled away.
 
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Alright guys, I wanted to report back. The dealer data logged while reproducing the problem and sent it off to Kia. Kia recommended to replace the fuel lines, so they replaced them and now the car does not experience fuel cut and in fact pulls much harder up to redline most likely because the computer is allowing full boost since it is not going lean. It has been a month long journey to get it fixed all because they wouldn't listen to my original suggestion. If you are experiencing this issue or anything similar you should absolutely look to the fuel lines first.

Edit: They also replaced the in tank fuel pump.
 

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This is normal
Thanks.

As far as specific charts from KGIS good luck, most useful info there is TSbs and even those are limited to what they tell you.
I was just looking for a table that would specify boost pressure should be within say 16-18 PSI at RPM 1750-3000 with WOT if fuel pressure, and other stuff, is met. Not really GDS system to look at data... just some basic info to know if the boost is too low or not. I have maybe seen once 17 PSI, max is 16 with most of the time 13-15. Dealer refuses to do anything as... there is no codes and no TSB for my car.

There is a link on the forum for the full service manual with most of the test procedures and what the specs are but not specifics on fuel pressures at specific points. Since RPM, coolant temp, ambient temp, intake pressure, intake temp, cam position/timing, afr/lambda (wideband O2 sensor), knock sensor, TPS, throttle demand position sensor and current fuel rail pressure could all be used to determine whether pressure needs to go up or down and calculated 100s of times a second is a little beyond my skills without software to lend a hand.

Sorry for jumping around from one topic to another and back again in the post, just multitasking at work and keep getting pulled away.
I looked for it, could not really find.
I'll keep looking, but if you recall where it is, let me know.

I got access to Veloster manual, but does not have all what I need. Plus it is Hyundai.

It has been a month long journey to get it fixed all because they wouldn't listen to my original suggestion.
They never do. I feel like they think I am a moron who knows nothing about cars. Everytime I see an issue, they ignore it or say it is "normal".
 

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Alright guys, I wanted to report back. The dealer data logged while reproducing the problem and sent it off to Kia. Kia recommended to replace the fuel lines, so they replaced them and now the car does not experience fuel cut and in fact pulls much harder up to redline most likely because the computer is allowing full boost since it is not going lean. It has been a month long journey to get it fixed all because they wouldn't listen to my original suggestion. If you are experiencing this issue or anything similar you should absolutely look to the fuel lines first.

Edit: They also replaced the in tank fuel pump.
I definitely am going to go with 6th fuel line kit. It looked like a safety mod to me anyways, but with my encounter the other day with this issue its a must now. I wonder how the factory replacement holds up over time. Will you run into the same issue later? Id rather spend a bit and go with a quality piece
 

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I will report back if my replaced line starts failing again. I will upgrade when either a.) the new stock parts fail or b.) I am actually modding my car for power.
 

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Discussion Starter · #72 ·
2200 psi is way too high. And yes the dealer's do make you feel dumb. But it's sometimes not them. It's tech line, they are not customer facing and make the final calls and some of those guys have no hands on real world experience.

If you think your line is kinking water the fuel pressure and throttle, floor it then when it cuts you will see a rise to around 2200 psi then it will dip to like 30% of that pressure then shoot right back up almost immediately. Hope this helps.

So far my replacement line is holding up. Will upgrade later
 

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How is 2200psi way to high? At wot I hold 2300psi the whole time.
 

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Discussion Starter · #75 ·
Aaaaaaand it's back. Just under 17k miles on the odometer. No appointments till next week. Will keep every one posted
 

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I wonder . I read an article that all turbo cars should change fuel filters at 10k. The article stated that at WOT the motors pull the most amount of fuel and tax the system . IF the filter is not clear it will be like sucking a straw and crap blocking the flow out of the tank , will cause the line to buckle . Because the forte and veloster fuel line can be pinched it kills fuel to the motor and the ecm would see this and cut boost. If you upgrade the fuel line the new line will lesson this effect but not kill the problem .
 

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I wonder . I read an article that all turbo cars should change fuel filters at 10k. The article stated that at WOT the motors pull the most amount of fuel and tax the system . IF the filter is not clear it will be like sucking a straw and crap blocking the flow out of the tank , will cause the line to buckle . Because the forte and veloster fuel line can be pinched it kills fuel to the motor and the ecm would see this and cut boost. If you upgrade the fuel line the new line will lesson this effect but not kill the problem .
The filter sock that filters the fuel is on the inlet side of the in tank fuel pump, not the outlet. This sock would have to be filled with a good amount of debris before it would cause problems. You never know though so it wouldn't hurt to check it.

That theory is sound, but it cuts due to the fuel pressure hitting 2500
How do you know it's capping out for sure an backing off? A datalog with torque pro would show this very easily.
 

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Discussion Starter · #79 ·
Torque is what gave me those answers. At first I thought I was hitting a boost limiter and watched that. Then I found fuel pressure and saw it would raise to 2480ish when the car would die. Boost was not consistent when the car would fail. Also they replaced the line. They said they actually had to hook up a fuel pressure gauge to the low side cause there is no other way to get a reading. However boost is a contributing factor as it rises the ecu wants to dump more fuel but only the pressure goes up cause it's starving then his 2500psi and safety kicks in.
 

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Discussion Starter · #80 ·
Also my line was replaced last October so almost a year with the new line and only 3 months with the original.
 
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