Air Intake/Mileage question

[Deadlock281]

I have a friend who drives a 1995(96) Tran Sport with about 180,000 miles and its running really rich (more fuel then air) and is using a lot more gas then it was when he got it. The temperature here has recently, and suddenly, dropped to cold and I'm wondering if this could be the cause.

-OR-

Is it the fact that the hole to bring air into the air filter is only like 4"x1" rectangle. Could I simply fix this this problem by cutting the hole to make it larger and allow a larger air flow to the engine so that it runs a little more even on his fuel/air ratio???

[LMP]

WHen I got mine on dec 30 1993, I quickly realised the fuel burn in city driving for short trip was high and the smell was rich. However on the open road, it was quite good. My assumption was that to make sure the car would start in cold temperatures, the "curve" installed in the computer was very rich cold....on the assumption that anyway, the engine would heat up fast and would return rapidly to a precisely calibrated part of the curve. Well here in winter and short trips, this never happens in such a way that closed loop operation may never be reached; operation on longer trips allows for that though.
Since this is based on coolant temperature, I tricked the computer by installing a switcheable resistor in the thermistor circuit and after starting and running for a few seconds, I switch the resistor in and the computer thinks the coolant is already around 80F (instead of -20) and leans the mixture: the rich smell goes away, and mileage increases A LOT. The effect of the resistor in cold temperatures is such that if it is forgotten IN for starting , the engine will simply not start: too lean. Once really warm, the thermistor value overwhelms that of the resistor and the resistor has no effect then as mixture in these conditions is already OK.
May be other factors are involved in your case: any condition that prevents closed loop operation will lower fuel mileage and default values used by the computer in case of sensor failure are all to ensure the engine will run hence are on the rich side.
Failure of oxygen sensors is a possibility. Is the Check Engine Light ON? reading the codes (95/96) requires a scanner.

[Deadlock281]

Originally Posted by LMP

WHen I got mine on dec 30 1993, I quickly realised the fuel burn in city driving for short trip was high and the smell was rich. However on the open road, it was quite good. My assumption was that to make sure the car would start in cold temperatures, the "curve" installed in the computer was very rich cold....on the assumption that anyway, the engine would heat up fast and would return rapidly to a precisely calibrated part of the curve. Well here in winter and short trips, this never happens in such a way that closed loop operation may never be reached; operation on longer trips allows for that though.
Since this is based on coolant temperature, I tricked the computer by installing a switcheable resistor in the thermistor circuit and after starting and running for a few seconds, I switch the resistor in and the computer thinks the coolant is already around 80F (instead of -20) and leans the mixture: the rich smell goes away, and mileage increases A LOT. The effect of the resistor in cold temperatures is such that if it is forgotten IN for starting , the engine will simply not start: too lean. Once really warm, the thermistor value overwhelms that of the resistor and the resistor has no effect then as mixture in these conditions is already OK.
May be other factors are involved in your case: any condition that prevents closed loop operation will lower fuel mileage and default values used by the computer in case of sensor failure are all to ensure the engine will run hence are on the rich side.
Failure of oxygen sensors is a possibility. Is the Check Engine Light ON? reading the codes (95/96) requires a scanner.

Thanks man, I'll see if i can get something done using your information. So basically cutting a hole in the intake wouldn't work?

[LMP]

Originally Posted by Deadlock281

... So basically cutting a hole in the intake wouldn't work?

Well...my bottom line says it all.... Frankly no, this is not a factor. I still use this intake size without alteration.
THIs diagram
www.avigex.ca/xport/enginesensors.jpg
tells where I have installed the "temperature modifier" (2.2 k resistor and switch at right). Practically, one wire connects to ground, the other to yellow wire entering B9 at 24 pin connector C2 near right hand suspension tower .
NOw this is for the record only because temperatures you experience at this time are just relatively cool , not enough in my opinion to inflict a dramatic change in mileage....so I suspect there is more to look for...once more, is the CEL on? ANd..is it a '95 or '96? if '95, which engine?

[Deadlock281]

Originally Posted by LMP

Well...my bottom line says it all.... Frankly no, this is not a factor. I still use this intake size without alteration.
THIs diagram
www.avigex.ca/xport/enginesensors.jpg
tells where I have installed the "temperature modifier" (2.2 k resistor and switch at right). Practically, one wire connects to ground, the other to yellow wire entering B9 at 24 pin connector C2 near right hand suspension tower .
NOw this is for the record only because temperatures you experience at this time are just relatively cool , not enough in my opinion to inflict a dramatic change in mileage....so I suspect there is more to look for...once more, is the CEL on? ANd..is it a '95 or '96? if '95, which engine?

Well like I said, it's not my car so I'll have to get back to you on the model year and engine (if 95). My friend and I both live very busy lives, so it might not be until next week when I can get you the full information. I'm pretty sure it says "Sport Tuned 3800" or something on the side. I didnt really pay attention to the engine when I was under the hood, just the intake, but I'm pretty sure it was an inline 6 cylinder.

[LMP]

If is says 3800 that is a '95....as '96 were all 3.4