Arrrggghhhhh!!!!
- Thread starter Brentbba
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- Thread starter
- #22
Thx - that was my thought too - why do you have to remove it as all the ports to plug or blow air into are readily accessible w/o removal. FSM says remove.
Ok..So i am at 7200 ft this week (Green Valley Lake) and just opened up my gas tank. It did vent a little more than what i am used to... Does venting alleviate the problem (temporarily at least)? One thing i do notice at altitude is my truck starts differntly....Meaning, at home (Long Beach) i have the "high idle" deal when it starts and then it eventually slows down once it warms up a bit. Up here, it always starts what i would consider to be more normally...I starts fine and idles around 1k RPM or so then slows down to a normal idle. Does this mean anything? Plugged CC ?
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- #24
Did you hear any 'boiling' when you opened the gas cap? Both Eric and I had this very disturbing and distinctive sound. A little more than normal would be expected I'd think since it's a pressurized tank and you filled up at sea level before driving to altitude.
The issue is going from low to high altitude. As you get higher in altitude, the atmospheric pressure decreases. In your tank, you have fuel and air in equilibrium in the liquid phase and vapor phase balanced by the vapor pressure of the fuel. As you gain altitude, the fuel vaporizes due to the lower atmospheric pressure. If the tank cannot vent, pressure will build. That's why when you opened your gas cap, it vented for some time. Once the pressure of the air space above the liquid fuel was equalized with atmosphere, the liquid boiled to equalize pressure with the air space above. Or something like that....
As a real world example: water boils at 100 deg C at sea level but maybe 80 or 90 deg C at 6000'. By opening the gas cap, you effectively went from sea level to 7000' immediately.
Now, I am suspecting that if you or I were to vent the tank as soon as we got to that altitude, everything would be fine.. That's why SoCal80 did not experience this issue. His tank was already acclimated to the altitude.
I think
Here are some references:
Vapor pressure - Wikipedia, the free encyclopedia
Vapor Pressure
As a real world example: water boils at 100 deg C at sea level but maybe 80 or 90 deg C at 6000'. By opening the gas cap, you effectively went from sea level to 7000' immediately.
Now, I am suspecting that if you or I were to vent the tank as soon as we got to that altitude, everything would be fine.. That's why SoCal80 did not experience this issue. His tank was already acclimated to the altitude.
I think
Here are some references:
Vapor pressure - Wikipedia, the free encyclopedia
Vapor Pressure
- Thread starter
- #27
No worries - shoot, as far as I know there could be several issues causing the misfire in addition to the opened VAF. Lots of 'stuff' got moved, taken off an put back on during the HG, so any of the old valves, hoses, etc. could be a contributing culprit.
The issue is going from low to high altitude. As you get higher in altitude, the atmospheric pressure decreases. In your tank, you have fuel and air in equilibrium in the liquid phase and vapor phase balanced by the vapor pressure of the fuel. As you gain altitude, the fuel vaporizes due to the lower atmospheric pressure. If the tank cannot vent, pressure will build. That's why when you opened your gas cap, it vented for some time. Once the pressure of the air space above the liquid fuel was equalized with atmosphere, the liquid boiled to equalize pressure with the air space above. Or something like that....
As a real world example: water boils at 100 deg C at sea level but maybe 80 or 90 deg C at 6000'. By opening the gas cap, you effectively went from sea level to 7000' immediately.
Now, I am suspecting that if you or I were to vent the tank as soon as we got to that altitude, everything would be fine.. That's why SoCal80 did not experience this issue. His tank was already acclimated to the altitude.
I think
Here are some references:
Vapor pressure - Wikipedia, the free encyclopedia
Vapor Pressure
Nice explanation. Will read the links another time...now back to month end.
Failed Smog
Hey Brent,
If you were directed to a Test Only station, go to the BAR (Bureau of Automotive Repair) website and get the information on the Consumer Assistance Program (CAP). You can apply for CAP and they will direct you to a station that will diagnose and repair your 80. The best part is the state pays $500.00. It's worth the time to check it out.
Good Luck
Paul
Hey Brent,
If you were directed to a Test Only station, go to the BAR (Bureau of Automotive Repair) website and get the information on the Consumer Assistance Program (CAP). You can apply for CAP and they will direct you to a station that will diagnose and repair your 80. The best part is the state pays $500.00. It's worth the time to check it out.
Good Luck
Paul
- Thread starter
- #29
Thanks - I did pass smog once we leaned out the VAF. I'm aware of this program. It's both income based (I don't qualify) or directed based (i.e. directed to a smog only or gold shield station). While I qualify under that part, my emmissions have been tampered with in all likelyhood because the VAF has been opened from factory sealed and adjusted. Regardless, that portion of the program has a $100 deductible and I paid Yotamaster less than that for shop labor to find the tampered with VAF and adjust it back to a leaner mix. That leaner mix got me passed.
Issue of the VAF could be some or all of the problem. I'm hoping installation of a used unit that hasn't been messed with will tell me if the VAF adjustment was masking something else we haven't determined yet or not.
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- Thread starter
- #30
Got around to replacing the VAF and testing the charcoal cannister on this dreary 5th of July - drizzle down here in south OC.
VAF replacement was a piece of cake. FSM says the gasket between the air filter assembly and VAF is a non-resusable part, but it looked darn near brand new and since I don't have a new one, just resued it. FSM said disconnect the battery, which I did before starting. This effectively resets the ECU. She's running a little rough and low idle on initial start up, but it'll take a few drives before the ECU relearns, so jury is out on the VAF replacment.
On to the charcoal cannister test.
Took the cannister out. Just figured it would be easier. From the '94 FSM testing:
a. Using low pressure compressed air blow into tank pipe and check that air flows without resistance from the other pipes.
This passed. I could feel air coming out from both the purge pipe and the bottom pipe.
b. Blow air into purge pipe and check that air does not flow from the other pipes. If a problem is found, replace the charcoal cannister. FSM says .68 psi - that's damn near nothing. I turned my compressor down as far as I could (probably more than .68 tho).
Failed! No air from the tank pipe, but air flowed very freely from the bottom pipe.
I went ahead and cleaned the filter in the cannister by blowing 43 psi compressed air into the tank pipe keeping the purge pipe closed.
Took the part number off the cannister - OUCH - $271 to replace from an online place I've found that has prices comparable to CDAN that I use for budget purposes only.
Don't know what failing test b really means - valve in the tank not performing properly? Any clues or thoughts?
VAF replacement was a piece of cake. FSM says the gasket between the air filter assembly and VAF is a non-resusable part, but it looked darn near brand new and since I don't have a new one, just resued it. FSM said disconnect the battery, which I did before starting. This effectively resets the ECU. She's running a little rough and low idle on initial start up, but it'll take a few drives before the ECU relearns, so jury is out on the VAF replacment.
On to the charcoal cannister test.
Took the cannister out. Just figured it would be easier. From the '94 FSM testing:
a. Using low pressure compressed air blow into tank pipe and check that air flows without resistance from the other pipes.
This passed. I could feel air coming out from both the purge pipe and the bottom pipe.
b. Blow air into purge pipe and check that air does not flow from the other pipes. If a problem is found, replace the charcoal cannister. FSM says .68 psi - that's damn near nothing. I turned my compressor down as far as I could (probably more than .68 tho).
Failed! No air from the tank pipe, but air flowed very freely from the bottom pipe.I went ahead and cleaned the filter in the cannister by blowing 43 psi compressed air into the tank pipe keeping the purge pipe closed.
Took the part number off the cannister - OUCH - $271 to replace from an online place I've found that has prices comparable to CDAN that I use for budget purposes only.
Don't know what failing test b really means - valve in the tank not performing properly? Any clues or thoughts?
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- Thread starter
- #31
VAF update - ran every little errand I could yesterday with the beast to get the ECU reset and brought her to work today. Idle is much, much improved...knock on wood. Let's hope she stays that way.
Eric - any further thoughts on the charcoal cannisters?
Eric - any further thoughts on the charcoal cannisters?
As far as I can tell, there should be one-way flow from the CC to the engine through the purge port, based on the theory of operation. I cant find a good diagram of the internal workings to verify this, just the one in the FSM which is vague.
I am going to pull mine this week and spray some carb cleaner in the tank and purge ports to try to loosen things up. I'll post the results. Maybe you can try this on your purge port. Dont use too much, just squirt a little, turn it over a few times, repeat. Worth a shot.
You didn't say what pressure air you were using, but I was just blowing softly into the hose (like blowing through a straw into a glass of milk to make bubbles). This amount of pressure is what gave me the results posted on my thread. If I blew harder, I could overcome whatever was blocking the air and it would come out of the other ports. So I think these tests are pressure sensitive.
I am going to pull mine this week and spray some carb cleaner in the tank and purge ports to try to loosen things up. I'll post the results. Maybe you can try this on your purge port. Dont use too much, just squirt a little, turn it over a few times, repeat. Worth a shot.
You didn't say what pressure air you were using, but I was just blowing softly into the hose (like blowing through a straw into a glass of milk to make bubbles). This amount of pressure is what gave me the results posted on my thread. If I blew harder, I could overcome whatever was blocking the air and it would come out of the other ports. So I think these tests are pressure sensitive.
- Thread starter
- #33
Anything under about 10 psi the guage won't register, but I turned it down until there was just a wisp of air coming out - probably less than blowing bubbles into milk and got air out the bottom pipe.
FSM says not to try to clean, but I guess we don't have much to loose do we.
FSM says not to try to clean, but I guess we don't have much to loose do we.
Charcol Can
I will be following this, my CC only has a fuel smell on very hot days, in the desert. But I have now been noticing a lot of vacumm pressure in the gas tank when fueling lately. It is actually sucking in air not releasing it. Maybe CC as a culpret.
I will be following this, my CC only has a fuel smell on very hot days, in the desert. But I have now been noticing a lot of vacumm pressure in the gas tank when fueling lately. It is actually sucking in air not releasing it. Maybe CC as a culpret.
- Thread starter
- #35
Nothing new to report here. Still a minor misfire at idle. Less so when the truck is completely warm and driven for awhile. Runs great at speed.
As the only owner, to my fading knowledge, the fuel filter buried under the 2nd row seats by the gas tank has never ever been changed in the 16 years I've had the truck.
I wonder if at idle there's just not enough flow thru what's got to be a very dirty filter sock, but at speed there's enough flow from the fuel pump to fire all 6 cylinders w/o issue.
There aren't any fuel filters of any kind in the engine bay are there?
As the only owner, to my fading knowledge, the fuel filter buried under the 2nd row seats by the gas tank has never ever been changed in the 16 years I've had the truck.
I wonder if at idle there's just not enough flow thru what's got to be a very dirty filter sock, but at speed there's enough flow from the fuel pump to fire all 6 cylinders w/o issue.
There aren't any fuel filters of any kind in the engine bay are there?
- Thread starter
- #39
Update:
The misfire is still present even with the used/unmolested VAF installed. She's now leaking oil too! Dozen or more drops on the driveway in less than a week. She's banished to the street now.
Back to the misfire - friend is a mechanic at Tustin Lexus and said test the EGR valve. FIL brought down a pressure guage over the holiday. Plugged it into the EGR valve on the DS where the hose from the intake manifold goes to the EGR valve. If I understand correctly, I should be able to pressurize that connection to the EGR valve and it should hold pressure. We couldn't even get any pressure developed. Does this mean a bad/failing EGR valve? Lexus mechanic said that could also be causing the misfire. FSM on the engine misfire line for engine diagnostics does mention the EGR as a possible cause...along with about a dozen other things too!
I'm so frustrated with the continuing idle misfire that I'm ready to take the old gal out back, part her out and shoot the rest of her to put her out of my misery!
I really don't want to visit a dealer, because they're just going to want to start replacing things and that'll get expensive fast.
Is it worth the trip to see John at SDTrux? Good diagnostician? I need someone I can both trust and get these engine issues resolved.
I'm probably going to sell my DD Miata as both my wife and I think the uncomfortable sport seats in it have contributed to my current back issue (buldging disk). I either need to get the 80 very reliable or it'll go as well and I'll get an FJ. I know a few of you (raygunn) have gone the opposite direction and are happy back in an 80. I've got too much love into my cruiser to be real objective. I'm almost to the point of just wanting to spend the $$ to replace the engine in the 80 as opposed to a car payment for 5 years, get the leather on the interior redone and drive the hell out of the 80 until it dies on the side of the road or I die of another heart attack
The misfire is still present even with the used/unmolested VAF installed. She's now leaking oil too! Dozen or more drops on the driveway in less than a week. She's banished to the street now.
Back to the misfire - friend is a mechanic at Tustin Lexus and said test the EGR valve. FIL brought down a pressure guage over the holiday. Plugged it into the EGR valve on the DS where the hose from the intake manifold goes to the EGR valve. If I understand correctly, I should be able to pressurize that connection to the EGR valve and it should hold pressure. We couldn't even get any pressure developed. Does this mean a bad/failing EGR valve? Lexus mechanic said that could also be causing the misfire. FSM on the engine misfire line for engine diagnostics does mention the EGR as a possible cause...along with about a dozen other things too!
I'm so frustrated with the continuing idle misfire that I'm ready to take the old gal out back, part her out and shoot the rest of her to put her out of my misery!
I really don't want to visit a dealer, because they're just going to want to start replacing things and that'll get expensive fast.
Is it worth the trip to see John at SDTrux? Good diagnostician? I need someone I can both trust and get these engine issues resolved.
I'm probably going to sell my DD Miata as both my wife and I think the uncomfortable sport seats in it have contributed to my current back issue (buldging disk). I either need to get the 80 very reliable or it'll go as well and I'll get an FJ. I know a few of you (raygunn) have gone the opposite direction and are happy back in an 80. I've got too much love into my cruiser to be real objective. I'm almost to the point of just wanting to spend the $$ to replace the engine in the 80 as opposed to a car payment for 5 years, get the leather on the interior redone and drive the hell out of the 80 until it dies on the side of the road or I die of another heart attack
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Is your 80 throwing a code? Ever since i've owned mine, it seemed to have a little stutter at idle... like
arrhythmia. (sorry no pun intended!) Then I got the PITA P0401 over the summer and the CEL would come on from time to time...
I figured I'd leave it alone as others on this forum seemed to do. Funny thing is I cleared the code long enough to get a smog done, which passed no problem. However a few weeks back when it got up into the 90's the CEL came back on and it started pinging really bad and running warm (around 200-210* compared to 190-195* normally). Even when the outside temps cooled to normal it continued to ping... So I finally had my friends shop check the EGR system and sho enuf it was a bad VSV..Changed it along with the leaking valve cover gasket and a couple of bad vacuum lines and she runs like a champ, even the irregular stutter at idle is gone!! ((Knock on wood and pray to God..) especially since she has 220k on the odometer.
Kudo's to the PO!!
Hope you can get the issues worked out.
arrhythmia. (sorry no pun intended!) Then I got the PITA P0401 over the summer and the CEL would come on from time to time...
I figured I'd leave it alone as others on this forum seemed to do. Funny thing is I cleared the code long enough to get a smog done, which passed no problem. However a few weeks back when it got up into the 90's the CEL came back on and it started pinging really bad and running warm (around 200-210* compared to 190-195* normally). Even when the outside temps cooled to normal it continued to ping... So I finally had my friends shop check the EGR system and sho enuf it was a bad VSV..Changed it along with the leaking valve cover gasket and a couple of bad vacuum lines and she runs like a champ, even the irregular stutter at idle is gone!! ((Knock on wood and pray to God..) especially since she has 220k on the odometer.
Kudo's to the PO!!
Hope you can get the issues worked out.