Does ECM utilize ambient air temperature sensor?

doggydaddy

New Member
Messages
12
Hello All,

Im hoping someone could help answer this question definitively.

Does ECM utilize ambient air temperature sensor?

I'm trying to chase down throttle hesitation that is causing stalling. During diagnosis I found my intake temp reading are about 10 degrees off, I have a new MAF sensor coming. Looking at ECM live readings, I'm getting these values:

80580

My dashboard temp indicates the correct temperature, I have already replaced the ambient sensor in the mirror. I just dont want to waste my time chasing a sensor if it's not a value the ECM is using. My research is finding alot of issues with climate control but nothing definitive about the ECM?

Thanks!
 

Swedish Paul

Member
Messages
1,807
That’s something I noticed on my GS. I think there is a temp sensor on the MAF and I sometimes get fuel trim issues and wonder if this is something worth replacing because it will give wrong readings in combination with the MAF.
 

conaero

Forum Owner
Messages
34,594
There is indeed a temp sensor in the MAF that by the looks of it is faulty.

The ECU is thus going to richen the fuel air mix.

Had 3 4200’s in with hesitation and stalling, 2 were pedal pots the other was the MAF where the previous service centre had removed a BMC air filter to clean it, the top rubber seal tore and deposited the bits of rubber in the MAF.
 

Swedish Paul

Member
Messages
1,807
How hard/easy is it to change the temp sensor on the MAF? Also, is it an expensive part (don’t laugh)?
 

doggydaddy

New Member
Messages
12
It’s internal so it’s a new MAF. About £130
Thanks for the reply conaero. I understand the intake air temp sensor is integral to the MAF. So the ambient air sensor is not utilized by the ECM then? Its confusing because I'm accessing the ECM module to get the live ambient air sensor value which is wrong???
 

conaero

Forum Owner
Messages
34,594
Ah I see, your talking about the wing mirror sensor. The MAF has its own sensor.

No, I don’t think it affects the Ecu.
 

doggydaddy

New Member
Messages
12
There is indeed a temp sensor in the MAF that by the looks of it is faulty.

The ECU is thus going to richen the fuel air mix.

Had 3 4200’s in with hesitation and stalling, 2 were pedal pots the other was the MAF where the previous service centre had removed a BMC air filter to clean it, the top rubber seal tore and deposited the bits of rubber in the MAF.

Conaero, this got me thinking about the hesitation/stalling issue Ive been troubleshooting. I didn't consider the drive-by-wire components. I did a quick test with the car in neutral and blipping the throttle. If I pushed the accelerator slowly, revs would climb. If i pushed it any faster, no revs. Is this what you were seeing on the cars with the failed pots? Here's a short video I took:

Pedal Actuation Test Video
 

conaero

Forum Owner
Messages
34,594
Yes that is clearly not right. The throttle bodies rarely fail so I would do the pedal pot first, it’s not expensive, used about £70, new about twice that.

There are rumours an Alfa GTV 916 is the same. I can’t confirm this but it shares a lot of parts so probably.
 

doggydaddy

New Member
Messages
12
Yes that is clearly not right. The throttle bodies rarely fail so I would do the pedal pot first, it’s not expensive, used about £70, new about twice that.

There are rumours an Alfa GTV 916 is the same. I can’t confirm this but it shares a lot of parts so probably.

I just ordered a new one from scuderia, thanks for the tip!