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First time working with computer controlled classic. Can someone tell me what all this controls? Car is over heating. Would this cause that by chance? My son had it out last night and think he may have not put back in properly?
The ECM controls whether the fan turns on, in certain cars. Not sure about yours. Regardless, if it "overheats" at above 35 mph or so, it's not due to the fans in any manner way shape form or fashion, and therefore not the ECM.
Let's start at the beginning. Define "overheating". Then let's attack it one step at a time.
Your 86 tpi ecm does control the engine fan.
key on engine off jumper the connector at the drivers side knee level.
this is the aldl A To pin B turn the key to accessory position and see if the fan kicks on. If it does it could be the cts coolant temperature sensor front of intake that’s not giving the computer the correct reading. What temperature does the engine reach ? Verified with an infrared gun ?
The ECM controls whether the fan turns on, in certain cars. Not sure about yours. Regardless, if it "overheats" at above 35 mph or so, it's not due to the fans in any manner way shape form or fashion, and therefore not the ECM.
Let's start at the beginning. Define "overheating". Then let's attack it one step at a time.
gauges are not reliable in it but creeps up to 250 plus. Service engine light turned on then smoke from engine.
Your 86 tpi ecm does control the engine fan.
key on engine off jumper the connector at the drivers side knee level.
this is the aldl A To pin B turn the key to accessory position and see if the fan kicks on. If it does it could be the cts coolant temperature sensor front of intake that’s not giving the computer the correct reading. What temperature does the engine reach ? Verified with an infrared gun ?
don’t have infrared gun but should get one soon. I do see the fan kick in in idle after running for 10 minutes or so. After it kicks on the temp gauge drops down to 220 ish. I read it should have a normal operating temperature of 180-190. Is that right?
Last edited by Bluesting70; May 11, 2023 at 03:00 PM.
Thermostat temp in these cars is usually about 195°. At some point they switched to metric designations and they're not exactly the same, but close within acoupla °. Like, 90°C or something. That's what it should run at, driving down the road at cruise speeds like 45 - 70 or the like. Might take some time to reach equilibrium but that's where it should eventually end up.
A fan switch in the head would have turned the fan on at about 235° and off at about 210°. Not sure what the ECM controlled version is set for but I'd expect it to be pretty similar. Since the boiling point of 50/50 water/AF coolant at 16 psi is about 265 - 270°, that's plenty cool enough to stay out of trouble. Make sure your system has no leaks and the rad cap is good, so that it will hold pressure properly; and run between 30% & 50% regular green antifreeze in it. If it has any leaks it will spew because the boiling point will be so much lower because of the lower pressure; and the AF does lots of good things besides lowering the freezing point, including raising the boiling point. Maybe add a bottle of Water Wetter https://www.autozone.com/antifreeze-...2oz/486218_0_0 to help heat transfer.
If the fan isn't running then it's time to figure out why. Sounds like that's all that's wrong with it.
Pretty sure you can fix that crack with flexible bumper repair. Do it from the inside so it doesn't make a giant blob where you can see it.
Update. Ran the car under 30 mph for about 30 minutes in the neighborhood. Infrared shot at the front of the block right next to the water pump read 200F when the fan would kick in then drops to about 193F. Then proceeded to take it down a highway for 15 minutes at 50 mph. After about 10 minutes the service engine light lit up and the transmission showed signs of shifting late in the rpms. While engine running and back to the driveway the temp at the same spot read 220F. Check transmission fluid level and read in acceptable range. The transmission does have a leak and the driveline does jump hard when shifting to R or D or P. Is that engine temp too high for what the mission was? Is there something with the transmission symptoms that would cause the engine to run too hot?
thanks for any help and any advice with the transmission issues.
Sounds like it's doing largely as it was designed to do.
You gotta understand, people come on here all the time with "my car is overheating", and when we press them for what that means, they say stuff like "well I saw my gauge get up to 220 and I shut it off immediately because water boils at 212". wRong. Pure water at sea level pressure may boil at 212°, but coolant mix in the proper concentration at cooling system pressures of 15 psi or so are a WHOLE OTHER MATTER. Or, "I just think that's too hot, heat is [insert complaints here about power or whatever], I want it to run at 180", without the least bit of understanding anything beyond their whim compared to some number on a gauge. Or, "the gauge goes all the way up within 2 minutes of starting the car but I drove it like that all the way to my girlfriend's house last night and nothing bad happened [never any mention of what it did on the way back after she kicked you to the curb], should I take out the thermostat". Or, "there's bubbling and hissing noises from [insert leaky broken part here] and water [never "coolant"] dripping off the engine somewhere, I can't afford a [whatever is broken] right now, can I [buy and put on all kinds of cheeeeep but expensive hack-job stuff] and make it all just go away?" There's some other n00b kind of posts that appear on this forum several times a week like that, although those right there are probably about 80% of them. Gets really annoying, I can assure you. We out here can't tell whether you're One Of Those from a single post about this sort of thing.
Definitely check your lower air dam; the car will tend to run hotter than it should at high speeds if it's not right. Doesn't sound like you have a problem there but it's dark out now so I can't see your car, you'll need to check it out yourself.
Sounds like it's doing largely as it was designed to do.
You gotta understand, people come on here all the time with "my car is overheating", and when we press them for what that means, they say stuff like "well I saw my gauge get up to 220 and I shut it off immediately because water boils at 212". wRong. Pure water at sea level pressure may boil at 212°, but coolant mix in the proper concentration at cooling system pressures of 15 psi or so are a WHOLE OTHER MATTER. Or, "I just think that's too hot, heat is [insert complaints here about power or whatever], I want it to run at 180", without the least bit of understanding anything beyond their whim compared to some number on a gauge. Or, "the gauge goes all the way up within 2 minutes of starting the car but I drove it like that all the way to my girlfriend's house last night and nothing bad happened [never any mention of what it did on the way back after she kicked you to the curb], should I take out the thermostat". Or, "there's bubbling and hissing noises from [insert leaky broken part here] and water [never "coolant"] dripping off the engine somewhere, I can't afford a [whatever is broken] right now, can I [buy and put on all kinds of cheeeeep but expensive hack-job stuff] and make it all just go away?" There's some other n00b kind of posts that appear on this forum several times a week like that, although those right there are probably about 80% of them. Gets really annoying, I can assure you. We out here can't tell whether you're One Of Those from a single post about this sort of thing.
Definitely check your lower air dam; the car will tend to run hotter than it should at high speeds if it's not right. Doesn't sound like you have a problem there but it's dark out now so I can't see your car, you'll need to check it out yourself.
What "code" did the ECM display?
I hear you on all that for sure. I’ve been a member on the C3 forum for a while and see similar but just like I don’t like my time wasted I respect others time. I’m learning these cars pretty quickly. I’m surprised how warm they run. I’ll keep an eye on it but will move on. I need to get this hard jumping and hard to shift transmission fixed. Never worked on automatic before so I’m learning that now. Thanks for advice on the air dam.
Sounds like it's doing largely as it was designed to do.
You gotta understand, people come on here all the time with "my car is overheating", and when we press them for what that means, they say stuff like "well I saw my gauge get up to 220 and I shut it off immediately because water boils at 212". wRong. Pure water at sea level pressure may boil at 212°, but coolant mix in the proper concentration at cooling system pressures of 15 psi or so are a WHOLE OTHER MATTER. Or, "I just think that's too hot, heat is [insert complaints here about power or whatever], I want it to run at 180", without the least bit of understanding anything beyond their whim compared to some number on a gauge. Or, "the gauge goes all the way up within 2 minutes of starting the car but I drove it like that all the way to my girlfriend's house last night and nothing bad happened [never any mention of what it did on the way back after she kicked you to the curb], should I take out the thermostat". Or, "there's bubbling and hissing noises from [insert leaky broken part here] and water [never "coolant"] dripping off the engine somewhere, I can't afford a [whatever is broken] right now, can I [buy and put on all kinds of cheeeeep but expensive hack-job stuff] and make it all just go away?" There's some other n00b kind of posts that appear on this forum several times a week like that, although those right there are probably about 80% of them. Gets really annoying, I can assure you. We out here can't tell whether you're One Of Those from a single post about this sort of thing.
Definitely check your lower air dam; the car will tend to run hotter than it should at high speeds if it's not right. Doesn't sound like you have a problem there but it's dark out now so I can't see your car, you'll need to check it out yourself.
What "code" did the ECM display?
code 43. Any insight to that code? The rpm gauge is erratic. At 20-30 mph the gauge goes into the red but the crank doesn’t sound that high so I gather the gauge is off. Does that rpm reading affect the tranny? Probably a dumb question but as I mentioned, never worked on an automatic. My c3 was stock 4 speed and I changed it out for a 5 speed tkx.
Last edited by Bluesting70; May 14, 2023 at 08:43 PM.
