Thrasher chips

[smallv6]

I have heard that these chips run in open loop.
Why is this?
Also will this affect readings with my Turbo-link?
Thanks

 

[granitestategn]

I believe they have open loop idle, not 100% open loop. I have a Thrasher 92 and I noticed that at idle the open loop decimal point on my Scanmaster 2 flashes (meaning it's in open loop). As soon as it comes off idle it stops flashing. I believe the open loop idle is a "feature" of the Thrasher chips and is the way they get a smooth idle. It seems like mine idles rich. The car does run good.

 

[Scott231]

Thrashers idle in open loop mode and puposely rich = smooth idle. The chip also runs in open loop mode at WOT and if you remove the O2 sensor (yes, the code will know it and respond accordingly).

Note Open Loop means the O2 sensor is ignored for fueling correction...nothing else. The ECM will continue to alter fueling as needed based on the other sensors/chip parameters.

 

[rb68rr]

I recently started driving my car with the 02 sensor unplugged while using a Thrasher 92 chip and seem to get a lot lower knock count on my scanmaster! Is there some way this effects the reading on the scanmaster? Thanks, R.B.

 

[Scott231]

Without the O2 sensor, you are prolly running a richer fuel curve (as the computer is not trying to lower the fuel volume). Accordingly, you are getting less knock...and not harming your O2 sensor to boot!

 

[timstips]

So Scott, are you saying that you can run more boost if you unplug the 02 sensor with a Thrasher chip????????????????????????

 

[timstips]

ttt

 

[BADINBLACK6]

So I can run my car without the 02 sensor with my thrasher chip? What are the advantages of not using the 02 sensor?

 

[tim87tr]

Originally posted by Scott231
Without the O2 sensor, you are prolly running a richer fuel curve (as the computer is not trying to lower the fuel volume). Accordingly, you are getting less knock...and not harming your O2 sensor to boot!

So when running leaded race fuel and the Thrasher chips, there would be no damage to the O2 with it unplugged? And the car still runs ok at the track being in PE mode or open loop before WOT? But you would not get O2 readings to check your fueling. Yea, I know everyone says that is not the best info, but I don't have an EGT yet.

I have ran a Thrasher 97 and then the 100 at Morocco this time, so I'm very interested in how this works. BTW, Scott S., I never did see you at Morocco, were you there? Tim

 

[Scott231]

Originally posted by timstips
So Scott, are you saying that you can run more boost if you unplug the 02 sensor with a Thrasher chip?<snip>

If this results in more fuel being added where you are running more boost, then yes. However, the ability to run more boost is moreso influenced by fuel octane than fuel volume. Removing the O2 sensor from the equation does not immediately mean you can run more boost.

 

[Scott231]

Originally posted by BADINBLACK6
So I can run my car without the 02 sensor with my thrasher chip? What are the advantages of not using the 02 sensor?

You will be running in Open Loop all the time. As such, changes to fuel pressure really do become a tuning tool. (In Closed Loop the ECM will compensate to eliminate the benefits of extra fuel from extra pressure.)

 

[Scott231]

Originally posted by tim87tr
So when running leaded race fuel and the Thrasher chips, there would be no damage to the O2 with it unplugged?

No! You have to remove the O2 sensor altogether. Either plug the hole with an old, dead O2 sensor or purchase an O2 sensor plug from NAPA.

[ And the car still runs ok at the track being in PE mode or open loop before WOT? But you would not get O2 readings to check your fueling. Yea, I know everyone says that is not the best info, but I don't have an EGT yet.

Sure, why wouldn't it? A car that is "in tune" will not be making any fueling adjustments based on the O2 sensor anyway. Trying to tune your car by only removing the sensor is foolish though. With the sensor in place and running Close Loop, there are no 'real time' adjustments being made for the current O2 reading jsut what has been stored in the Integrator and the Block Learn parameters. You can get the same "fuel pressure changes mean something" tuning ability with a chip that has the BLM lock at 128 at WOT, but don't expect to buy one from anybody but a Thrasher distributor for $25.

BTW, Scott S., I never did see you at Morocco, were you there? Tim

All Day Saturday. TSM car #2088, FAST V6 license plates from Ohio. I know for a fact that I was the only one there towing with a White Toyota Land Cruiser.

 

[timstips]

Steve, right now I have the Thrasher 92 chip in my car and I'm running it with the 02 sensor disconnected. When I go to the track and I want to change to the Thrasher 108 do I change chips without unplugging the orange wire? Or do I have to connect the 02 sensor back up, put in the Thrasher 108, drive it for awhile, then disconnect it? Thanks, Tim.

 

[timstips]

I'm sorry, I mean't Scott not Steve!

 

[timstips]

ttt

 

[Scott231]

I would do the latter to be safe.

 

[Ken Cunningham]

Scott S: I have been running one of your Thrasher blue tops for quite awhile now, always with my BLM's at rock bottom (105). My fuel mileage is pretty terrible at 16-17. Changed maf, O2 sensor, experimented with lots of different pcv combos, different fuel pressures. Nothing seems to lighten the load of fuel that the chip wants to dump in. WOT is not bad, with O2's at a nice safe 800-900. But I think my spool up would be gnarlier, and my mpg better, if I could lean out my off-throttle fueling. If I ran w/o the O2 sensor, could I then tune with fuel pressure? Or should I pay heed to your warning: "Trying to tune your car by only removing the sensor is foolish"? W/O the O2 sensor the O2 readings are meaningless, of course, but what about the BLM? Would they still indicate anything meaningful in the absence of O2 data?

I remain your confused and humble servant,

 

[Scott231]

Originally posted by Ken Cunningham
<snip>If I ran w/o the O2 sensor, could I then tune with fuel pressure?

Yes, but note that fuel pressure changes are "across the board".

Or should I pay heed to your warning: "Trying to tune your car by only removing the sensor is foolish"?

Well if you are running 105 now, I'd say you are not that far off from a good tune now. It is worth a try if you have already eliminated other possibilities (i.e. you would not fall into the "only removing the sensor" category).

W/O the O2 sensor the O2 readings are meaningless,

Actually without the sensor you will not get any O2 readings.

but what about the BLM? Would they still indicate anything meaningful in the absence of O2 data?

If you do not reset the ECM, the BLM will stay at whatever it last was. You could reset it to 128 (unplug orange wire) and play with FP but I'd save that until after you tried playing with fuel pressure and a "fixed" BLM number.

 

[Ken Cunningham]

My 105 was run with leaded race gas mix, Thrasher 108, no cat and no O2 sensor. Boost was too high and detonation pulled out some timing and I lost a lot of boost in 3rd gear. I'm convinced if I had just couple of more runs, dropped my boost to a sane number, that I would have run quite a bit better. Bench racing aside: I run maybe 3x/year in full-boogie mode, the rest of the year I'm busy putting 18,000 miles of highway, city and suburb driving (and spanking a few 'stangs, 'vettes, supras, and various posers) so the tune that I am now concerned with is the basic driving-around tune. And that tune is too rich for my blood! In reading your post, it seems too dicey to run routinely w/o the O2 sensor. I would get feedback from neither the O2 readings nor the BLM settings to know whether or not I'm too lean or too rich. Tune by blasting about and seeing my knock count and retard? No thanks! BTW, when I did my last track runs w/o O2 sensor, my scan tool (AutoXray) did show values in the O2 cells: very tight range of 420-448. I don't consider them meaningful, just curious.

 

[rb68rr]

So Scott, do you still get optimum performance with the fuel pressure set at 45psi no matter if the boost is 16psi or 22psi while running without the 02 sensor?