Low power after rear valve cover change
02-09-18, 09:09 AM
#16
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Prior to doing the repair, about six months earlier, the number 2 bank upstream catalytic converter went bad with a split down its side at about 139 - 140k miles. This is the straight through converter, one inlet, one outlet, located at the front of the vehicle. I replaced it, used the same O2 sensor, had no exhaust leaks and the car ran fine. About 6 months later (approximation, don't remember; probably 3 - 6 months), it lost an ignition coil (#3) and the car started missing. We drove it for four or five more days (limited driving, probably less than 100 miles total) until the coils I ordered online came in. They were off brand coils, not sure of the mfr. The night before I installed the coils, plugs, valve cover gaskets and spark plug seal rings, while driving, the number 1 bank upstream catalytic converter ("Y" shaped, two inlets, one outlet) developed a hole in the side of it, making a lot of exhaust noise. I bought a new one, from Walker, and installed it, replacing the O2 upstream sensor. This was done at the time I did the coil/spark plug/valve cover repairs; not sure if they are related. I used NGK Iridium plugs, gapped at 0.044" and used a thin coat of anti-seize on the threads. The vehicle has NO MISSING at all until about 2,000 rpm, +/-, when the bogging occurs and the fuel trims go to crap. I will monitor all the recommended issues by both of you this afternoon/tonight and report back. Thank you very much for your help!!
02-09-18, 09:36 AM
#17
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IN the closed loop system, it is hard to find cause and effect.
One possible cause can be oil based cam advance OCV, which controls your spark timing. We may have been chasing the wrong issue.
Salim
One possible cause can be oil based cam advance OCV, which controls your spark timing. We may have been chasing the wrong issue.
Salim
02-09-18, 09:43 AM
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One more thing....
One thing I forgot. I did change the oil and filter while doing the repairs. Used Mobil One 5W-30 fully synthetic. But I wouldn't think that would have ANY effect on the engine's performance. With the exception of ignition miss due to a bad coil, the engine ran great. It even had the original spark plugs..... I thought I was going above and beyond, changing plugs, il, fixing small oil leak at rear valve cover, etc.... Oh well! LOL!
02-09-18, 10:17 AM
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More clarification please
What is "oil based cam advance OCV" and how do you check that. The car ran great (except for ignition miss) before repairs. To my knowledge, I did not touch anything dealing with the cam advance system or anything under the valve covers. Please clarify what to check and how.... THANKS!!
02-09-18, 12:34 PM
#20
The VVTi system is all oil controlled.
One question; when not under load, does it completely rev like normal? Any chance the exhaust sounds like jet at high velocity?
If you were to tell me the symptoms and not mention any of the repairs my first guess remains unmetered air into the engine or a bad MAF.
That said the powerless no throttle response thing seems a lot like a plugged CAT. If you end up stumped and not making progress, I suggest you create an exhaust leak after the primary CATs. If no help, move forward.
I dont think one bad coil for a few days would take out a primary CAT but who knows.
One question; when not under load, does it completely rev like normal? Any chance the exhaust sounds like jet at high velocity?
If you were to tell me the symptoms and not mention any of the repairs my first guess remains unmetered air into the engine or a bad MAF.
That said the powerless no throttle response thing seems a lot like a plugged CAT. If you end up stumped and not making progress, I suggest you create an exhaust leak after the primary CATs. If no help, move forward.
I dont think one bad coil for a few days would take out a primary CAT but who knows.
02-09-18, 01:05 PM
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2013FSport
*Thank you about the VVTi system. How do you check it to insure it operates properly?
*The engine does NOT rev normally whether under load or not. Under no load it will LIGHTLY rev to about 1,800 - 1,900 rpm and encounter bogging/stumble, etc. It will not go above 2,500-3,000 loaded or unloaded, under ANY conditions. Under the hood, idling, it sounds fine. Grab the throttle and blip it to 1,500-1,800 rpm and it sounds good. At about 1,900-2,000 rpm it sounds like it is running out of fuel. Horrific bogging and distressed intake sounds. Let off and it idles fine after a second or two to recover from the bogging. There are no high velocity jet sounds in the exhaust. Also, the fuel trims look awfully good at idle for there to be a significant amount of unmetered air entering the engine. It idles great.
*The vehicle ran great prior to the repairs (except #3 ignition miss) and IMMEDIATELY, upon starting, had catastrophic bogging/stalling/poor running. I don't think that cats stop up immediately like this. I have experienced a plugged cat before. This vehicle ran perfectly normal prior to the loss of the #3 ignition coil and ran pretty good with the car missing, other than the obvious effects from an ignition miss. The number 1 bank upstream cat is brand new.
*The bad coil did not cause the cat to go bad. It was purely coincidental. It was a rusted out hole at the lower end about the size in diameter of a dime; maybe a little smaller. It is possible that the miss could have dumped raw fuel/air in it and ignited, but it was rusted out after 140k of mileage. The other one had failed about 3-6 months earlier. Pure coincidence. I included it because I wanted to let readers know that it had been removed and replaced and the O2 sensor was retained. Not blaming the miss for the cat failure.
*The engine does NOT rev normally whether under load or not. Under no load it will LIGHTLY rev to about 1,800 - 1,900 rpm and encounter bogging/stumble, etc. It will not go above 2,500-3,000 loaded or unloaded, under ANY conditions. Under the hood, idling, it sounds fine. Grab the throttle and blip it to 1,500-1,800 rpm and it sounds good. At about 1,900-2,000 rpm it sounds like it is running out of fuel. Horrific bogging and distressed intake sounds. Let off and it idles fine after a second or two to recover from the bogging. There are no high velocity jet sounds in the exhaust. Also, the fuel trims look awfully good at idle for there to be a significant amount of unmetered air entering the engine. It idles great.
*The vehicle ran great prior to the repairs (except #3 ignition miss) and IMMEDIATELY, upon starting, had catastrophic bogging/stalling/poor running. I don't think that cats stop up immediately like this. I have experienced a plugged cat before. This vehicle ran perfectly normal prior to the loss of the #3 ignition coil and ran pretty good with the car missing, other than the obvious effects from an ignition miss. The number 1 bank upstream cat is brand new.
*The bad coil did not cause the cat to go bad. It was purely coincidental. It was a rusted out hole at the lower end about the size in diameter of a dime; maybe a little smaller. It is possible that the miss could have dumped raw fuel/air in it and ignited, but it was rusted out after 140k of mileage. The other one had failed about 3-6 months earlier. Pure coincidence. I included it because I wanted to let readers know that it had been removed and replaced and the O2 sensor was retained. Not blaming the miss for the cat failure.
02-10-18, 12:15 PM
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Results
I ran the car to obtain some data. I warmed it up until it was in closed loop and held the rpm constant at particular readings to get these results. I did not go above 1,750 rpm because the car was not capable. At anything above 1,750 rpm, the bogging just increased and the rpm would begin to fall requiring more throttle, which lead to more bogging. If you kept increasing throttle, the engine was under a significant laboring condition (NOT mechanical or load, but insignificant fuel) and would die. It would restart and idle fairly easily after a few engine revolutions. Here are the results:
************---------Idle Speed (~600)--------------1,000 RPM---------------------1,500 RPM-------------------------1,750 RPM
Parameter
MAF-------------------0.65--------------------------------1.00-------------------------------2.10----------------------------------2.70
Ign Adv---------------16.5--------------------------------18.0-------------------------------26.5----------------------------------26.5
STFT1--------------From -2.0 to 0.0---------------From -3.1 to 1.6----------------From 0.0 to 3.8--------------------From -19.5 to 6.5 ** (This one swings erratically at 1,750 rpm)
STFT2--------------From -1.5 to 0.0---------------From -1.6 to 0.0----------------From 0.0 to 3.8--------------------From -1.6 to 0.0
LTFT1----------------3.1------------------------------From 0.8 to 1.6---------------------0.8-------------------------------------7.0
LTFT2----------------1.6----------------------------------(-0.8)------------------------------6.3-------------------------------------2.3
O1-------------------0.650---------------------------------0.665---------------------------0.650----------------------------------0.670
O2------------------From 0.05 to 0.150-----------From 0.8 to 0.265---------------------0.690----------------------------------0.640
O3-------------------0.650---------------------------------0.655---------------------------0.610----------------------------------0.650
(Sorry, I had to use dashes to align the columns)
It seems to me the MAF values are not going up linearly, like one would expect. Shouldn't the value at 2,000 rpm be double the value at 1,000 rpm? The value at 1,750 rpm is 2.7 times that of the value at 1,000 rpm. Theoretically speaking, it should only be about 1.7-1.8 lb-m at 1,750 rpm, based o a value od 1.0 lb-m at 1,000 rpm. Please comment. Like I say, everything except the miss worked great before I disassembled it..... the bogging and fuel problems magically begin to occur about 1,800 -1,900 rpm. HELP!!! LOL!!
************---------Idle Speed (~600)--------------1,000 RPM---------------------1,500 RPM-------------------------1,750 RPM
Parameter
MAF-------------------0.65--------------------------------1.00-------------------------------2.10----------------------------------2.70
Ign Adv---------------16.5--------------------------------18.0-------------------------------26.5----------------------------------26.5
STFT1--------------From -2.0 to 0.0---------------From -3.1 to 1.6----------------From 0.0 to 3.8--------------------From -19.5 to 6.5 ** (This one swings erratically at 1,750 rpm)
STFT2--------------From -1.5 to 0.0---------------From -1.6 to 0.0----------------From 0.0 to 3.8--------------------From -1.6 to 0.0
LTFT1----------------3.1------------------------------From 0.8 to 1.6---------------------0.8-------------------------------------7.0
LTFT2----------------1.6----------------------------------(-0.8)------------------------------6.3-------------------------------------2.3
O1-------------------0.650---------------------------------0.665---------------------------0.650----------------------------------0.670
O2------------------From 0.05 to 0.150-----------From 0.8 to 0.265---------------------0.690----------------------------------0.640
O3-------------------0.650---------------------------------0.655---------------------------0.610----------------------------------0.650
(Sorry, I had to use dashes to align the columns)
It seems to me the MAF values are not going up linearly, like one would expect. Shouldn't the value at 2,000 rpm be double the value at 1,000 rpm? The value at 1,750 rpm is 2.7 times that of the value at 1,000 rpm. Theoretically speaking, it should only be about 1.7-1.8 lb-m at 1,750 rpm, based o a value od 1.0 lb-m at 1,000 rpm. Please comment. Like I say, everything except the miss worked great before I disassembled it..... the bogging and fuel problems magically begin to occur about 1,800 -1,900 rpm. HELP!!! LOL!!
Last edited by rt1970ls6; 02-10-18 at 12:33 PM.
02-10-18, 12:29 PM
#23
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I ran the car to obtain some data. I warmed it up until it was in closed loop and held the rpm constant at particular readings to get these results. I did not go above 1,750 rpm because the car was not capable. At anything above 1,750 rpm, the bogging just increased and the rpm would begin to fall requiring more throttle, which lead to more bogging. If you kept increasing throttle, the engine was under a significant laboring condition (NOT mechanical or load, but insignificant fuel) and would die. It would restart and idle fairly easily after a few engine revolutions. Here are the results:ParameterIdle Speed (~600)1,000 RPM1,500 RPM1,750 RPMMAF0.651.002.102.70Ign Adv16.5182726.5STFT1From -2.0 to 0From -3.1 to 1.6From 0.0 to 3.8From -19.5 to 6.5STFT2From -1.5 to 0.0From -1.6 to 0.0From 0.0 to 3.8From -1.6 to 0.0LTFT13.1From 0.8 to 1.60.87LTFT21.6-0.86.32.3O10.6500.6650.6500.670O2From 0.05 to 0.150From 0.8 to 0.2650.6900.640O30.6500.6550.6100.650It seems to me the MAF values are not going up linearly, like one would expect. Shouldn't the value at 2,000 rpm be double the value at 1,000 rpm? The value at 1,750 rpm is 2.7 times that of the value at 1,000 rpm. Theoretically speaking, it should only be about 1.7-1.8 lb-m at 1,750 rpm, based o a value od 1.0 lb-m at 1,000 rpm. Please comment. Like I say, everything except the miss worked great before I disassembled it..... the bogging and fuel problems magically begin to occur about 1,800 -1,900 rpm. HELP!!! LOL!!
Dont know what the issue could be, and basically throwing a blind shot in the air, but does anyone if the ECM has a fail safe mode for a bad MAF sensor? If your hitting a RPM load problem, and IFFFFF it works like other vehicles, unplug the MAF and see how the vehicle behaves.
02-10-18, 01:30 PM
#26
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02-10-18, 01:50 PM
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I understand that the Check Engine Light (CEL) is primarily emissions related. I do NOT have a CEL and when I scanned the computer with a scan tool there were no computer codes for any issues at all - clean.... Any suggestions?
02-10-18, 06:40 PM
#28
rt1970ls6,
what are the units of the MAF values? If it is grams/s, it is way too low across the board.
In general it appears your issue resides with bank 1, as the fuel trims appear correct for bank2. This points away from the MAF. If I was to throw a part at it, I would change the bank1 A/F sensor. Or swap bank1 and bank2 sensors and see if the issue moves with the sensor.
what are the units of the MAF values? If it is grams/s, it is way too low across the board.
In general it appears your issue resides with bank 1, as the fuel trims appear correct for bank2. This points away from the MAF. If I was to throw a part at it, I would change the bank1 A/F sensor. Or swap bank1 and bank2 sensors and see if the issue moves with the sensor.