Ronny

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I added IAT control for fueling(8746EBL). I had problems in that both new sensors would not show in logs. I bought one and then assumng defective I replaced it as well. No go. Lead from ECU showed 5V. Verified correct pin used as well(black21). IAT 23 and IAT 25 flags checked. Using EBL IAL/CTS tables.

I was told to try this:

I believe you suggested a test for my IAT function/EBL. You suggested a 1K OHM resister to determine if the IAT sensor is OK. ECU lead-Resister-ground. It should show in the datalog as a pseudo reading.
The 1K OHM comes in a .25 Watt and a .50 watt? Which one?

I added the resister (.50 watt) and it raised the reading in WU from 104F(no IAT no sensor in place) to 124F with the test resistor in place. That tells me the ECU and WU is functional. Now the Q is why does it not work with GM sensor in place?

JP86SS

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It would appear that wherever you have installed the sensor, there is no path to the Engine or ECM ground.
You didn't use teflon tape did you?

va454ss

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Where do you have it grounded?

Ronny

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It is grounded to same wire that TPS shares. The resistor I used shared same ground and changed the deg F in log. So I will asume the ECU is OK and all is functional. Next I guess I will test resistance of the sensor itself. Now I have two of them new in box! Should I place in freezer check ohms and then warm it up a bit and compare? The prior location was under the air cleaner base with tywrap and now it is going just behind my AC at end of cold air duct.

va454ss

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Which sensor are you using? Just out of curiosity, have you tried a different ground point?

I have the birdcage style and its grounded to same point as the EBL.

Ronny

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ECU is 8746 but now EBL. Rebuilt ECU was supposedly for a 1992 F body 305 TBI but as you know is now EBL specific without regard to model. Sensor is for that vehicle. Is it possible IAT that year is not a 5V devise(5V at that lead from ECU was confirmed)? Last night I checked ground and it is fine. As stated sharing with TPS at stock wire harness access point. As stated the resister(RS) did affect the deg F. Moved it from 104F (sensor disconnected) to to 124F (resister connected). That should confirm all is OK right? Now I did not modify tables yet as expected to see the datalog to report temp without respect to table vales(100% coolant). Also flags unchecked currently. Bin as when resister was connected earlier.

I suspect my error somewhere.

My IAT is shaped kind of retangular plastic on top bottom with a V shaped bimetal strip with a pin on open end of V. I tried ohm on it last night and showed .6 on meter when frozen and .8 when above room temp. I expected a bigger swing in resistance but?

Sure I can move ground but since the TPS is fine using it why would the IAT be different? It too reports to ECU.

RFmaster

Ronny

IAT is a temperature variable thermistor that has very low resistance when hot (about 110 Ohm for Temp = 150C) and about 40 kOhm for -40C. At room temperature (25C (73F) it should be around 2.7kOhm. Connection wise, it pulls down ECM IAT input line (which is pulled up to +5 V reference via pull up resisitor). You need a good ground return back to ECM (TPS ground should be OK)

//RF

Ronny

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No polarity I presume? Why would the RS resister effect a change when the IAT is placed in line do nothing at same connections? Note that with IAT "connected" vs unconnected(open line from ECU) result was same 104d F. This AM it was positioned just inside valve covers next to TBI for a test. Must be my user error. Are all IAT operating the same on resistance as far as the GM family goes? I would think so

Ronny

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OBTW. For a connector I am using a simple push fit that I bought at NAPA for a single (trailer) running light. Any reasosn why that would not work> Fitment was perfect.

JP86SS

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I was thinking it was the physical housing not grounding to the surrounding metal correctly and causing the strange reading. I'm not sure if the housing is needed to be grounded on those or not. I drew them on my home made schematic with a ground but don't remember why.
I may have it drawn incorrectly.

Ronny

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Housing? I dont have a housing. maybe that is the issue? The sensor is tywrapped to the base of the KN cannister. Just sitting there. ECU to one of the contacts then other contact to ground. Sensor in series. Are you suggesting sensor should be wired parallel? I am not to hep on electronics!
Image does not show IAT.

JP86SS

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The actual sender housing may need to be grounded.
I'm not 100% on that but you could connect a jumper cable to the sender and connect to the engine and see if the signal changes.
Easy enough to try.

RBob

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The IAT sensor housing doesn't need to be grounded. Ronny, it sounds like you don't have an actual IAT sensor. With it unplugged from the connector it should measure about 3,000 ohms (3K) at room temperature.

Measure the sensor before you do anything else.

If it continues to measure low resistance (as posted above) then go get an IAT for a '92 Camaro with a 3.1l V6. It will be the birdcage style. Take your DVM (ohm-meter) with you when you go to purchase it. And check it at the counter. It should read about 3K ohms, which could be from 2.7K through 3.3K dependent upon the actual temperature.

RBob.

Ronny

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I am using air cleaner temp sensor? This exact one

http://www.rockauto.com/catalog/rafr...G-emissionpart

As I said this is second new one. Must be my user error.

Rock auto lists another for same application. This one

http://www.rockauto.com/catalog/rafr...G-emissionpart

How is it they are totally diff in shape? Yet same application 1992 Chev Camaro 305TBI.

This is the "only" one listed for V6

http://www.rockauto.com/catalog/rafr...G-emissionpart

RBob

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From RockAuto:

1992 CHEVROLET CAMARO RS 3.1L 189cid V6 MFI (T) : Emission : Air Charge Temperature Sensor Save My PlacePrint Send these listings to a friend Related Parts
Item Price Core Total Advice
AIRTEX Part # 5S1007 More Info
If Replacement Pigtail is Needed Use 1P1016.

$20.79

Note that the image is also from RockAuto.

RBob.

Ronny

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Thank you. I will return mine to Advance Auto and see if they have that unit.

Ronny

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Thanks to RBob and all. IAT is now functional. I used the item RBob placed in thread. Take a look at my "not so cold" air. This winter I will weld a bung into the 45 deg elbow and place the IAT there. Meantime it is tierapped to the support for radiator fan. Coolant temp sitting in traffic is 199F sensor reads 99F. I think that is good right? Environmental air temp is 62F yesterday.

Question? I am using EBL IAT/Coolant tables. Any reason to tweek them? Cold start I see my "commanded" A/F is now immedaitely changed per WB. It more closely resembles the commanded A/F. I will see commanded to 13.0 as an example and reading 13.5 on WB. I am happy with that. B4 was very lean as using 100% coolant table during warm up. Car runs so much better when cold on coolant. I have a cold-cold manifold as no crossover using Edel RPM heads with Holley Projection manifold. Comments?

Ronny

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ttt

RBob

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If the AFR is tracking OK then no need to change the IAT/CTS blend table.

RBob.

Ronny

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My OL coolant/AFR tables do not match the observed A/F on my WB. I see about .50 leaner than the table on my WB. I am thinking that is due too my VAFPR/BPC tables being off. Do you agree? I need to calibrate that table with a mighty vac but have not yet invested the $60 to do so. Initially I used Dominic's values as we both use same Aeromotive reg/same injs/same BPC BUT I tweeked them a bit to get my commanded A/F at idle(13.8/1 @ 38MAP/62 VAC) to read same on WB. I observed lean with his values at idle. I believe my WB is calibrated correctly. I hope my WB is not seeing fresh air at idle(reversion from tailpipe) as WB sensor is 18 inches back of header collector. If that is the case my idle A/F may not be read accurately by WB. No ext leaks. Seems there is a relationship between fore mentioned tables?

2tonevette

Ronny,
I had mine mounted close to were you did on my 82 vette she was getting way to much engine heated air. I moved her inside the actual air cleaner near the tbi opening and used rubber washers to isolate it from the metal, that brass seemed to pick up and hold some heat when metal to metal... I then used some clear RTV to seal the large rubber washer and nut and the brass... that seemed to make it run cooler. I don't know if you want to really screw it into a bung? I know mine was ok when driving but the heat soak effect when the car was turned off and then restarted mad it go way up... I was happy with the results seemed to make the car smoother on the go pedal... I had about a good 30 degree drop moving it inside the air cleaner on a dual setup...

Dominic Sorresso

Ron,

My WB was IN the collector. I think you want as as close to the motor as possible. And I was running C/L at idle as well as PT. My O2 sensor Xpoints were set on the lean side for idle due to the 108d LSA in the cam I had.

Ronny

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Hi Dom! I had too many sensor failures. Was in ext pipe about 2 inches behind the collector flange. Innovate suggested I move it back. I only had one spot suitable. That I will guess is 14-16 inches back. Right in front of the pass storage compartment. No further failures resulted.

My IAT is attached to the radiator fan support. I saw 100 deg IAT and 190 coolant this AM on ride to office 50 deg envionmental air temp this early AM/

Dominic Sorresso

Ron,

My ZT-2 was mounted in the collector of my TPIS headers for over a year with no issue. Where is your NB installed? Any issues with it? In fact, I just installed it on my ZR yesterday in the same spot. As for the IAT, I had installed the ZR-1 sensor(plastic bird cage) when I used it for my 84. I had it on the side of the radiator shroud.

Ronny

iTrader: (1)

NB in ext pipe 2 inch behind collector flange. heated NB.