Assuming the tuners are of equal ability, there's a lot you can verify with a dyno that you simply have to guess at otherwise. And a chassis dyno such as the Dynojet can be used very effectively for light load tuing - it has a brake just for that purpose. But that said, a good mail order tuner can get very close with the commoner variety combos and certainly do a better job than a boob with a dyno. The dyno is not magic, it's just a tool. The more exotic your combo is, the better I'd feel recommending a dyno tune vs. mail order.

Rich

 

Two completely different scenerios guys. Driveability and WOT. Driveability is by far the most difficult piece to tweek in when cam overlap gets large. It also seems that many people have other contributing factors such as ignition problems, header leaks, vacuum leaks, etc. which make driveability tuning even more of a nightmare. To tweek driveability, it takes logs and SOTP feedback. Send you logs to your tuner and you have a shot. It's still not as good as having your tuner sit right in the car to feel the stumble or bog.

Now


WOT is a piece of cake. Go to dyno or use a WB. Do a pull or log a blast down the track. Adjust PE. Rinse and repeat. From what I've seen, if your AFR is in the 12's or 13's NA, all the tweeking in the world might net you another 5 or 10 HP.

2 cents

 

Not at all what I was asking. I was asking what ecm's and pcm's you were making your comments about. If it be OBDII then I have no experience with them, so you may be right.
I'm not going to get into some of the things that you said, but I feel that some of them might not be accurate for all pcm/ecm's. That's why I'm asking if you're just referring to the OBDII cars...cause it seems like you're implying that what you said covers all ecm/pcm's.

And I completely agree with what some of the rest of you have said. If you're taking a bone stock car and slapping it on a chassis dyno to tune wot then you shouldn't have much of a problem as the idle and part throttle should be fairly well taken care of by the stock program.
If you're talking about a modded car, then just putting the car on a dyno to tune wot is a complete waste. You can spend hours upon hours doing the idle and part throttle tuning trying to get things to just an acceptable level. And then spend 1 hour on the dyno nailing a timing and fuel curve.

 

You got to take care of part throttle stuff first. Everythign revolves around that and alot of people don't understand that.

I had a guy get mad at me cause he didn't understand that I will not just tune on the dyno, it has to be GOOD around town first. It was a street car too. Oh well.

For instance last saturday I spent 1.5 hours tuning on the road (502 BB chevelle) then took it on the dyno for anthor hour. The car is good to go now.

 

not to keep harping on this but...

 

Trying to **** yourself or what?

I've seen plenty of mail order tunes that were so far off it was sick. Alvin's results may not be typical for everyone. Nothing will ever beat having the car right there with you to tune it. Period.

 

I am Alvin and those results are typical. Check speeddensity.org's two NE dyno days we did this summer. The most I got out of any 93 I mail order tuned was about 7 at the wheels.

period

 

Unless your full time job is custom tuning your statement about having the car in your face is way off base. This is why 90% of the cars I tune that were tuned on a dyno require a total retune.

Just because the car is with the tuner means dip if they do not know what the hell they are doing which is many of the dyno shops where the guys running it are wrenchers and not trained on the functions of engine management, EPA and GM enhanced features.

The car does not have to be sitting under me, what I need is good PCM scanner data which is much more important for a valid tune then blowing a quickie strapped on a chassis dyno for 30 second pulls.
I hate to say it but there is a hugh difference with airflow when car is driven and sitting on a dyno with 2 wheels not turning, tripping off traction control errors and the hood open.

I find it interesting cars, (street and pro racing), boats and even an airplane with LSx engines I tuned and never saw them and all run OK, in fact one took a SCCA TI stock title this year and I still have never seen the car.
I just tuned a 1929 chevy with a Z06 powertrain with a SC that is in Norway and never will see the car in person.

 

I know you are Alvin.
All I was saying was that just because your abilities and knowledge allow you to get the results you claim, that not everyone that people can buy a tune from have that same knowledge/ability. I was not knocking your ability, just the way that you presented it. Reread what I said, you took it wrong.
And I don't need to check any posts on speeddensity.org for anything.

Alvin, you know that dyno numbers aren't the only thing that indicate a good tune So you gained 7 horse at the wheels on a dyno...big deal. Great job on nailing the fuel curve and timing map.

Before I started helping friends with their pcm work, they had been getting chips and files from some of the "gurus". None of them were worth a ****. On a 396ci 93 camaro, the wot tune was pretty darned good, but the part throttle made you not even want to drive the car. The owner was extremely disappointed with the cars performance. He convinced me to get the stuff and learn how to tune his car. Once we did that, it was a night and day difference. The car went from blowing black smoke out of the exhaust from a roll, to blowing the ET streets away.
Having the car in front of me and being able to scan and drive it made all the difference in the world. And this was without a wideband.
No mail order file would ever have duplicated what he and I were able to do in 1 afternoon.
A couple of other friends had gotten pcm files from a fairly popular tuner also. Part throttle on each was great. Wot was a totally different story. Lots of knock and dangerously lean. A complete waste of money. Again, a couple hours of scanning and tuning made all the difference in the world.
So by not having the car available to them, the people that these mail order tunes were purchased from were basically making a guess as to how each car was going the behave. Had the car been right there with them, I don't think either tuner would have had a problem these cars.
Based on these experiences, I have no problem telling anyone that a mail order tune is only as good as the assumptions that the tuner makes about the car. A tune that is fairly common will of course be more accurate when purchased mail order due to the fact that the tuner has probably figured a good base file to use after 30 tries. But if the car was right there with them, it would be better. How can you argue with that?

Something that often gets overlooked is the fact that not everyone has the ability to scan their cars and check the accuracy of a mail order file. They are counting on someone to do them right the first time, not after some trial and error. And I'm willing to bet that 75% of those that do have the tools available don't even know what they are looking at when looking at a datalog. So they are still counting on your abilities.
Ever notice some of the extremely basic questions that get asked on this board? I'm willing to bet that a majority of those questions are asked by people that had payed for a mail order tune and were not happy with it in some way, so they went out and bought a cable and downloaded freescan or bought datamaster. And now they are trying to learn how to do it themselves for one reason or another. Had the car been tuned by someone that actually had access to the car, this probably wouldn't be necessary.

 

No, it's really not. Can you honestly tell me that if you had a car in your possession and you were able to drive it that you wouldn't be able to put a better tune in it than if you were just looking at a datalog?
And besides, how many guys that order mail order tunes can provide datalogs of their car to the tuner? Sure can't be all of them. So you can't rely on that information to provide someone with a tune.

Did I say anything about having to strap a car to a dyno to tune it? Why are you still trying to argue that point if I agreed with you that just strapping a car to a chassis dyno is not how you tune a car? Reading is a skill.

Ok, fine. Assume that we all aren't dopes and that some of us (besides you) do have a good enough understanding of this stuff to tune a car.
Everything else being equal, would one of your mail order files be better than one that you did with the car in your possession? If the answer is anything other than "no", you're kidding yourself and anyone that reads this.
I will, however, agree with you that your mail order file will probably be better than the guy down the street that bought a dyno and is advertising his tuning abilities. Who knows who he is and what knowledge he has.

Does everyone have the ability to supply you with this required pcm scanner data that you need in order for you to in turn supply them with a mail order file? So your mail order tunes are only available to someone that can supply you with a datalog...that leaves quite a few people on the outside looking in.
And stop arguing the chassis dyno stuff. When did having the car in your possession mean that you were strapping it to anything other than the road?Stop assuming that the only other option to a mail order file is a file done on a dyno, and that you are the only one that knows how to tune a car.

To answer the original post...
With all things being equal, a file done with the car being available to the tuner will be better than a mail order file. Just be careful who you let change things inside of your pcm. If all you're buying is a "dyno" tune and it isn't a full-on tune, then you shouldn't waste your money. Part throttle and drivability must be done before wot dyno stuff.
If you aren't comfortable with anyone local to you that can tune your car and your only option is a mail order file, caveat emptor.

 

Dan's right. To sum it up, in rank order from best to worst:

1. good tuner with access to the car
2. good tuner without access to the car but with PCM log files
3. good tuner with just a description of the vehicle

1-3 >> bad tuner. However, the way to learn tuning is with the car in front of you! Also, tuning is an iterative process, no matter who is doing the tune and how they are doing it, the tune will be better as changes are made, the results observed and further changes made based on the response.

The thing I have seen with cars brought in for tuning is that at least 1/2 of them have problems that must be corrected before any tuning will be effective. They have problems ranging for bad plugs and wires, dying fuel pumps, clogged injectors, defective ignition components or sensors, broekn valve springs, mis-adjusted valves, etc., etc. And there is no way to tune around a mechanical/electrical problem. These must be fixed first. A mail order tuner can't diagnose or fix these problems! So, a for a mail order tune to be effective, the car must be in proper operating condition in the first place.

Rich

 

totally untrue, most tuners would not spend the time to go drive the car for ALL engine condtiions to properly get the data needed to correctly tune, nor would most even want to drive the car to its limits, your dreaming if you think a tuner is going to blow his day just driving cars around all day where as not only does the car owner do a better job of doing a testrun, he also learns about what the engine managment is telling him by learning to use the scanner, but also then is part of the tuning process and the end result is my tunes are in part slanted to that owners own input.
As to mail order, when done in this fashion, a good tuner knowing he has to get tune correct on 1st shot will tend to put a lot more effort into the tune where the slacket tuner just bangs tunes out so its not the method of tune its most so called tuners know crap about tuning and think of themselves as cyberspace tuning gods where in most cases tuners like me have seen your tunes since your customers have had to come to me to fix the tune,
ie, one I got a few days ago with one of those cyberspace tuners, the car bends 3 valves within 1 week of being DYNO tuned.
I find in the tune, rev limiter set to 7,000 RPMs, stock heads, knock and misfire circuits turned OFF so was torque management no wonder the valves bent costing the car owner $2400 in repairs so here we have a car that was in tuner's hands and this is a norm I see all the time and whats worse is guys who know nothing about valid tuning methods running around playing cyberspace tuning consultant cause they got a tuner product and now think they are a tuning pro

 

so all you need to tune a car right is some logs with something like autotap? what all would someone have to log for you to do it properly? please tell me what all i should log and how much do you charge? do you have more experience than the madwolf dud that tunes on here?

 

Do you have a webpage? Pricing? etc...

 

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