Engine wont rev above 2500 RPM's

Tiny
CHREES
  • MEMBER
  • 2006 HYUNDAI TUCSON
  • 2.0L
  • 4 CYL
  • FWD
  • MANUAL
  • 204,723 MILES
What cause the engine not to rev past 2500 rpm's? As being a mechanic I tried many things but have not found out what the problem is. I checked the catalytic converter, the sensors ( CPK, CMP, TPS, O2, MAF) everything is okay. Replaced the fuel pump, the injectors, the spark plugs, the sparks plugs cables (all four). I replaced the piston rings, the cylinder head but the engine will not rev past 2500 rpm's. Replaced the ECM after checking the harness from ECM to every sensor or actuator, the problem is still the same. The only thing I have not replaced are coils. The engine runs very well at idle even when I switch the A/C on. There is no misfires. When I compare the engine data with data from known good engine, the only thing that is different is the injection time. The broken engine injection time reaches 12 ms when the good engine injection will not go above 3 ms at the same speed. Thanks in advanced.
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Tuesday, October 4th, 2016 AT 2:11 PM

8 Replies

Tiny
KEN
  • ADMIN
Hello CHREES,

I would disconnect the exhaust and drive the car to see what happens, you might have a plugged muffler etc.

Please let us know what you find so it will help others.

Best, Ken
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Friday, October 7th, 2016 AT 12:27 PM
Tiny
CHREES
  • MEMBER
Hello Ken!
Before replacing everything I replaced I disconnected the exhaust manifold from the cylinder head. The engine kept acting the same.
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Friday, November 4th, 2016 AT 11:34 AM
Tiny
CHREES
  • MEMBER
I think there's something wrong with the injection time. I compared these datas with datas from a known good engine and the injection time was very different.
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Friday, November 4th, 2016 AT 11:40 AM
Tiny
KEN
  • ADMIN
Another thing that will do that is the mass air flow sensor. Try to clean it first but you might need to replace it.

Here is a guide

https://www.2carpros.com/articles/mass-air-flow-service

and

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Let me know

Best, Ken
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Friday, November 4th, 2016 AT 1:12 PM
Tiny
CHREES
  • MEMBER
Hello Ken !
I've already replaced the MAF sensor even though there was no dtcs related to MAF. The MAF I removed from my vehicle? Works very well in another vehicle. I replaced every sensor on the engine. I also replaced the ECM. I wasn't a brand new ECM. I got it from eBay.
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Saturday, November 5th, 2016 AT 3:07 AM
Tiny
KEN
  • ADMIN
So when it revs doest it had go torque or does it have low power until it reaches 2500 RPM? I am thinking it must be the camshaft actuator that is giving you problem, does the computer show any codes?
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Monday, November 7th, 2016 AT 8:19 AM
Tiny
CHREES
  • MEMBER
Hello Ken
I'm very sorry. You first told me to remove the exhaust and you were right. Th me cat converter was clogged. I told you I had checked it before but I inspected it using an endoscope through the hole of the heated oxygen sensor. I completely removed the exhaust manifold as you said and the engine revolutions can reach the red area. Thank you very much.
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Saturday, November 19th, 2016 AT 1:19 AM
Tiny
KEN
  • ADMIN
Good to hear, please use 2CarPros anytime we are here to help.

Best, Ken
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Saturday, November 19th, 2016 AT 9:37 AM

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