PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
exhaust backpressure at high rpm
exhaust backpressure at high rpm
hey guys, can someone help me figure out this 1.8 bar exhaust backpressure? rpm is 5400 on this capture. i've removed everything besides the exhaust manifold itself and it is still there. the engine is 2.2 10v 5cyl na. i don't like this huge vacuum on intake pull aswell. looks like the engine is not breathing both intake and exhaust. can the valves somehow not open fully because hydraulic lifters or cam lobes are bad? or is it appropriate for this engine and it is just made this way? maybe porting the head is an option? what should i try to do next 
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
Re: exhaust backpressure at high rpm
Hello and welcome,
Initially looking at your trace I'd say the valve train has a fault present. The rounded pockets are a clear indication that the valves are not opening and closing as they should be. More testing required before digging in deeper.
Maybe do an idle test and let us see how the trace looks there as well.
Initially looking at your trace I'd say the valve train has a fault present. The rounded pockets are a clear indication that the valves are not opening and closing as they should be. More testing required before digging in deeper.
Maybe do an idle test and let us see how the trace looks there as well.
Re: exhaust backpressure at high rpm
This is a typical view for 5400 rpm and is not used for analysis.
Do this test at idle or starter rpm.
Attach a file.
P.S.Look at the website of the manufacturer of your device. You will find many examples.
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Steve Smith
- Pico Staff Member
- Posts: 1587
- Joined: Sun Aug 25, 2013 7:22 am
Re: exhaust backpressure at high rpm
Hello and thank you for the post
This is a great subject for discussion and one where we have to accept a number of physical limitations of the engine
The following link has this covered viewtopic.php?p=89711#p89711 where similar questions were raised
I have to agree that high rpm testing with the WPS is going to be both challenging and raise further questions based on the physical dynamics of the internal combustion engine
As mentioned by Kona, Cranking & Idle tests will reveal numerous characteristics about the cylinder performance and a momentary WOT “snap test” will capture increased compression based on increase airflow. These would be the recommended in-cylinder tests
Could I ask, is there a concern with the performance of this engine or would this be an experiment?
How is the power output against specification?
How is the peak airflow against specification?
I hope this helps, take care……Steve
This is a great subject for discussion and one where we have to accept a number of physical limitations of the engine
The following link has this covered viewtopic.php?p=89711#p89711 where similar questions were raised
I have to agree that high rpm testing with the WPS is going to be both challenging and raise further questions based on the physical dynamics of the internal combustion engine
As mentioned by Kona, Cranking & Idle tests will reveal numerous characteristics about the cylinder performance and a momentary WOT “snap test” will capture increased compression based on increase airflow. These would be the recommended in-cylinder tests
Could I ask, is there a concern with the performance of this engine or would this be an experiment?
How is the power output against specification?
How is the peak airflow against specification?
I hope this helps, take care……Steve