ECU differences on C5
 

I read a post on a corvette page on Facebook where someone stated that if you want to tune your car you should stay away from 97 and 98 model years. Is there a big ECU / software differences between the years on C5's? If so, can someone explain the differences?

Also interested in info. Got a 99 on the way but I always heard the 2000+ ecu is more desirable.

Wondering what the best route is for tuning a car with basic bolt ons at most.

Unless you plan on exceeding 500 crank HP there is actually no benefit of going to a newer model ECM---
Here is what the limiting point is on the 97-98 ECM's
The MAF table on a 97-98 ECM tops out at 11250 HZ which is an airflow measurement equal to about 500 crank HP any more airflow than that the MAF will simply read the last value at 11250 and you will lean out your engine
Now on a 99 and newer ECM the MAF table has been extended to 12000 HZ which can handle up to 600 + HP without exceeding the table
This is why many high HP early C5's switch to a newer year ECM---But it should be the only reason you would ever need to The 97-98 ECM has all the tables you would ever need to tune any combination up to 500 crank HP
PS This is of course only if you choose to use your MAF and retain the stock open/closed loop system AND your front 02's that control all of your P/T fueling
I would always recommend to use the stock tuning system on any car driven on the street---As the ECM/MAF/02's always are adjusting your fuel to compensate for load altitude-- and air density-------------There are a couple of other ways to tune without using your MAF and 02's --One is called a "semi open loop tune" which does not use the front 02's and the other is called a "speed density tune" which does not use the 02's AND it does not use your MAF------These type tunes are best suited for dedicated race only type applications and I would not recc. them on the street--as they allow no adjustments to fueling for altitude changes temperature changes or air density changes and would need to be re-tuned at every racing event----

Thanks for the informative answer tblu92. I have learned about the limits the hard way, the car is fitted with a ECS Novi kit this summer. We are at 481 at the wheels, and have turned back the rev limiter because of the lean situation. Safe up to 6000 rpm. Considering a SD tune to pick up the rest of the potential, but not sure. Cars running real nice and close to stock now out of boost.

The forum should ban you from posting in the scan and tune sections.


No seriously, they should.

:thumbs:

Hope all is well Doug.....

Ed M

You kind of guys have ripping off un- suspecting customers for years by overcharing them for tunes like a SD tune and ECM swaps that are un needed for daily driver NON dedicated race cars---
Sure if a car is a race only application you may want to tweek out every last HP --But at what cost ? drive ability and life of your engine
An ECM update on a daily driver is a waste of money and effort---
All the facts and HP limits of certain years ECM'sI mention is true---
Rather than doing a simple tune you sell people ECM upgrades and SD tunes and overcharge the for something that they do not need
YOU should be banned on an open forum for not addressing the customer's ultimate goals----I can sleep at night by being honest--Can You?
I have the right to my opinion as do you---But don't make it ugly as you have chosen to----ultimately it shows your true character--A whiney rip off tuner---

I do have to say that from doing business with ECS and Doug this year, I haven't seen what you are acusing him/them of. It has been a good process where I feel Doug has served my needs without trying to push something on me that I don't need. Actually I have got a lot of tuning help and tips for free together with my Novi 1500 kit.:thumbs:

If you have a great working relationship with Doug @ ECS, you should of just taken this question to him then? Wait, Doug did post in your thread and offered nothing to help you.

Posting on the public forum will bring different answers, because there is always different ways to get to the same place.

I honestly thought that the reply from Doug @ ECS and the supporting reply from Ed @ TheVetteDoctors were jokes with a buddy tblu92. Now reading this reply from tblu92 it appears not so.

What a public self defacement on your companies part to state unnecessary ugly comments. You two should appologize to tblu92, and save face, what you did was not needed to help the OP.

Does that sound familiar, maybe when mommy had to tell you to stop misbehaving. You guys live on public opinion, grow up guys and stop disrespecting people on a public forum (don't care for tblu92, so what, we don't care). You guys could be the best in the Corvette aftermarket, but rub people the wrong way and I would bet they will not give their hard earned money to you.

OP sorry I didn't have anything to offer to your question, I hope you get your answer.

Funny thing is that I do not charge more for SD tunes, so incorrect information yet again.

The simple truth here is that tblu92 constantly gives out false information on this forum, many forum members have informed him of this. This is why tuners like Ed from VD's have chimed in along with myself.

I am not the forum tuning police, nor do I want to be, but if you are giving your misinformation to a customer of mine then I am obligated to reply. That does not mean that I want to.

That makes sence if you're concerned for customers on the forum.

It might make sence to do it in a way that protects your company image.

So much misinformation on the net, you can't save them all. :D

Consider the origin of the term speed-density. It's all about calculating fuel flow as a function of engine speed and air density. If the ECU doesn't know the air density (e.g. by measuring temperature and pressure), then it isn't doing speed-density. And if the ECU is measuring those things, then altitude/temperature/density changes are all accounted for - no retuning necessary.

and there are hundrets of millions of cars on the planet running sd just fine.

I appreciate tblu92 posts. This section is fairly dead on tuning talk so he's a welcome addition IMO.

Curious what's the inaccuracy in his post about ECUs? I believe you can use front O2 in CL with SD... maybe I misunderstood his post. Also both VE and MAF account for mass which adjusts for altitude and temp... there's calcs for temp and MAP will adjust for altitude in VE.

Forum is for discussion... more of this and we'll all be smarter. Instead of just stating someone's wrong without explanation.

These are the facts and work arounds as I know based on this threads topic...

The issue with the 97/98 pcm's starts with their lack of processing power and memory....

Additional issues with these vintage PCM’s include the use of a Secondary VE table (half the MAP resolution) when tuning in Speed Density (MAF fail) as well as operating only under the Low Octane table so you lose your Knock protection. But to compensate for these shortfalls, you can load an HP Tuners or EFI Live Enhanced multi-bar Operating System (EOS) to provide a 2 bar VE table, support multi-bar MAP sensors and re-establish the High/Lo Octane tables. However we always have an equal and opposite reaction....they operate only in Speed Density mode....no MAF if that is what you desire.

If you want to build a big power setup with these PCM's and use MAF, then all you need to do is go to a Cartridge LS3/7 MAF (will require MAF and IAT table tuning), increase the charge pipe diameter (i.e 4") and this will give you over 25% increase in frequency range essentially giving you the equivalent of 14000+ hz based on the original setup. If you are increasing the airflow so much that you will exceed the 512 g/sec of Mass Airflow hardcoded limit, then you can perform a full Scaling effort on the tune and with a 50% scale factor, you can essentially increase the air and spark axis limits to 1024 g/sec and 2.0 g/cyl respectivley. A plus to this solution is you also can increase the Injector Flow rate to a whopping 1024 lb/hr....All this and you still can maintain your MAF/Blended tune strategy without sacrificing the discussed "environmental compensation". Now of course this is a bit more than just a simple tune, so normally it would cost a bit more as well....

Other issues that make these PCM's not as attractive is the use of a Secondary VE table as well as operating only under the Low Octane table when tuning in Speed Density (MAF fail) so you lose you Knock protection. But we have an option for these shortcomings as well, both HP Tuners and EFI Live offer Enhanced/Custom Operating System (E/COS) which can be loaded to return many of the missing features as well as increase many like a 2 bar Primary VE table, support multi-bar MAP sensors and re-establish the High/Lo Octane tables just to name a few.

As stated above, the second option is to operate in speed density but here you are limited to only a single bar VE table which can work with a large cam/bigger displacement setups but has limitations when you go FI. Not to say you can't do it, but as stated, your last column/row of the spark and VE tables will have to be set to the absolute maximum values leaving little or no resolution from 100 to 105 kPa or .96 to 2.0 g/cyl. At least the Scaling strategy above will get you back some resolution up top but does sacrifice some resolution down low.

So essentially there are more ways to skin the cat as they say relative to attaining high power output from these PCM's. And power levels really don't play a part in selecting the correct PCM because as Tuners we have several options we can choose from. One other good reason to switch out this PCM would be if you wanted to run Flex Fuel….the 0411 is a good choice that gives you both the flex fuel accommodation as well as Drive by Cable drivers if needed…

These are the facts at least as far as I have attained over the years to provide our customers the most reliable and well mannered vehicle….And basically whether you choose MAF or SD you are still getting "environmental" adjsutments and by selecting the SDCL strategy, it will give you the best of both worlds.

I also don't believe anyone alluded to changing out PCM's for standard bolt on modifications. I did a 98 twin turbo, 700 rwhp setup in a 1998 Corvette using the stock PCM. Car drives like stock and will melt the tires if you so decide....and the car has been running for 8 plus years :-)

Ed M

Then why chime in you tool? I love the fact Doug said what he did. There are so many people giving out false information and steering people in the wrong direction its incredible. CF is one of the worst offenders. Doug did also post in this thread to help him.

There are plenty of times I start a thread and ask the vendor I got the part from. Its called educating yourself. Go vote for hilary again.:crazy2:

You're Sooooo internet cool!

Looking at all the posts, I often think it would eliminate a lot of the discussion if we could all put more information in our opening thread. When I first read the opening discussion I thought of my friend who has a stock 98 C5 and was just curious. Had the original thread contained the information about it putting out 480+ HP with boost, then I would have realized what information he was really looking for. I know it is easier to say this than do as I have also started threads without putting in all the needed engine changes.

In retrospect I agree with you, allthough my first post was just trying to get the basic facts, not necessaraly linked to my situation

WRONG an SD tune does NOT take AD or altitude changes into consideration--It fuels the engine soley on numbers programmed into your VE table----And makes no adjustments to altitude air density--
This is why it is mostly a race only decision on a dedicated race car and with someone who has the software to make changes at every location
Yes you may make an SD tune work on a DD car but you risk the fact of a catastrophic lean down and the drive ability on the street will suffer--more so on an automatic car---
Using the stock OL/CL system with a MAF gaurantees the fueling at PT will always be trying to correct itself to the Stoich of 14.68-1
And then the VE table is only then being used as a reference to adjust fueling during " rapid changes in airflow" with an SD tune the the VE table is used soley to fuel both P/T fuel and WOT fuel with no adjustments at PT to achieve Stoich of 14.68-1