Need some help guys...

[Jobodizo]

False alarm. 24 hours later and it’s -71 out again. FMFL

Tried to start the car and it cranked, sputtered, died. Pulled the battery for 30 min and got the temp back. Took ~5-7 sec of cranking but it did start after that and ran SUPER rich.

Any thoughts, guys? I’m on day 7 of car rental here. It’s almost like it’s forgetting to look for the temp after a certain amount of time with battery power?

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[ugstang17]

First things first here. Since crystal balls and magic 8 balls are fictitious, how about some history before a bunch of spit in the wind guessing? Was the car completely stock before the install? And exactly what kit did you purchase....meaning is it a full turn key kit that is all edelbrock OR is it a tuner kit with a third party tune? What CEL codes are currently present and is the car in limp mode? What hand held tuner are you using? Have you verified that the data you provided the supplier is correct on the shipping list with regard to the tune? Before a bunch of blind guessing begins this 411 needs to be provided to establish a better baseline to base a theory of approach on.

 

[Jobodizo]

@ugstang17 if only the magic 8 ball had a car problem version.

The car was not "stock" when I put the kit on, but had nothing on it that would affect tune. Only thing even related to engine running parameters is the K&N drop in, but if that's doing this I'll eat my shoe (the kit also it came with a drop in green filter). I did suspension, Steeda IRS stuff, driveshaft, and exhaust...pretty much all the "warranty saving" stuff when it came to the engine itself.

The kit is a 15865 complete stage 1 kit which came with an SCT X4, tune (91 octane in my case), 47lb Ford Performance injectors, and the blower has the Eaton 2650 rotor pack. Edelbrock says no BAP is required for the provided injectors/tune. Only thing I bought for the install was coolant (Ford orange prediluted). All of the harnesses were PnP until I soldered the AIT harness into the MAF harness. So I'm no longer getting NO reading, the reading just doesn't make sense.

As far as the tune, and all I did during programming was select the 3.55 diff. To get the tune I supplied them with ECU strategy and ECU SWPN read from the X4.

With the way it stands right now, since Edelbrock gave me the new throttle extension harness and I soldered the AIT harness, I'm no longer in limp mode and have no CEL. The AIT is just reading -71*F, which means the car is DUMPING fuel trying to start. It'll crank, turn over, sputter, die. It WILL start if I pull the battery and let the temperature reset to match (within a few degrees) the head temp reading. As far as I know, the car would run if I just unplugged the battery every time I stopped somewhere, I just can't do that.

Any other info that would be helpful?

 

[ugstang17]

So what you need to do now is probe the IAT sensor with your volt/ohm meter and see what the resistance reads. It should be reading close to or near the ambient temp the car is sitting in prior to being started and with a cold engine. OAT's in your area are 25-50 degrees currently I am guessing so that means it the sensor is working correctly it should read between 123.5K ohms and 60K ohms. Lower resistance than that if it is sitting in a heated or insulated area (reference the chart). If it does read in that correct range, start the car and just let it sit and idle up to temp. Do not attempt to probe the sensor with it running. Lower the hood while its running to allow heat to build up and change to give the sensor time to respond and start changing. Monitor the reading from the dash. If the dash changes to -71 again, immediately shut the car off and take the sensor reading again in ohms with your meter. What does it read now? Wiggle the sensor to see if the reading abruptly changes and record that also. Then let the car sit and cool down. After time has passed take the reading again without starting the car. Did the sensor reading change massively as in going from from like 925Kohm to suddenly 123.5 - 60kohm again? With KEOE (nost starting the engine) does your LCD IAT display read -71 still or has it changed to something closer to the ambient air temp around the car? There are several possibilities here. Rather make an informed conclusion rather than a spit-wad-at-he-wall guess without any data.

Take these readings because they are the first steps into resolving the issue. A good indication would be that you are seeing greater than 925Kohm on the sensor when the LCD display reading is at -71F when this happens. Then we only need to ascertain if there is a problem in the wiring harness they sent you, a problem in the sensor itself OR a possible connection issue where the adapter harness connects into the car. I agree that the ECU is seeing -71F and saying WHOA! I need to add fuel because the ait is fricking dense! So focus stricly on resolving this and then if other issues persist we can put that issue behind and move on. Make sense?

 

[Jobodizo]

@ugstang17 makes sense, thanks. I'm sure if it wasn't my car and I was helping to diagnose I'd be doing all these things, but because I'm freaked out I'm bouncing all over the place, lol. Any idea what voltage the car is supposed to be supplying to IAT probe?

 

[ugstang17]

The output of the IAT signal (if it's the same as on the 14 down) should be 5 volts or so. The voltage is dropped across the IAT sensor. The path is completed back to an internal common on the ECU called sig-return. They do this to isolate signals from noise. Be VERY cautious checking voltage on the ECU. You could damage the unit if the probe you are using to read the 5vdc slips and shorts to frame ground. Also remember that you may not be able to get a good reading if you attempt to read the 5vdc signal to frame ground because it is part of an isolated circuit within the ECU. So this means you need to read the 5vdc across the pins and again be careful you don't arc the probes together attempting to do that.

My hunch is that since the ECU is dumping fuel it is getting a proper feedback of some nature that is within the limits of the sensor range in the table within the tune for IAT. We will only know more when you probe that sensor and notate the resistance. This is the first step. If the ECU was not putting out any voltage at all I would conclude that you would have a CEL. AN indication of 0 volts or 5 volts would generate an out of range code as a guess. That is how most spans within equipment are set up today. They span inside the 0-5vdc something like .5-4.5vdc and anything outside of that range is seen as out of range and generates a fault (CEL).

Hope this helps.

 

[Jobodizo]

Ok here we go:

Couldn’t get run resistance obviously, because the engine would code for an open circuit. The 21 number is after 10-15 seconds of heat soak with me jumping out, unplugging, getting the meter on it. Numbers essentially track when you consider it was IAT of 86* by the time I reconnected the sensor and checked again.

The IAT appeared as normal and the car restarted just fine after this. It’s supposed to be in the 50s here through Wednesday morning, so if this is a cold-related thing I might not get my -71 until then. I’ll update if it pops up again. Intermittent weirdness is almost scarier than consistent.

 

[ugstang17]

The readings are showing low but they are close. 50F on the sheet indicates 50.016K and your actual is 47.33K (2.686K diff). The 74F is 21.9K and actual should be just under 30K. Since the sensor is not linear, I cannot calculate exact temps but it does appear that the sensor is reading low. It appears that the sensor is not providing the proper temp range. Have you rung our your wiring harness to make sure you don't have an intermittent open? I am trying to figure out why your kohm readings are low (temp display should be reading higher) yet the -71F on the display indicates that the sensor is reading greater than 1 megohm though it is only rated to -40F.

21.96kohm should be indicating a temp closer to 90F and not 74F according to the chart.
47.33kohm on your initial reading is within 1 degree of proper reading according to the chart.

How long does the car have to run to get the -71F temp? Or does it read like that after sitting overnight? Try to get a reading on that sensor when the display is showing -71F. There is something very odd going on there. given the OAT's the IAT range at warm up and sitting at idle should be 40-120F. That would be a resistance reading anywhere between 75K and 11K on the sensor. When the display indicates -71 if you take your reading on the sensor as you have and it reads within this range, then I suggest you have a corrupted tune file. The only other possibility would be that they installed the wrong IAT sensor (assuming other vehicles may use another sensor range) or the sensor itself is bad. You have verified your wiring several times so I doubt there is an issue there.

Otherwise as I would have to do at work some times, pick the phone up and call the tech support guys and tell them your findings. Maybe they have run across this before as well. Having done tech support in the past I kept a running log of problems so I cold see trends. They surely do the same thing. If I can be of more help let me know. Just PM me.

 

[ugstang17]

BTW did that sensor ship installed on the unit? I was just looking again at the photo of the back side and that is a scary thing to have hanging out there and making it through shipment without being damaged in some way. It could be cracked and you may never know it.

if you choose to call edelbrock ask them if you could remove the IAT sensor from the circuit and put a 30kohm resistor in place just to see what the display on the car reads with KOEO (Key on engine off). The display should read 77F with exactly 30K ohm resistance on the circuit. Don't do this unless they approve it. I don't want to risk your warranty trying this without their consent. Make sure its 30K (30000 ohms). 1/2 watt should be fine.

 

[Jobodizo]

It only reads the -71 when I come back to it after sitting overnight (or some undefined long period of time). I’ll probably just have to wait til it happens again to get a reading.

Haven’t touched the ecu. Other than the door latch recall it’s never been out of my possession, so nobody should have at any point either.

I called tech support Thursday after the new PnP harness didn’t fix it. Tony (supercharger guy) spent about 1.5 hours on the phone with me, doing everything including taking control of my computer to download the SCT voltage file. I was waiting for a call back Friday with the results but he went home early, then he was out sick today. Hopefully I can catch him tomorrow.

Yes, the sensor shipped on the unit. Maybe I can just convince them to send me a new sensor so I can rule it out.

 

[ugstang17]

Check that reading in the morning (KOEO) and then measure the resistance with everything shut off as you initially did. If its way out it indicates a bad sensor 925K is the max range on the chart so in 30F+ ambient air it should be no where near this resistance and that would indicate a flaky sensor. If however the sensor reads within the range I noted above that could indicate a questionable table for IAT in the tune.

Do you have the old harness laying around? If so you could cut the end off and plug it in and that would give you a much easier source to read the voltage across the two pins with KOEO. I suspect that the voltage should be about 5vdc with the sensor out of circuit. JUST BE VERY VERY CAREFUL IF YOU DO THIS. If you feel teh least bit hesitant don't do it unless the Edelbrock guy would ask you to.

 

[Burkey]

As an electrician, I’m gonna say that the sensor is looking very suspect.
The biggest problem with stuff like this is that it can often present as “fine” when you apply a multimeter but can/will fail once you introduce voltage/load/heat/vibration/moisture/day of the week etc etc
In short, it’s sometimes difficult to replicate the exact conditions that cause the fault in the first place and you can drive yourself nuts in the process. Often the resolution is based on a best guess rather than any absolute confirmation via a multimeter.
As @ugstang17 has mentioned, the location isn’t ideal for shipping.
Outside of that, faulty production of electrical components can and will occur from time to time so it may not even be related to the shipping.
Hope you get it sorted soon, best of luck with it.

 

[ugstang17]

As an electrician, I’m gonna say that the sensor is looking very suspect.
The biggest problem with stuff like this is that it can often present as “fine” when you apply a multimeter but can/will fail once you introduce voltage/load/heat/vibration/moisture/day of the week etc etc
In short, it’s sometimes difficult to replicate the exact conditions that cause the fault in the first place and you can drive yourself nuts in the process. Often the resolution is based on a best guess rather than any absolute confirmation via a multimeter.
As @ugstang17 has mentioned, the location isn’t ideal for shipping.
Outside of that, faulty production of electrical components can and will occur from time to time so it may not even be related to the shipping.
Hope you get it sorted soon, best of luck with it.

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).

 

[Jobodizo]

Thanks for the info @Burkey I’m with you and am leaning in that direction also.

Yah, would love to get that measurement. The last 2 days I’ve been prepared to get it it hasn’t done it. I’m “hoping” it’s a temp based fault in the sensor that will present tomorrow morning when it finally drops back into the 30s here.

 

[ugstang17]

^^^ 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.

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