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Tish
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WOW! that cold air is really gonna up the HP.
ypena02
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What does it read when on?
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Jobodizo
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- Thread starter
- #21
Going to hold off starting at for now. It’s run rich a few times now because of the IAT error, and I’m starting to get worried for my spark plugs and O2 sensors. Just spent the last hour and 15 minutes on the phone with Edelbrock tech support. With their supplied harness plugged in, I was reading -71° F and with the original harness plugged into the MAF sensor I was reading 169° F. Reverted back to the stock tune while I was on the phone with them and started getting an accurate reading with it plugged directly in. At this point I think the prevailing thought is that now there is an issue with the tune.
ugstang17
Well-Known Member
Does the reading stay at -71 all the time? If so pull the sensor out and do a resistance check in open ambient air. Note that value. Then hold the sensor in your hand to induce heat into it and see if the value changes. It should as the sensor is a thermistor that varies with temp. If it does not then the sensor is bad. I don't know what the resistance range to temp range the sensor is so you may have to again contact Edelbrock on that.
The IAT circuit if the same as the 11-14 has a signal output running from the ECU called IAT to one side of the thermistor passing through the thermistor and then back to the sig rtn in the ECU for completion of circuit. So as the thermistor changes resistance (not sure if up or down can be either way) with an increase in heat, the drop across the sensor changes the signal at IAT and calculated accordingly. YOu may wish to recheck connections as well. Also one of the two pins feeding the IAT2 sensor sould have a voltage output from the ECU going to the sensor. The only other thing I could think of is that the sensor by CHANCE (wouldn't know why) is polar sensitive and the wires are crisscrossed where you repaired them. That needs to be resolved or the car will not pull timing when IAT temps go above 130-135F.
The IAT circuit if the same as the 11-14 has a signal output running from the ECU called IAT to one side of the thermistor passing through the thermistor and then back to the sig rtn in the ECU for completion of circuit. So as the thermistor changes resistance (not sure if up or down can be either way) with an increase in heat, the drop across the sensor changes the signal at IAT and calculated accordingly. YOu may wish to recheck connections as well. Also one of the two pins feeding the IAT2 sensor sould have a voltage output from the ECU going to the sensor. The only other thing I could think of is that the sensor by CHANCE (wouldn't know why) is polar sensitive and the wires are crisscrossed where you repaired them. That needs to be resolved or the car will not pull timing when IAT temps go above 130-135F.
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Jobodizo
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- #23
It did the entire time I was out there last night, but ambient only moved from ~42-40*F in that time. So far I've put off removing the thermistor hoping it's just the wrong curve in the tune or something...I've already lost enough skin on my hands from the K brace.
Don't know. I have another call scheduled with them for when I get home from work tonight, so I can ask then. Being a thermistor, resistance should go up with increase in temperature. If I don't get resolution tonight, I'll put it out and test it.
It got the same reading with the new harness they sent and with the old that I repaired. Shouldn't have been possible to change wire polarity with my repair because one wire goes directly from the factory harness interface the the factory MAF interface without breaking. The only wires I soldered are the return side where the factory MAF return, factory harness return, and runner thermistor return interface.
So far I've gotten a strong recommendation for Finishline Performance (if they're good enough for Terry...) for if I can't resolve this myself. Anybody else within a couple hours drive of Louisville that anybody would recommend?
ugstang17
Well-Known Member
Disconnect the harness at the IAT2 sensor (the one on the SC). I am assuming it is accessible though they can be located in a different place based on different makers. Then connect a meter up to the sensor and set the meter to read resistance. Note the resistance value. Then start the car and allow it to warm up (you will get a CEL for the out of range because to if being disconnected) and observe the sensor resistance. The resistance should change as the inlet air rises that is passing over the sensor. My suspision based on what you are telling me is that the sensor is bad. This will be confirmed by seeing very little if any change in resistance while the engine is warming up. You won't damage the engine. You won't damage the SC. Contact Edelbrock and ask them what the resistance range on the sensor is. This will also confirm your findings further. I am confident you have a bad temp sensor that is so far out of range to the cold side that the ECU is calculating the IAT at -71. When temp sensor goes bad it usually fails hard to one full end of the spectrum or the other.
You've got this if Edelbrock will simply send you another temp sensor to install.....assuming it isn't buried in the SC housing and not accessible. My IAT sensor is exposed and mounted right on an intake runner on the passenger side between Cyl 2-3. But that is a 2300 TVS Ford Racing setup. The edelbrock as I recall from seeing the build videos may have the sensor in a different or tighter location.
You've got this if Edelbrock will simply send you another temp sensor to install.....assuming it isn't buried in the SC housing and not accessible. My IAT sensor is exposed and mounted right on an intake runner on the passenger side between Cyl 2-3. But that is a 2300 TVS Ford Racing setup. The edelbrock as I recall from seeing the build videos may have the sensor in a different or tighter location.
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Jobodizo
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- #25
@ugstang17 can and will do. The sensor isn’t quite that easy to get to, but it is accessible.
Also, thanks for the vote of confidence. Been losing my stuff over here for the last week!
Also, thanks for the vote of confidence. Been losing my stuff over here for the last week!
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ugstang17
Well-Known Member
I just found you a sensor chart for an IAT2 sensor used on 2011 Mustang GT setups. If you can pop the harness on the MAF end and read resistance there we can isolate this using the chart I have found and linked in here.
http://juchems.com/ServiceManuals/viewfile9e9d.pdf
According to the chart the sensor resistance at 14F (-10C) is approximately 160Kohms. My guess is that given the -71F the sensor will be reading greater than 250kohms which would be way off the chart. So as temp drops Resistance increases on the IAT2 sensor if it is similar to the chart I am referencing. It also appears to be a 1-5vdc input circuit the ECU is looking for. The ECU will provide 5vdc to the sensor and the sensor's resistance change will determine how much of that potential is dropped to the ref- pin going back to the ECU. What is seen on the IAT signal is what will be referenced as the voltage to degreeF the sensor is scaled to in the ECU table.
Hope this helps. Let me know if you are in need of help and we can go deeper into it on PM if need be.
http://juchems.com/ServiceManuals/viewfile9e9d.pdf
According to the chart the sensor resistance at 14F (-10C) is approximately 160Kohms. My guess is that given the -71F the sensor will be reading greater than 250kohms which would be way off the chart. So as temp drops Resistance increases on the IAT2 sensor if it is similar to the chart I am referencing. It also appears to be a 1-5vdc input circuit the ECU is looking for. The ECU will provide 5vdc to the sensor and the sensor's resistance change will determine how much of that potential is dropped to the ref- pin going back to the ECU. What is seen on the IAT signal is what will be referenced as the voltage to degreeF the sensor is scaled to in the ECU table.
Hope this helps. Let me know if you are in need of help and we can go deeper into it on PM if need be.
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Jobodizo
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- #27
So, good and bad news…
The bad news is I had a scheduled time for Edelbrock technical support to call me this afternoonwhen I was going to be home from work, only to get home and call when I hadn’t heard from him to find out he only works half days on Fridays.
I was able to talk to somebody else, and he was able to give me their resistance curve for the temperature sensor in the runners. It’s sleeting outside right now, but I’ll get outside first thing tomorrow morning and check it out. Here it is if anybody is interested:
HOWEVER... I had disconnected my battery disconnect to fully charge the battery in case there was more tuning to be done today. Because of, in addition to other things, the 45 minute wait time on hold with the Edelbrock, the car was on the charger and the battery was essentially disconnected for about two hours. I just reconnected the battery so that I could lock the doors for the night. Just for shits and giggles, I checked the gauge cluster and the IAT reading absolutely matches the head now. WTF?
The bad news is I had a scheduled time for Edelbrock technical support to call me this afternoonwhen I was going to be home from work, only to get home and call when I hadn’t heard from him to find out he only works half days on Fridays.
I was able to talk to somebody else, and he was able to give me their resistance curve for the temperature sensor in the runners. It’s sleeting outside right now, but I’ll get outside first thing tomorrow morning and check it out. Here it is if anybody is interested:
HOWEVER... I had disconnected my battery disconnect to fully charge the battery in case there was more tuning to be done today. Because of, in addition to other things, the 45 minute wait time on hold with the Edelbrock, the car was on the charger and the battery was essentially disconnected for about two hours. I just reconnected the battery so that I could lock the doors for the night. Just for shits and giggles, I checked the gauge cluster and the IAT reading absolutely matches the head now. WTF?
ugstang17
Well-Known Member
The 14F - 212F range has the same resistance as the pdf file I attached. That's good to know. Ford just does not provide the full range since it isn't applicable to IAT2 apparently. I could only speculate as to why the reading on the display screen is now working properly. The only possibility is if the voltage on the system was so low that the ECU could not produce the 5vdc out IAT so the drop measured was way off. That is a spitting in the wind hunch. These S550's are so bizarre compared to my 14 and 13 GT setups. I am really starting to miss them. I may even hold off doing any more, take the deep plunge (my idea of spending big anyway) and trading for a 13/14 GT500 this summer. I keep saying this but I have to get the Ford tech manuals and prints for this platform.
I would def start the car and let it idle up and see if the IAT is rising as it naturally will as the engine warms up and the car is sitting still with the open element air intake device. I'd still check the resistance afterward and see that it matches what the sheet says the resistance at that temp should be.
YOU DUH MAN!!!!
I would def start the car and let it idle up and see if the IAT is rising as it naturally will as the engine warms up and the car is sitting still with the open element air intake device. I'd still check the resistance afterward and see that it matches what the sheet says the resistance at that temp should be.
YOU DUH MAN!!!!
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Jobodizo
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- #29
Think I’ve got it!!!
After my successful temp measurement last night I tried to drive it this morning. I had a temp measurement, but the second I started the engine the temp measurement disappeared. After making sure the thermistor checked out, I just went ahead and hardwired the thermistor extension directly into the MAF harness and bypassed the stupid plug and play stuff. Half hour test drive and not a second without a temp measurement! Woohoo! Thanks everybody for the help along the way, especially @ugstang17!
After my successful temp measurement last night I tried to drive it this morning. I had a temp measurement, but the second I started the engine the temp measurement disappeared.
After making sure the thermistor checked out, I just went ahead and hardwired the thermistor extension directly into the MAF harness and bypassed the stupid plug and play stuff. Half hour test drive and not a second without a temp measurement! Woohoo! Thanks everybody for the help along the way, especially @ugstang17!
ugstang17
Well-Known Member
no sweat man. glad you got it all ironed out. Bring that sucker to Edgewater Raceway some time next season and blow the cobwebs out of it. They should open around March weather pending.
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