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Discussion Starter #1
I’m gonna try to explain the best I can do bare with me. I installed my dc headers on 4-20-19 and ever since I started the car I’ve had rpm issues. My car has a cai and a catback also. I installed them in this exact order. First I removed the y pipe. Then I took off both heat shields. Then I started removing the front manifold and got down to the last bolt then I had to remove the compressor. After I got the front one off I immediately put on the header and tightened it up. Then I started removing the rear manifold until the last bolt where I had to remove the alternator so I disconnected the battery before that. Then the rear manifold cane off and I put the new header on. For the top bolts of the rear manifold I went through the top between the firewall and the intake using a long extension. I did not remove the throttle body or intake manifold. And I did not disconnect the throttle cables. So now here’s my problem driving home today on (4-25-19) my car would basically act like it was in cruise control when it wasn’t. I could push in the clutch at highway speeds (60mph) and it would rev back to 3500rpm on its own. I pull in my driveway and let it sit and it idles fine at 1k or little less but if you tap the gas to around 2k rpm it revs up to 3k on its own then back down to 1k or little less. I have cleaned the pcv and the iac. I have sprayed brake cleaner around my cai and other hoses to see if there’s a vacuum leak but can’t find that either. I also unplugged the iac while it was running, I unplugged the tps while it was running, and I unplugged the maf while it was running. All of them are working properly because when I unplugged them the car ran really rough after each one. So does anyone have any options or opinions what my problem could be? Thank you
 

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Just a thought.....start the car and rev the car by hand at the throttle and see if you see the cables are getting bound up. good luck
 

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Discussion Starter #5
If I have a exhaust leak it would prob be where the y pipe and resonator connect but I’m not 100 percent sure if I have one.
 

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did you use new gaskets on everything? You have to make sure the manifold bolts are really tight else it will leak. Double check you dont have your TPS and iAC valve connectors wrong. The gray one goes into the TPS sensor.
 

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Discussion Starter #7
Manifold bolts are really tight. I’m gonna be checking them again tomorrow because it says to check them after 300 miles to make sure none of them loosened. And as far as gaskets I reused the manifold gaskets because in another post everyone was saying you could reuse them and they looked fine. Where the headers and y pipe bolt up I put new gaskets there but I had to reuse the old gasket where the y pipe and resonator bolt up and it was in rough shape
 

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Did you install the MAF the correct way? Usually there is an arrow on it, should be pointing at the engine.
To find exhaust leaks, get the front up, grab a friend, start the car and have your friend block off the exhaust outlets while you listen and feel around the exhaust for leaks.

Disconnecting the battery loses fine learning in the ECU. It takes some driving to let it sort things out.
 

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Discussion Starter #9
Maf is installed correctly the arrows point towards the throttle body. Car was running completely fine before the headers.
 

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Discussion Starter #11
I’m gonna do a smoke test tomorrow and I’m gonna clean my throttle body and mess with the throttle cables also
 

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Discussion Starter #14
Update: thanks everyone I think I fixed the problem. I cleaned the throttle body, cleaned the iac, and adjusted the throttle cables because I noticed there was a toothpick size opening because it didn’t close all the way. I reset the ecu and now my car is finally idling in the 700s again. Give it gas and it drops right back down without the restrictor plate. If anything changes I’ll let y’all know. Thanks again
 

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Update: thanks everyone I think I fixed the problem. I cleaned the throttle body, cleaned the iac, and adjusted the throttle cables because I noticed there was a toothpick size opening because it didn’t close all the way. I reset the ecu and now my car is finally idling in the 700s again. Give it gas and it drops right back down without the restrictor plate. If anything changes I’ll let y’all know. Thanks again
Sooooo.......we will assume you had an idle issue before? Since you didn't remove intake, TB or other parts, your throttle cables MUST have been tight before.......
Just saying.....
 

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Discussion Starter #16
Well my rpms is still fine idling around 750. But I’m still getting codes? My codes are P0171, P0174, p0507, and p0113. My idling is fine, it doesn’t hang anymore or rev on its own anymore. Any ideas?
 

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I recently had the same problem with my 03 tib. It would hang at round 3500 when you rev it in neutral and slowly drop to around normal idle but only if I revved around 3/4 + peddle. Then al of a sudden one day it started to down shift when cruising at 45 mph at 1/4 paddle. Thinking trans issue first then got a cel for a few different systems evap leak injectors circuit misfire knock ect one by one fixed them but still same problem then I thought about a pickup I had once with irradic idle and turned out to be TPS. So I checked the TPS with a multimeter checked ok closed and wot butvas you slowly opened the throttle it would suddenly spike at 1/4 throttle then drop back a normal linear curve in the resistance test. bingo swapped it out, ni more throttle hang or downshifting runs great now. Check it next but be sure to check it for smooth ohm increasing as you open it. Not just closed and wot.
 
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