[Z06] Decrease in MPG after Vararam?
Thread Starter
Instructor
Joined: Sep 2019
Posts: 226
Likes: 18
Decrease in MPG after Vararam?
I have a 2002 C5 Z06 with 35k miles. In the city I would get 15 mpg which already seems low? And I just installed the vararam intake yesterday and now I’m getting 13.9-14 mpg, is this normal? My car is completely stock otherwise. This is not spirited driving either, just city not highway.
Drifting
Joined: Mar 2018
Posts: 1,365
Likes: 414
From: New Jersey
After installing the Vararam I noticed a big decrease in mileage too. You have to take a look at your fuel trims. I had a check engine light and P0171 and P0174 were coming up. Long term fuel trim was at 25%. It was affecting my gas mileage by around 5 mpg. I used the Trinity to lean it out and gas mileage is now better than before the installation of the Vararam. I think I still need a real tune but I am waiting until I do some more mods.
Drifting
Joined: Mar 2018
Posts: 1,365
Likes: 414
From: New Jersey
The air temp is read by the computer so it will adjust fueling based on that and the air flow into the engine. The Vararam somehow screws up the MAFs air flow reading's. So the computer is adjusting for a signal that is not real. It thinks the engine is lean and adds fuel when it does not have to causing the engine to actually run rich. That is why the long term fuel trims get out of wack and the check engine light comes on.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 226
Likes: 18
After installing the Vararam I noticed a big decrease in mileage too. You have to take a look at your fuel trims. I had a check engine light and P0171 and P0174 were coming up. Long term fuel trim was at 25%. It was affecting my gas mileage by around 5 mpg. I used the Trinity to lean it out and gas mileage is now better than before the installation of the Vararam. I think I still need a real tune but I am waiting until I do some more mods.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 226
Likes: 18
The air temp is read by the computer so it will adjust fueling based on that and the air flow into the engine. The Vararam somehow screws up the MAFs air flow reading's. So the computer is adjusting for a signal that is not real. It thinks the engine is lean and adds fuel when it does not have to causing the engine to actually run rich. That is why the long term fuel trims get out of wack and the check engine light comes on.
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Drifting
Joined: Mar 2018
Posts: 1,365
Likes: 414
From: New Jersey
As long as your check engine light is off the computer will up to a point relearn the fuel trims as you drive and you should be OK. To fix this you either need a handheld tuner or a canned tune that ECS sells for $150. You can read your fuel trims and other engine parameters with a cheap $20 OBD2 Bluetooth code reader and your phone. The long and short term fuel trim s will tell you what's going on with your car. You could have an air leak at one of the couplers that will create the same kind of problem.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 226
Likes: 18
As long as your check engine light is off the computer will up to a point relearn the fuel trims as you drive and you should be OK. To fix this you either need a handheld tuner or a canned tune that ECS sells for $150. You can read your fuel trims and other engine parameters with a cheap $20 OBD2 Bluetooth code reader and your phone. The long and short term fuel trim s will tell you what's going on with your car. You could have an air leak at one of the couplers that will create the same kind of problem.