Mountains
Thursday, December 31, 2015
Friday, December 18, 2015
In Memory of Leaves
It was a long autumn that I missed completely, only getting to experience it teetering on the doorstep or sprawled on the couch. Will have to try again next year.
Wednesday, December 9, 2015
Need more Crass Bypass Gas: Iron Duke EGR Valve Swap
Or
The ChevOldsmobuiac's EGR valve finally died in a way that surprised me.
The majority of the A-body oldsmobile cutlass cieras on the road are demotivated by 4-cylinder Iron Duke engines. The upshot is that the engine is shared with many other GM vehicles, including the S-10, Fiero, and of course, the Grumman LLV that your postman probably dreads driving at work every day, so there is a lot of information available about the care, feeding, and repair of the powerplant, even though there are many production line tweaks that can make swapping major components (heads chief among them) difficult if researched first.
The Haynes manual notes that the EGR Valves tend get carboned up and sieze. Part of my regular maintenance has been depressing the diaphram to ensure that the valve could actuate.
A few months ago, the Check Engine light started coming on after the engine warmed up (it seemed like after 15-30 minutes of operation... I could almost pick the intersection after a week of commuting), after the light went on, the engine would noticeably ping/rattle under moderate acceleration. While I initially suspected another faulty ECM module, reading the codes yielded a consistent bad EGR valve code (Code 44 also for lean exhaust).
Low and behold, with the engine at idle, the valve was fully closed, as could be felt on the back of the diaphram with engine air filter off.
Of note, the EGR valve on this car is completely mechanical: it is connected directly to the intake manifold and it is regulated by a pinhole orifice on the EGR valve body. It slowly opens and closes as engine vacuum changes: under idle, moderate accelleration, and coast, it is open. Under heavy load, it closes.
Detailed photos of the new valve:
The diaphram appears to be a silicone membrane.
Pinhole that regulates gas flow to the intake manifold.
Serial Number.
Exhaust goes into the round orifice and out the square one.
Closed position.
Open position. When you open the valve, the cover the vacuum nipple, it should stay open. Otherwise, there's a leak in the diaphragm.
The box it came in. Recognize the part number?
Old EGR valve exposed under the air filter snorkel. I should have covered the TBI, but I was on crutches with I did this operation, and wasn't interested in making a lot of trips.
Old EGR Valve. Interesting: Old part number does not match the new one. Hope this works.
Carboned up old valve.
I'm totally guilty of smearing a bit of antisieze on the port the last time I took off the EGR valve, because it was corroded on pretty well.
Vacuum test the new valve one more time. It's kind fun, after all.
Side by comparison. Note: Hecho en Chine. I feel a little bad for whoever made the new valve, since they will probably never see any car that it is designed for. Then again, maybe I should feel happy for them, since all the cars they will see were made in this century.
Bottoms looks pretty similiar. Gasket is stuck on the old valve.
The swap was pretty trivial. It took about 10 minutes with a couple of different 13 mm wrenches to reach under the diaphram and navigate all the hardware on the top of the engine. I highly recommend a deep-offset 12 point, 13-mm wrench for this job. A flex head ratcheting gear wrench might also work, but I didn't have one to test. For completely visible bolts, they were awfully obscured. With plain wrenches, you might have to disconnect the throttle cables to get enough swing to get the bolts out. This is not a good party for your socket set.
While you're at it, I suggest replacing the now very rusty bolts with new ones and putting a dab of antisieze on them. What possesses car makers to put iron bolts in aluminium parts is beyond me, and is certainly a sign that large portions of our engineering population failed basic chemistry.
In the end, the engine appears to be a lot happier. For a long time there's been a lingering burble/valve rattle sound that I now realize must of been pinging due to lean mixture. That sound is now completely gone. This engine does not have a ping detector, so this might be worth looking at if you have mysterious pinging. The EGR valve had to be very dead for the computer to turn on the check engine light.
Another note is that this probably means that you can't put a plate over the EGR valve on fuel injected engines without remapping the ECU to accept and adjust the mixture. I'm not sure how exactly the car knows the exhaust gas is missing from the mixture, but I'll be it has to do with a combination of manifold pressure and the position of the idle air control valve. Long story short: unless you know how to remap an ECU, getting a blockoff plate will not help you on the TBI engines. Since my EGR was failed in the closed position, it was functionally the same as a block off, and the computer remained unhappy and drivability was compromised by excess pinging.
The ChevOldsmobuiac's EGR valve finally died in a way that surprised me.
The majority of the A-body oldsmobile cutlass cieras on the road are demotivated by 4-cylinder Iron Duke engines. The upshot is that the engine is shared with many other GM vehicles, including the S-10, Fiero, and of course, the Grumman LLV that your postman probably dreads driving at work every day, so there is a lot of information available about the care, feeding, and repair of the powerplant, even though there are many production line tweaks that can make swapping major components (heads chief among them) difficult if researched first.
The Haynes manual notes that the EGR Valves tend get carboned up and sieze. Part of my regular maintenance has been depressing the diaphram to ensure that the valve could actuate.
A few months ago, the Check Engine light started coming on after the engine warmed up (it seemed like after 15-30 minutes of operation... I could almost pick the intersection after a week of commuting), after the light went on, the engine would noticeably ping/rattle under moderate acceleration. While I initially suspected another faulty ECM module, reading the codes yielded a consistent bad EGR valve code (Code 44 also for lean exhaust).
Low and behold, with the engine at idle, the valve was fully closed, as could be felt on the back of the diaphram with engine air filter off.
Of note, the EGR valve on this car is completely mechanical: it is connected directly to the intake manifold and it is regulated by a pinhole orifice on the EGR valve body. It slowly opens and closes as engine vacuum changes: under idle, moderate accelleration, and coast, it is open. Under heavy load, it closes.
Detailed photos of the new valve:
The diaphram appears to be a silicone membrane.
Pinhole that regulates gas flow to the intake manifold.
Serial Number.
Exhaust goes into the round orifice and out the square one.
Closed position.
Open position. When you open the valve, the cover the vacuum nipple, it should stay open. Otherwise, there's a leak in the diaphragm.
The box it came in. Recognize the part number?
pndOld EGR valve exposed under the air filter snorkel. I should have covered the TBI, but I was on crutches with I did this operation, and wasn't interested in making a lot of trips.
Old EGR Valve. Interesting: Old part number does not match the new one. Hope this works.
Carboned up old valve.
I'm totally guilty of smearing a bit of antisieze on the port the last time I took off the EGR valve, because it was corroded on pretty well.
Vacuum test the new valve one more time. It's kind fun, after all.
Side by comparison. Note: Hecho en Chine. I feel a little bad for whoever made the new valve, since they will probably never see any car that it is designed for. Then again, maybe I should feel happy for them, since all the cars they will see were made in this century.
Bottoms looks pretty similiar. Gasket is stuck on the old valve.
The swap was pretty trivial. It took about 10 minutes with a couple of different 13 mm wrenches to reach under the diaphram and navigate all the hardware on the top of the engine. I highly recommend a deep-offset 12 point, 13-mm wrench for this job. A flex head ratcheting gear wrench might also work, but I didn't have one to test. For completely visible bolts, they were awfully obscured. With plain wrenches, you might have to disconnect the throttle cables to get enough swing to get the bolts out. This is not a good party for your socket set.
While you're at it, I suggest replacing the now very rusty bolts with new ones and putting a dab of antisieze on them. What possesses car makers to put iron bolts in aluminium parts is beyond me, and is certainly a sign that large portions of our engineering population failed basic chemistry.
In the end, the engine appears to be a lot happier. For a long time there's been a lingering burble/valve rattle sound that I now realize must of been pinging due to lean mixture. That sound is now completely gone. This engine does not have a ping detector, so this might be worth looking at if you have mysterious pinging. The EGR valve had to be very dead for the computer to turn on the check engine light.
Another note is that this probably means that you can't put a plate over the EGR valve on fuel injected engines without remapping the ECU to accept and adjust the mixture. I'm not sure how exactly the car knows the exhaust gas is missing from the mixture, but I'll be it has to do with a combination of manifold pressure and the position of the idle air control valve. Long story short: unless you know how to remap an ECU, getting a blockoff plate will not help you on the TBI engines. Since my EGR was failed in the closed position, it was functionally the same as a block off, and the computer remained unhappy and drivability was compromised by excess pinging.
Auto Parts Epiphany
I'm beginning to think, nay, truely believe, that most replacement car parts, even OEM replacement parts, are inferior to the components originally installed on the car.
The immediate case in point is the parking brake cables on the ChevOldsmoBuiac, my 1990 GM a-body oldsmobile. The original cable worked perfectly for 20 years, though it eventually seized, piece by piece (it has 3 sections), over the past 5. A few years ago I replaced the last piece and thought I was good forever.
These cables seize because the outer sheathing coils rust and expand, constricting the nylon coated inside. The new cables apparently had inferior environmental protection, and so now have suddenly decided that they can barely budge.
Similiarly, the original brake cylinders (rear) and brake calipers (front) have required periodic replacement due to leaks and seizing every few years since the originals were replaced in 2007 or so. If memory serves, we're on the third set.
We also blow through rear pipes and mufflers at a rate of one ever 3 years. It's kinda nuts.
Far cheaper than a car payment, since I'm doing the work, but still kinda nuts.
I don't think this holds across the board, of course, I swapped the OEM shocks and struts in the Olds for Monroes in 2005 and they've been great. I only am thinking about replacing them now due to dry rotting bushings and the impressive amount of rust present.
Perhaps a descerning shade tree mechanic would do well to attempt to source and install only premium parts.
Except I mostly do that, and it doesn't seem to help.
The immediate case in point is the parking brake cables on the ChevOldsmoBuiac, my 1990 GM a-body oldsmobile. The original cable worked perfectly for 20 years, though it eventually seized, piece by piece (it has 3 sections), over the past 5. A few years ago I replaced the last piece and thought I was good forever.
These cables seize because the outer sheathing coils rust and expand, constricting the nylon coated inside. The new cables apparently had inferior environmental protection, and so now have suddenly decided that they can barely budge.
Similiarly, the original brake cylinders (rear) and brake calipers (front) have required periodic replacement due to leaks and seizing every few years since the originals were replaced in 2007 or so. If memory serves, we're on the third set.
We also blow through rear pipes and mufflers at a rate of one ever 3 years. It's kinda nuts.
Far cheaper than a car payment, since I'm doing the work, but still kinda nuts.
I don't think this holds across the board, of course, I swapped the OEM shocks and struts in the Olds for Monroes in 2005 and they've been great. I only am thinking about replacing them now due to dry rotting bushings and the impressive amount of rust present.
Perhaps a descerning shade tree mechanic would do well to attempt to source and install only premium parts.
Except I mostly do that, and it doesn't seem to help.
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