With all the 'cant' and 'wont work' responses I now know which method I am going to try first 
My Tempo EFI conversion
- Thread starter rmoe88
- Start date
Well, most people come onto these message boards to help and guidance. If you just want to learn the hard way then why bother posting?
The problem is that the "not working" mode may not be obvious to you. It may only throw your gauge and the MS off a little (depends on the resistors used). It could also damage both the gauge and the MS. Why try to fight physics? Electricity works in a very straitforward and defined way. There isn't really much point in trying to explore other theories.
The problem is that the "not working" mode may not be obvious to you. It may only throw your gauge and the MS off a little (depends on the resistors used). It could also damage both the gauge and the MS. Why try to fight physics? Electricity works in a very straitforward and defined way. There isn't really much point in trying to explore other theories.
edited out (wasnt clear)
now since i have done some thinking on it, if they are like the newer cars i have worked on, one thing that would blow using one sensor out of the water is if they use different voltages.
The cars i have worked on have power coming from the gauges, going through the variable resistor (temp sensor) and to ground (engine) with the gauge messureing the current able to get through to show the temp. Do the falcons and mustangs use the same style of system? also i think the new car had a 12v system.
If i recall right the MS uses a 5v system for its temp feedback. Is the gauge system a 5v system in our old cars? If its 12v then it would be difficult to make it work.
now since i have done some thinking on it, if they are like the newer cars i have worked on, one thing that would blow using one sensor out of the water is if they use different voltages.
The cars i have worked on have power coming from the gauges, going through the variable resistor (temp sensor) and to ground (engine) with the gauge messureing the current able to get through to show the temp. Do the falcons and mustangs use the same style of system? also i think the new car had a 12v system.
If i recall right the MS uses a 5v system for its temp feedback. Is the gauge system a 5v system in our old cars? If its 12v then it would be difficult to make it work.
I think they are 5v also (voltage regulator on the gauge cluster) but I am guessing that the MS will want a very constant 5v and not one that wanders like the factory setup will.
plenty of room for two senders or even three on the motor.
plenty of room for two senders or even three on the motor.
bort -- alright man, its cool. If it is 12v it wont work, at least without using some diodes to keep the 12v gauge from flowing over to the 5v MS (that might cause your damage prediction). even with diodes i have no idea what signels the MS will get. Its a no-go.
Turbo -- if the gauge is a 5v system then there could be a way, a capasitor would get rid of any factory "wanderings", i think. LOL im sorry if i sound stubborn, i keep reading you post saying "plenty of room for two dang it!" but all i see is "for the love of god get one sensor to work!" but really, if i end up using two im going to look for one of those "street tee's" you posted about, sounds like a good setup. where do you think i could find one?
Turbo -- if the gauge is a 5v system then there could be a way, a capasitor would get rid of any factory "wanderings", i think. LOL im sorry if i sound stubborn, i keep reading you post saying "plenty of room for two dang it!" but all i see is "for the love of god get one sensor to work!"
but really, if i end up using two im going to look for one of those "street tee's" you posted about, sounds like a good setup. where do you think i could find one?A street Tee or male branch tee should be avaliable at any hardware store.
The problem with two gauges is a very simple one. The gauge has an output voltage, apparantly in this case 5v. The gauge has an internal resistor. The sensor is a resistor. The internal resistor and the sensor are connected in series. This is called a voltage divider. The ratio of the two resistances will determine the voltage downstream of the internal resistor and upstream of the sensor. The gauge reports this voltage which it displays on a dial calibrated for temperature.
The megasquirt works the same way.
As the resistance of the sensor changes with temperature, the ratio changes, and as such the measured voltage changes. Here is the problem: If you connect two gauges (or a MS and a gauge) you are going to have two voltage sources and two internal resistors. If they are both the exact same voltage(not physically possible), your problem will lie in the changing of the voltage divider circuit. you will have put the two internal resistances in parallel. As a result, their cumulative value will be reduced, changing the ratio of the upstream and downstream voltages. This will throw off both devices signifigantly.
If, in the more credible case, the voltage sources are slightly different, You will have all sorts of weird issues. Current will be flowing from the highest voltage point in the circuit to all points lower. That includes from the higher gauge into the lower one. This will cause you all sorts of interesting issues that I can't really even predict.
If one is at 12v and the other 5v, the outcome is pretty straitforward. The 5v one will most likely be damaged.
This isn't a mystery. It is just a basic electric circuit. You can try it and find out for yourself, or you can listen to me or anyone else who has half a clue how electricity works and save yourself the headache.
The problem with two gauges is a very simple one. The gauge has an output voltage, apparantly in this case 5v. The gauge has an internal resistor. The sensor is a resistor. The internal resistor and the sensor are connected in series. This is called a voltage divider. The ratio of the two resistances will determine the voltage downstream of the internal resistor and upstream of the sensor. The gauge reports this voltage which it displays on a dial calibrated for temperature.
The megasquirt works the same way.
As the resistance of the sensor changes with temperature, the ratio changes, and as such the measured voltage changes. Here is the problem: If you connect two gauges (or a MS and a gauge) you are going to have two voltage sources and two internal resistors. If they are both the exact same voltage(not physically possible), your problem will lie in the changing of the voltage divider circuit. you will have put the two internal resistances in parallel. As a result, their cumulative value will be reduced, changing the ratio of the upstream and downstream voltages. This will throw off both devices signifigantly.
If, in the more credible case, the voltage sources are slightly different, You will have all sorts of weird issues. Current will be flowing from the highest voltage point in the circuit to all points lower. That includes from the higher gauge into the lower one. This will cause you all sorts of interesting issues that I can't really even predict.
If one is at 12v and the other 5v, the outcome is pretty straitforward. The 5v one will most likely be damaged.
This isn't a mystery. It is just a basic electric circuit. You can try it and find out for yourself, or you can listen to me or anyone else who has half a clue how electricity works and save yourself the headache.
part of the problem really is that the factory gauge is calibrated for the postion on the head which I think is a cool spot so the gauge from teh factory reads high. When I placed my autometer gauge sender in this location I get about 10-15 degrees cool of a reading (after changing t-stats a coupel of times even) moved it up by the t-stat housing and reads normal. trying to use one sender for both will make one of them read "off" a little bit. granted you could adjust for this on the MS settings but since there is room on the motor for a second sender I would just go that route.
run the stock gauge sender at its location on the head and theMS sender could be placed in the t-stat housing (you will need one with a port there) or in the street TEE for the heater hose. you can also put the MS sender in a heater hose manifold (like a small union for heater hoses that has a NPT hole in it for a sender or switch)
run the stock gauge sender at its location on the head and theMS sender could be placed in the t-stat housing (you will need one with a port there) or in the street TEE for the heater hose. you can also put the MS sender in a heater hose manifold (like a small union for heater hoses that has a NPT hole in it for a sender or switch)
Think of all the things that they said couldnt be done and where we would all be if no one ever tried? Thats what I was meaning with my post about knowing which way I was going to try. I was not saying anyone was wrong and this board is one of the few places where there is a lot of good information. I did not mean to insult anyone and if I did I am sorry.
Has some one here tried hooking it up the way we are asking about and it has not worked?? Reading a bit on the main MS site it would seem possible since you can calibrate the thing if you choose to, it may be more trouble than its worth but we could all bolt in V8s if we wanted to and most of us choose not too. I admit that I have read very little of the MS info and if it says somehwere that it can not be done feel free to point it out. Mr Bort, even you in one of your posts said that the MS "most likely" does it a certain way. The reason I am now interested in looking further into doing it that way is to be different, see if it works, if it does it would be kinda neat. The whole reason we are here in the inline6 world and looking at EFI is that we want to be different.
From an electronic design standpoint (please correct me if I am wrong) there is no reason that someone couldnt design a HIGH IMPEDANCE (say something like an EFI computer) circuit to monitor but not have a signifigant effect a LOW IMPEDANCE circuit (say like a basic gauge in a vintage car). I know of several examples of this in my industry. Weather or not the temp sensor circuit in the MS is/was designed or can be modified like this I dont know. The vintage ford circuit may not be low impedance which would further complicate things but I have not yet looked into that either. Im not trying to put anyone down with this next part but feel a SIMPLE example may help those following along to better grasp what we are talking about... These are examples not numbers that have anything to do with this specific issue. Lets say that the temp sender reads 10 ohms at 'normal' temps. In this case this is low impedance. Lets also say that your gauge reads cold at 20 ohms and hot at 0 ohms. At 10 ohms your gauge is going to read normal. Lets say we add in parallel another device (this could be another gauge or computer or simple resistor) into this circut that is also 10 ohms, now the gauge is going to be seeing 5 ohms because the voltage is being further divived by the new source of resistance in the circiut. The gauge will be reading 1/4 higher even though the temp has not changed. If the thing you add is a much higher resistance (impedancce). Lets say 1000 ohms, it will only change the resistance the gauge is seeing by 0.1 ohms which will not change the reading by a signifigant amount. (Im half asleep at the moment so feel free to correct my math even tho it still explains the concept if Im wrong) The trick is that you have to design that 1000 ohm part to be able to have the sensitivity you need for what you are trying to do. There are other dynamics that come into play with sending units and gauges so my example is not perfect but as a general theory I think it will help people understand what the questions is all about.
What I have read about location is they want it somewhere that responds quickly. The other thing about temp sensors is they need to be in the flow so it would not work well to put a T in the existing location and then install both sensors. That would work for something like oil pressure but not as well for coolant. Since everything about the MS can be calibrated exact location does not seem to be critical as long as it sees something that tracks with the engine temp. In the 80's I do seem to recall that it was fairly common to see a sensor in the top of the T stat housings.
Im stuck in a snow storm in a crappy hotel in the middle of WI so I may take some time to do some more reading on MS and look at some of the fourms. I know a few guys running older systems but have never looked to see what they did for sensors when the snow melts and I see them at the spring shows I will have to see what they did.
Has some one here tried hooking it up the way we are asking about and it has not worked?? Reading a bit on the main MS site it would seem possible since you can calibrate the thing if you choose to, it may be more trouble than its worth but we could all bolt in V8s if we wanted to and most of us choose not too. I admit that I have read very little of the MS info and if it says somehwere that it can not be done feel free to point it out. Mr Bort, even you in one of your posts said that the MS "most likely" does it a certain way. The reason I am now interested in looking further into doing it that way is to be different, see if it works, if it does it would be kinda neat. The whole reason we are here in the inline6 world and looking at EFI is that we want to be different.
From an electronic design standpoint (please correct me if I am wrong) there is no reason that someone couldnt design a HIGH IMPEDANCE (say something like an EFI computer) circuit to monitor but not have a signifigant effect a LOW IMPEDANCE circuit (say like a basic gauge in a vintage car). I know of several examples of this in my industry. Weather or not the temp sensor circuit in the MS is/was designed or can be modified like this I dont know. The vintage ford circuit may not be low impedance which would further complicate things but I have not yet looked into that either. Im not trying to put anyone down with this next part but feel a SIMPLE example may help those following along to better grasp what we are talking about... These are examples not numbers that have anything to do with this specific issue. Lets say that the temp sender reads 10 ohms at 'normal' temps. In this case this is low impedance. Lets also say that your gauge reads cold at 20 ohms and hot at 0 ohms. At 10 ohms your gauge is going to read normal. Lets say we add in parallel another device (this could be another gauge or computer or simple resistor) into this circut that is also 10 ohms, now the gauge is going to be seeing 5 ohms because the voltage is being further divived by the new source of resistance in the circiut. The gauge will be reading 1/4 higher even though the temp has not changed. If the thing you add is a much higher resistance (impedancce). Lets say 1000 ohms, it will only change the resistance the gauge is seeing by 0.1 ohms which will not change the reading by a signifigant amount. (Im half asleep at the moment so feel free to correct my math even tho it still explains the concept if Im wrong) The trick is that you have to design that 1000 ohm part to be able to have the sensitivity you need for what you are trying to do. There are other dynamics that come into play with sending units and gauges so my example is not perfect but as a general theory I think it will help people understand what the questions is all about.
What I have read about location is they want it somewhere that responds quickly. The other thing about temp sensors is they need to be in the flow so it would not work well to put a T in the existing location and then install both sensors. That would work for something like oil pressure but not as well for coolant. Since everything about the MS can be calibrated exact location does not seem to be critical as long as it sees something that tracks with the engine temp. In the 80's I do seem to recall that it was fairly common to see a sensor in the top of the T stat housings.
Im stuck in a snow storm in a crappy hotel in the middle of WI so I may take some time to do some more reading on MS and look at some of the fourms. I know a few guys running older systems but have never looked to see what they did for sensors when the snow melts and I see them at the spring shows I will have to see what they did.
The later housings off the 4 bolt balancer cars had a port in them (I think most emissions motors did for a thermal vaccum switch) I have a couple of them laying around.
like I said you could also just get a manifold that splices in a heater hose. that would be the easiest method.
The problem I see with trying to use a gauge sender is that the voltage regulator in the dash might be 5v +- 1v....I don't think the MS would like the voltage moving around that much.
like I said you could also just get a manifold that splices in a heater hose. that would be the easiest method.
The problem I see with trying to use a gauge sender is that the voltage regulator in the dash might be 5v +- 1v....I don't think the MS would like the voltage moving around that much.
Hey Moe, did you get a TPS and find out how it clears the valve cover? If you got it did you get the oem style ford one or mod something else to fit?
Convert, you are mostly right but thats not how the MS is setup to work.
That would work if you were using a voltmeter to measure the voltage on the stock line. With a sufficiently high impedance across the meter you woudn't signifigantly effect the gauge reading.
But if the MS is designed to work with a variable resistance sensor, then that is not how it works. it works the same as the gauge does, and as a result regardless of the impedance you will have odd issues.
you obviously have some understanding of electronics, so you draw yourself out a circuit with two voltage sources, two resistors and then combine into one resistor the to ground. Then figure out the branch currents and tell me what you find
That would work if you were using a voltmeter to measure the voltage on the stock line. With a sufficiently high impedance across the meter you woudn't signifigantly effect the gauge reading.
But if the MS is designed to work with a variable resistance sensor, then that is not how it works. it works the same as the gauge does, and as a result regardless of the impedance you will have odd issues.
you obviously have some understanding of electronics, so you draw yourself out a circuit with two voltage sources, two resistors and then combine into one resistor the to ground. Then figure out the branch currents and tell me what you find
changing topics, i started running fuel line today (finaly) i had to stop about 1/2 way through because it was only me running it and it has gotten so long that i need another set of hands to help hold it in place and take messurements.
One question i have is should i use my stock hard line for my supply line? I got 25' of new line from jegs, and if i only run a new return line it will be nice, the new hard line will go from the tank all the way to the TB with very little rubber inbetween. But if i have to run a new supply line also, then i would have to have the hard lines comming just to the front of the engine. That would mean i would have to use about 2-3 feet of rubber lines on each hard line to make it to the ThrottleBody.
Will the stock line work? I dont really know if it is "stock" it looks like it has been installed by someone else by hand, the straight parts of the line are slightly crooked just like my new ones are because the line came to me rolled up. The line in there now doesnt leak and i dont suspect any rust, but will it wistand higher pressures?
convert -- im going to run to napa and kraigen today to see if thay have one in stock, if not im going to order it from ebay tonight. give me a week and ill tell ya if its a bolt on or not.
One question i have is should i use my stock hard line for my supply line? I got 25' of new line from jegs, and if i only run a new return line it will be nice, the new hard line will go from the tank all the way to the TB with very little rubber inbetween. But if i have to run a new supply line also, then i would have to have the hard lines comming just to the front of the engine. That would mean i would have to use about 2-3 feet of rubber lines on each hard line to make it to the ThrottleBody.
Will the stock line work? I dont really know if it is "stock" it looks like it has been installed by someone else by hand, the straight parts of the line are slightly crooked just like my new ones are because the line came to me rolled up. The line in there now doesnt leak and i dont suspect any rust, but will it wistand higher pressures?
convert -- im going to run to napa and kraigen today to see if thay have one in stock, if not im going to order it from ebay tonight. give me a week and ill tell ya if its a bolt on or not.
Small Update
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I got a TPS installed on my TB. Its not a stocker though. My dad had a tps from his jeep laying around so i used that. I havent bolted it onto the engine yet but it looks like it will fit, its compact. Its almost a bolt on, i had to file a lip off of the body of the tps and thats it, the 2 bolt holes line right up too. The sensor can be found off of 97-? jeep TJ wrangler (4 and 6 cyl) i think all the 2000's jeeps will have the same sensor since jeeps havent changed too much, but the brand new 2007's might be different i dunno (new body style, could be engine differences too). Ill post some pictures tonight.
I have the idle motor off of the TB. To adjust the idle now, i just removed the aluminum plug from a hole on the side of the TB and under it was threads to screw in a bolt. That bolt will now open and close the throttle blades (just like on our carbs) ill put pics on tonight.
I am toying with the idea of bolting the idle motor back on, and make it set the idle to around 1100rpm only when the car is moving at a specific speed (like above 5mph) This would be nice because the shifting would be much smoother. Now when its at its 600rpm, the engine has to re-accelerate everytime i shift and that causes a small jerk. What do you guys think, good idea or bad?
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I got a TPS installed on my TB. Its not a stocker though. My dad had a tps from his jeep laying around so i used that. I havent bolted it onto the engine yet but it looks like it will fit, its compact. Its almost a bolt on, i had to file a lip off of the body of the tps and thats it, the 2 bolt holes line right up too. The sensor can be found off of 97-? jeep TJ wrangler (4 and 6 cyl) i think all the 2000's jeeps will have the same sensor since jeeps havent changed too much, but the brand new 2007's might be different i dunno (new body style, could be engine differences too). Ill post some pictures tonight.
I have the idle motor off of the TB. To adjust the idle now, i just removed the aluminum plug from a hole on the side of the TB and under it was threads to screw in a bolt. That bolt will now open and close the throttle blades (just like on our carbs) ill put pics on tonight.
I am toying with the idea of bolting the idle motor back on, and make it set the idle to around 1100rpm only when the car is moving at a specific speed (like above 5mph) This would be nice because the shifting would be much smoother. Now when its at its 600rpm, the engine has to re-accelerate everytime i shift and that causes a small jerk. What do you guys think, good idea or bad?
Funky Cricket
Well-known member
hint- heel-toe...
sounds nice, where are the pics!! hehe
sounds nice, where are the pics!! hehe
Picture
There is the TPS i made work. on the picture to the left you see the different colored black area, thats where i had to use a file and take of a little ridge of plastic so that it would fit. Ooo yea, i forgot this, i also had to take a small file and remove .01" from each side where the throttle blade thingy touches inside the TPS. It took all of 1 minute to do, no biggy.
I think this will fit. If it doesnt fit with the plug that connects to it, i will just shave off the plug fitting on the TPS and soder wires to the pins.
These are much much easier to find than the stock one. If you can find a stocker then i would get it, but a jeep one will do. I havent tested it on the Megasquirt yet though but it should be fine.
The picture of the idle adjust screw didnt turn out (damn phone camera) but if your doing a fuel injection conversion you will have no problem figuring it out
There is the TPS i made work. on the picture to the left you see the different colored black area, thats where i had to use a file and take of a little ridge of plastic so that it would fit. Ooo yea, i forgot this, i also had to take a small file and remove .01" from each side where the throttle blade thingy touches inside the TPS. It took all of 1 minute to do, no biggy.
I think this will fit. If it doesnt fit with the plug that connects to it, i will just shave off the plug fitting on the TPS and soder wires to the pins.
These are much much easier to find than the stock one. If you can find a stocker then i would get it, but a jeep one will do. I havent tested it on the Megasquirt yet though but it should be fine.
The picture of the idle adjust screw didnt turn out (damn phone camera) but if your doing a fuel injection conversion you will have no problem figuring it out
Larryejoh -- Wow, that sounds very cool . Do you have any pics? Yea im using the vac, i have a duel advance dizzy, why do ya ask?
Funky Cricket -- i didnt get your hint lol, what do ya mean by heel-toe?
I have a new question... Im going to be needing plug ends for the things like the TPS, the Injector, the o2 sensor and so on, Can i get these ends at like Autozone? or do i have to order them off of the internet? If its the internet, does anyone have a link to a good seller?
. Do you have any pics? Yea im using the vac, i have a duel advance dizzy, why do ya ask?Funky Cricket -- i didnt get your hint
lol, what do ya mean by heel-toe?I have a new question... Im going to be needing plug ends for the things like the TPS, the Injector, the o2 sensor and so on, Can i get these ends at like Autozone? or do i have to order them off of the internet? If its the internet, does anyone have a link to a good seller?
