Kinda new to this stuff, though I do understand a lot of mechanics as I help run a family garage here in PA. Don't be afraid to throw out advanced terminology and such. 2001 Cavalier 2.2L4. Not an engine made for performance in the first place, but I notice it runs much better in open loop and loses some serious torque and low end power as soon as it goes into closed loop. I'm guessing the preset timing/fuel curves of the open loop system aren't the most efficient route but make better power. That leads me to believe these engines have something to gain from a better tune job (besides busted pistons like my first engine). Not looking to spend too much money on a car with an economy engine, but if there were a cheap way to trick the car into open loop all the time without throwing a code, that would be clutch. I understand this will cut my mileage in half, but I figure anything I do can be reversible if I'm going on a long haul somewhere. Any ideas that don't involve buying a $300 PROM chip or going for the all expensive re-flash? I could be making an idiot out of myself here, but theoretically, all the readings from the sensors come down to a few volts (MAP, IAT, Sensor 1 Bank 1, Sensor 2 Bank 1). Thus, if I could make something to intercept these signals and manipulate them to what I want (economy or power) and stay within the accepted parameters, the car would run exactly how I want it to with no codes, right?
"In Oldskool we trust"
I'm guessing your O2 sensor is garbage which is why it runs better when it doesn't use the information it sends out, and runs based off the VE tables in the tune only.
The cheap way to force open loop operation is merely unplugging your upstream O2 sensor.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
The 02 sensor that's probably junk is the upstream sensor(bank 1 sensor 1)? Won't unplugging it just set a code, causing the car the run erratically anyway?
"In Oldskool we trust"
Here is some info for you. Hopefully this helps you understand how our cars operate better.
Open loop the car runs off the "Tune" so to speak. Closed loop the car uses the sensor's and some preset data. The ECU strives for a 14:7:1 air fuel mixture while in Closed loop which is going to give you the best fuel mileage. The ECU can and will switch from closed loop to open loop if certain things happen. Examples: RPM and TPS readings go above a certain setting (usually full throttle above 3400 RPM's will do it).
Unplugging the O2 sensor forces the car into closed loop, and yes throws a code.
So from reading your post the car already does what you want it to do.
FU Tuning
Thanks for the info. Yes, the car works well and doesn't have any real problems. I just noticed a huge power difference when it switches to closed loop (i have a scanner that gives me real time information). I'm always looking for a cheap way to manipulate the computer into doing something that can promote power, though I know they usually don't exist. Just thought if anyone would know any tricks, it'd be here.
"In Oldskool we trust"
Just in case, does anyone know where I can find a PROM chip for the 2001 2.2L4?
"In Oldskool we trust"
no "chips" after 1995. You'll need to find someone locally with HPT and grap a wideband if you want to do it right...
My opinion - running open loop all the time completely untuned is a waste of fuel and won't be optimal for power either. suggest you follow the advice above and check the operation of your primary O2 if its not running well under closed loop
Ok, here's the deal with the upstream O2 sensor... I put a header on a long time ago but the provided hole for the sensor was too far down and the harness didn't reach anymore. So I went to a junkyard and clipped a real long peice of wire from an 02 sensor with the same plug (I think it was a olds alero). I then soldered the peice in. I can assure you the wires are connected correctly. Would this create a communication problem? Because if that's the case, buying a new O2 won't help anything since I'll have to cut the wires and lengthen them anyway. Tried to talk to GM about a universal GM sensor that had a longer cable, but they just couldn't get what I was trying to tell them.
"In Oldskool we trust"
John Higgins wrote:Unplugging the O2 sensor forces the car into closed loop, and yes throws a code.
*open* loop. The code(s) it will throw will just be related to saying your O2 sensor doesn't work properly (obviously because it's unplugged).
Use a heated O2 sensor if it's farther than stock location.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
[ion wrote: C2]John Higgins wrote:Unplugging the O2 sensor forces the car into closed loop, and yes throws a code.
*open* loop. The code(s) it will throw will just be related to saying your O2 sensor doesn't work properly (obviously because it's unplugged).
Use a heated O2 sensor if it's farther than stock location.
You are correct sorry.
Trust me there is enough wire in the stock harness to reach the O2 sensor, and for the 2200 OHV motors there is a couple company's that sell extension kits. You probably do need a heated O2 sensor. If you do a search in performance section you will find info on the topic.
FU Tuning
[ion wrote: C2]John Higgins wrote:Unplugging the O2 sensor forces the car into closed loop, and yes throws a code.
*open* loop. The code(s) it will throw will just be related to saying your O2 sensor doesn't work properly (obviously because it's unplugged).
Use a heated O2 sensor if it's farther than stock location.
Just to clear things up, so if its unplunged it "wont" switch to closed loop right?
GMR has got nothing on this
DOHC_tuner wrote:[ion wrote: C2]John Higgins wrote:Unplugging the O2 sensor forces the car into closed loop, and yes throws a code.
*open* loop. The code(s) it will throw will just be related to saying your O2 sensor doesn't work properly (obviously because it's unplugged).
Use a heated O2 sensor if it's farther than stock location.
Just to clear things up, so if its unplunged it "wont" switch to closed loop right?
Correct. Since the car uses O2 sensor in Closed Lopp, it can not operate in Closed Loop properly.
FU Tuning
Should I just go for the wideband that way I'm ready for tuning if I ever so choose? Basically, will a wideband O2 sensor work with the stock ECM?
"In Oldskool we trust"
Ryan Pitt wrote:Should I just go for the wideband that way I'm ready for tuning if I ever so choose? Basically, will a wideband O2 sensor work with the stock ECM?
Most widebands have a 5v output that can be used for the ECU. That is your choice. I prefer to use a normal narrowband O2 sensor for the ECU.
FU Tuning
