Air Temperature sensor
#1
Air Temperature sensor
I'm trying to go through the entire ignition and EFI system one item at a time to find the cause(s) of my poor idle. Some parts are on order so I decided to check a few items that I've been remiss to verify. First thing this morning was my Air temperature sensor.
I've read that the ATS is only a minor trim to the EFI and not very important so I've never even bothered to check that it was working. I should have.
My ATS was reading wildly off spec. It was 60F this morning and I was looking for somewhere between 300 and 400 Ohms. I metered it at 2.4 KOhms. With that reading I am suspicious that it's a coolant temp sensor that someone put in there. I jumped the harness connector out and instantly the RPMs dropped and she ran smoother.
Driving with the ATS jumped out she has no dead spot coming onto the throttle any more! Idle is improved, acceleration is far smoother and power is up. Partial throttle response feel right, not hesitant and meek. Huge difference! Probably as big a change as any repair/mod I've done so far.
That ATS is not just a minor EFI trim.
I've read that the ATS is only a minor trim to the EFI and not very important so I've never even bothered to check that it was working. I should have.
My ATS was reading wildly off spec. It was 60F this morning and I was looking for somewhere between 300 and 400 Ohms. I metered it at 2.4 KOhms. With that reading I am suspicious that it's a coolant temp sensor that someone put in there. I jumped the harness connector out and instantly the RPMs dropped and she ran smoother.
Driving with the ATS jumped out she has no dead spot coming onto the throttle any more! Idle is improved, acceleration is far smoother and power is up. Partial throttle response feel right, not hesitant and meek. Huge difference! Probably as big a change as any repair/mod I've done so far.
That ATS is not just a minor EFI trim.
The following 2 users liked this post by JigJag:
Grant Francis (10-06-2016),
NathanDD6 (10-07-2016)
#2
I'm trying to go through the entire ignition and EFI system one item at a time to find the cause(s) of my poor idle. Some parts are on order so I decided to check a few items that I've been remiss to verify. First thing this morning was my Air temperature sensor.
I've read that the ATS is only a minor trim to the EFI and not very important so I've never even bothered to check that it was working. I should have.
My ATS was reading wildly off spec. It was 60F this morning and I was looking for somewhere between 300 and 400 Ohms. I metered it at 2.4 KOhms. With that reading I am suspicious that it's a coolant temp sensor that someone put in there. I jumped the harness connector out and instantly the RPMs dropped and she ran smoother.
Driving with the ATS jumped out she has no dead spot coming onto the throttle any more! Idle is improved, acceleration is far smoother and power is up. Partial throttle response feel right, not hesitant and meek. Huge difference! Probably as big a change as any repair/mod I've done so far.
That ATS is not just a minor EFI trim.
I've read that the ATS is only a minor trim to the EFI and not very important so I've never even bothered to check that it was working. I should have.
My ATS was reading wildly off spec. It was 60F this morning and I was looking for somewhere between 300 and 400 Ohms. I metered it at 2.4 KOhms. With that reading I am suspicious that it's a coolant temp sensor that someone put in there. I jumped the harness connector out and instantly the RPMs dropped and she ran smoother.
Driving with the ATS jumped out she has no dead spot coming onto the throttle any more! Idle is improved, acceleration is far smoother and power is up. Partial throttle response feel right, not hesitant and meek. Huge difference! Probably as big a change as any repair/mod I've done so far.
That ATS is not just a minor EFI trim.
The coolant temp sensor measures around 2.4k at 80 deg. F. So that is way out of the range for an ATS input.
Good work!
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Doug (10-05-2016)
#3
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Grant Francis (10-06-2016)
#4
My connectors are still labeled thank goodness!
FYI, the difference between disconnected and jumped is pretty huge. 2.4KOhms is big resistance, but D/C'd is bigger. If your sensor is just off bit maybe it's not such a big ECU hit, but D/C'd or broken connection it's got to be >+5% fueling based off idle speed change and sudden milage boost. Smells better too!
FYI, the difference between disconnected and jumped is pretty huge. 2.4KOhms is big resistance, but D/C'd is bigger. If your sensor is just off bit maybe it's not such a big ECU hit, but D/C'd or broken connection it's got to be >+5% fueling based off idle speed change and sudden milage boost. Smells better too!
#5
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Grant Francis (10-06-2016)
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#8
I think it is on the AJ6 Engineering website. The ATS is just a mixture trimming device, and disconnecting it enriches the mixture by about 10% max, I think. There may well be a difference between disconnecting it and having the wrong sensor in there, no idea.
Greg
Greg
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#12
Turns out my air temp sensor is just failed. It isn't a water temp sensor. Got a new one on order.
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Jonathan-W (10-10-2016)
#13
This is a public service announcement.
With guitars...
--The Clash
According to Sean's Jaguar XJ-S pages, there are two different Air Temperature Sensor Part Numbers. Pre-HE and HE. They have wildly different output specifications. The HE model almost perfectly matches the output spec of the Coolant temperature sensor!
My sensor is fine. The problem lies elsewhere...
With guitars...
--The Clash
According to Sean's Jaguar XJ-S pages, there are two different Air Temperature Sensor Part Numbers. Pre-HE and HE. They have wildly different output specifications. The HE model almost perfectly matches the output spec of the Coolant temperature sensor!
My sensor is fine. The problem lies elsewhere...
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NathanDD6 (10-16-2016)
#14
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#16
Currently not running. Choking out. Melted cats "fixed" but still giving me trouble. Not related to the above ATS as far as I know.
#17
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