I have seen this topic come up a lot in discussion lately and there seems to be some misinformation floating around out there. Since I have EXTENSIVE experience in this area, I will offer some useful information for the community to consume.
There are several rumors floating around on this and other boards talking about how much "better" the OBD II flashible PCM is vs. the OBD I (95 Bonneville) PCM that has the removable chip. I think it is time for some facts to remove the "fog of war."
Just so we can make sure everyone is on the same sheet of music, there are a few things that need to be explained first and foremost:
The 95 PCM will currently NOT directly control a 4T65-E / 4T65-EHD correctly. The main electrical difference between the 65 and 4T60-E is the 60 does NOT have a pressure control force motor to control line pressure, rather, it has a vacuum modulator. There is no readily available provision in current programming software (that I know of) that will allow another output of the PCM (say the canister purge) to control the PCS (pressure control solenoid) of the 65/65HD, yet. Time may change all of that. So if you want to use a 65/65HD auto trans, you are going to have to stick with the OBD II flashible PCM.
Now that we got that out of the way, lets talk about differences of technology. While it is true that the OBDII PCM is more advanced than the OBDI unit, there is really little difference when it comes to drivability and performance. In fact, if you pull codes on the OBDI unit, you might be surprised to find trouble codes similar to OBDII standards. The OBDII unit may have a couple of years on its OBDI counterpart, but the extra technology is most likely there to handle the more complex OBDII emissions monitoring and not specifically for enhanced performance or drivability.
The fact is I just completed a 3800 II SC swap into a customer's 85 SE a short time ago and used a 95 Bonne PCM. There are more than enough tunable tables in the OBDI PCM to satisfy your performance and/or drivability needs. I will even go as far as to suggest that it is probably easier to program the OBDI PCM to work with the L67 minus all of the OBDII crap that the fiero does not have, nor has room for, than it is for the OBDII unit. In fact, a popular aftermarket L67 PCM reprogramming company rep told me that they could NOT even disable pass-key in the 98 OBDII PCM. (I can easily turn it off on the 95 programming by the click of my mouse button.) FYI: the 95 OBDI PCM controls a modded 3800 II SC engine just fine with a little massaging to the programming.
Now lets talk about costs. The OBDII PCMs are more expensive and less plentiful (because they are vehicle and year specific). The OBDI units were used in 94-95 Bonnevilles and Park Avenues with the VIN 1 SC series I 3800 engine and were also used in the same 95 year cars that had the Series II naturally asperated 3800. Another fact is that there are a lot more 94 and 95 bonnevilles and park avenues in the junkyards that will most likely have their PCM intact vs. a newer car. It might be a foregone conclusion that these earlier units might be easier to get ahold of for less money.
As for the programming, there are currently only a few companies out there that will do "custom" programming on the OBDII units. They also seem to be priced around $500 or so for a mail-order (sight unseen) reprogram in which most places will not insure compatibility with slighly modded engines. Most companies state that in order to offer the most compatible reprogram, they will need your car on a dyno so they can get some real-time feedback. While this is true and ideal for the car, it is not wallet friendly. (so much for just $500) Furthermore, most companies will not offer many free "adjustments" to the programming so it is going to cost you extra if you decide to upgrade the pulley or exhaust down the road. Don't get me wrong, I don't think anyone should do anything for free, but how can they justify $500+ per PCM reprogram? Come on, the software and the short amount of time they spend using it can't cost that much when they claim they do 1000's of PCM's a year. I think that amount of money is BS. You will think so too.....
Or you can go with the OBDI PCM (provided you don't have a 4T65-E trans). For the do-it-yourselfer, there is programming for these units available thru www.tunercat.com and some others less known. The tunercat base software program costs $70. Then you will need the $5b definition file at an additional cost of $20. On top of that, you will need a programmer ($150) and an eprom eraser (UV LIGHT) $50. You might need additional blank 27C512 eproms to burn to at a cost of about $5 ea. So far, the grand total for the DIY 95 PCM reprogram is approx: $300. Far less than the actual $700+ you are going to have to pay for OBDII reprogramming, dyno time, reprogramming rep time, etc. Of course, the DIY route is going to require you to spend some time doing it and getting your car just right. But at least you can change stuff right now and don't have to ship your PCM off and be without the car.
Now I know someone is going to bring up the topic of how long will it take me to DIY the 95 PCM and what kind of help can I expect from the internet. I tweaked the 95 PCM programming from stock to work very well with a modded series II 3800 SC engine and 4T60-E trans with a 3.33 final drive in less than 3 hours. I had a near perfect program in less than 6 hours of driving and tweaking. As far as what kind of online support can you expect? For one, I am here and my email box is always open; ask around, I am always willing to help out when I can. I am sure there are many others out there that are willing to do the same.
Want to run the 95 PCM with the Series II 3800 SC engine and a 4T60-E trans but don't want to do it yourself? Just email me and I will be happy to let you know where to get your chip done for less than $50.
I estimate the 1/4 mile performance of the aforementioned L67 swapped fiero to be a traction-limited 13.1 @ 105 mph on a decent day. The car only had BFGoodrich Radial T/A 205 65 r 14s on it last time I drove it. The owner was going to get some 16" rims and stickier tires last time I talked to him. Doubt he will ever take it to the track.
Just to be clear, this is not a thread I started for the purpose of turning into a flame war. I just want to try to help my fellow fiero owners save some loot when it comes to this seemingly expensive hobby.
It is a "double edged sword"...the more ppl that get into the OBD2 reprogram market the lesser the price of the reprogram...well so I hoped! I also feel 300 bucks to remove my speed limiter is not justifiable...talk less of a custom reprogram...it is blatantly not palatable to me...however some might think otherwise...time will surely tell, in the mean time I will enjoy my 108mph speed limiter!
------------------ 3800 II v6 intercooled turbo...CWP!
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11:19 PM
Jul 11th, 2003
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
It is a "double edged sword"...the more ppl that get into the OBD2 reprogram market the lesser the price of the reprogram...well so I hoped! I also feel 300 bucks to remove my speed limiter is not justifiable...talk less of a custom reprogram...it is blatantly not palatable to me...however some might think otherwise...time will surely tell, in the mean time I will enjoy my 108mph speed limiter!
------------------ 3800 II v6 intercooled turbo...CWP!
nocutt, am I to understand that you also have a 3800 Series II Turbocharged powered Fiero? Do you have any pictures that you would be willing to share? I would like to see them if you don't mind. Thanks.
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12:17 AM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
nocutt, I will have to agree 110% with you on the issue of justifiable costs. When doing the LT1 OBDI flashible PCM programs, adjusting rev and speed limiters takes less time than downloading the program from the PCM! I got in a "heated discussion" with an aftermarket vendor (OBDII PCM reprogrammer) a while back and their reasoning behind charging $500 for a slightly custom reprogramming was "because that is what the market will support." In other words, they charged that amount because they could, not because they should. I do no believe in greed, thus is the reason why I try to do chips for others very cheaply. I charge enough to cover the cost of my software, material, and small amount of time that is required for a reprogram. Just for comparison, hypertech charges $120 or so for a chip for an 89 camaro in which when compared to a stock program, there was only slight adjustments made to a few tables. However cheated some of you may be feeling after reading this, you must realize that companies like hypertech offer products that must be compatible for the broad scope of vehicles on the road that could be all different. Does that justify the $120 price tag? I don't think so, but that is what they think the market will support...for now.
[This message has been edited by Darth Fiero (edited 07-11-2003).]
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12:27 AM
RBeaubien Member
Posts: 775 From: Glendale (Phoenix), AZ, USA Registered: Mar 2002
As for the programming, there are currently only a few companies out there that will do "custom" programming on the OBDII units. They also seem to be priced around $500 or so for a mail-order (sight unseen) reprogram in which most places will not insure compatibility with slighly modded engines. Most companies state that in order to offer the most compatible reprogram, they will need your car on a dyno so they can get some real-time feedback. While this is true and ideal for the car, it is not wallet friendly. (so much for just $500) Furthermore, most companies will not offer many free "adjustments" to the programming so it is going to cost you extra if you decide to upgrade the pulley or exhaust down the road. Don't get me wrong, I don't think anyone should do anything for free, but how can they justify $500+ per PCM reprogram? Come on, the software and the short amount of time they spend using it can't cost that much when they claim they do 1000's of PCM's a year. I think that amount of money is BS. You will think so too.....
WRONG! Contact Dave Buckshaw at dhp@calidadllc.com for OBDII programming for the 3800 engines. For $350 (not $500), he took my computer for a 2000 Buick Park Ave Ultra and re-programmed it with the following changes:
1. Disable transmission error codes 2. Change Fan turn on/off to appropriate temperatures for a 180*F thermostat 3. Change rev limiter to 6200 rpm 4. Remove speed limiter 5. Optimize fuel/spark curve for 91 octane fuel and 3.25" SC pulley. 6. Disable Passkey 7. Change base idle speed from 700 to 800 rpm. 8. Match the speedometer setting for 215/60R15 tires. Those are stock tires on a Fiero.
All changes were performed perfectly and I have a 13.1s 1/4mi runner.
WRONG! Contact Dave Buckshaw at dhp@calidadllc.com for OBDII programming for the 3800 engines. For $350 (not $500), he took my computer for a 2000 Buick Park Ave Ultra and re-programmed it
Well, that is not what Charles Beyer at DHP told me. He was talking about $500+ to do about what you told me you got done for $350. Maybe I should have just talked to dave.
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01:41 PM
PFF
System Bot
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
I will be using an L67 with TH125 (yes, a TH125) and I'm looking at PCM/ECM options.
An OBDI PCM, since it's supported by Tunercat looks like a good choice here. How much rewiring is necessary?
Will, an AWD Pontiac 6000 w/ 3800IISC would be freaking awesome! As far as your PCM options; you can use the 95 Bonneville PCM and then "fool" it in the way of transmission controls by wiring in light bulbs in place of the shift solenoids, a spare coolant temp sensor in place of the trans temp sensor, and either use a trans range position switch for a newer 125-C (3T40) or wire up a series of relays to your P/N switch wire to make the PCM think it is in N or DRV3. I think the newer gear range sensor would be your best bet. Look for OBDII Sunfires and Cavaliers at the junk yard. It will be nice once tunercat can enable and disable the transmission codes in the software.
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01:45 PM
Will Member
Posts: 14299 From: Where you least expect me Registered: Jun 2000
Tunercat can't disable automatic trans control in the OBDI computers? That sucks. I hate jerry rigging stuff like that. Do you know how soon he's coming out with that?
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01:57 PM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
Tunercat can't disable automatic trans control in the OBDI computers? That sucks. I hate jerry rigging stuff like that. Do you know how soon he's coming out with that?
good question; maybe you should ask him. I have been working with him on my turbocharged 3800 install and has been helping me and supplying me with "special" tuner files to address my specific issues. I think for something as simple as turning off trouble codes, he would be willing to help you out.
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02:34 PM
mrfixit58 Member
Posts: 3330 From: Seffner, Fl, USA Registered: Jul 99
Good note. Thanks for taking the time to write it up. For that, I give you a "+" rating.
Additionally, you mentioned the chip in an 89 Firebird. I'm putting a 89 350 TPI into my 68 Camaro complete with 700r4 and 3.27:1 rear end. I'm interested in shutting off the EGR. Can you help me with a chip?
Also, the 92/93 3800SC code has a 125C flag that can be set (you have to disable the F31 flag.) I haven't tried it but it *should* work with a 125C. The problem is GM had a habit of adding flags and then hijacking the code section for something else. I suspect they left that intacted in the 92/93 code.
TK
[This message has been edited by TK (edited 07-11-2003).]
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05:13 PM
Will Member
Posts: 14299 From: Where you least expect me Registered: Jun 2000
Good note. Thanks for taking the time to write it up. For that, I give you a "+" rating.
Additionally, you mentioned the chip in an 89 Firebird. I'm putting a 89 350 TPI into my 68 Camaro complete with 700r4 and 3.27:1 rear end. I'm interested in shutting off the EGR. Can you help me with a chip?
Absolutely. In fact, I have the complete hack for that car so I can do almost anything with that chip including setting the RPM rev limiter to something more useful than the factory 10081 rpm setting.
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07:14 PM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
What features does the 94/95 code have that the 92/93 doesn't? Any?
If it's that easy, I'll try the 92/3 code when I get around to the project. GMEPro is better than Tunercat for this app?
Where to I get GMEPro?
I have not tried setting up the 92/93 PCM to work with the series II 3800 SC as of yet. From what I have seen, the 94/95 PCM has stuff like traction control and active ride control -- basically stuff that would be useless in a fiero. TK would probably know more than me pertaining to the differences between the two models.
nocutt, am I to understand that you also have a 3800 Series II Turbocharged powered Fiero? Do you have any pictures that you would be willing to share? I would like to see them if you don't mind. Thanks.
Darth Fiero...no I don't have a fiero...the engine is in an '88 chevrolet beretta GTU! 6 years and counting...I actually talked to ALL the recepients of the OBD2 (3800S2) reprogramming and I was quoted for 5bills to remove speed limiter and raise rev-limiter. The issue was that it will take about the same amount of time to do this changes...maybe, maybe not...I am not a PCM guru, however I do know what it will entail. I have also been told that some ppl get charged for 2bills or 3bills...so in actuality there is no given standard but really the politics of who you know..."yes that it is heresy and I said it"! Nothing wrong with this, but sometimes this is like a slap in the face...2 parameters for 5bills no thank you, you might have this field cornered...the question now is for how long ???
------------------ 3800 II v6 intercooled turbo...CWP!
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07:41 PM
Jul 12th, 2003
Freshj Member
Posts: 1250 From: Holly, Michigan Registered: Nov 2001
Originally posted by Darth Fiero:Well, that is not what Charles Beyer at DHP told me. He was talking about $500+ to do about what you told me you got done for $350. Maybe I should have just talked to dave.
Yes! Talk to Dave. I just had my PCM done yesterday. He's very professional and changed all that I asked for, plus the usual tweaking. My speedo reads right, I no longer have a constantly lit MIL, my fan operates correctly, etc. It was well worth it IMO. Highly recomended!
from what I have been hearing, dave is the guy to talk to over at DHP. unforetuneately, I talked to the other two people and had a very bad experience. If I was going to use the OBDII PCM, then I guess DHP might be the way to go but I would much rather use something that I can tune myself. There is nothing like being able to make changes right here on the spot if I have a problem rather than shipping the PCM off and have my car be disabled for however long it is gone.
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02:03 PM
RBeaubien Member
Posts: 775 From: Glendale (Phoenix), AZ, USA Registered: Mar 2002
Yes! Talk to Dave. I just had my PCM done yesterday. He's very professional and changed all that I asked for, plus the usual tweaking. My speedo reads right, I no longer have a constantly lit MIL, my fan operates correctly, etc. It was well worth it IMO. Highly recomended!
Dave is actually working on a end-user program to modify the PCM code in 99 and newer setups. I hope he finishes soon!
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03:35 PM
Jul 13th, 2003
Freshj Member
Posts: 1250 From: Holly, Michigan Registered: Nov 2001
Dave is actually working on a end-user program to modify the PCM code in 99 and newer setups. I hope he finishes soon!
I can't see it being that tweakable, due to the fact that would severly cut into his business. Most likly it will be just a MAF and timing adjustment. There is already a ICCU done by ZZP that allows you to change on the fly, but that requires the PCM to be reprogrammed to recieve the input from the ICCU.
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02:58 PM
rockcrawl Member
Posts: 2528 From: Lehigh Valley, PA Registered: Jul 2000
I've used the '94-95 ECM to run a few Series II 3800SC Fieros. I use GMEPro to edit. The fastest one I've built so far ran 13.1 with a 3.4" pulley and 3.06 gears. The others are not too far behind.
I just realized yesterday that there are two different knock filters used in the 3247 memcals. So I did some research and found that the '94 uses a different knock sensor than the '95. Anyone know anything about this? Are the two sensors interchangeable or does the sensor need to be matched to the filter? I've had some experience with the 7730 using a 5.7 liter knock sensor with a 5.0 liter knock filter and the results are pretty horrible. I'm wondering if this is something we need to look out for with the '94-95 3800 ECM.
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08:56 PM
Jul 14th, 2003
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
I've used the '94-95 ECM to run a few Series II 3800SC Fieros. I use GMEPro to edit. The fastest one I've built so far ran 13.1 with a 3.4" pulley and 3.06 gears. The others are not too far behind.
I just realized yesterday that there are two different knock filters used in the 3247 memcals. So I did some research and found that the '94 uses a different knock sensor than the '95. Anyone know anything about this? Are the two sensors interchangeable or does the sensor need to be matched to the filter? I've had some experience with the 7730 using a 5.7 liter knock sensor with a 5.0 liter knock filter and the results are pretty horrible. I'm wondering if this is something we need to look out for with the '94-95 3800 ECM.
You might be on to something. I too have learned about the pitfalls of GM knock sensor filters when using the 7730 ECM. I have not looked in on the differences between the 94 and 95 knock sensors myself. On my particular swap, I am using the 95 N/A 3800 Series II memcal knock module filter that is setup for 2 knock sensors. This particular setup seems to be more sensitive than the SC filter but that is totally ok with me. From what I have read in GM manuals over the years, you need to match the knock sensor to the filter for it to work correctly.
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05:19 AM
Will Member
Posts: 14299 From: Where you least expect me Registered: Jun 2000
Isn't the frequency an engine makes when it detonates a function of bore? Obviously the filter is tuned to the bore of the engine, and probably to frequency/voltage characteristics of the sensor. The bore difference should be what makes the 350 and 305 sensors incompatible. Since there's no bore difference between 3800's the knock sensor incompatibility should be significantly less.
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06:52 PM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
Isn't the frequency an engine makes when it detonates a function of bore? Obviously the filter is tuned to the bore of the engine, and probably to frequency/voltage characteristics of the sensor. The bore difference should be what makes the 350 and 305 sensors incompatible. Since there's no bore difference between 3800's the knock sensor incompatibility should be significantly less.
good question and assumption. However, GM does list 2 diff p/n between the SC and non-SC 3800's so I am assuming that the non-SC 3800 has 2 knock sensor instead of one because it has to be more sensitive. The 94/95 SC only runs one because of SC noise (I am assuming). I am running the 2 95 3800 II N/A sensors and it is hyper sensitive it seems.
