86 22r Misses/Stumbles After an Hour of Highway Driving
06-23-2009, 10:06 AM
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86 22r Misses/Stumbles After an Hour of Highway Driving
I'm on a trip from VA to NYC and my 86 Toyota truck (Carbureted 4-speed, 2wd) lets me down. And again on the way back. Trip from hell.
The problem seems to only occur after an hour or so of highway driving. What it starts doing is running like crap. Maybe this is called "missing". The engine is really rough, loss of power, if I let off the gas it bucks, if it is not in gear it will stall. Very rough but higher rpms make it more consistant. If I let the truck sit for a few hours, back to normal. And it never does this on my drive to work which is 20 miles on the interstate. The carb has been tuned recently, I replaced the plugs, rotor, cap, wires, vacuum lines look good, thermostat is new and runs on the cool side and it has a brand new fuel filter. Anybody have any idea what is going on?
BTW, is it okay to drive a 4-speed at highway speeds of 70-75mph? I mean, there's no overdrive but it doesn't sound like it is straining. What RPMs is the engine running at at this speed?
Thanks for the help
-Nick Napoda
The problem seems to only occur after an hour or so of highway driving. What it starts doing is running like crap. Maybe this is called "missing". The engine is really rough, loss of power, if I let off the gas it bucks, if it is not in gear it will stall. Very rough but higher rpms make it more consistant. If I let the truck sit for a few hours, back to normal. And it never does this on my drive to work which is 20 miles on the interstate. The carb has been tuned recently, I replaced the plugs, rotor, cap, wires, vacuum lines look good, thermostat is new and runs on the cool side and it has a brand new fuel filter. Anybody have any idea what is going on?
BTW, is it okay to drive a 4-speed at highway speeds of 70-75mph? I mean, there's no overdrive but it doesn't sound like it is straining. What RPMs is the engine running at at this speed?
Thanks for the help
-Nick Napoda
06-23-2009, 11:46 PM
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When it starts acting up, check the fuel level in the float chamber. There's a sight glass on the side of the carb's float bowl (assuming it's stock) and the fuel level should be approximately mid-way in the sight glass. If it's not where it should be, the float and fuel pump are possible culprits, and both should be checked. Also, if the fuel level is low, the fuel filter should be checked / replaced as well- they're not expensive and having a clean filter is never a bad thing. If the fuel level is high, restrictions in the return line from the fuel pump to the tank can cause that, but most likely the float is saturated and needs replaced, particularly if the carb has been on the engine for quite a while.
If that doesn't help, post back.
If that doesn't help, post back.
Last edited by abecedarian; 06-23-2009 at 11:48 PM.
06-24-2009, 12:38 AM
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Sounds like you are building an excessive amount of heat. The kind that takes more than 20 miles to generate. At this point I would not rely on your trucks sensors. I would get a digital infrared handheld thermometer if the carb advise above does not do it for you. I would take a reading from several areas of the trucks power plant as well as from specific areas such as certain points on the transmission, the radiator fins, the coolant if you can, the oil from the dip stick. the oil pan. etc. after a trip to work and then collect these over a period of days and then compare the averages of these against the next time you drive 60 - 100 miles. I am going to assume that if your transmission is hot after a work day trip (20) that it is going to be very hot after a longer haul (60-100). Then that might be an area to isolate for a closer look but I am thinking that the power plant itself is getting too hot and this might be for several reasons that will need to be systematically isolated and tested. Two that immediately come to mind are the chemical composition of the gasoline and the flow of the cooling system itself.
E85, if you use it, may be slowly killing your engine.
Rust, in your cooling system may allow it to get overwhelmed and the excessive heat from the transmission is not helping. Of course I am assuming too much only so that you can have a few options on your end to chew on and try out. It will take a few days to get some readings and a digital thermometer can be had for less than $10 at harbor freight. If you are using E85 then burn off the tank and then top off with actual gasoline before your next long haul test. also you might want to derust with evaporust, the flush water will tell the tale of that assumption. Maybe, maybe not. Perhaps the heat build up from the excessive heat disrupts the proper air fuel mixture. Again, too much heat. Supported by the cool down period. Maybe you need an evaporust flush, maybe you need a new radiator, maybe you need to drive 60 no matter how painful.
happy testing.
E85, if you use it, may be slowly killing your engine.
Rust, in your cooling system may allow it to get overwhelmed and the excessive heat from the transmission is not helping. Of course I am assuming too much only so that you can have a few options on your end to chew on and try out. It will take a few days to get some readings and a digital thermometer can be had for less than $10 at harbor freight. If you are using E85 then burn off the tank and then top off with actual gasoline before your next long haul test. also you might want to derust with evaporust, the flush water will tell the tale of that assumption. Maybe, maybe not. Perhaps the heat build up from the excessive heat disrupts the proper air fuel mixture. Again, too much heat. Supported by the cool down period. Maybe you need an evaporust flush, maybe you need a new radiator, maybe you need to drive 60 no matter how painful.
happy testing.
06-24-2009, 12:57 AM
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How does the transmission, being a 4 speed, affect the engine's temp... if I may ask?
And how does knowing the 4 speed's temp fix the problem?
Not trying to argue or anything... just trying to learn about other's troubleshooting techniques.
And how does knowing the 4 speed's temp fix the problem?
Not trying to argue or anything... just trying to learn about other's troubleshooting techniques.
Last edited by abecedarian; 06-24-2009 at 12:59 AM.
06-24-2009, 04:30 AM
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Guilty by association.
First, I hope that the carb advice hits the nail on the head, end of story. However, if that is ruled out, then perhaps the ignition coil approach may uncover the concern. Again, I hope that advice bears fruit but if it does not at least we have ruled out two considerations and the search continues after two sharpshooters pulled the trigger. Me? I'm a shot gunner. I am not a subject matter expert like you two. I have respect for your ability to zero in on a short check list but I use the use the scatter gun approach in this matter by chance and not by choice. So that said, please allow me to address your two questions out of my respect for you.
"How does the transmission, being a 4 speed, affect the engine's temp... if I may ask?"
Simple, it does not.
Some back ground
A four speed transmission in a vacuum is the same as a 2 speed or a 16 speed. So the transmission being a four speed does not affect the engines temp. With that in mind revolutions per minute, in a vacuum, also do not affect the engines temp or the transmissions temp. However, combine the two; transmission and rpm and now you do have a chip in the thermodynamic game. Since I consider the engine and the transmission to be part of a single unit, the drive train, heat from one is either directly transfered to the other via the bell housing, frame or sheet metal or indirectly via radiant heat. I once drove a Unimog in low gear over some open terrain and the transmission became so hot that it was uncomfortable to have my thigh near it. Likewise, in pulling a boston whaler on a trailer over some unpaved roads up and down hills, the transmission became very hot. Metal is a good conductor of both heat and sound. When the concord was flying, and it flew faster than the speed of sound, why could one still hear the roar of the jet engines inside the cabin? Metal. So, yes I do believe that the metal of a hot transmission hinders more than helps the engines ability to cool itself. Do I think that it is a big factor? No. It is not a big factor but it is a factor. Maybe it represents .0001% or .1% A four speed transmission in fourth gear at 75 mph is going to build more heat than that same set up at 50 mph. Maybe 68 MPH at a certain atmospheric condition is all the trucks transmission can handle before it overwhelms its ability to cool itself, so running at 75 for 20 miles may equal .0001% and after 50-70 minutes it becomes .1% or 10%. A big factor? No. A factor? Yes. Is .1% enough to break the camels back? Maybe. I like the ignition coil tip. Just how hot does that sucker get at 20 miles and how hot is it when things start to sour? How much juice is it kicking out? Pull over and take some readings. Are they normal compare them with other trucks that have similar set ups. But to get back to the original question.
A hot transmission affects the engines temp by direct metal to metal contact. Is it a ball buster? No. Is a hot transmission made hotter by winding a four speed in forth gear up to 60 MPH a ball buster? No, but it may hinder the engines ability to cool itself even if it is a little itty bitty bit. 75mph? Coupled with a compromised cooling system? Running E85? Sucking in hot air, disrupting the fuel air mixture ratio? Maybe the heat vapor locks the fuel supply in the lines but only after a certain under hood temp is reached and that makes it run lean and hot, hot, hot and causing premature detonation. Maybe, maybe not.
Next, "And how does knowing the 4 speed's temp fix the problem?"
If the transmission heats up to a point that affects the engines ability to cool itself properly, maybe .1% then perhaps lowering the transmissions temp may yield .01% and that may stop the entire chain of events. This can be tested by driving at 60mph for over an hour. Perhaps, if the cooling system is a little rusty, an evapo-rust session may be enough to make the hot transmission a non factor. Or cutting a hole in your hood or using a ram air intake. In my mind, my approach revolves around heat. Somewhere, something is getting too hot. What is it and why. I have not been able to isolate that yet. I only know that we kinda know how and since that is all I have to work with, then I'm taking it and busting some bird shot into it, sometimes recon by fire works. Either way, it's Nicks yota and at the end of the day the only approach that really matters is his. My 2runner will run at 120 mph all day and has no problems with heat management, I don't know who nick is but I do know he has a problem, one I am interested in so I do what I can and over all I think I can help more than hinder.
Beside Universities used to be nothing more than forums at one time that makes me both teacher and student.
First, I hope that the carb advice hits the nail on the head, end of story. However, if that is ruled out, then perhaps the ignition coil approach may uncover the concern. Again, I hope that advice bears fruit but if it does not at least we have ruled out two considerations and the search continues after two sharpshooters pulled the trigger. Me? I'm a shot gunner. I am not a subject matter expert like you two. I have respect for your ability to zero in on a short check list but I use the use the scatter gun approach in this matter by chance and not by choice. So that said, please allow me to address your two questions out of my respect for you.
"How does the transmission, being a 4 speed, affect the engine's temp... if I may ask?"
Simple, it does not.
Some back ground
A four speed transmission in a vacuum is the same as a 2 speed or a 16 speed. So the transmission being a four speed does not affect the engines temp. With that in mind revolutions per minute, in a vacuum, also do not affect the engines temp or the transmissions temp. However, combine the two; transmission and rpm and now you do have a chip in the thermodynamic game. Since I consider the engine and the transmission to be part of a single unit, the drive train, heat from one is either directly transfered to the other via the bell housing, frame or sheet metal or indirectly via radiant heat. I once drove a Unimog in low gear over some open terrain and the transmission became so hot that it was uncomfortable to have my thigh near it. Likewise, in pulling a boston whaler on a trailer over some unpaved roads up and down hills, the transmission became very hot. Metal is a good conductor of both heat and sound. When the concord was flying, and it flew faster than the speed of sound, why could one still hear the roar of the jet engines inside the cabin? Metal. So, yes I do believe that the metal of a hot transmission hinders more than helps the engines ability to cool itself. Do I think that it is a big factor? No. It is not a big factor but it is a factor. Maybe it represents .0001% or .1% A four speed transmission in fourth gear at 75 mph is going to build more heat than that same set up at 50 mph. Maybe 68 MPH at a certain atmospheric condition is all the trucks transmission can handle before it overwhelms its ability to cool itself, so running at 75 for 20 miles may equal .0001% and after 50-70 minutes it becomes .1% or 10%. A big factor? No. A factor? Yes. Is .1% enough to break the camels back? Maybe. I like the ignition coil tip. Just how hot does that sucker get at 20 miles and how hot is it when things start to sour? How much juice is it kicking out? Pull over and take some readings. Are they normal compare them with other trucks that have similar set ups. But to get back to the original question.
A hot transmission affects the engines temp by direct metal to metal contact. Is it a ball buster? No. Is a hot transmission made hotter by winding a four speed in forth gear up to 60 MPH a ball buster? No, but it may hinder the engines ability to cool itself even if it is a little itty bitty bit. 75mph? Coupled with a compromised cooling system? Running E85? Sucking in hot air, disrupting the fuel air mixture ratio? Maybe the heat vapor locks the fuel supply in the lines but only after a certain under hood temp is reached and that makes it run lean and hot, hot, hot and causing premature detonation. Maybe, maybe not.
Next, "And how does knowing the 4 speed's temp fix the problem?"
If the transmission heats up to a point that affects the engines ability to cool itself properly, maybe .1% then perhaps lowering the transmissions temp may yield .01% and that may stop the entire chain of events. This can be tested by driving at 60mph for over an hour. Perhaps, if the cooling system is a little rusty, an evapo-rust session may be enough to make the hot transmission a non factor. Or cutting a hole in your hood or using a ram air intake. In my mind, my approach revolves around heat. Somewhere, something is getting too hot. What is it and why. I have not been able to isolate that yet. I only know that we kinda know how and since that is all I have to work with, then I'm taking it and busting some bird shot into it, sometimes recon by fire works. Either way, it's Nicks yota and at the end of the day the only approach that really matters is his. My 2runner will run at 120 mph all day and has no problems with heat management, I don't know who nick is but I do know he has a problem, one I am interested in so I do what I can and over all I think I can help more than hinder.
Beside Universities used to be nothing more than forums at one time that makes me both teacher and student.
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06-25-2009, 05:21 AM
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Thanks for the advise. The carb float and the ignition coil both sound like viable suspects.
As for those of you that named excessive heat, well... The truck's temperature sensor is accurate, believe me, and the engine itself is not overheating. HOWEVER, I do think this problem could be related to heat in that some other engine related system may be heating to a point where it acts up, a part which is obviously not monitored by the main temperature sensor. The truck has not acted up this week, I will have to wait till i do a longer drive for an opportunity to observe the problem again. How do I check to see if my ignition coil is bad??
Nobody answered my transmission question, only got off topic by it. I'm simply wondering what RPMs the truck is doing at 75mph with a 4 speed. My truck has no tach so I don't know.
As for those of you that named excessive heat, well... The truck's temperature sensor is accurate, believe me, and the engine itself is not overheating. HOWEVER, I do think this problem could be related to heat in that some other engine related system may be heating to a point where it acts up, a part which is obviously not monitored by the main temperature sensor. The truck has not acted up this week, I will have to wait till i do a longer drive for an opportunity to observe the problem again. How do I check to see if my ignition coil is bad??
Nobody answered my transmission question, only got off topic by it. I'm simply wondering what RPMs the truck is doing at 75mph with a 4 speed. My truck has no tach so I don't know.
06-29-2009, 11:50 AM
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You need to know the rear tire diameter(or ideally the actual circumference), the rear diff ratio, and the transmission gear ratio. From there you can just plug that info into one of the many rear axle calculators on the 'net if you prefer not to do it manually. For example, my truck would turn around 4100rpm @ 75mph assuming a 4.10 ring & pinion, 25.3" tall tire, and a 1.00 4th gear.
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