Are there separate temp sensors for the ECU and the Gauge on our cars? The car is running like it is in cold mode. My temp gauge reads between 170 and 180 but I think most vehicles have separate temp sending units for the ECU and the gauge.

Will the scanning software show if this is the issue?

 

Gauge is in the side of the engine and the other is in the water pump housing.

 

Gauge temp sensor is in the driver's side head, between #1 and #3 spark plugs.

If you put a scanner on the PCM, it will show you the temp reading being fed to it by the coolant temp sensor in the water pump housing.

Courtesy of Shoebox:

http://shbox.com/1/temp_sensor2.jpg

http://shbox.com/1/temp_sensor1.jpg

4th Gen LT1 F-body Tech Articles

 

Thanks for those links. Great info.

Cable should get here in a day or 2. I'll post back when I have some info from the scans.

 

I filled the tank up and calculated my mileage again. On this tank I did not drive very conservatively. A little hot rodding, not so gradual acceleration etc. I got 17mpg as apposed to 16mpg when driving very conservatively for a full tank.

The cable gets here today so hopefully I will know more this eve. Maybe a faulty TPS.

 

There is so much data, its amazing what you can find is wrong with the Datalogs.

 

Ok, pulled the codes and I am getting:

MALF 48: MAF System Fail

Other than the low ac pressure code thats the only bad code. It's running in open loop because of the MAF error.

 

I'm searching through the forums on the error for more troubleshooting info but I measured the voltage and I get 12V on pink and 5V on yellow (MAF connector unplugged and car not running).

 

https://www.camaroz28.com/forums/lt1...bvious-459571/

Assuming you read this one. Sounds like unless the unit is dead it is something to do with the wiring.

 

The voltages on the MAF look fine (12V and 5V). I did a 15 min drive yesterday. Half city half freeway and logged the whole trip. I exported it to CSV. If someone wants to take a look at it if can be downloaded here...

Drive 1 log file

I was incorrect when I said the car is running in open loop. It does switch over to closed loop after driving for a bit. Not sure what data bit that is though.

 

If someone wants to play the actual log file back on datamaster here is the link to download it:

Drive 1 DM File

I believe the reason I am getting DTC 48 was because I unplugged the MAF when the car was running the other day to see if it made a difference. I'm resetting the codes and I'll recheck again today after I drive it.

Do the fuel trims look normal or are those values indicative of an air leak somewhere?

I also noticed the O2 sensors would vary quite a bit from each other. Is that abnormal?

 

The .csv link works, but the .uni doesn't.

It goes into closed loop right where it's supposed to, at 206 seconds run time.

Each bank of the engine is controlled independantly. The O2 sensor volts will not be the same, and often not even close in closed loop. When you go into pwer enrichment mode (PE) they will stabilize and they should be close.

A vacuum leak would affect it more at idle and in the low load cells. In Cell 16 (idle) it's actually pulling out a bit of fuel on both banks. Low load cells aren't too bad. The elevated LTFT's (140+) are in the higher loead cells.

Give me some time to look at it.

 

Doh. I fixed the link.

Thanks for the help. Im out on the boat salmon fishing with the family but ill check in later.

 

So I reset the computer and took it for another drive and I did not get any MAF codes so the DTC 48 was because I unplugged it while running.

On this drive I got on the freeway and did a couple full throttle pulls in 6th and the car just stumbled (around record 3650 in the logs below).

Drive 2 CSV file

Drive 2 UNI file

Is it normal for the car to tumble wile doing 55mph in 6th giving it full throttle? It also stumbles really bad off the line unless I get the RPM's up a little.

 

Sometimes the wot stumble are from not enough fuel pressure or not enough voltage from the alternator. Have you ran the car with the fuel pressure gauge hooked up during these runs and how does your voltage look at these times also? Both easy to check and the voltage can be seen on the datalog, but I can't look right now. I would get into the high 10's and low 11's for the voltage readings and it affected my cars performance.