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So I picked up a v6 t5 RS. Trans shifts good, no grinds, no popouts, no weird noises. Here is the issue I'm having. When I shift into 2nd going slow/normal it engages fine and increases speed just fine. But lets say I get on it going a little fast, going into second, again it goes in fine but when I go to accelerate it kinda jerks/wobbles back and forth but then it goes away within a second or two as speed increases. What could this be. Again there is no strange noises or grinds or etc. I know my torque arm mount is trashed I just ordered that, but I doubt that is the problem. Car has been neglected. I Swapped out the original fluid mount out for an auto one. I'm gonna be replacing the atf in it as well, I'm sure that will help. Also does anyone know the energy suspension torque arm bushing part no? Since there are two, one facing one way and the other the other way. Car is a bone stock 88 2.8 v6 t5 Rs. Thanks
Does it feel/sound like an actual transmission problem, or is the “jerks/wobbles” severe, reminiscent of being on a bucking bronco.
The bucking bronco thing is a notorious feature of V6 Camaros.
Feels like the engine loses ALL power momentarily, and the instantly comes back, and the instantly loses it again - this can go several cycles in machine-gun fashion. Very harsh.
Does it feel/sound like an actual transmission problem, or is the “jerks/wobbles” severe, reminiscent of being on a bucking bronco.
The bucking bronco thing is a notorious feature of V6 Camaros.
Feels like the engine loses ALL power momentarily, and the instantly comes back, and the instantly loses it again - this can go several cycles in machine-gun fashion. Very harsh.
Yeah that's exactly what it feels like, a bucking bronco for a like a second or two then goes back to normal. It's not that bad and doesn't do it always. What is the cause of this? Could it be a clutch problem? But in only does it in 2nd . Can this eventually lead to 2nd gear failure or worse?
I think it is a communication problem, either within the ECM, or between the ECM and the sensors that feed it.
I've been chasing this demon for longer than I care to admit in my car.
FWIW, I recently installed a new dash cluster, which included a new Vehicle Speed Sensor (part of the dash cluster). The VSS feeds the ECM. The old VSS was telling my ECM that I was frequently going 254mph, even though my speed was actually about 35mph. Now that my ECM knows how fast the car really is going, I haven't had a bucking bronco issue.
If your ECM is being fed crazy data from a sensor, the ECM doesn't know better. It just assumes you are going 254mph. Or that your engine temperature is 40 degrees when its actually 190 degrees. Or that your Mass Aiflow Sensor is flowing no air.
All I can suggest is that you get set up to scan live data. I had no idea that the VSS was telling crazy stories to my ECM until I figured out how to get TunerPro working.
I've finally gotten set up to read live data.
$100 used laptop
$85 Moates cable
Free Tunerpro software
Its kind of a PITA to find the various files you need to install to make TunerPro actually function.
You'll need:
a BIN file (the operational data specific to your car - motor size, RPM limits, injector specs, etc. - on your car's EPROM chip), and
an XDF file (interface "mask" that allows TunerPro to talk to your car's ECM), and
an ADX file (tells TunerPro what to show you)
I won't swear I expressed that exactly right, but I think I'm close.
Eventually, if you really get into it, you can "tune" your car - change fuel map - delete systems - change threshold for activation of systems, etc. Honestly, I really only care about this computer stuff so I can diagnose. I doubt I will be getting into making fuel-map changes anytime soon. No reason to do that anyway unless you do stuff like add turbos, or outright replace motors with something very different than the original motor, but while still trying to make the original computer play nice with the new motor.
Its a chore to track down those configuration files from forums or samaritans on the internet. Then figure out how to install them and make it all work. The information is out there. Its just that none of it seems to be in the first place(or second or third places) that you look. If you are in a hurry, your head will explode before your car does.
The point is, at the end of the day, if you can't see what your car's computer sees, you are working in the blind, and you are only guessing at what is the issue.
I'm 99% sure your "bucking bronco" thing is in the car's computer system, and has nothing to do with the moving parts of your transmission.
You need to be able to pull up a screen that looks something like this if you want to sort out computer issues.
I'll also mention that the fact that your car only "does it" in second gear likely has very little to do with the fact that the car happens to be in second gear.
In all likelihood the only thing that second gear has to do with it is that the ECM is calculating "load" on the motor based on what the ECM knows about the configuration of the car's motor, when it is travelling at a certain speed, and at a certain RPM, and at a certain manifold pressure.
Which just happens to coincide with a frequent condition when you happen to be in second gear.
The ECM runs some lightning-fast calculations based on some seriously erroneous input-data from a bad sensor (or several bad sensors), and it cuts fuel, or gushes fuel, and puts out the fire in your motor momentarily.
Then when the ECM gets more data about the ****-condition happening in the motor, it corrects again, and the fire comes back. At least until that condition that set it off in the first place re-occurs. Then you're back on the bronco.
One last remark about this bucking-bronco thing being a common complaint with V6 cars.
While I think most third-gen cars tend to be neglected by their owners, it is my belief that owners of V6 cars tend to be markedly more neglectful than owners of V8 cars. Not suprising that the more-neglected cars are more known for driveability issues.
Good luck sleuthing and repairing yours.
You don't have to "drop an LS in it" because everybody tells you should.
I already have an LS car. Its awesome. My LS car also will try to kill you every time you curl your toes inside your shoe.
I'm leaving my third-gen car as a little old V6 because I like it that way. Wide open throttle in second gear. 45 mph baby!!!
I think it is a communication problem, either within the ECM, or between the ECM and the sensors that feed it.
I've been chasing this demon for longer than I care to admit in my car.
FWIW, I recently installed a new dash cluster, which included a new Vehicle Speed Sensor (part of the dash cluster). The VSS feeds the ECM. The old VSS was telling my ECM that I was frequently going 254mph, even though my speed was actually about 35mph. Now that my ECM knows how fast the car really is going, I haven't had a bucking bronco issue.
If your ECM is being fed crazy data from a sensor, the ECM doesn't know better. It just assumes you are going 254mph. Or that your engine temperature is 40 degrees when its actually 190 degrees. Or that your Mass Aiflow Sensor is flowing no air.
All I can suggest is that you get set up to scan live data. I had no idea that the VSS was telling crazy stories to my ECM until I figured out how to get TunerPro working.
I've finally gotten set up to read live data.
$100 used laptop
$85 Moates cable
Free Tunerpro software
Its kind of a PITA to find the various files you need to install to make TunerPro actually function.
You'll need:
a BIN file (the operational data specific to your car - motor size, RPM limits, injector specs, etc. - on your car's EPROM chip), and
an XDF file (interface "mask" that allows TunerPro to talk to your car's ECM), and
an ADX file (tells TunerPro what to show you)
I won't swear I expressed that exactly right, but I think I'm close.
Eventually, if you really get into it, you can "tune" your car - change fuel map - delete systems - change threshold for activation of systems, etc. Honestly, I really only care about this computer stuff so I can diagnose. I doubt I will be getting into making fuel-map changes anytime soon. No reason to do that anyway unless you do stuff like add turbos, or outright replace motors with something very different than the original motor, but while still trying to make the original computer play nice with the new motor.
Its a chore to track down those configuration files from forums or samaritans on the internet. Then figure out how to install them and make it all work. The information is out there. Its just that none of it seems to be in the first place(or second or third places) that you look. If you are in a hurry, your head will explode before your car does.
The point is, at the end of the day, if you can't see what your car's computer sees, you are working in the blind, and you are only guessing at what is the issue.
I'm 99% sure your "bucking bronco" thing is in the car's computer system, and has nothing to do with the moving parts of your transmission.
You need to be able to pull up a screen that looks something like this if you want to sort out computer issues.
Funny you mention that because I'm getting a code 24 for VSS, also a code 34 for MAF, also my cooling fan turns on within minutes of a cold start. I swapped out my cts thinking that would solve that issue but no go. I checked fan wiring and everything is un nmolested.
Sounds to me like I need a new VSS from your experience. From what you explained the vss is sending the wrong data to the ecm thus making my fan turn on so soon when my coolant temp hasn't even budged. Thanks for the info buddy. Everything corresponds to exactly what your saying.
I'm gonna tear into the cluster, previous owner told me that they swapped out clusters, maybe they didn't hook it up or maybe its missing the vss sensor. I'm gonna be ordering the moates cable soon. Could you send me a copy of the BIN XDF and ADX if you don't mind.
Can the piece that goes on the trans tailhousing go bad causing a vss code? Or does the sensor go bad? I'm gonna be searching for a ne cluster/vss. Kinda hard to come by at the junkyard. I'll try posting in the wanted classifieds.
One last remark about this bucking-bronco thing being a common complaint with V6 cars.
While I think most third-gen cars tend to be neglected by their owners, it is my belief that owners of V6 cars tend to be markedly more neglectful than owners of V8 cars. Not suprising that the more-neglected cars are more known for driveability issues.
Good luck sleuthing and repairing yours.
You don't have to "drop an LS in it" because everybody tells you should.
I already have an LS car. Its awesome. My LS car also will try to kill you every time you curl your toes inside your shoe.
I'm leaving my third-gen car as a little old V6 because I like it that way. Wide open throttle in second gear. 45 mph baby!!!
Neglected alright, When I went to look at the car they had tons of stuff piled on top of it, flat tires, tons of junk inside. Surprisingly the interior was in great shape. Headliner is great not sagging and visors are mint, door panels also look great, They told me they were the second owners, I still haven't checked but I wouldn't be surprised being the car is in great shape. No rust whatsoever on the floors, I was kinda iffy about buying since they said it wasn't running but they assured me it ran great and that it had no problems. And for 500 bucks I was so willing to take the risk, I asked them if we could try to start it and sure enough it started up instantly within the flick of the key but died instantly also but that's all I needed to hear. Very stock, was not messed with much, Still has all the header bolts intact....good sign of low miles It had the original trans mount. (switched it to auto mount), Has the original spare and jack... doesn't look like it was ever used. Wouldn't start so I swapped out the original pump and started right up. Just trying to get her back up and running great.
Moates has a lot of good stuff on how to use their wires and gadgets, but not much as far as the actual files you need to use TunerPro.
Gearhead-efi has tons of BIN files and XDF files (sometimes called ADS files) and ADX files. I found this a little unsettling that some hobbyists's website was the only apparent lifeline between my bucking bronco and the tools that *might* help me contain it. Swallow your axieties, and read.
TunerPro used to have a library of files, but I'm pretty sure that library is gone. Maybe moved to Gerahead-efi?
If you need a gauge cluster, you can often find them quite inexpensive on Jason Fritz's Facebook parts group. I got mine for $65 shipped, and OMG what difference it has made. Check out Jason's group at https://www.facebook.com/groups/1087103164731763/
Jason is very responsive if you send him a message on Facebook messenger.
I was looking for a CALPAK chip, and Jason searched dozens of ECU's in his stock looking for one for me. Which it turned out he didn't have, but man, for a request from a just-once previous customer, that's above and beyond the call of duty. I wasn't just impressed. That blows me away.
Anyhow the VSS is that yellow box-thing (about the size of a trial-size box of dental floss) plugged into the back of the gauge cluster behind the tachometer.
The thing on the tailhousing of the transmission is just the switch that turns on your backup lights when you put the car in reverse.
I believe the VSS is on your transmission after all. Pretty sure that's where they put it on the 90-92 cars.
I have a 1992 Firebird plugged into the list for "My Garage" on the Advance Auto app (because I have a Firebird motor sitting on my back porch).
Advance Auto says the VSS for the bird with the 3.1 uses this part: https://shop.advanceautoparts.com/p/...m=Speed+Sensor
I believe the VSS is on your transmission after all. Pretty sure that's where they put it on the 90-92 cars.
I have a 1992 Firebird plugged into the list for "My Garage" on the Advance Auto app (because I have a Firebird motor sitting on my back porch).
Advance Auto says the VSS for the bird with the 3.1 uses this part: https://shop.advanceautoparts.com/p/...m=Speed+Sensor
Yeah I have a 92 3.1 auto, it's my daily driver, no problems with that. But I picked up a 88 2.8 manual, this is the one I'm dealing with the bucking problem. Yeah I know the vss on 90-92 is on the tail and the vss on the 88 is on the back of the cluster. Ill check with the facebook link you referred me too. So the new vss fixed your bucking problem indefinitely ?
Moates has a lot of good stuff on how to use their wires and gadgets, but not much as far as the actual files you need to use TunerPro.
Gearhead-efi has tons of BIN files and XDF files (sometimes called ADS files) and ADX files. I found this a little unsettling that some hobbyists's website was the only apparent lifeline between my bucking bronco and the tools that *might* help me contain it. Swallow your axieties, and read.
TunerPro used to have a library of files, but I'm pretty sure that library is gone. Maybe moved to Gerahead-efi?
If you need a gauge cluster, you can often find them quite inexpensive on Jason Fritz's Facebook parts group. I got mine for $65 shipped, and OMG what difference it has made. Check out Jason's group at https://www.facebook.com/groups/1087103164731763/
Jason is very responsive if you send him a message on Facebook messenger.
I was looking for a CALPAK chip, and Jason searched dozens of ECU's in his stock looking for one for me. Which it turned out he didn't have, but man, for a request from a just-once previous customer, that's above and beyond the call of duty. I wasn't just impressed. That blows me away.
Anyhow the VSS is that yellow box-thing (about the size of a trial-size box of dental floss) plugged into the back of the gauge cluster behind the tachometer.
The thing on the tailhousing of the transmission is just the switch that turns on your backup lights when you put the car in reverse.
Ok So the vss on the back of my cluster is bad right, do the speedo cables go bad on these things?
Moates has a lot of good stuff on how to use their wires and gadgets, but not much as far as the actual files you need to use TunerPro.
Gearhead-efi has tons of BIN files and XDF files (sometimes called ADS files) and ADX files. I found this a little unsettling that some hobbyists's website was the only apparent lifeline between my bucking bronco and the tools that *might* help me contain it. Swallow your axieties, and read.
TunerPro used to have a library of files, but I'm pretty sure that library is gone. Maybe moved to Gerahead-efi?
If you need a gauge cluster, you can often find them quite inexpensive on Jason Fritz's Facebook parts group. I got mine for $65 shipped, and OMG what difference it has made. Check out Jason's group at https://www.facebook.com/groups/1087103164731763/
Jason is very responsive if you send him a message on Facebook messenger.
I was looking for a CALPAK chip, and Jason searched dozens of ECU's in his stock looking for one for me. Which it turned out he didn't have, but man, for a request from a just-once previous customer, that's above and beyond the call of duty. I wasn't just impressed. That blows me away.
Anyhow the VSS is that yellow box-thing (about the size of a trial-size box of dental floss) plugged into the back of the gauge cluster behind the tachometer.
The thing on the tailhousing of the transmission is just the switch that turns on your backup lights when you put the car in reverse.
Ok So the vss on the back of my cluster is bad right, do the speedo cables go bad on these things? Just wanna rule out any other components. So from what you said fixing the vss will get rid of my code 34 also.
I need a bell housing for my 89 rs. got the t5 wc v6. its a 2.8 but 350 going in it. i need the sbc bell housing. its a father son project we have had hotrods a plenty but alway bought em and just upkept not a build to this extent. Be new for our own cars only usualy work on customer cars to this extent at least try not to lol. doing a swap need one badly. the ones on ebay are just more than what i thought they would be ill have a v6 bell housing to trade on if anybody has alot of cars for parts and likes to do a little swapping with boot. anybody hears anything send me a pm or reply to this please. Im a new member first third gen.any help or leads appreciated guys.
Post in the classifieds wanted section . Your post is unrelated to the topics here.
I don’t think the v6 t5 will work behind a 350 and even if it did it’s short live.
Maroe624, do you have analog dial gauges on your ‘92?
If you have analog dial gauges with the old fashioned wire-and-sheath speedometer cable, the VSS is attached to the backside of the instrument cluster.
I thought that starting 1990, all third gen cars went to digital dash. The digitals have speedometer-by-wire. Senders for speedometer and VSS on the digital-dash cars are located on the transmission.
All I can tell you regarding the VSS replacement being THE FIX for my car is that the bronco has remained absent since I installed the replacement dash. It hasn’t been long since the replacement dash went in. So, I’m not making any sudden claims of permanent success.
I’m no wizard when it comes to these cars. I’m more like the stray dog who persists in showing up at the back door, and who is happy when someone throws me a bread crust now and then.
I thought I had the bronco whipped many times.
When I replaced the MAF, then it came back...
When I replaced the ECM, then it came back...
When I replaced the distributor, then it came back...
When I replaced the alternator, then it came back...
When I replaced the battery, then it came back...
When I buttoned up every sketchy vacuum line I could find...
So, I’m kind of spinning on any hope that I will solve the bronco.
I pretty much expect it to be stomping on my grave after I’m gone.
I have smoke-machine on order, to chase the ghost of the bronco, even if I have truly put it to bed by stray dog persistence.
Every 30 year old car HAS TO have multiple vacuum leaks, right?
Maroe624, do you have analog dial gauges on your ‘92?
If you have analog dial gauges with the old fashioned wire-and-sheath speedometer cable, the VSS is attached to the backside of the instrument cluster.
I thought that starting 1990, all third gen cars went to digital dash. The digitals have speedometer-by-wire. Senders for speedometer and VSS on the digital-dash cars are located on the transmission.
On my 92 I have the stock original dial gauges. The speedo does not have a speedo cable its digital with the vss buffer box hidden under the headlight switch, and the vss sender on the trans tail...89 -92 got the vss buffer box underneath the headlight switch. 82-88 have the vss box behind the cluster. I think only some firebirds got the digital dash, I don't think i have ever seen a camaro with digital dash unless it was aftermarket. My speedo on my 88 does not work at all, I am gonna be digging into it this friday.
All I can tell you regarding the VSS replacement being THE FIX for my car is that the bronco has remained absent since I installed the replacement dash. It hasn’t been long since the replacement dash went in. So, I’m not making any sudden claims of permanent success.
I’m no wizard when it comes to these cars. I’m more like the stray dog who persists in showing up at the back door, and who is happy when someone throws me a bread crust now and then.
I thought I had the bronco whipped many times.
When I replaced the MAF, then it came back...
When I replaced the ECM, then it came back...
When I replaced the distributor, then it came back...
When I replaced the alternator, then it came back...
When I replaced the battery, then it came back...
When I buttoned up every sketchy vacuum line I could find...
So, I’m kind of spinning on any hope that I will solve the bronco.
I pretty much expect it to be stomping on my grave after I’m gone.
I have smoke-machine on order, to chase the ghost of the bronco, even if I have truly put it to bed by stray dog persistence.
Every 30 year old car HAS TO have multiple vacuum leaks, right?
Haha I feel you brother. It's really very satisfying though when you finally fix a problem you have been chasing for a while. Hopefully It doesn't come back for you and hopefully it's gone when I replace my vss. So the vss does more then just tell you the speed your going right?? surprising
So I couldn't wait till friday to inspect the cluster and just removed it now. Seems in pretty good shape and the speedo cable was attached and vss box was there. Snapped a few pics.
I was looking at the numbers and aren't the numbers on the vss box supposed to match the numbers on the cluster itself. Aren't the vss boxes cluster specific??
Previous owner said they swapped out the cluster and maybe they put on the old vss to the new cluster??? Wouldn't that cause it to not work? Everything is hooked up and my speedo is not working so something is up. Unless the cable is broken. I'm gonna follow it to the trans friday and check it its cracked or something.
I’m pretty sure the VSS converts the signal generated by the spinning cable into an electical signal that reports to the analog-face speedometer, and separately reports to the ECU.
If the speedometer isn’t moving, you either have a a busted speedometer, or a busted VSS, or a busted speedometer cable.
You could disconnect the cable at the transmission, and spin it with a drill to test. If the dash-end spins the cable is probably OK.
Posted in the classifieds asking for a cluster. Got a few hits. Waiting for pms. Hopefully a deal is made. What is a fair price for a cluster bro? I'm thinking like 60 bucks.
Hey what up. So I posted in the wanted section and got a few replies. They quoted me like 100 bucks for a nice shape v6 cluster. But before I pulled the trigger I wanted to check my local junkyard to see if I got lucky. Hopefully I did. Probably not.. Picked up a VSS from a 86 v6 auto with the 85 mph cluster. I'm gonna try it out. Are their specific vss's for auto and t5 trans? Or are they the same? Ill try it out. Also picked up a sweet 87 IROC 140 cluster in great shape. Do you think This one will work for the v6? I know the trans and diffs are geared differently but hey maybe the speed sensors work the same idk. If not Ill try to see if anyone wants to trade a v6 cluster for this one with cash on top.
Hey I was just checking out my 2.8 and their is a sensor on the passenger head at the back by the dizzy. What does this one do? Looks like a temp sender but that one I already replaced with a temp gauge.
Ran an instrument comparison test of the V8 dash in the V6 car.
Moral of the story: Dash always reads low - both tachometer and speed.
Comparing tachometer: Dash vs. Timing-Light vs. TunerPro
Comparing speedometer: Dash vs. Waze vs. TunerPro
On the tachometer test, I believe the timing-light and TunerPro were telling the truth.
The dash gauge was lying. The dash gauge gave consistently low readings. There is some inconsistency in the report below, because its almost impossible to get the motor to lock in to an exact RPM condition. The various reported gauge readings are close, but not precise. At moderate driving, add about 300 RPMS. At full beans, add about 600 rpms.
On the speedometer test, I believe Waze and TunerPro were telling the truth.
The dash gauge was lying. The dash gauge gave consistently low readings. Waze and TunerPro gave identical speed readings. Even though the speedometer dial is inaccurate, this is good information, as I am confident that the VEHICLE SPEED SENSOR in the instrument cluster is feeding accurate information to the ECU, even though the speedometer dial is showing an incorrect reading. Around town, add about 6 MPH. On the highway, add about 8 MPH.
Hey I was just checking out my 2.8 and their is a sensor on the passenger head at the back by the dizzy. What does this one do? Looks like a temp sender but that one I already replaced with a temp gauge.
If you (or anybody else) knows where the coolant temp sensor (on a 1988 manual transmission V6) that reports to the ECM is located, l'd like to know too. TunerPro tells me there are two temp sensors reporting to the ECM, one is coolant temp and the other is manifold air temp.
My understanding is that a THIRD temp sensor (coolant temp on the driver-side head) is just a "dumb" sensor that reports only to the dash gauge.
Are you sure you aren’t looking at the cold start injector?
I"m talking about this one. Looks like another temp sender. Could this one be causing my fan to come on prematurely? Does this one feed the ecm or the gauge as well. ? This is behind the pasenger side head right on the corner. I didn't mess with it much but it does seem to have the same connector as the knock sensor I think. I'm gonna replace it. I'm sure its rusted as well.
If you (or anybody else) knows where the coolant temp sensor (on a 1988 manual transmission V6) that reports to the ECM is located, l'd like to know too. TunerPro tells me there are two temp sensors reporting to the ECM, one is coolant temp and the other is manifold air temp.
My understanding is that a THIRD temp sensor (coolant temp on the driver-side head) is just a "dumb" sensor that reports only to the dash gauge.
I did some digging. Driver side head coolant temp sender is for the gauge in the cluster.
Sensor "CTS"Coolant temp sensor is for the ecm, Located beneath throttle body on the intake manifold black and yellow wire.
The one behind the passenger side head is called the cooling fan switch which tells the fans when to come on. I'll be swapping this one out tommorrow see if it fixes my problem with fan coming on prematurely. Part Number: SW502
I guess the switch for the fan is the item on this diagram listed as "N13 - Fan Override Switch"
And clearly it is listed as not ECM controlled.
So, we've actually got FOUR temperature sensors on this V6 motor?:
1. coolant temp - reports to ECU - located near thermostat housing
2. manifold air temp - reports to ECU - located near throttle body
3. coolant temp - does not report to ECU - reports only to dash gauge - location of sensor is near front of driver-side head
4. fan override switch - does not report to ECU - reports only to fan relay - location of sensor is near rear of passenger-side head
Why "override" switch, and not just "fan switch."
What is being overridden that would logically require such designation.
Apologies if I'm beating the subject to death.
Pic copied from a previous cold-start-injector thread.
Ignore red arrows in this context.
These are the sensors/switches and their functions ;
In the intake manifold at the front left hand side , there are two , the CSI switch , which reads the coolant temp and controls the CSI only , no ECM involvement , and the ECM's coolant temp sensor which does tell the ECM the coolant temp so the ECM can rich/lean the mixture depending on engine temperature and command the radiator fan to turn on at the proper temp .
The passenger's side cyl head near the back of the engine , the "fan override switch" , this switch controls the radiator fan in the event the ECM fails to . Just as the fuel pump has two means of control (Oil pressure switch and ECM control of the fuel pump relay) , the radiator fan relay has 3 means of control and can be commanded by either the ECM temp sensor , the passenger's side fan override switch , or by putting the A/C control to the "Max cool" position , thus three independent means of triggering the radiator fan depending on engine temperature conditions/A/C control lever position .
The drivers side cyl head at the front of the head , this sensor controls the dashboard mounted temperature gauge only , no ECM involvement .
Mounted in the incoming airflow of the air induction system , the IAT sensor , Intake Air Temp , which reports to the ECM the temperature of the ambient air coming into the manifold , used by the ECM to tailor fuel mixture to the ambient air temp .
So there are 5 devices measuring temperature ;
1, CSI switch (No ECM involvement)
2 , ECM coolant temp sensor (Reports to ECM , Will control mixture/timing as well as the radiator fan)
3 , Fan override switch (No ECM involvement but will "cover for" the ECM if the ECM fails to command the fan , hence it's name "fan override switch" . Normally the ECM should be in command of the fan , but if for whatever reason it does not , the fan override switch will prevent a cooked engine)
4 , Dash gauge sensor (No ECM involvement)
5 , IAT sensor (reports ambient air temp to the ECM)
Also , just to throw it into the mix , the "02 sensor" in the exhaust is technically a temperature sensor also , It's not directly measuring the amount of oxygen in the exhaust flow despite it's name , it's actually measuring the exhaust temperature and the ECM extrapolates it's readings into an oxygen reading of ; higher temp = lean mixture = more oxygen , lower temp = rich mixture = less oxygen .
I hope I helped you and feel free to ask as many questions as you need to understand the functioning of these systems .
Last edited by OrangeBird; 07-18-2018 at 05:55 AM.
Reason: Clarify a point that I didn't explain too well in my first posting of this answer , the function of the fan override switch .
I still have not swapped out the "fan override switch" so I don't know if that's the cause of my fan coming on within minutes and staying on. Will know by saturday.
So I have been driving it after my little tuneup. I replaced every ignition component, pick up coil, icm, cap rotor, plugs, ig coil. Runs better. Have a few more pronounced issues.
It Idles high in neutral(T5). My tach is not so accurate it reads around 3000 . But sounds more like 2500-2000. Does not matter if its hot or cold. Well I guess it really never gets to operating temp since the cooling fan comes on within minutes and stays on.
Never turns off. Even if I drive for an hour or so and park the car, then I come back say 20 minutes later and try to start the fans come on as soon as I turn the ignition switch (car off).
Only time fans turn off is if I park it overnight. Next morning on cold start they are off. Few minutes and they come on.
Sometimes at cold start it starts up but very rough sounds like its misfiring, I have to give it gas, raise the rpms and hold it there then the idles sounds better.
Earlier I was under the hood and I was revving the engine and noticed there is this rattling noise coming from the egr whenever I would revv it. Could this cause a rough idle/ high idle. I'm gonna swap as well.
Still a few thing I wanna check. I wanna adjust tps, remove iacv and check for clogged passages, Swap out stock injectors to newer rochester injectors, replace fuel filter. Might swap out fpr just to eliminate causes.
With regard to the high idle, have you done a complete check for vacuum leaks?
A good timing light will have a tachometer function. Compare the timing light RPM to your dash.
Does your car still have the "cannonball" vacuum reservoir underneath the charcoal cannister?
Today I made some progress. Looked around and no vacuum leaks to be found. But will be replacing some plumbing when I swap injectors. Some plastic lines have black tape on them(previous owner).
I do have the vacuum ball but still haven't thoroughly inspected those lines I have a simple autozone timing light so I cant test the tach accuracy just yet.
So today I swapped out the old 'fan override switch". I measured the resistance on it and it was all over the place. Kinda rusty too. Swapped in the new switch and fired it up. Old switch was bad.
Fan didn't come on after a few minutes so I knew that was it. I waited for it to warm up to see when the fans would come on. To my surprise my "equus" mechanical gauge is deadly accurate. Fan turned on exactly at 238 degrees farenheit. Problem fixed.
I will be swapping out egr, old injectors, fpr and fuel filter. See if it fixes my high idle. Still haven't had time to swap in my "new" v6 vss . Will update soon
So I swapped out my stock injectors for a set of 92 3.1 injectors. Swapped out fpr, still had the original fpr, had been in there 30 years. Was falling apart.
I made sure I had no leaks from the plastic lines, secured everything down. Swapped out some vacuum lines. Before the swap It would take few seconds to start up and most of the time require me to give it gas and It would idle rough but eventually fix itself.
Now It starts up almost instantly idles great, old injectors were the single pintle design. I fixed the high idle problem. Tracked it down to the throttle body butterfly spring. Wasn't closing all the way. Sprayed some WD-40 and fixed the issue.
Still have a few issues though. When downshifting it stalls out. Lets say I go 1st, 2nd,3rd and 4th. When I begin to downshift..........I'm in fourth...downshifting to 3rd goes good.........rpms coming down...........then if I try to downshift to 2nd or just push the clutch in to come to a stop, rpms drop all the way and it seems like it wants to fix the idle but then stalls.
Any idea what this could be. My egr makes a rattle when I rev up my engine. I plugged my egr vaccum line to see if that's what's causing the stalling. Will test drive tomorrow.
Another thing I tested my TPS with a DVOM. With key on car off I'm getting 0.38 v at the tps wire. I read that it's supposed to be at 0.54 v? Volts go up good and at WOT it tops out at 4.29 v. Is this ok or does it need adjusting??
Oh and another thing W.E.G., the bucking bronco seems to have disappeared. Haven't had any bucking since injector swap. Still getting a code 34 and 24. Still haven't had a chance to put in my new vss.. I checked voltage at MAF connector and it checks out. What can I clean the MAF with?
So I kept getting code 24 with code 34 together even after replacing maf sensor with a new unit. So I finally got around to changing my torque arm bushing from hell, and While I was down there I checked the cable and it was broken right were it goes into the trans. Cool. Picked up a new cable hooked everything back up. Speedo works now. Does code 24 and code 34 go together? I have no codes now and was wondering what does the vss have to do with code 34?
07-01-2018, 09:43 PM
Funny you mention that because I'm getting a code 24 for VSS, also a code 34 for MAF, also my cooling fan turns on within minutes of a cold start. I swapped out my cts thinking that would solve that issue but no go. I checked fan wiring and everything is un nmolested. 
Haha I feel you brother. It's really very satisfying though when you finally fix a problem you have been chasing for a while. Hopefully It doesn't come back for you and hopefully it's gone when I replace my vss. So the vss does more then just tell you the speed your going right?? surprising
Hi W.E.G. , 
Was falling apart.