I have been burning a few chips for my MAF setup and I was wondering if I convert to SD it is harder to easier to tune? For example if I get a new cam would it be easier to tune my PROM with a SD or MAF ECU? Converting my car from MAF to SD is no problem for me. Just wondering which would be easier for a beginner tuner like myself.

 

SD is alot more intuitive.
Fooling with the MAF Scalers and stuff takes along time to learn, and lots of practice to get the knack of.

Just go to WWW.TUNERCAT.COM, and get a copy of the 42 Demo, and then look at the VE table, and the look at your MAF stuff.

 

Having played with both, I have to agree with Bruce too.

If the engine is not too radical and you can get a MAF Scalar table that is fairly close to 128/128, then I would give the nod to MAF only because you didn't have to mod the MAF Scalar Tables.

I have found that in 1989 alone, GM has over 5 different MAF Scalar Tables for different TPI configurartions. Most of these BINS were for the same enigine (L98 auto). Of all the MAF Scalar tables, I find the ARAP yields the closest to 128/128. So if you can use the ARAP MAF Scalar Tables and get 128/128 (or fairly close) then life is easy.

However, if you find that even with the MAF Scalar tables that you are getting wildly varying BLM/INTs (half above and half below 128), then you have no choice but to adjust your MAF Scalar Tables.

At this point, SD definitely gets the nod. As Bruce said, it is far more intuitive and if you get a "system" (data capture and developing averages from the captured data), you can get 128/128 BLM/INTs very quickly and easily.

Another advantage to SD over MAF is that you can accurately correct for elevation and ambient air temp. MAF has to use the MAF sensor to compensate for all those (elevation and air temp) and while it does it "okay" it is far from perfect. With SD, you can dial it in exactly - if you wish to take the time to do it.

 

Well what do you guys think should I stick with MAF or if I am willing do the work to swap to SD is it really worth it or am I going to make things harder for me? The reason I say this is because of a comment on chevythunder.com:

"The map sensor used on 1990-92 TPI systems, replacing the MAF system of earlier years. It is not as accurate as the maf in calculating air mass, only as detecting the load of the engine through manifold vacuum. The speed density as it is called is very sensitive to anything that is modified that will upset the preset calibrations in the prom, engine performance suffers as the engine wears and systems degrade. But it is still popular for swaps as the wiring is less involved, air intake plumbing is usually simplified, and the map sensor (around $30) is considerable cheaper than a maf sensor"

 

Heh heh, another "informative comment" by a person who has not burnt eproms for both cars - if he has burnt eproms at all. (I'm being polite, you should hear what I REALLY THINK).

I would say that if you are not planning on making a LOT of HP, you can "push" the MAF system quite far - but it isn't quite as accurate. The biggest problem is the "maxing of the MAF @ 255 gm/sec". Any potent 350/383 can do that at fairly low RPMs.

Right now I have been helping a buddy with a 383 that is running MAF and probably produces somewhere between 450-500 HP. Through various "kludges" I have "overcome" the 255 gm/sec limitation, but we are finding "skewing" of the MAF Scalar tables and once you need to mess with those, it's an exercise of "compromises".

We have always planned to go SD, but we purposely wanted to see how far we could push MAF. We have exceeded beyond our original expectations, but we are already finding some serious short comings.

 

I'll take it from you. You know a godly amount about TPI. It's SD time!

 

Based on your current mods listed, you could "practice" with your MAF system. The neat thing, is once you finally convert to SD, it will only cost another $20 to get the $8D TDF from TunerCat.

Don't get me wrong and think that I am implying that MAF is bad. It's not. It works quite well when you consider that GM was only producing 245 HP from the L98s in it's "hey day" before the LT1's introduction.

Also, I ALWAYS recommend that people get into eprom burning as one of the first things they should do BEFORE they even start to mod their car. The guys that have the hardest time is the guy that has built his "383/434 with a Miniram, AFR 210s, solid roller yada yada and now can't even a custom eprom to work".

Though SD and MAF are different (primarily the VE Tables that control fuel), what you would learn from initally "playing" with MAF is easily "transferred" to SD.

 

While the article is about 10% true...yes SD is easily upset by changes like cams and heads, I prefer it for the exact same reason Grumpy and Glenn do...simplicity. Although I have not tuned any MAF systems, I have looked at the PROM in my '85 IROC enuf to know that I don't want to mess with it.

The article is wrong when it says SD is innacurate compared to MAF. Manifold pressure and rpm are a direct function of air flow. Or so my physics professor says.

 

So tell me again why GM switched back to MAF systems on the 4th gen F-body?

I have not yet tuned or burnt a SD prom, so I cannot comment on how easy/hard to do is. But I have had good luck with tuning my car with the '89 ARAP $6E code. I haven't come close to the limits of the MAF. I think I hit a max of 210 gm/sec. I can say with experience that a small change in the MAF counts tables, can make a big change in the BLM numbers. Just takes a little time to dial it in.

Seems like to me if your MAF system works, just go with it. How much does a new (SD) ecm and harness cost anyways?

Just my 2 cents!

 

In the 4th gen stuff they were having to get ready for the OBDII diagnostics. That requries a double check independently of the primary system for redundancy. All the latest stuff is a whole generation of smog laws newer.

If MAF was in fact better, then someone ought to cal the guys at F1, CART, IRL, TRANSAM, and the other EFI racing classes. Other then when I having to use an oem system I don't know of any serious racing that uses a MAF.

What seems to you, is just your opinon. If you were to further research the topic, you might change your mind.

 

And what may we ask are the authors credentials in even knowing which end of a screwdriver to hold?.

Nowadays you need an ENGLISH degree to work for a magazine. You get more points for spelling then having any serious underhood time.

He's so poorly informed that he should have his crayons taken away.

 

I agree partly with the initial quoted blurb from the original post. If you are really picky about engine tuning and want a simple system to do it with......go with SD. If you want an engine to run OK without tuning the PROM......go with MAF. It will try to adapt to an engine it was not designed for slightly better than SD.
I can feel the flames coming for saying this.
J

 

No flames are deserved for that. It's true. My cam is totally wrong, and I am very happy that my MAF makes it run okay (after a hand full of startups, driving, cool downs, for the BLM's to halfazz come around) But, I also realize that I would benefit heavily from tuning, whether I keep MAF, or go SD, or beyond, which is why I'm here.

I think in the case of TPI, the SD makes a better showing because of the limits of the MAF (though a translator & more capable MAF could change that), the faster ECM, and the easier tuning. In all, I get the impression 90-92 SD is better than 86-89 MAF, but in all, an improved MAF system, as on later '90's GM cars is a better system for a daily driver.

It's just ironic how the application, and date used of a system can make it seem better. In the 5.0 & 351W world, MAF is considered better, here SD is considered better, and on LT1's, MAF is considered better, but the ECM, and many other variables of the whole system have to be taken into acct. and neither system should be crucified based on one application.

Flame away

Matthew

Edit: No need for the first part...the remainder is as typed.

 

I don't want to be a "bad guy" but over the years a lot of the "earlier MAF" users have used the argument "then why did GM go back to MAF" as to justify their system. Point is the new system is COMPLETELY DIFFERENT and uses both MAF and SD. It is a completely different system. Also for a number of guys running "4th Gens" that have "experimented" they are finding they are running faster in SD MODE ONLY! Imagine that!

The point is (as made by JMD), MAF is a "bit forgiving" when it comes to calculating "fuel". But this is ONLY TRUE IF the MAF calibration is correct in the first place. I have looked at 5 different MAF bins for 1989 cars alone ALL with a different MAF Scalar calibration and ALL for the same vehicle (350 auto). So which MAF Scalar is the best one? They can't ALL be right?

Yes, IF you can get away with a "minor" change to the MAF Scalar table great. But when you need to make a change to the upper part of ANY of the 6 MAF Scalar tables, then ALL 6 NEED TO BE RESCALED....if you have to do that...IT'S A BITCH. I'll take SD any day in that situation.

Another problem with MAF, is that it does EVERYTHING (elevation, humidity and ambient air temp). The system in Third Gen cars does not use ANY OTHER SENSOR to make corrections. YES, THE MAT IS USELESS FOR CALCULATING FUEL ON A 3rd GEN MAF CAR. It only controls the EGR.

Unfortunately, the MAF is prone to error and if you tune your car "perfectly" for sea level, it is will not be "perfectly" tuned for a different elevation or air temp. With SD you can "perfectly tune" for all those conditions. A major reason racers prefer SD.

Also, a MAP sensor is a heck of a lot cheaper (and easy to find at a wrecking yard) than a MAF sensor. If I had a MAF car, the MOMENT the MAF sensor died, I would convert to SD. Converting to SD is cheaper than a new MAF sensor if you use parts from a wrecking yard.

Lastly, for the argument "well I can use a MAF system for a modified engine without burning an eprom". Then you are just looking for a "plug 'n play" solution and destined to come in "second place". Even IF the MAF Scalar tables are "128/128" perfect after modifying your engine, what about "the spark advance"?

Anyone who's been burning eproms for a while will tell you it's the spark advance that is far more crucial to developing power. I've played with my SD system (along with MAF) and even if I am "a little off" in my fuel, it doesn't have anywhere NEAR the effect that "a little change in spark does".

Only 2* of spark advance can make the difference between "optimal", "slow" and "massive detonation". So the argument that "MAF is more forgiving" is utter non-sence when you want to optimize your power. MAF need an eprom just like SD IF you want the most power out of your engine. And the difference between, an optimal engine and "runs okay" can be quite significant EVEN on a stock motor.