Hyundai Tucson P0173 Case Study Part 2
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Date: 2020-08-05
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Comments and reviews: 10
Kevin
EDIT: Just finished the video. Good diagnostics guys, and it made for a fascinating video. Although this diag may have taken a bunch of time, I guarantee that neither one of you will forget it. Its also a solid reminder (for me too) never to forget the basics. There is no fault code for low compression. Relative compression is a quick test to do. Either way, rest assured that the vast majority of technicians would never find this one and if they did, it would be after they WAGed an engine into the car.
ORIGINAL:
If you are working on a vehicle with a shared plenum and MAF sensor, a vacuum leak will almost never cause a lean problem on one bank on its own. The only reason I say almost never is because I also say never say never. except I just did. Anyway, if you think about it logically, vacuum leaks cause lean conditions on MAF equipped cars because of false air, i. e. air getting into the engine without going through the MAF. This reduces the MAF sensor airflow reading which will throw off the fuel calculation on BOTH banks by a very similar amount, regardless of where the vacuum leak is. The only possible exception I could see is if the vacuum leak was at the port of a cylinder and causing enough of a leak to make that cylinder misfire. That would send more air out the exhaust from that cylinder since it didn't fire which could make that bank more lean, but both banks would still be lean.
I've also seen engines with completely wasted manifold gaskets, huge splits in the manifold, oxygen sensors loose, etc. None of them ever ran lean enough to set a code. The effect of exhaust pulses creating a vacuum behind them and potentially pulling air in past a leak is so slight at idle and part load that it seems to be a non-issue.
Its also worth noting that on speed density/MAP sensor cars without MAF sensors, vacuum leaks may not cause a lean code and, depending on where the leak is, it could even cause a rich code. I see people stumble over this fact all the time. MAP sensor vehicles calculate fuel injection and load amounts based off of manifold vacuum, the actual amount of intake air is calculated not measured. So, if there is a vacuum leak, manifold vacuum drops and the MAP sensor compensates for it. If the leak amount is huge to the point where the engine idles too high with the throttle or IAC completely closed, then it might code. Otherwise, aside from huge leaks at the intake port or leaks on specific hoses reducing vacuum to individual components, MAP sensor cars generally don't get too bothered by vacuum leaks.
Another note, as I continue to watch, generally speaking on MAF sensor cars where you have a bank specific breathing problem (valvetrain issue, bank specific exhaust issue, etc) the bank that is running the most lean is usually the healthy bank. The reason is that the unhealthy bank will typically have a reduced demand for air and will lower the overall air intake into the engine. That reduces the MAF sensor reading, reducing the ECM fuel calculation, but because the healthy bank is still wanting just as much air as usual, it will show as lean and the fuel trims will increase for the healthy bank. This throws a lot of people off, including very good techs, because the fault codes will usually set for the healthy bank and not the unhealthy one. This can also include misfire codes because it is much easier to make an engine misfire due to a lean condition than a rich one.
reply
EDIT: Just finished the video. Good diagnostics guys, and it made for a fascinating video. Although this diag may have taken a bunch of time, I guarantee that neither one of you will forget it. Its also a solid reminder (for me too) never to forget the basics. There is no fault code for low compression. Relative compression is a quick test to do. Either way, rest assured that the vast majority of technicians would never find this one and if they did, it would be after they WAGed an engine into the car.
ORIGINAL:
If you are working on a vehicle with a shared plenum and MAF sensor, a vacuum leak will almost never cause a lean problem on one bank on its own. The only reason I say almost never is because I also say never say never. except I just did. Anyway, if you think about it logically, vacuum leaks cause lean conditions on MAF equipped cars because of false air, i. e. air getting into the engine without going through the MAF. This reduces the MAF sensor airflow reading which will throw off the fuel calculation on BOTH banks by a very similar amount, regardless of where the vacuum leak is. The only possible exception I could see is if the vacuum leak was at the port of a cylinder and causing enough of a leak to make that cylinder misfire. That would send more air out the exhaust from that cylinder since it didn't fire which could make that bank more lean, but both banks would still be lean.
I've also seen engines with completely wasted manifold gaskets, huge splits in the manifold, oxygen sensors loose, etc. None of them ever ran lean enough to set a code. The effect of exhaust pulses creating a vacuum behind them and potentially pulling air in past a leak is so slight at idle and part load that it seems to be a non-issue.
Its also worth noting that on speed density/MAP sensor cars without MAF sensors, vacuum leaks may not cause a lean code and, depending on where the leak is, it could even cause a rich code. I see people stumble over this fact all the time. MAP sensor vehicles calculate fuel injection and load amounts based off of manifold vacuum, the actual amount of intake air is calculated not measured. So, if there is a vacuum leak, manifold vacuum drops and the MAP sensor compensates for it. If the leak amount is huge to the point where the engine idles too high with the throttle or IAC completely closed, then it might code. Otherwise, aside from huge leaks at the intake port or leaks on specific hoses reducing vacuum to individual components, MAP sensor cars generally don't get too bothered by vacuum leaks.
Another note, as I continue to watch, generally speaking on MAF sensor cars where you have a bank specific breathing problem (valvetrain issue, bank specific exhaust issue, etc) the bank that is running the most lean is usually the healthy bank. The reason is that the unhealthy bank will typically have a reduced demand for air and will lower the overall air intake into the engine. That reduces the MAF sensor reading, reducing the ECM fuel calculation, but because the healthy bank is still wanting just as much air as usual, it will show as lean and the fuel trims will increase for the healthy bank. This throws a lot of people off, including very good techs, because the fault codes will usually set for the healthy bank and not the unhealthy one. This can also include misfire codes because it is much easier to make an engine misfire due to a lean condition than a rich one.
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Russell
I knew if the P0173 code wasn't caused by an intake manifold air leak or fuel pressure problem it would be caused either by an exhaust system air leak or a loss of compression, as far as the MAF sensor goes, a dirty one actually caused a rich condition in a Lexus that Scanner Danner was working on.
As far as the Hyundai Tucson goes, I'd just replace the cylinder head & camshaft as well as do an oil & filter change on it, if aluminium shavings are a worry just pull the oil pan off then check the oil pickup screen then clean it out if it's dirty or clogged.
I spoke to a mechanic in 2005 who was working as a fitter on mining equipment as I drove a Holden VL Commodore which had a hybrid Nissan RB30DE twin cam engine fitted that I built for it, he was talking about how they had the same front camshaft bearing issue in the single cam engines (RB30E) as a chemical reaction would occur which would cause the aluminium to corrode which would in turn cause the camshaft to seize & snap timing belts.
I said that I haven't had a problem with them & that the problem may have been caused by not changing the oil, maybe it was the same problem for the Tucson engine.
I've had alluvial sand come out with the engine oil in my 5. 7 litre Chevrolet LS1 V8 engine, it started in 2011 & a tiny bit came out last year even after I did a hydraulic lifter change & I had the oil pan removed to get a crack repaired & to replace the oil pan gasket, I'm not sure where it came from last year as I had the cylinder heads removed to replace the lifters as well as having the oil pan removed.
My point is it was frightening how much sand was coming out of it, I even have it a flush & a whole lot of sand came out of the rear oil gallery when I removed the plug.
The moral to that is that the engine has done about 100, 000 kilometres since 2011 & the engine hasn't failed, it has been going with no problems every since December 2018 when I did the lifter replacement!
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I knew if the P0173 code wasn't caused by an intake manifold air leak or fuel pressure problem it would be caused either by an exhaust system air leak or a loss of compression, as far as the MAF sensor goes, a dirty one actually caused a rich condition in a Lexus that Scanner Danner was working on.
As far as the Hyundai Tucson goes, I'd just replace the cylinder head & camshaft as well as do an oil & filter change on it, if aluminium shavings are a worry just pull the oil pan off then check the oil pickup screen then clean it out if it's dirty or clogged.
I spoke to a mechanic in 2005 who was working as a fitter on mining equipment as I drove a Holden VL Commodore which had a hybrid Nissan RB30DE twin cam engine fitted that I built for it, he was talking about how they had the same front camshaft bearing issue in the single cam engines (RB30E) as a chemical reaction would occur which would cause the aluminium to corrode which would in turn cause the camshaft to seize & snap timing belts.
I said that I haven't had a problem with them & that the problem may have been caused by not changing the oil, maybe it was the same problem for the Tucson engine.
I've had alluvial sand come out with the engine oil in my 5. 7 litre Chevrolet LS1 V8 engine, it started in 2011 & a tiny bit came out last year even after I did a hydraulic lifter change & I had the oil pan removed to get a crack repaired & to replace the oil pan gasket, I'm not sure where it came from last year as I had the cylinder heads removed to replace the lifters as well as having the oil pan removed.
My point is it was frightening how much sand was coming out of it, I even have it a flush & a whole lot of sand came out of the rear oil gallery when I removed the plug.
The moral to that is that the engine has done about 100, 000 kilometres since 2011 & the engine hasn't failed, it has been going with no problems every since December 2018 when I did the lifter replacement!
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Peter
Hyundai should have been informed, was this a defect in manufacturing, I know it's in a junkyard by now if not right after this. I was driving my 2001 lesabre on the highway one night and all of a sudden the cel came on and I felt the car lose power, I carry my actron scanner with me so I plugged it in and it had a po301 code, the engine sounded ok, I checked the spark plug and even tried another one cleared the code and drove it until it got really bad and noisy, I took it apart and found the lifter on number one cylinder had shattered I couldn't believe it, I replaced it put it together and a couple of hundred miles later it did it again so I assumed the lifter damaged the cam or vise versa, I change the oil every 3 to 4000 miles so I ordered a new camshaft which from advanced auto of all places they were the only place that had one at a reasonable price it was 200 anywhere else wanted up to 400, the lobe on the lifter was a mess so again I don't know which damaged which, installed all new lifters and the new cam and it's been fine for over two years now, I discovered the 3. 8 has a roller valve train which was interesting.
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Hyundai should have been informed, was this a defect in manufacturing, I know it's in a junkyard by now if not right after this. I was driving my 2001 lesabre on the highway one night and all of a sudden the cel came on and I felt the car lose power, I carry my actron scanner with me so I plugged it in and it had a po301 code, the engine sounded ok, I checked the spark plug and even tried another one cleared the code and drove it until it got really bad and noisy, I took it apart and found the lifter on number one cylinder had shattered I couldn't believe it, I replaced it put it together and a couple of hundred miles later it did it again so I assumed the lifter damaged the cam or vise versa, I change the oil every 3 to 4000 miles so I ordered a new camshaft which from advanced auto of all places they were the only place that had one at a reasonable price it was 200 anywhere else wanted up to 400, the lobe on the lifter was a mess so again I don't know which damaged which, installed all new lifters and the new cam and it's been fine for over two years now, I discovered the 3. 8 has a roller valve train which was interesting.
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Dan'sMeTube
Watched the two videos again!
Enjoyed them again for the first time! There was enough time to forget what the real issue was. Here's another thumbs up.
Looks like there's enough rigidity in the camshaft to keep the timing belt in tension without the front bearing! It's also interesting that cam bearing was the first point of failure!
This case, huge part required!
I think these videos is what got me watching PHAD.
Thanks for the conclusion chat at the end!
reply
Watched the two videos again!
Enjoyed them again for the first time! There was enough time to forget what the real issue was. Here's another thumbs up.
Looks like there's enough rigidity in the camshaft to keep the timing belt in tension without the front bearing! It's also interesting that cam bearing was the first point of failure!
This case, huge part required!
I think these videos is what got me watching PHAD.
Thanks for the conclusion chat at the end!
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craig
Unbelievable video. Congratulations to both of you. Leads credence that pilots are taught while flying in the clouds with no visibility, trust your instruments. In this case the instrument was the relative compression test. I used to think that all check engine light codes were only emissions related, which was true in this case but the check engine light was from a highly unusual mechanical problem, not a confuser problem. Thanks once again for the education. Craig
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Unbelievable video. Congratulations to both of you. Leads credence that pilots are taught while flying in the clouds with no visibility, trust your instruments. In this case the instrument was the relative compression test. I used to think that all check engine light codes were only emissions related, which was true in this case but the check engine light was from a highly unusual mechanical problem, not a confuser problem. Thanks once again for the education. Craig
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william
Late 80's Mazda 323 came in shop, crank/no start after repeated short start and run conditions. Ckd cam timing, good but 2 plug wires seemed reversed. Reset the spark plug wires and car started and ran now. To get to bottom of who/why wires were reversed. Found cam gear pin had sheared and gear had spun exactly 180 degrees!
New cam and gear got car running, but damaged cam journals had customer set cat up for sale.
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Late 80's Mazda 323 came in shop, crank/no start after repeated short start and run conditions. Ckd cam timing, good but 2 plug wires seemed reversed. Reset the spark plug wires and car started and ran now. To get to bottom of who/why wires were reversed. Found cam gear pin had sheared and gear had spun exactly 180 degrees!
New cam and gear got car running, but damaged cam journals had customer set cat up for sale.
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John
That's quite astonishing. One of those ones where the skeptic within wants to call B. S. if someone at the pub told you. but you had the root cause literally sitting there in your hand. I have heard of Yamaha camshaft sprockets twisting on the shaft and throwing timing out, but a twisted camshaft, this is just bizarre. Thanks for the awesome videos: )
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That's quite astonishing. One of those ones where the skeptic within wants to call B. S. if someone at the pub told you. but you had the root cause literally sitting there in your hand. I have heard of Yamaha camshaft sprockets twisting on the shaft and throwing timing out, but a twisted camshaft, this is just bizarre. Thanks for the awesome videos: )
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Jgizzy
Ivan is one smart dude, and a great personality to boot -- you two make a great duo! I love the enthusiasm and mind-sharing trying to tackle the problem, it makes it so much more fun. This is one of my favorite videos. Have Ivan back sometime! Wait for a real tricky car for you to tag-team and make more great content.
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Ivan is one smart dude, and a great personality to boot -- you two make a great duo! I love the enthusiasm and mind-sharing trying to tackle the problem, it makes it so much more fun. This is one of my favorite videos. Have Ivan back sometime! Wait for a real tricky car for you to tag-team and make more great content.
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Margaret
This 2-part video was as exciting as any detective show and quite enjoyable. I'm glad it was solved in the end. Maybe I missed it but I never understood what caused the problem in the first place. Was it a failure of maintenance on the part of the owner or a previous bad repair?
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This 2-part video was as exciting as any detective show and quite enjoyable. I'm glad it was solved in the end. Maybe I missed it but I never understood what caused the problem in the first place. Was it a failure of maintenance on the part of the owner or a previous bad repair?
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Wes
Excellent video you guys. So basically the electronics, MAF, can adapt fast enough to supply the correct fuel ratio for the cylinders with the good compression but the computers preset default values can which is why the values reversed when the MAF was disconnected. Interesting.
reply
Excellent video you guys. So basically the electronics, MAF, can adapt fast enough to supply the correct fuel ratio for the cylinders with the good compression but the computers preset default values can which is why the values reversed when the MAF was disconnected. Interesting.
reply
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