tune vs no tune. safe?

Hi im trying to prove a friend wrong im saying that its not safe to run a 3.4 mps on a stock tune with proper mods. 98' gtp open cone intake, 104's, ported front manifold, 3" dp, 180* tstat. still need a tune right?

He can run that without a tune. I would be more concerned with if he is knocking or not. Hope he has something to scan with.

Edit: most mods you can run on a stock tune but of course you benefit more with a tune.

Yeah.

KR is the important thing.

Who cares if it's a stock tune or not.

I'd be willing to bet it isn't knock free with those mods though.

the stock tune is pretty resilient. i bet that car is running fairly well with what its got.

Stock tune will be fine I ran one in my 98 for a good while

The only reason I tell people to get a tune before dropping pulleys is because the stock tunes are programed to cut injectors in certain situations. That can hurt a stock motor, but it is more dangerous once a smaller pulley is used.

When does it cut injectors? I'm just wondering because I'm running stock tune on my comp g until I get bigger injectors and it seems to get lean every now and again for no reason.

I ran ok for a week on a stock tune after dropping pullies

My car would probably run better on a stock tune.

:th_shakinghead2:

Depends what you mean by safe. If your friend thinks adding more hot air with the same timing and fueling and not looking at KR is safe, then yea its safe.

Regarding the stock tune vs aftermarket tune, why can't we just disconnect the battery for a long enough time, and then let the computer relearn everything? Should it then be able to learn the proper fuel ratios, etc? I understand the aftermarket tune can turn on fans at a lower temp, get rid of rev limiter and speed limiter, but in general, isn't this what computers in vehicles are designed to do?

P.S. I am obviously no mechanic, so please explain without calling me a moron. :th_scratchhead:

Kilroy said:

Regarding the stock tune vs aftermarket tune, why can't we just disconnect the battery for a long enough time, and then let the computer relearn everything? Should it then be able to learn the proper fuel ratios, etc? I understand the aftermarket tune can turn on fans at a lower temp, get rid of rev limiter and speed limiter, but in general, isn't this what computers in vehicles are designed to do?

P.S. I am obviously no mechanic, so please explain without calling me a moron. :th_scratchhead:

Click to expand...

Because your PCM doesn't learn much at all.

Adjusts the fuel a bit here and there, and adjusts the transmission pressure. That's about it.

More advanced PCMs will adjust everything from timing to fuel to boost to shift points and so on.

So our PCMs are rather dumb then? Why can't we buy these "Bully Dog" devices that are supposed to be the cat's meow for diesel engines?? Why do our gas engines need a $1,000.00 piece of equipment, and THEN have to pay for everytime we want to tune the engine? Why don't we get something as simple as device that gives us a Stock setting, a power setting, and a milegae setting??? I realize on a diesel they just change the point the wastegate opens up to give more power, but still??

Well actually....

$300 buys you a DHP.

Unlimited tunes for any 3800 powered car.

$500 for HPT, $100 worth of credits for each car, then tune unlimited number of times with that interface. $500 HPT comes with $400 worth of credits.

You can buy canned tunes. They're a couple hundred if you don't send back a PCM for the core charge. Probably not a good idea to send your factory one away in case you have issues.

Handheld tuners like that are typically only worth owning if your vehicle has a turbo, or a very conservative factory tune. The reality of your car is, the factory tune is a great street tune in terms of fueling and timing and there is no boost control via PCM. That is simply pulley size.

If you want to talk expensive, $500-800 for a tune for my Volvo granted you mail in your PCM so they can flash it. $800-1000 gets you a handheld that gives you two options, stock or the tune you paid for. Bought some new exhaust parts and what a stage 2 tune? Extra $100+ please. Have those exhaust parts when you're buying the kit and what that tune from the get go? Still have to pay that $100.

Thinking about it, most non domestic cars cost that much for tunes.

Even those handheld devices for other platforms aren't cheap at all. Especially considering they don't allow you to really do anything. They can't datalog your vehicle or edit any part of the PCM like HPT/DHP can.

Thanks a bunch for the info Matt. Learned alot. Is there any computer programs one can buy? I have a ggod OBDII - USB interface cable, that allows me to read dang near anything on my GP, is it possible to use this setup to change values as well?

Unfortunately you're stuck using either DHP or HPT.

You have to use both the software and interface.

matt5112 said:

Unfortunately you're stuck using either DHP or HPT.

You have to use both the software and interface.

Click to expand...

:th_crying1:

Is there anything to watch if buying a used DHP, or is that not a good idea?

Not that I'm aware of, there might be differences in the interface firmware and so on which might limit which models you can tune.

HPT isn't worth buying used unless there are two credits for every $100 over $100 the person is asking for it. Unless a bunch of year/model/engine families are unlocked.