The discussion brought up reprogrammed ECMs and knock sensors.
What are you SC/Turbo guys doing to prevent detonation? Is anyone running a reprogrammed PROM in a '85 ECM wired with a knock sensor? Is there any real documentation by someone who's done this? Us future SC/Turbo guys wanna know
If I hear detonation In my turbo'd V-6 I just turn back the timing on the MSD BTM via the remote dial. Usually I only get detonation if I have to run 90 or lower octane gas, So I just turn the timing back when I get the lower octane gas. Mines not the best solution to the problem but it works.
Originally posted by sluppy123: If I hear detonation In my turbo'd V-6 I just turn back the timing on the MSD BTM via the remote dial.
You're only hearing HEAVY detonation. From what I've read, you won't be able to hear light detonation, so you may be causing damage without knowing it. Too bad the MSD unit doesn't have an input for a knock sensor.
Anyone else have knowledge on this?
[This message has been edited by fierosound (edited 12-03-2002).]
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12:39 AM
fierosound Member
Posts: 15190 From: Calgary, Canada Registered: Nov 1999
The reason for the 1985 ECM is it has the hook up for a Knock sensor. For some reason this is the only year that had it. I have a knock sensor on mine with Ed/Travis piggy back computer, with the rising fuel regulator, and 2 bar map sensor. It also has the custom chip from Design One Systems. After Ed got through Dyno tuning it, it runs great with no detonation. I am running around 10 lbs of boost. The knock sensor can save your engine.
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07:33 AM
Dennis LaGrua Member
Posts: 15475 From: Hillsborough, NJ U.S.A. Registered: May 2000
Knock sesnors are a good safeguard against engine damage caused by detonation. However, forged racing pistons, a noisy exhaust, or valvetrain can induce knock retard un-necessarily and cause you to lose power. GM used a couple of different knock sensor with different sensitivities on engines which made more noise. I believe that the knock sensor used on the LS1 is the least sensitive unit to extraneous engine noise. Yes the 1985 V6 Fiero ECM ( P/N 1226869 )did have the input buffers onboard to enable a knock sensor interface but it was never used by GM. The circuit consists of a knock sensor and a GM ESC module. The knock sensor signal is fed to the ESC module who's output is then fed to pin B7 of the ECM. However, don't get too excited. You can't just wire in a knock sensor, ESC module and expect it to work. It won't. Changes in the chip program need to be made. The knock sensor feature needs to be switched on, and a knock retard table added to the program. The trouble is that since this feature was never used or programmed by GM, the address locations that were reserved for these features are left blank. Therefore there is no way of defining and understanding the code. I believe that it can be done but much trial and error is needed. I'm sure that someone has discovered the code but so far all chip software prgrams that I have examined make no mention of it..
I use 93 octane and also some octane booster. The latter if I am really pushing the car while doing autocross or some drag racing. No problems with detonation so far. The car also runs a little on the rich side so I believe that helps.
Hmmmmmm. I looked in the 85 code and it appears they only disable Code 43 ESC. There is no enable or disable for ESC specifically. The tables are all addressed. The ESC module is part no. 16126761 brodcast code ANRZ (in the one's I've seen)
Knock sensor is P/N 10456287.
ESC signal is fed into terminal B7.
Anything else Dennis?
Terry
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09:31 PM
Dennis LaGrua Member
Posts: 15475 From: Hillsborough, NJ U.S.A. Registered: May 2000
Hmmmmmm. I looked in the 85 code and it appears they only disable Code 43 ESC. There is no enable or disable for ESC specifically. The tables are all addressed. The ESC module is part no. 16126761 brodcast code ANRZ (in the one's I've seen)
Knock sensor is P/N 10456287.
ESC signal is fed into terminal B7.
Anything else Dennis?
Terry
If I read it correctly; your post disagrees with what I have stated. You claim that the knock tables are addressed the knock switch is always active and that only code 43 is disabled. I guess that I've missed this big time. If what you say is the case then knock retard should take place with just the addition of the hardware. The part numbers of the knock sensor and ESC modules are the ones that I'm using on my setup. The ESC module is powered to 12 V ignitioon and ground and it's signal is fed into pin 7 as you confirm. I'll recheck and rap my headers with a wooden club and see if the timing moves. I'm really hoping that you are correct on this one.
I hate to say it , but dennis is right. Just enabling the knock sensor code check is only part of the equation. The fiero chip was never intended to make use of knock sensor inputs so it will read knock if it interfaces correctly, but will not know by how much to retard timing and what maximum retard is.
I have burnt many chips for different vehicles which all use knock sensors and can tell you there is more than one table that deals with knock retard. there are also many unseen tables that tell the ecm how to interperate knock sensitivity and frequency (as in knock counts rec'vd) that are well hidden in the program itself. I consider myself very proficient in GM ECM programming and can tell you that searching for a table with limited information on the programming available is problematic at best. You might be lucky enough to find the proper tables to enable knock and tell the ecm what to do, but there could be some other switch or parameter located somewhere else in the ecm telling it to not allow knock retard where you may never find it. The only way to know for sure is to find a complete hack or dissassembly for the ecm/prom in question and look over the 100s of pages of code and find what needs to be changed.
Your best bet is to upgrade the ecm. Lets face it, the fiero ECM is ok, but there are better things out there that can be made to work with minimal effort (not to mention faster ecms). For example, you could re-pin the ecm connectors and install a 7730 ecm with a 90-92 camaro/firebird 3.1 chip and go. It already has knock input (it even has the ESC module in the cal-pak) as well as runs off speed density like the fiero. Better yet, there is software already available thru www.tunercat.com that supports this setup.
Even better than that, you could install a syclone/typhoon ecm. These systems were speed density (MAP sensor) utilizing a 2-bar sensor (up to 15psi boost), supported a distributor, used a knock sensor, and has even more tunable features than the 7730 ecm. Obviously changes would need to be made to make it fully compatible with a supercharger but tunercat also has programming available for this setup as well. I think this setup would be the best way to go because the ecm is already setup for boost. The sy/ty ecm was also used in GM FWD Quad-4 applications so finding a computer would not be hard; you would just have to buy a cal-pak assy to reprogram.
Good luck with your project.
------------------ 1987 Pontiac Fiero Coupe #18,838 3800 Series II SFI; 4T60-E Trans w/ 3.33 final drive; Terminator exhaust; 4 wheel vented disc conversion; Walbro 307 fuel pump; W-body air box w/ K&N filter; Rear 32mm sway bar; 134a functioning A/C; GM CD player w/ factory location sub; much more and...a stock GN's TURBO on the way!
Yep, several people are running the Syty/Subird code in 7749's. I did it in of my one Fiero's for a bit.
Sorry that I don't have every single calibration table memorized. I sent Dennis the option flag addresses for the module and updated GMEPro.
My specialty is the 3800SC.
Terry
[This message has been edited by TK (edited 12-04-2002).]
Well TK, looks like i need to get with you when I embark on my turbo upgrade. I plan on using the '95 3800 Series II PCM that is already in the car since tunercat has software out for the $5B code (series I SC). I was thinking of using an LT1 MAF upstream of a GN turbo and intercooler because it is already compatible with this PCM. Anything I need to be on the lookout for? Will the MAF help the ecm during the turbo lag transition? thanks for any info you can supply.
[This message has been edited by Darth Fiero (edited 12-04-2002).]
[This message has been edited by Darth Fiero (edited 12-04-2002).]
I am by no means an expert on ECM's. The Design One Systems Stage II kit comes with a knock sensor, 2 bar map sensor, new chip for the 1985 computer, and instructions to hook up and enable the knock sensor. I followed them, and it seems to work fine. Ed at Enginnered has Dyno tuned the car and has not mentioned any timing retard problems. I run around 10 lbs of boost. Kevin at Design One may be a good source for questions concerning how to enable it.
Well TK, looks like i need to get with you when I embark on my turbo upgrade. I plan on using the '95 3800 Series II PCM that is already in the car since tunercat has software out for the $5B code (series I SC). I was thinking of using an LT1 MAF upstream of a GN turbo and intercooler because it is already compatible with this PCM. Anything I need to be on the lookout for? Will the MAF help the ecm during the turbo lag transition? thanks for any info you can supply.
They are compatible, but not the same. Just drop the mass tables into the code. Sounds like you got it covered.
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09:53 AM
Dec 5th, 2002
fierosound Member
Posts: 15190 From: Calgary, Canada Registered: Nov 1999
If what you say is the case then knock retard should take place with just the addition of the hardware. I'm really hoping that you are correct on this one.
This seems to be the case. I believe this is what RSM (S/C kit) and Design 1 (turbo kit) are doing.
I suppose a person could just buy Design 1's Stage 2 kit for $800 It would just be nice to be able to "make your own".
The Stage Two System which is an add on to Stage One, includes all of the features as follows:
Engine Control Module - The Engine Control Module (ECM) is modified to accept input from a knock sensor in order to control the ignition timing . When detonation (knock) is detected by the knock sensor, the ignition timing is retarded to eliminate the knock. This allows the ECM to compensate for varying conditions which may be conducive to knock, like low octane gasoline or excessive heat in the combustion process. The result is a more optimum control of the engine under all operating conditions: that means efficient and reliable, high performance power.
Knock Sensor - The knock sensor detects detonation in the engine combustion chambers and supplies information to the ECM about its severity. The ECM uses this to reduce the ignition advance in order to eliminate the detonation. If the engine is operating in the boosted mode, the ECM will retard the ignition timing to eliminate the harmful detonation.
[This message has been edited by fierosound (edited 12-06-2002).]
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10:17 PM
Dec 8th, 2002
fierosound Member
Posts: 15190 From: Calgary, Canada Registered: Nov 1999
UPDATE. YOU CANNOT just add the knock sensor, ESC module and wiring to the 85 Fiero ECM to achieve knock control. A change to the chip program IS required. The feature must be switched on. I was able to do this on my chip with many many thanks to tips from TK who's understanding of programming is far better than mine. TK wrote and sells good prom editor software called GMEpro. I am looking at and playing with the evaluation version now and it looks pretty nice, and well thought out. For all of you aspiring chip programmers, it's something to consider purchasing.
I'll be getting Lyndon at Wester's Garage ( www.ecmprogrammer.com ) to program the fuel/timing maps AND "switch on" the EST feature. The only other thing I'd need is a wiring diagram on how it all fits together.
Am I correct?
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08:58 PM
Dec 14th, 2002
fierosound Member
Posts: 15190 From: Calgary, Canada Registered: Nov 1999
Well, basically that's it minus having wastegate control.
Start with an 85 chip, enable the ESC, ESC code, 2 bar, set all of the map limits up, spark table down, add the needed fuel, and a bunch of other things.
Then get all children inside and crank the key.
You might want to start with a known 2 bar chip. There are many, many calibrations that need to be adjusted under 2 bar conditions to get it to run right and protect the engine.
Dennis has spent far more time digging into actually firing up a 2 bar 85 ECM than me. I just know the code fairly well. Ping him.
