Need some help guys...

[Burkey]

We are on the same path. I like to isolate the fault as much as possible and not just guess at it based on the symptom. That is why I have reserved to make a foregone conclusion until I see some additional checks. I want to see what the resistance is with the display reading -71F. Theoretically that value should not even be reached based on the datasheets I found or the one Edelbrock provided him. -40F is just under 1meg. But for some reason Edelbrock has spanned the sensor much wider than this. So I want to know the resistance when it reads -71. If that resistance is greater than 1meg then we can conclude that the sensor is likely whacked or the wrong sensor (they use this head unit for other mfgr's as well) or there is a corrupted file that is used in the algorithm to convert the resistance to a known numeric value (IOW - the data/process used to span the sensor).

Agreed.
Honestly, the advice you’ve provided so far has been absolutely EXCELLENT. I’m not even going to vaguely dispute that. Top notch.
All I’m saying is that “sometimes” you can’t get sensors to play the game, making the fault finding game basically impossible.
If you can get it to play along, that’s a whole other story of course.

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[Burkey]

^^^ Sounds like half of the work orders I go out on at work......intermittent. Hard to fix something when it ain't broke. Finally the problem raises its head and I can isolate it down once it gets intermittent enough over time. Likewise I just don't want to falsely conclude a bad IAT sensor, and then you convince Edelbrock to send you a new one and it ends up not being the problem. That -71F is puzzling being it isn't even on the resistance sheet for the sensor.

Is it possible that -71 is simply the max (min) reading that the ECU will even recognise?
Eg. If the resistance went to let’s say somewhere closer to infinite, would the ECU just call it quits at -71?

 

[Jobodizo]

That would be my guess. Sensor essentially opens, but not quite, and the computer sees just enough to keep from throwing the code. Otherwise why would it ALWAYS be -71?

 

[ugstang17]

Is it possible that -71 is simply the max (min) reading that the ECU will even recognise?
Eg. If the resistance went to let’s say somewhere closer to infinite, would the ECU just call it quits at -71?

If it is it is IMHO very close to being at a point that the ECU would sense an out of range state or simulated open in the circuit based on the data found on page 2 of this thread. AT some point a CEL should be generated. IF OP disconnects the sensor he gets an out of range IAT CEL. So that suggest to me that below a certain level on the 0-5v range that the temp is spanned to (based on the resistance range of the thermistor) the ECU will generate a CEL (out of range or open sensor). What is odd though is the datasheet on page two only indicates that the sensor span ranges from -40F - +150F. It may go higher than that (hopefully because IAT's can go higher than 150 on a really hot day in slow moving traffic with an open air kit on higher boost applications using he stock HE. SO the sensor may be capable of higher than that and edelbrock is only providing standard seen operating range for this boost application.

I am pretty confident that the IAT is the issue. However since I am not standing in front of the vehicle doing all the checks I would like to, to be more conclusive so I cannot say for sure. And I hate to guess at another persons expense and/or effort. What would be interesting would be to pull the sensor out of the unit, hook a multimeter to it to measure resistance, set up another meter with a thermocouple and measure temp F and place the sensor in a freezer to see how high the resistance will go and compare to the temp. Then hit it with a hair dryer and see how low the sensor will go in resistance. Afterwards compare those findings with the table Edelbrock provided the OP.

Why span to -71F is my other question if that is a legit output? Climate zones capable of that level of cold are very few and its doubtful they seek Mustangs. Anchorage, AK in January averages 11F so its doubtful it would get anywhere near -71F there and if it did I doubt anyone would be driving their FI mustang that day. LOL! So I don't even get why the temp is spanned that low if it is.

 

[Jobodizo]

@ugstang17 and @Burkey I HAVE A VERIFIED CAUSE!!! 66.5kohm at 39* ambient!

 

[Burkey]

@ugstang17 and @Burkey I HAVE A VERIFIED CAUSE!!! 66.5kohm at 39* ambient!

Fuck YES!!!!!!!
Ding ding ding...we have a winner
Nice one mate. Really glad you found it. Sucks when things aren’t going in the right direction

 

[ugstang17]

Appears it would be the IAT. I'd push on that seeing the additional data. 66.5Kohm should be displaying about 45F according to your sheet. With a 15% accuracy based on the datasheet you are on the edge of being in the range of the sensor. At 66.5Kohm according to the sheet and given +/- 15%, 15% less 45F would be 38.35F. But given the intermittent findings and seeing this reading as it is I am inclined to believe the IAT is damaged. See if they will send you a new one. As Burkey has mentioned if hte sensor has been damaged it could be flaking out intermittently when it warms up or just through expansion and contraction from warm to cold over time. You've proved out your wiring with little doubt.

Sorry to be so skeptical. I remember reading some time back on another site about an SC maker who fudged their IAT temps lower to proclaim they had the most efficient flowing SC on the market. All they had done was throw a correction factor into tune on the IAT. There is a place in the tune tables to correct for this based on location of the IAT. IAT sensors are to be as close to the cylinder as possible in SC applications(Greg Banish - Advanced Tuning pg 25). When that is not possible as in the case of some centri setups, there is a correction factor input to allow for the heat the air will pick up between the IAT and the cylinder. This is also used even on PD applications when the sensor is actually in the runner like on Roush, VMP, and the older Saleen and Whipple configs. I can't speak for the current Whipple since I have not seen one yet. I only mention this because of the inability to look at the tune data to see if there is an issue there. I hate taking the unseen for granted. It has bit me in the ass in the past. Not being argumentative here, just questioning the unknown.

one last thing.....With your SCTX4 (I am assuming they sent the tune on an X4 right?) set the gauge setting up to monitor IAT and see how it compares to the LCD display. If you really wanted to get crafty download Livelink II form the SCT website to your laptop, and datalog through the X4. Creating a cfg is very easy. The datalog saves as a .csv file that can be opened with Excel spreadsheet as well. I personally like to look at my logs on Livelink II because it graphs everything. I've never been a big fan of datalogging on the handheld and then having to download it to the laptop to look at everything. PITA in my opinion.

I'll STFU now and wait to see what that IAT sensor replacement does for you.

 

[Jobodizo]

I just want it to be over.

I started this fiasco when (apparently) EVERYBODY at Edelbrock was on vacation. A week later I finally got ahold of a tech guy who sent me harnesses. Then I spent 1.5 hours on the phone with him when the harnesses didn't work. Then he was supposed to call me back at 5pm my time the next day when I got off from work, but I called later when I hadn't heard from him and discovered he leaves at 2. Now he's been out sick since and nobody else wants to help me because "they don't know what direction he was headed." Thousands of dollars into a $40k car only to have to rent a car for 2 weeks. I just want my car back. If Edelbrock wastes postage sending me a $20 (retail) sensor only to have it not work, I'm ok with that.

Not bashing, @ugstang17 , just desperate at this point. I'm a mechanical guy, so things that go zap I only loosely understand and I'm out of my element. Wiring for me falls under the "jack of all trades, master of none" heading.

If I don't have a concrete answer by the end of the week, I'm towing my car up to Lebanon Ford for them to install a Roush system (since they do an unholy amount of Roush installs). Don't know where that'll leave me with Edelbrock, but I'll get my money back somehwere. Whether it's a forum member who's willing to troubleshoot or a refund.

 

[ugstang17]

PM sent, Nothing personal taken. We're just trying to solve the puzzle. 30+ years troubleshooting electronics/electrical/electromechanical...doesn't make me an expert, dosen't make me right, just trying to use my skills/eperience to help another enthusiast out of a tight spot.

 

[Jobodizo]

They say the calibration is correct, but they’ll check it again. They’re overnighting a sensor. Hopefully this finally gets me there. Fingers crossed.

 

[ugstang17]

They say the calibration is correct, but they’ll check it again. They’re overnighting a sensor. Hopefully this finally gets me there. Fingers crossed.

 

[Jobodizo]

No go guys. They sent the new sensor, I installed it, -74*. I pulled the harness, disassembled the plug, squeezed the contacts, added dielectric grease, reassembled, -74*. Pulled the battery for 5 seconds, 32*. Let it sit over night, -74*.

 

[ugstang17]

That is what I was afraid of. What is the resistance at that temp? Then compare it to the resistance on the one you took out of the car. If its way less than 1 meg They have an issue with how they have spanned the sensor or they have a bad fun on sensors. Datalog it also and see if the IAT is different on the IAT than on the display. That way if they are the same they can't blame the car for the issue. Also datalog the MAF readings. That way they can see both. I only say this because the harness is splitting the IAT and MAF signals so the IAT2 can be seen on IAT making the IAT in the AIr intake path unused.

THat brings up another thing. Up until 2015 or so these kits ran IAT2 straight into the ECU. THey did not splice into the MAF harness and redirect IATs sensor to IAT. Make sure the tech support guy isn't having a brain fart and looking at IAT2 curves rather then IAT on the base tune they sent you. If it has not been properly spanned you could have a properly working IAT sensor but have a bad reading. You have to eliminate the probable faults when troubleshooting. If it wasn't for the frickin snow coming I would be tempted to invite myself down to look at it with you. But the man above is apparently planning to dump 4-6" on us Saturday.

This can be solved man. Don't lose faith. It may require some higher intervention but trust me they can resolve it. Give them a call and tell them I recommended you and see if they have come across this. Brian is one that will give you some quick tips if its something he has seen to avoid you having to haul the car up there. I am sure he has installed some of these. Terry Reeves is a distrib for the E-force. So chances are he's done them and may have seen this problem. Just duckduckgo.com and search Finishine performance. OR PM me and I will send you their number.

 

[Jobodizo]

@ugstang17 I'm relatively new to tuning anything without jets and power valves. What's the (4th grader) difference between IAT and IAT2? I didn't realize there was more than one? When I was getting my P0113 I'm pretty sure the X4 read "IAT2 high."

When datalogging, will IAT show up on the x4's default program? Or do I need to create one with this livewire program?

I have every intention of calling Finishline today. I seriously doubt I'll get anything done at work, lol. I'm also going to call Brenspeed. They're 4 hours away, so I'm not actually going to tow the car there when Finishline is 2 hours away, but they're kinda the eForce unofficial YouTube spokespeople. Maybe one of these shops has seen something...

 

[ugstang17]

IAT will be on the default log file on the X4. IAT2 will not be a factor on 15+ setups. However that all said, it is easier to download livelink II to a laptop, link it to the X4 hooked to the car and create configuration (cfg) and datalog through that. You have my phone number so you can call me if you want to step through it together. The livelink will prompt you on what all to do. I can also make a cfg for you to use so all you have to do is save it to a folder and then select if when you use live link. PM me with an email address if you want to go this route. Otherwise you can datalog through the X4 OR initially just use the gauge function and monitor IAT (should be a default as I remember) and see what it reads when you connect up. You have 8-12 PIDs on teh gauge function you can select and/or change to monitor in that mode on the X4. I have only played with it a little bit as my previous two cars were on X3 and that function was not available on them.

I am at work so if you call leave a VM if I don't answer. I'll look up the area code for your area so I know its not a person trying to peddle me a back brace or medicare (they think I am my dad I guess).

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