air intake sensor?

dwhiskie · Sep 14, 2006

air intake temp sensor?

Is there anyway to check this to see if its working? There is 5v going to it but when I was at the dyno, the guy said it was showing a reading of 29* but he would wiggle the wires at the connector and the graph was moving all over the place.

vristang · Sep 14, 2006

Sounds like the problem is with the connector/plug, and the sensor may be just fine.

JRichker has some good posts on diagnosing the ACT/ECT.

You may be able to see the problem just by looking at the plugs?

jason

mob · Sep 14, 2006

Are you talking about the ACT? (air charge temp sensor) If you pull the codes itll probably tell you if its not reading correctly. I had to replace mine a few days ago, 18 bucks, id go ahead and replace it if you havent before, mine was black when i pulled it out.

dwhiskie · Sep 14, 2006

I ran codes awhile back and nothing to do with it came up. But if its just 18. or so I will replace it. Thanks

HISSIN50 · Sep 14, 2006

It might not spit a code because the temperature reading is within absolute spec (though not correct for the situation).

Before replacing the sensor, I'd check the wiring and connections. A new sensor will also read off if the wiring is bad.

Good luck.

dwhiskie · Sep 15, 2006

HISSIN50 said:
It might not spit a code because the temperature reading is within absolute spec (though not correct for the situation).

Before replacing the sensor, I'd check the wiring and connections. A new sensor will also read off if the wiring is bad.

Good luck.

The only check I know was to check volts at the connector and I got 5v. I wiggled the wires and it didnt change the reading. I did pull it out and the wire thats hangs in between is touching one of the sides and was all black and I dont see on the new one the wire in the center is not touching the sides so maybe it was grounding itself out? Just a thought.

HISSIN50 · Sep 15, 2006

You can ohm the sensor out. This allows you to see the signal return (it's a thermistor and you can also check it using the volt scale on your meter. Out of habit, I check resistance). You can have 5 volts going into the sensor but if the output is poop (because of the sensor or a wiring issue), it matters not.

Also as I recall, more resistance equates to a lower temp. So if you were reading really cool temps, there could be a wiring issue (like a semi-short, or just a bad ACT). You could ohm out the return wire between the puter and ACT (or just use your meter at the ACT pin at the puter - then you see exactly what the puter sees).

That post about ACT/ECT values from Jrichker [that Jason mentioned] will help. JR will probably post the info in the morning.

Good luck.

jrichker · Sep 15, 2006

Computer Pin 25 ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Computer Pin 7 ECT signal in. at 176 degrees F it should be .80 volts

The ACT & ECT have the same thermistor, so the table values are the same.

Here's the table: The values are +/- 15%, so don't get worried if your readings vary a little bit.

Voltages are measured across the two connector pins of the sensor with the sensor connected.
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

dwhiskie · Sep 15, 2006

jrichker said:
Computer Pin 25 ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Computer Pin 7 ECT signal in. at 176 degrees F it should be .80 volts

The ACT & ECT have the same thermistor, so the table values are the same.

Here's the table: The values are +/- 15%, so don't get worried if your readings vary a little bit.

Voltages are measured across the two connector pins of the sensor with the sensor connected.
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

So in order to do the voltage check at the connector I need to tap into the 2 wires, start car and as it warms up I should see voltage drop? If volts do drop then that should tell me there isnt a problem with the wiring correct? Which wire do I use for +? Thanks

90_Red_LX · Sep 15, 2006

Is there an advantage to having it in the airbox? Such as it reads cooler air so the eec adds more timing? Just curious if it's worth the trouble to relocate it.

dwhiskie · Sep 15, 2006

90_Red_LX said:
Is there an advantage to having it in the airbox? Such as it reads cooler air so the eec adds more timing? Just curious if it's worth the trouble to relocate it.

It also adds more fuel

90_Red_LX · Sep 15, 2006

What all does it take to relocate it? Is the factory wiring long enough to reach it?

dwhiskie · Sep 15, 2006

90_Red_LX said:
What all does it take to relocate it? Is the factory wiring long enough to reach it?

Not even close .... in my case I dont want to move, I just want to fix it because I only get 10 miles/gal now

vristang · Sep 16, 2006

90_Red_LX said:
What all does it take to relocate it? Is the factory wiring long enough to reach it?

When it comes to car tuning there are basically 2 camps.
One feels that ANY change from what the factory did, will be an improvement.
The other feels that the factory did a good job of providing a solid reliable tune.

I am in the latter group. Here is why...
The ACT was mounted in the intake manifold where it would measure the temperature of the incoming charge rather accurately. In other words, the temperature that the ACT picks up is going to be VERY close to the actual temp of the air when it hits the back of the intake valve.
All uses of the ACT signal are based upon the assumption that the ACT is in a given location.
Both Ignition Timing and Injector Pulsewidths will be affected by relocating the ACT to the air box.
Whether or not relocating the ACT will improve performance will depend on the car.

I acknowledge that I could be completely wrong on this, but I figure that Ford set the 5.0 up this way for a reason. Ford invested a great deal of resources in the A9* computers.

My thoughts on the matter,
jason

cj99 · Sep 16, 2006

mines not even hooked up. when i dropped the new motor in and was hooking up wires i found it , but nothing plugged into it. nor do i see a place for it. its right next to the water temp plug right ?
i have a performer intake and dont know where to put it ?
what do you think i should do about it. looks like basicly the same plug as the water temp.

HISSIN50 · Sep 16, 2006

I'd only note that for anyone (90 Red LX, et al) who needs to move the sensor to the airbox, JRichker has a nice little write-up outlining extending the wires and what to do.

In general, the cars designed for the ACT to be in the air inlet/airbox seem to be really finicky about the ACT calibration. ACT's in the lower can have hair growin' off of 'em and still can read halfway decently. For instance, the T4 processor starts to hose with the tune with very mild ACT temps; it takes considerably more heat for an A9 processor to change things up.

I have always thought like Jason in that the OEM R&D (millions spent) is tough to beat. I only hose with it if I have an issue and it's most feasible (read cheapest) to fix it another way.

And I have wondered if there is a correction factor for the differing ACT locations (air box vs lower).

Good luck.

vristang · Sep 16, 2006

cj99 said:
mines not even hooked up. when i dropped the new motor in and was hooking up wires i found it , but nothing plugged into it. nor do i see a place for it. its right next to the water temp plug right ?
i have a performer intake and dont know where to put it ?
what do you think i should do about it. looks like basicly the same plug as the water temp.

The plugs on the ACT and ECT should be similar, but not the same.
The ACT and ECT are internally the same thing. Externally, the ACT element is more exposed to better sense the rather rapid changes in temperature that can be seen in the intake.

The ECT is on the pass. side and threads into the heater tubes.

I don't remember where the stock ACT was. My Lightning lower has it in the runner of #5.

If there are no threaded holes common to an intake runner in the Edelbrock intake, then you have the option of drilling and tapping a hole, or locating the ACT somewhere else.
Without the ACT signal the computer is in an alternate strategy. This is not really a "limp" mode, but it isn't ideal either.

Search through some old threads on Edelbrock and ACT. You should find a couple of common methods of dealing with this issue.

Personally, I would try very hard to keep the ACT in the lower intake manifold. But having the ACT mounted anywhere is better than not having it at all.

jason

jrichker · Sep 16, 2006

dwhiskie said:
So in order to do the voltage check at the connector I need to tap into the 2 wires, start car and as it warms up I should see voltage drop? If volts do drop then that should tell me there isnt a problem with the wiring correct? Which wire do I use for +? Thanks

Two safety pins can be used to probe the wiring from the rear of the connector. Connect the black wire on the DVM to the black/white wire on the sensor. Connect the red wire on the DVM to the lt green/pink wire on the sensor

The ACT relocation in my case was due to the use of an Explorer intake manifold which had no place for the ACT. That's why I put it in the airbox.

dwhiskie · Sep 16, 2006

jrichker said:
Two safety pins can be used to probe the wiring from the rear of the connector. Connect the black wire on the DVM to the black/white wire on the sensor. Connect the red wire on the DVM to the lt green/pink wire on the sensor

Thanks, I will try that today and respond back what I find out.

The ACT relocation in my case was due to the use of an Explorer intake manifold which had no place for the ACT. That's why I put it in the airbox.

dwhiskie · Sep 16, 2006

Ok. Drove it around to get it up to temp (180*Stat) and volts were right around .8 when temp gage was a little under 180 so the wiring must be fine. I replaced the sensor so I hope its working but will know forsure when I take it back to the dyno. Thanks for your help

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