Who here drives a non-hybrid automatic and normally gets 50+ mpg

[sl2eggplant]

I'll give the HAI another try probably in two weeks but I need to stabilize my mpg on my current setup and get a baseline for engine timing and load on the scangauge. I am expecting 48 +/- 1 mpg with the stock intake and no other changes to the car at the moment.


I've had the HAI in the car for at least 2 months in different configurations with temps from 100 - 240 depending on traffic. I definitely think most or all of the gains that I thought were from the HAI were actually from improved hypermiling. My thought is while I may be using less gas with the HAI, I have less power (obvious) so I need more throttle to maintain my speed (60 mph). Another thought is my car's pcm is just plain stupid.

About the gas pump error. The pump only had one little clicker thing to set at while most pumps I seen have 3 clicker things to set your gas flow. The gas was flowing in much faster than normal so it stopped at 8.2 gallons (~48.7 mpg). At that time, I knew that I was going to do much worse than expected and continued to pump once more and it stopped at 8.7 (~46 mpg) gallons. While the pump error is there, I'm pretty sure I topped off to what I normally do at my other gas station or pumped less than normal due to the high pump flow. Either way, I definitely burned more gas this round with the HAI and the scangauge erroneously inflated my mpg.

[Phantom]

Sl2eggplant how do/did you have the HAI ran? Did you just have the air filter open to the engine with no shielding or did you pipe hot air in?

If your engine cuts spark timing when it sees higher IAT (Intake Air Temp) you could try moving the sensor closer to the filter, that will help it see accurate temps since the sensor does not get heat soaked as much thinking the temp is higher.

[Tygen1]

Opps, I forgot one thing...let me elaborate.

Less power means a higher TPS which the PCM thinks means a higher load which normally means pulled timing. Typically our PCM's are designed to not have as much ignition advance as they could run. Short of buying nice software to reporogram the PCM, I ended up fooling the PCM into thinking it was at a lower load, even if the TPS was high. You may have read some threads I had about the vacuum leak giving me better mpg. Once I got the wideband I found that I was not lean like I thought, it was simply just more ignition timing. The vacuum leak made the PCM not believe the MAF and therefore it determined I must be at a lower load and that advanced the timing to near max. When this was coupled with the HAI, that's when I started to see the nice low GPH's and tremendously improved highway mpg. The ZX2 is starved for timing. With the lean burn set up I am using now, I am just bleeding off voltage from the MAF, which no doubt makes the PCM believe there is a light load. So I see max advance when bleeding off voltage from the MAF.

This may help you, but I don't know how your Saturn will react?

[C3H8]

another way of increasing ignition timing is by installing a 5K or 10K ohm potentiometer on the throttle position sensor. solder 1 of the 2 wires on the pot to the throttle position sensor's output wire, and the other wire to a ground.

then you have to use a scangauge or obd2 monitor to watch ign timing as you slowly increase the pot's resistance. this fools the computer into thinking the throttle is closed more then it really is, so it advances timing. on an automatic trans, this has the added benefit of lowering the rpm's at which the trans shifts, for more economy. my car has a manumatic trans, and when i have it in auto mode with the pot connected, it shifts into second egar at 10mph, 3rd at 20, 4th at 35 and locks up the torque conveeter at 40. in manual mode there is no differenced with or without the pot, except for the increased ignition timing.

another benefit of a pot on the tps, is that the torque converter stays locked up more often, even if you open the throttle a good bit. it still unlocks as it should when you punch it, or go over 50% throttle though. but for an ecomodder like myself, its virtually always locked up when driving at +40mph.

the last benefit i can think of, is that when decelerating from high speed, the computer cuts fuel more quickly, and cuts it for a longer amount of time because it thinks the throttle is closed more often. think of it as an automatic injector kill switch.

you can install the pot on the dash or centre console if you want. then s an option a on-off switch to one of the pot's wires so that you can disable the pot and return the car back to normal mode. also, once you have the pot dialed in, you can simply remove it and install a resistor in its place which has an identical value of resistance. a on-off switch also works with the resistor.
this frees up the pot to be used on another sensor, such as the map, iat, or maf, etc.

fooling around with a pot anbd the iat has a similar effect of advancing the ignition timing when you fake the computer into thinking the air is colder then it really is. it has a negative effect of watcing to add more fuel when you make the iat read cold, but the throttle position sensor that i previously lowered its value counteracts this. also the o2 sensor will not let the computer add more fuel soi the intake air temp sensor is also a good mod to do.

i have tried adding a pot to the map sensor, and this also effects timing and fuel but the computer quickly (in a matter of 2-4 seconds) relearns and works around the fueling change with the map sensor. this also has the effect of undoing any changes to the ignition timing that was made by changing the value of the map sensor. so for me at least, map sensor is not worthwhile mod.

what i have doscovered is that you can not perminantly alter any fueling tables by changing the value of any engine sensor. (with the exception of open loop mode such as a cold start). you can only change the ignition timing and transmission shift points.

[sl2eggplant]

Originally Posted by Phantom

Sl2eggplant how do/did you have the HAI ran? Did you just have the air filter open to the engine with no shielding or did you pipe hot air in?

If your engine cuts spark timing when it sees higher IAT (Intake Air Temp) you could try moving the sensor closer to the filter, that will help it see accurate temps since the sensor does not get heat soaked as much thinking the temp is higher.

I used a 3in flexible dryer hose and routed it to my air box. The three main configurations are

(1) Point the dryer hose right above the exhaust manifold (no shield)
(2) Same as (1) but added large aluminum foil pan shield
(3) Point the dryer hose away from the exhaust manifold

Keep in mind, I have a full wooden belly pan so minimum temps are around 100 - 110 F. The IAT has always been placed inside the air box probably a couple of inches below / outside of the air filter. Stock IAT location is in the plastic hose/funnel 2 or 3 inches outside of the air box.

[sl2eggplant]

Originally Posted by Tygen1

Opps, I forgot one thing...let me elaborate.

Less power means a higher TPS which the PCM thinks means a higher load which normally means pulled timing. Typically our PCM's are designed to not have as much ignition advance as they could run. Short of buying nice software to reporogram the PCM, I ended up fooling the PCM into thinking it was at a lower load, even if the TPS was high. You may have read some threads I had about the vacuum leak giving me better mpg. Once I got the wideband I found that I was not lean like I thought, it was simply just more ignition timing. The vacuum leak made the PCM not believe the MAF and therefore it determined I must be at a lower load and that advanced the timing to near max. When this was coupled with the HAI, that's when I started to see the nice low GPH's and tremendously improved highway mpg. The ZX2 is starved for timing. With the lean burn set up I am using now, I am just bleeding off voltage from the MAF, which no doubt makes the PCM believe there is a light load. So I see max advance when bleeding off voltage from the MAF.

This may help you, but I don't know how your Saturn will react?

Thanks Tygen1. Saturns don't have an MAF, only an MAP and obviously IAT. I'll have to research how other Saturn owners are able to make the mpg gains.

I drove the car to the doctors today and when the engine was warm and idling, the GPH was around 0.35 which is lower than what I had with the HAI at 0.37.

[sl2eggplant]

C3H8, thanks for the tip. Personally, I've been trying to stay away from the more exotic electrical mods because I simply don't understand how they work. I'm more focused on the simpler mechanical mods that work all the time i.e. weight reduction and aerodynamics. I know that I will eventually start tuning the engine as I exhaust the aero mods.