Performance Chips
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From: Southern California
Performance Chips
Hi Had a question about performance chips.
I have a 1990 automatic. Only mods done to my car is muffler bipass.
I put one in a Trans Am in the 80's and and I thought it helped but It could have been my imagination.
A couple questions:
Do you think the chips really do anything?
If so, which one is recommended?
How easy are they to install?
Thanks in advance for your suggestions?
I have a 1990 automatic. Only mods done to my car is muffler bipass.
I put one in a Trans Am in the 80's and and I thought it helped but It could have been my imagination.
A couple questions:
Do you think the chips really do anything?
If so, which one is recommended?
How easy are they to install?
Thanks in advance for your suggestions?
Race Director
Joined: Sep 2007
Posts: 12,162
Likes: 383
From: Johnson City, TN
The answer for the S3 is chips from Porken.
The answer for S4 is sharktuning, not chips.
Question for you: Has the intake and sensor refurb been done on your 90 S4? If not, it may have reverse-chipped itself to a low level of performance.
Also, have you done the flexplate release? Just curious, because I didn't see you mention it and its really important for your year.
The answer for S4 is sharktuning, not chips.
Question for you: Has the intake and sensor refurb been done on your 90 S4? If not, it may have reverse-chipped itself to a low level of performance.
Also, have you done the flexplate release? Just curious, because I didn't see you mention it and its really important for your year.
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From: Aztlan, aka SoCal
Performance Chips on the S-4 are very effective. I've had the AA chips, and now the Super Chip, and both have drastically improved the performance of my S-4. I sold my old AA chips to a guy in GB, and he told me he was very surprised at the improved performance of his S-4 with the AA chips. Sharktuning is probably more effective, but the price difference is like nite and day. I sold the AA Chips for $120. How much is Shark tuning
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Joined: Jan 2008
Posts: 4,077
Likes: 331
From: Friday Harbor, WA
I hate to be disagreeable 
but it's all a bit more complicated than this.
Some basics: The things that can be tweaked with chips, which effect power, are fuel (AFR) and timing. The LH does the fueling, and for a cat-equipped car it normally runs closed-loop when "cruising"-- i.e. the O2 sensor is used to adjust fuel for an optimum AFR. If the LH fuel map is off a bit, closed-loop will fix it. At high RPM or WOT the LH goes open-loop and just uses the map. The stock S4 map is a bit lean in the "cruise" ranges and overly rich in the "power" ranges. Optimizing fuel will have a small benefit in terms of power.
Ignition timing is where the "low hanging fruit" is usually found with respect to power. Advancing the spark will generally add power up to the point where detonation (knocking, pinging) occurs, or close to it. And therein lies the rub-- you want the engine working at peak power but not beyond the detonation point, because unchecked detonation is very hard on the engine (rings, ring-lands, head gaskets, things like that).
Starting in '87 the EZK processor incorporated knock-detection, with two knock-sensors (basically microphones) that listen for the beginning of detonation and retard the timing for that cylinder until it goes away. This allows the ignition timing to be set closer to optimum without risking engine damage. The EZK has a limit of 9 degrees max knock-retard, and if it detects a sensor fault then it puts in a constant 6-deg retard-- e.g. a knock-sensor or hall-sensor fault that prevents it from listening for knocks.
One more thing to remember: There are production variations with any machinery, and tolerances can either stack up favorably or unfavorably. So production design is necessarily conservative, to be sure that all of the units produced work within spec's. And operating conditions will also cause variations, e.g. carbon build-up will raise the compression ratio and make an engine more prone to detonation.
And after working with an ST2 for the last year, I can report with confidence that our '88 S4 with stock timing almost never does a knock-retard. There is opportunity to advance the timing, but only a few degrees in the high-load mid/high rpm range (i.e max torque) where it is already pretty close. A few degrees does "wake up" the mid-range to a degree. But I have no idea where this car is in the possible range of production tolerances, or how much carbon there is. And that's the difference between working on one example, versus a production run.
So what is in the aftermarket chips? The ones I looked at were from eBay and were AA clones, at least I assume so because they had an AA copyright in the firmware. Ooops.
The AA fueling map was modified to add more fuel in general. In the "cruise range" this is fine, the S4 is typically a bit lean there-- but this is also where it operates closed-loop so this has no effect. In the "power" ranges the S4 is already overly rich, so adding more fuel makes no sense-- but doesn't really hurt anything.
The AA ignition adds advance of course, 5 to 7 degrees in most places, which is within the range that the EZK knock-detect can deal with. Where it gets scary is high load in the 4000-5000 rpm range (the area where the "butt-dyno" has its greatest sensitivity), where the AA maps add 10 to 12.8 degrees of advance. That's a LOT, and right where the engine doesn't want it. However that will certainly wake up the butt-dyno, and also give the EZK's knock-retard something to chew on...
Remember that the max EZK knock-retard is 9 degrees, and if there is a sensor fault it retards only 6 degrees. That's apparently what the designers felt was a good margin-- in other words they did not expect the EZK knock-retard to exceed 6 degrees in normal operation, worst-case.
So now we crank in twice that much additional advance? More than the total range that the EZK can deal with? And without being able to monitor what is happening? That just doesn't make sense to me. I didn't hear any knocking when those chips were in there, but detonation is often inaudible. And I since I figured out what the maps were, I haven't had the courage to look at them with the ST2. Yes, I realize that I should be willing to sacrifice my engine for the good of the community-- But I am weak, and just can't bring myself to do it. It's such a nice motor...
but it's all a bit more complicated than this. Some basics: The things that can be tweaked with chips, which effect power, are fuel (AFR) and timing. The LH does the fueling, and for a cat-equipped car it normally runs closed-loop when "cruising"-- i.e. the O2 sensor is used to adjust fuel for an optimum AFR. If the LH fuel map is off a bit, closed-loop will fix it. At high RPM or WOT the LH goes open-loop and just uses the map. The stock S4 map is a bit lean in the "cruise" ranges and overly rich in the "power" ranges. Optimizing fuel will have a small benefit in terms of power.
Ignition timing is where the "low hanging fruit" is usually found with respect to power. Advancing the spark will generally add power up to the point where detonation (knocking, pinging) occurs, or close to it. And therein lies the rub-- you want the engine working at peak power but not beyond the detonation point, because unchecked detonation is very hard on the engine (rings, ring-lands, head gaskets, things like that).
Starting in '87 the EZK processor incorporated knock-detection, with two knock-sensors (basically microphones) that listen for the beginning of detonation and retard the timing for that cylinder until it goes away. This allows the ignition timing to be set closer to optimum without risking engine damage. The EZK has a limit of 9 degrees max knock-retard, and if it detects a sensor fault then it puts in a constant 6-deg retard-- e.g. a knock-sensor or hall-sensor fault that prevents it from listening for knocks.
One more thing to remember: There are production variations with any machinery, and tolerances can either stack up favorably or unfavorably. So production design is necessarily conservative, to be sure that all of the units produced work within spec's. And operating conditions will also cause variations, e.g. carbon build-up will raise the compression ratio and make an engine more prone to detonation.
And after working with an ST2 for the last year, I can report with confidence that our '88 S4 with stock timing almost never does a knock-retard. There is opportunity to advance the timing, but only a few degrees in the high-load mid/high rpm range (i.e max torque) where it is already pretty close. A few degrees does "wake up" the mid-range to a degree. But I have no idea where this car is in the possible range of production tolerances, or how much carbon there is. And that's the difference between working on one example, versus a production run.
So what is in the aftermarket chips? The ones I looked at were from eBay and were AA clones, at least I assume so because they had an AA copyright in the firmware. Ooops.
The AA fueling map was modified to add more fuel in general. In the "cruise range" this is fine, the S4 is typically a bit lean there-- but this is also where it operates closed-loop so this has no effect. In the "power" ranges the S4 is already overly rich, so adding more fuel makes no sense-- but doesn't really hurt anything.
The AA ignition adds advance of course, 5 to 7 degrees in most places, which is within the range that the EZK knock-detect can deal with. Where it gets scary is high load in the 4000-5000 rpm range (the area where the "butt-dyno" has its greatest sensitivity), where the AA maps add 10 to 12.8 degrees of advance. That's a LOT, and right where the engine doesn't want it. However that will certainly wake up the butt-dyno, and also give the EZK's knock-retard something to chew on...
Remember that the max EZK knock-retard is 9 degrees, and if there is a sensor fault it retards only 6 degrees. That's apparently what the designers felt was a good margin-- in other words they did not expect the EZK knock-retard to exceed 6 degrees in normal operation, worst-case.
So now we crank in twice that much additional advance? More than the total range that the EZK can deal with? And without being able to monitor what is happening? That just doesn't make sense to me. I didn't hear any knocking when those chips were in there, but detonation is often inaudible. And I since I figured out what the maps were, I haven't had the courage to look at them with the ST2. Yes, I realize that I should be willing to sacrifice my engine for the good of the community-- But I am weak, and just can't bring myself to do it. It's such a nice motor...
Not the sharpest tool in the shed
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Joined: Dec 2008
Posts: 8,856
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From: Chandler, AZ, USA, Earth, Milky Way Galaxy
I hate to be disagreeable but it's all a bit more complicated than this.
Some basics: The things that can be tweaked with chips, which effect power, are fuel (AFR) and timing. The LH does the fueling, and for a cat-equipped car it normally runs closed-loop when "cruising"-- i.e. the O2 sensor is used to adjust fuel for an optimum AFR. If the LH fuel map is off a bit, closed-loop will fix it. At high RPM or WOT the LH goes open-loop and just uses the map. The stock S4 map is a bit lean in the "cruise" ranges and overly rich in the "power" ranges. Optimizing fuel will have a small benefit in terms of power.
Ignition timing is where the "low hanging fruit" is usually found with respect to power. Advancing the spark will generally add power up to the point where detonation (knocking, pinging) occurs, or close to it. And therein lies the rub-- you want the engine working at peak power but not beyond the detonation point, because unchecked detonation is very hard on the engine (rings, ring-lands, head gaskets, things like that).
Starting in '87 the EZK processor incorporated knock-detection, with two knock-sensors (basically microphones) that listen for the beginning of detonation and retard the timing for that cylinder until it goes away. This allows the ignition timing to be set closer to optimum without risking engine damage. The EZK has a limit of 9 degrees max knock-retard, and if it detects a sensor fault then it puts in a constant 6-deg retard-- e.g. a knock-sensor or hall-sensor fault that prevents it from listening for knocks.
One more thing to remember: There are production variations with any machinery, and tolerances can either stack up favorably or unfavorably. So production design is necessarily conservative, to be sure that all of the units produced work within spec's. And operating conditions will also cause variations, e.g. carbon build-up will raise the compression ratio and make an engine more prone to detonation.
And after working with an ST2 for the last year, I can report with confidence that our '88 S4 with stock timing almost never does a knock-retard. There is opportunity to advance the timing, but only a few degrees in the high-load mid/high rpm range (i.e max torque) where it is already pretty close. A few degrees does "wake up" the mid-range to a degree. But I have no idea where this car is in the possible range of production tolerances, or how much carbon there is. And that's the difference between working on one example, versus a production run.
So what is in the aftermarket chips? The ones I looked at were from eBay and were AA clones, at least I assume so because they had an AA copyright in the firmware. Ooops.
The AA fueling map was modified to add more fuel in general. In the "cruise range" this is fine, the S4 is typically a bit lean there-- but this is also where it operates closed-loop so this has no effect. In the "power" ranges the S4 is already overly rich, so adding more fuel makes no sense-- but doesn't really hurt anything.
The AA ignition adds advance of course, 5 to 7 degrees in most places, which is within the range that the EZK knock-detect can deal with. Where it gets scary is high load in the 4000-5000 rpm range (the area where the "butt-dyno" has its greatest sensitivity), where the AA maps add 10 to 12.8 degrees of advance. That's a LOT, and right where the engine doesn't want it. However that will certainly wake up the butt-dyno, and also give the EZK's knock-retard something to chew on...
Remember that the max EZK knock-retard is 9 degrees, and if there is a sensor fault it retards only 6 degrees. That's apparently what the designers felt was a good margin-- in other words they did not expect the EZK knock-retard to exceed 6 degrees in normal operation, worst-case.
So now we crank in twice that much additional advance? More than the total range that the EZK can deal with? And without being able to monitor what is happening? That just doesn't make sense to me. I didn't hear any knocking when those chips were in there, but detonation is often inaudible. And I since I figured out what the maps were, I haven't had the courage to look at them with the ST2. Yes, I realize that I should be willing to sacrifice my engine for the good of the community-- But I am weak, and just can't bring myself to do it. It's such a nice motor...
but it's all a bit more complicated than this. Some basics: The things that can be tweaked with chips, which effect power, are fuel (AFR) and timing. The LH does the fueling, and for a cat-equipped car it normally runs closed-loop when "cruising"-- i.e. the O2 sensor is used to adjust fuel for an optimum AFR. If the LH fuel map is off a bit, closed-loop will fix it. At high RPM or WOT the LH goes open-loop and just uses the map. The stock S4 map is a bit lean in the "cruise" ranges and overly rich in the "power" ranges. Optimizing fuel will have a small benefit in terms of power.
Ignition timing is where the "low hanging fruit" is usually found with respect to power. Advancing the spark will generally add power up to the point where detonation (knocking, pinging) occurs, or close to it. And therein lies the rub-- you want the engine working at peak power but not beyond the detonation point, because unchecked detonation is very hard on the engine (rings, ring-lands, head gaskets, things like that).
Starting in '87 the EZK processor incorporated knock-detection, with two knock-sensors (basically microphones) that listen for the beginning of detonation and retard the timing for that cylinder until it goes away. This allows the ignition timing to be set closer to optimum without risking engine damage. The EZK has a limit of 9 degrees max knock-retard, and if it detects a sensor fault then it puts in a constant 6-deg retard-- e.g. a knock-sensor or hall-sensor fault that prevents it from listening for knocks.
One more thing to remember: There are production variations with any machinery, and tolerances can either stack up favorably or unfavorably. So production design is necessarily conservative, to be sure that all of the units produced work within spec's. And operating conditions will also cause variations, e.g. carbon build-up will raise the compression ratio and make an engine more prone to detonation.
And after working with an ST2 for the last year, I can report with confidence that our '88 S4 with stock timing almost never does a knock-retard. There is opportunity to advance the timing, but only a few degrees in the high-load mid/high rpm range (i.e max torque) where it is already pretty close. A few degrees does "wake up" the mid-range to a degree. But I have no idea where this car is in the possible range of production tolerances, or how much carbon there is. And that's the difference between working on one example, versus a production run.
So what is in the aftermarket chips? The ones I looked at were from eBay and were AA clones, at least I assume so because they had an AA copyright in the firmware. Ooops.
The AA fueling map was modified to add more fuel in general. In the "cruise range" this is fine, the S4 is typically a bit lean there-- but this is also where it operates closed-loop so this has no effect. In the "power" ranges the S4 is already overly rich, so adding more fuel makes no sense-- but doesn't really hurt anything.
The AA ignition adds advance of course, 5 to 7 degrees in most places, which is within the range that the EZK knock-detect can deal with. Where it gets scary is high load in the 4000-5000 rpm range (the area where the "butt-dyno" has its greatest sensitivity), where the AA maps add 10 to 12.8 degrees of advance. That's a LOT, and right where the engine doesn't want it. However that will certainly wake up the butt-dyno, and also give the EZK's knock-retard something to chew on...
Remember that the max EZK knock-retard is 9 degrees, and if there is a sensor fault it retards only 6 degrees. That's apparently what the designers felt was a good margin-- in other words they did not expect the EZK knock-retard to exceed 6 degrees in normal operation, worst-case.
So now we crank in twice that much additional advance? More than the total range that the EZK can deal with? And without being able to monitor what is happening? That just doesn't make sense to me. I didn't hear any knocking when those chips were in there, but detonation is often inaudible. And I since I figured out what the maps were, I haven't had the courage to look at them with the ST2. Yes, I realize that I should be willing to sacrifice my engine for the good of the community-- But I am weak, and just can't bring myself to do it. It's such a nice motor...
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Joe Kucinski
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I have been lapping for years using AA chips in my '88 S4, and I have yet to find knock codes when I use Theo J's diagnostic tool shortly after a track session.
Maybe the 94 octane I'm running helps. I was told by one company that sells AA clones (under their own brand name, once again dumping eprom showed AA copyright), that the mapping is for 91 octane.
Once again, just my experience. YMMV.
Maybe the 94 octane I'm running helps. I was told by one company that sells AA clones (under their own brand name, once again dumping eprom showed AA copyright), that the mapping is for 91 octane.
Once again, just my experience. YMMV.
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From: Gone. On the Open Road
What Jim and Landseer wrote: +928
If you haven't done the "20-year scheduled maintenance(*)" on your 928 you're probably down 30 to 60 HP.
(*) Plugs, Wires, Rotors, Caps, Intake Refurbish (All hoses, idle/WOT switch, knock sensors, resonance flap, etc.), fuel lines, Hall Sensor, Cam Cover Gaskets, In-tank fuel pump, LH rebuild and the list goes on...
Not to mention the scheduled maintenance items that can effect power: 02 sensor, Fuel filter, etc.
And then the other scheduled stuff rarely done: PSD Flush.
If you haven't done the "20-year scheduled maintenance(*)" on your 928 you're probably down 30 to 60 HP.
(*) Plugs, Wires, Rotors, Caps, Intake Refurbish (All hoses, idle/WOT switch, knock sensors, resonance flap, etc.), fuel lines, Hall Sensor, Cam Cover Gaskets, In-tank fuel pump, LH rebuild and the list goes on...
Not to mention the scheduled maintenance items that can effect power: 02 sensor, Fuel filter, etc.
And then the other scheduled stuff rarely done: PSD Flush.
