FAQ: How to tune the PCM? (Series II SC)

Basically, we have three choices when it comes to tuning our powertrain control modules:

1) Replace the PCM with an aftermarket version tuned to your specifications.
2) Re-write the PCM's code yourself.
3) "Trick" the PCM by using an AFC (Air/Fuel Calibrator).

1) There are companies (INTENSE, ZZP, DHP) who sell PCMs with generic performance tunes at fairly low cost. Most if not all of these won't work for the Riviera, which has its own code (BIN). For a price, these companies can custom burn a PCM that will work, but unless you know exactly what you need, this option probably isn't the best. Even the programmers will tell you that a dyno tune is recommended. This requires bringing your car in to run on a dynamometer, incurring additional costs. Obviously, this option is a 'set-it-and-forget-it' requiring the least know-how on your part, and you don't need to own any software or hardware, as the tuning service provides this. But keep in mind, if you make additional modifications, you need to go through the process all over again. If you like to tweak & tune, this can get expensive. Also, you are limited to where & when you can make a change, as visits must be scheduled with the shop.

2) Using a PCM programmer such as DHP's PowrTuner software (discontinued, orig price $390) or HPTuners ($500) to write your own PCM code is probably the best option if you really want to do it right. With these softwares, you can tweak everything from fuel curves, transmission shift behavior, to the speed governor and RPM limiters, and more. It's the ultimate mod for someone who really wants to customize their Riv's driveability. Here are some advantages:

• You can also get a pretty decent street tune without needing to pay for time on the dyno, just by doing some careful scanning, logging data and tracking results. Or, you can dyno tune just like the pros, except you or a programmer of choice can make the needed changes. You pay only for the dyno runs, and we have members who may be able to help you or tune for a reasonable fee.

• One big advantage of tuning yourself is being able to plug in and flash the PCM any time you want to. Didn't get it perfect the first time? Make a slight adjustment and try again, at no additional cost. New SC pulley to swap? You can scan & tune in your own driveway.

• An often overlooked advantage with using a tuner is the fact you don't actually need to remove your existing PCM unit to modify it - it's all done by plugging in. This means you don't have to purchase a 2nd physical unit - a back-up of your original BIN can be stored electronically, and uploaded back to your unit at any time.

Doing your own tuning can be a daunting task for many, as the learning curve is steep. This is where our tuning forums can help with any questions you might have. As mentioned, we have members willing to help you with questions, or even write/program tunes that will work for your car. You also must have some kind of computer, preferably a laptop, to run the software. You may also want a separate scanning package, especially with the DHP (DHP's scanner isn't the best). Check the Scans, Tuning, & PCMs section for more specific topics.

3) The AFC, more specifically the Tech Edge Mini AFC 2.2, is a small box that gets wired between your MAF (mass air flow) sensor and the PCM. This used to be the only way to tune the air/fuel curve for Rivieras. Sometimes referred to as a MAF translator, the AFC lets you to "fool" your PCM into adding or subtracting fuel from the air/fuel mix by altering the MAF signal in a very controlled manner. It allows you to in effect reprogram the PCM's MAFF (mass air flow frequency) table to get the fueling curve your engine needs to run with less KR. Usually this means adding fuel to keep up with all of the extra incoming air. The expected result is that knock will be eliminated and KR will go down, giving you back lost horsepower and enabling your engine to run more safely.

The AFC has been used with varying degrees of success. A major advantage with the AFC is the PCM always stays stock, so removing the AFC removes any 'programming'. It is a low cost option at a little over $100, and no software or computer is required to use. You can even 'dyno tune' with the AFC, in theory. However, the AFC can only adjust air/fuel, offering no transmission control or other tuning perks. For basic adjustments to the fueling curve, the AFC makes sense; for more in depth installations, reprogramming the PCM with a tuner is probably the best way to go. For info on how to tune with the AFC, check the Scans, Tuning, & PCMs section.

what would it take to completly replace our PCM and wires from ,say a GTP? i see rivman had that done on his 95' (the one with the swap'd engine) and i was wondering what something like that may cost and if its easier/cheaper that a DHP PT? what all would need to be replaced?

Not sure that it would be difficult, but buying a separate PCM isn't cheap. I think they're at least as much as the PowrTuner, maybe less at a salvage yard. I do know that with a PowrTuner you can effectively change all of the transmission settings to that of a GTP. From what I know that's the biggest percievable difference between the cars.

I believe you would have trouble with the security system. It wouldn't be worth the trouble.

i would probably need a tuner or tech 2 just to make it work. thanks for the info, im just trying to research all the options and ideas.

get a powrtuner. its the best mod i've ever bought.

fyi, you can find used ones on clubgp.com. with the new software updates, the powrtuner is open to all 98-02 3800's, so if its set up for a gtp, it doesnt matter, as long as your riv is a 98 or 99.

is see yours is a 96. if you get a used one, make sure you're getting a good deal, because it costs $100 to add another vehicle (at least it used to, i'd check dhp)

oh, yeah, also fyi: i got a gtp pcm from a friend and swapped it into my riviera just for the hell of it before dhp opened up the powrtuner, and it did the typical thing where it would start but die immediately. i even flashed it to a regal gs, since that was the second vehicle on my powrtuner, and that didnt work. the regals use class II data for the gauges, so a wiring harness from them wouldnt work.

i really want to hook up something to my laptop so i can tune my car whenever so if i see a race i can quick change it to race mode and hold the rpm's highrer

I used AutoTap. Tuning doesn't really work that way, though. Rewriting the PCM takes a couple mins, and you must have the car off. What you can do is tune the PCM so it drives/shifts differently when at WOT vs. normal. Once you see how much better the car drives with a tune, you won't want to use the factory settings ever.

Until you get a tuner, one way I used to hold the RPMs higher is to manually shift.

AA wrote:

I used AutoTap. Tuning doesn't really work that way, though. Rewriting the PCM takes a couple mins, and you must have the car off. What you can do is tune the PCM so it drives/shifts differently when at WOT vs. normal. Once you see how much better the car drives with a tune, you won't want to use the factory settings ever.

Until you get a tuner, one way I used to hold the RPMs higher is to manually shift.

what i found out is that when i hold it in first geat it shifts at 48 and when its in Overdrive its at 45 LOL but yes ill go and find more about auto tap is it easy to use

I was able to hold mine to 99 mph in 2nd gear by manually shifting (this was after a few mods, be careful).

yes my car is still goverened at 108 mph tho lol shhh i didnt test it haha jk i cant remember what gear i was in !!!! but it still shifts on its own !!! at 48 for me so i cant find much about tuners u kno my car and what will be done to it and im on a very low budget waht would u sugest for a tuner taht WILL work haha unlike my dads..

PowrTuner is $380. It's not cheap, but it's worth it.

AA wrote:

PowrTuner is $380. It's not cheap, but it's worth it.

would i definitely need a powrtuner if i get the 3.4 inch pulley and if i get the tuner will i be able to go to 3.25 without knock

98riviera98 wrote:

AA wrote:

PowrTuner is $380. It's not cheap, but it's worth it.

would i definitely need a powrtuner if i get the 3.4 inch pulley and if i get the tuner will i be able to go to 3.25 without knock

you will boost stack. You need to to be able to get the air out of the engine as well as it comes in. Headers and rockers do wonders.

oldsman105 wrote:

98riviera98 wrote:

AA wrote:

PowrTuner is $380. It's not cheap, but it's worth it.

would i definitely need a powrtuner if i get the 3.4 inch pulley and if i get the tuner will i be able to go to 3.25 without knock

you will boost stack. You need to to be able to get the air out of the engine as well as it comes in. Headers and rockers do wonders.

so will i be fine with the 3.4 inch pulley and air intake and pretty open exhaust i have no mufflers........ or would i need headers (idk bout putting on roller rockers uhhh sounds like alot of works because u need a air tank and twist ties@!!!!!!! according to AAs install!!! hahah Jk but is roller rockers and headers woow thats alot of $$$$

Agree with oldsman, you can program enough fuel with a tuner to run the 3.4", but a 3.25" needs additional mods to help flow. What he's calling "boost stacking" is what happens when you try to cram too much air into the engine with no way to push it out.

It's a lot of money, but compared to what you'd spend to get the same numbers out of a N/A engine, it's a bargain. Modding cars to be fast is expensive, period. We make up for the cost in already having a supercharger, and the fact that it's a Buick let's you save on insurance.

Btw, if you drop a valve while installing valve springs, you'll wish you'd bought a $20 air tank! If you think modding is expensive... try paying someone $1000+ to pull the heads and retrieve a dropped valve!

If you don't have a tuner, you need to make some other supporting mods to run a 3.4 safely. I'd recommend an MPS starting with a 3.5.

I picked up a DHP PowerTunr a few months ago. Personally, I wish I'd skip DHP's PowerTuner and spend an extra $100 for an HP Tuners setup. If you think you might be interested in tuning, save up $500, skip the $300 Autotap and go straight to an HP Tuner.

Why is HP Tuner better than DHP?

I don't care for HPT's pricing/car structure, but their software is just... better. I can't stand the UI of DHP's, it is sooo poorly designed. I don't think it's designed at all, it just kind of happened. It's a terrible scanner, I wish I still had my autotap. I could go off for hours about the things that irritate me about it but it's not really for this board.

My experience with HPT is from others locally who use it, and I'm just jealous every time I see theirs. It's obviously worth the extra dough.

All my opinions, and to some that stuff doesn't matter, but I can't stand the temperatures being recorded in METRIC ONLY, drives me up a friggin WALL, and that's just the start...

I also can't stand the DHP's scanner. I use AutoTap to scan, only tune with DHP. Maybe that's why I can put up with the PowrTuner's UI.

so what if i get one of those reprogrammed PCM's off of 3800performance.com will it work with my car if i get the 1998 buick regal GS one???? its 100$$ for it !!!

Nope, must have one custom tuned for the Riv. You're looking at probably $200. DHP may offer a better deal, as they already have a performance version of the Riv's BIN for PowrTuner users. You'd need to ask them or a seller of DHP products. W Body store would be a good place to start. Mike's very good to work with.

Fyi, I have the generic DHP BIN, and wasn't impressed. I wouldn't pay $100 for it. Only reason I use it is because the PowrTuner lets me change anything I want.

No, a regal PCM won't work in the Riv. You can get a Riviera PCM from a few vendors, DHP and Intense being two I am familiar with. I started with the Intense PCM and really really liked their changes from stock. However, that still isn't tuning. They come with changes so your fans work right with a 180 tstat, and they do change a few things like shift points, shifting pressure (crisper shifts), etc. You can choose a stock timing table or something more agressive. If you have a lot of KR do NOT choose a more agressive timing table, KR will only get worse. I don't know what they do to the fuel tables, but the things I really noticed had more to do with the transmission.

thats only for the 97+ rivs right?

One of the biggest complaints of INTENSE PCMs is the advanced timing causing KR.

'96s would be different, but I don't see why they couldn't do it. Someone needs to ask DHP to make one (maybe they already have).