GFORCE Performance chip

[Jackred]

Has anyone use this chip(Mfg.Part No 102277) on a stock 1998 350 engine? If so, what were the results?

[Hib Halverson]

1998s do not have "chips". The last Corvette to use a chip was 1993.

The calibration in a 1998 ECM has to be uploaded with either a hand held programmer or a PC.

Looking at Gforce's web site, it appears that the product is BS. They claim to be able to reprogram the engine's air/fuel ratios by connecting to the IAT input to the ECM. That, of course, is impossible.

What they are really doing is "fooling" the ECM into altering the fuel and spark schedules by "telling" the ECM that the IAT (intake air temperature) is lower than it really is. In some cases there can be significant differences in spark advance at lower IATs.

There is something to be gained by changing the ECM calibration but fooling the ECM with errant IAT data is not the way to do it.

I would avoid that product.

[DrNavyRet]

1998s do not have "chips". The last Corvette to use a chip was 1993.

The calibration in a 1998 ECM has to be uploaded with either a hand held programmer or a PC.

Looking at Gforce's web site, it appears that the product is BS. They claim to be able to reprogram the engine's air/fuel ratios by connecting to the IAT input to the ECM. That, of course, is impossible.

What they are really doing is "fooling" the ECM into altering the fuel and spark schedules by "telling" the ECM that the IAT (intake air temperature) is lower than it really is. In some cases there can be significant differences in spark advance at lower IATs.

There is something to be gained by changing the ECM calibration but fooling the ECM with errant IAT data is not the way to do it.

I would avoid that product.

This is what the "fuel management" devices for motorcycles have been doing for years. It is basically a piggyback to the ECM that fools the computer to make the fuel mixture richer. The two common mods on bikes are the air cleaner/housing and exhaust. Without the piggyback, the bike would run too lean and scorch the engine. Newer piggbacks work off the Oxygen sensors that are on newer bikes. On the Vette, I believe that our computer is "smart" enough to modify itself without any piggyback devices if your mods are air cleaner and exhaust.

[Hib Halverson]

This is what the "fuel management" devices for motorcycles have been doing for years. It is basically a piggyback to the ECM that fools the computer to make the fuel mixture richer. The two common mods on bikes are the air cleaner/housing and exhaust. Without the piggyback, the bike would run too lean and scorch the engine. Newer piggbacks work off the Oxygen sensors that are on newer bikes. On the Vette, I believe that our computer is "smart" enough to modify itself without any piggyback devices if your mods are air cleaner and exhaust.

Actually, the ability of late model Corvette engine controls to "compensate" for increased airflow across the engine is limited.

It's interesting that motorcycle "piggyback" devices are using the O2S data. Are the O2ses on newer bikes conventional narrow band devices such are used in car engines or are they wide-band O2Ses?

[DrNavyRet]

Actually, the ability of late model Corvette engine controls to "compensate" for increased airflow across the engine is limited.

It's interesting that motorcycle "piggyback" devices are using the O2S data. Are the O2ses on newer bikes conventional narrow band devices such are used in car engines or are they wide-band O2Ses?

The best way I can describe it is by example of my 2008 Street Glide. I have a resistor in place between the o2S and the ECM; this "fools" the ECM output for fuel at lower RPM. I have the Vance and Hinds FuelPac piggyback on the ECM to fool it at hgher RPM's. So I have two narrow bands . The newer devices are broader in effect so only one is needed. I haven't changed mine 'cause it's working well for me .

[Hib Halverson]

The best way I can describe it is by example of my 2008 Street Glide. I have a resistor in place between the o2S and the ECM; this "fools" the ECM output for fuel at lower RPM. I have the Vance and Hinds FuelPac piggyback on the ECM to fool it at higher RPM's. So I have two narrow bands.

Are you saying Harleys have two oxygen sensors? Also, does the engine controls system H-D uses have a closed loop and open loop modes or just closed?

The newer devices are broader in effect so only one is needed. I haven't changed mine 'cause it's working well for me .

Wow.
That sure is an odd way to change the calibration of engine controls. If it works on an H-D, so be it. Just curious, have you run your bike on a motorcycle dyno to see what the air-fuel ratio is doing?

I suggest not trying those strategies on a Corvette...especially wiring a resistor in series with oxygen sensors.

[DrNavyRet]

Are you saying Harleys have two oxygen sensors? Also, does the engine controls system H-D uses have a closed loop and open loop modes or just closed?
I have one O2S. The resister that "fools" the ECM is impacting the closed loop EFI operation which is under 4000rpm and up to 50% throttle. This is hooked from the O2S to the wiring harness that goes to the ECM. The Fuelpac is hooked up between the ECM itself and the harness that goes to the injectors, timing, etc impacting the open loop operation which is over 4000rpm and over 50% throttle.


Wow.
That sure is an odd way to change the calibration of engine controls. If it works on an H-D, so be it. Just curious, have you run your bike on a motorcycle dyno to see what the air-fuel ratio is doing?

[[The air fuel ration remains constant at 13.8:1]]



I suggest not trying those strategies on a Corvette...especially wiring a resistor in series with oxygen sensors.

[[I thought this strategy was weird when I set my bike up 3+ years ago. It did not make a lot of sense to me, but with time and experience, my bike is running fine, no popping exhaust noise; good power throughout the ranges; bike remains consistent in function. BTW, I pieced the info to do what I did from Forums like this one and put together the package. I do not have the background to put together the right pieces for my Corvette. I thought that the Diablo InTune might be the answer, but, from what I have gathered from the manufacturers and the forums. I'm not sure that it would do anything for my '04 vert 6 spd.]]

[Hib Halverson]

(snip)The air fuel ration remains constant at 13.8:1

Are you saying the AFR is at 13.8:1 at wide open throttle and high rpm?

[DrNavyRet]

Are you saying the AFR is at 13.8:1 at wide open throttle and high rpm?

That's what it was off throttle and that was my main concern that I didn't start out at a fuel starved level. Don't remember how it changed as we went through the RPM range as I was most interested from that portion as to HP changes. I remember there was a gain of almost 6 HP over stock at 5K.

[Mr. Lucky]

Are you saying Harleys have two oxygen sensors? Also, does the engine controls system H-D uses have a closed loop and open loop modes or just closed?


Wow.
That sure is an odd way to change the calibration of engine controls. If it works on an H-D, so be it. Just curious, have you run your bike on a motorcycle dyno to see what the air-fuel ratio is doing?

As both a Corvette and Harley owner, I think I can answer this. Yes, there are two sensors. They are the usual Bosch narrowband devices, and are installed in the head pipes, one per cylinder. For best performance on a basically stock bike (i.e., intake and exhaust only), conventional wisdom is to install either an inline device (to handle closed loop) and the "dealer download" (for open loop + to raise rev limiter), or an ECM piggy-back device, which eleiminates the O2 sensors and runs open loop all the time using a "map" stored in the device. For anything more radical (e.g., heads & cams) a dyno tune and computer adjustment is definitely recommended. The newer fuel injected bikes (and not just H-Ds) use the equivalent of OBD-1 in a speed-density system, so I think that's why this relatively crude setup works on them. I agree that it's not the way to go on a Corvette.

[DrNavyRet]

As both a Corvette and Harley owner, I think I can answer this. Yes, there are two sensors. They are the usual Bosch narrowband devices, and are installed in the head pipes, one per cylinder. For best performance on a basically stock bike (i.e., intake and exhaust only), conventional wisdom is to install either an inline device (to handle closed loop) and the "dealer download" (for open loop + to raise rev limiter), or an ECM piggy-back device, which eleiminates the O2 sensors and runs open loop all the time using a "map" stored in the device. For anything more radical (e.g., heads & cams) a dyno tune and computer adjustment is definitely recommended. The newer fuel injected bikes (and not just H-Ds) use the equivalent of OBD-1 in a speed-density system, so I think that's why this relatively crude setup works on them. I agree that it's not the way to go on a Corvette.

My riding buddy has newer touring HD's and he agrees with you. My bike is an '08 model; came with only one O2S as the system was hooked together with the crossover pipe. I changed the exhaust to a V&H Big Radius (true dual setup) but with only the one sensor as recommended for my '08 by V&H. The resister that I spoke of is the XiED setup. I did not use the O2S eliminator for the piggyback device (V&H FuelPac).

[Scottsredvette]

Hib,
Sorta back to the original question. Being mechanically challenged mself, is there any reason to put a chip in a pre 93 C4? Do they work or are they sorta like the snake oil of old? What changes would occur to the programming and would there be any advantage to going to an aftermarket chip? I see an awful lot of places sell them.

[Hib Halverson]

Hib,
Sorta back to the original question. Being mechanically challenged mself, is there any reason to put a chip in a pre 93 C4? Do they work or are they sorta like the snake oil of old? What changes would occur to the programming and would there be any advantage to going to an aftermarket chip? I see an awful lot of places sell them.

I can't speak to what's done by all suppliers of aftermarket chips, but most of the stuff that's mass-marketed or sold on the Internet may have some changes in the spark curve, changes to knock sensor strategy, changes to fan-on temps, elimination of the skip shift function in a manual chip, changes in shift points or shift quality ion automatic chips.

There will be an advantage to some of those changes but not a great advantage.

It's hard to give much more of an answer without knowing what your goals are in changing the chip.

[Scottsredvette]

I can't speak to what's done by all suppliers of aftermarket chips, but most of the stuff that's mass-marketed or sold on the Internet may have some changes in the spark curve, changes to knock sensor strategy, changes to fan-on temps, elimination of the skip shift function in a manual chip, changes in shift points or shift quality ion automatic chips.

There will be an advantage to some of those changes but not a great advantage.

It's hard to give much more of an answer without knowing what your goals are in changing the chip.

No goals, I'm perfectly happy with my 89 automatic Vert as is, all 240 supposed hp. I still get 27 mpg on the highway with regular gas and still like messing with the Mustangs up in the twisties in the mountains (Colorado boy). Can't outrun them but can still outhandle them. I was just curious. Computers and other prom controlled devices seem to get upgraded and improved all the time. I was just wondering if these chips are an improvement over the original programming and what the benefits might be (if any).

[Hib Halverson]

No goals, I'm perfectly happy with my 89 automatic Vert as is, all 240 supposed hp. I still get 27 mpg on the highway with regular gas and still like messing with the Mustangs up in the twisties in the mountains (Colorado boy). Can't outrun them but can still outhandle them. I was just curious. Computers and other prom controlled devices seem to get upgraded and improved all the time. I was just wondering if these chips are an improvement over the original programming and what the benefits might be (if any).

Ah...you're at altitude. That's why you can use 85-oct fuel.

Provided you're willing to spend some serious money on a good cal., I'd look for an aftermarket chip with more spark in it. At altitude that may get you a little more power in the mid-range but it will also make you go to 88 or 90-oct whichever is super unleaded in your area.

Your engine was only 240-hp at sea level, not at 5000-ft.