Horsepower gain from tuning alone? Maybe more too?

[J-Ri]

I've got a '01 Impala with the 3.4L, got the car extremely cheap and I'm not looking at putting any real money into it. I already have HP Tuners Pro, and I know you can gain a lot of power just by properly tuning the V8s (LS- mostly). Has anyone done just a tune on these V6s? If so, what power gain did you see? I just don't want to buy more credits and only gain a few HP. The 3.4 in the minivans make 5 more HP and torque than the Impalas, so I can at least gain that, but if that's the max, it's not really worth it to me. This is my daily driver now, and I know that without spending thousands I'm not going to make it a fast car. It just feels SOOOOO slow the first time I drive it after driving my supercharged Cavalier for a few days.

If it would help much, I would install a larger throttle body, the stock one is obviously more restrictive than the air intake hose and the upper intake, but also larger than the valves and runners. What do you think about a larger TB? Do these engines have problems with the TB icing up if the heater is bypassed?

I had also thought about slightly higher ratio rocker arms, but from what I've heard about the camshafts on these engines, I don't think I should add any stress to the valvetrain. What are the opinions of those with experience with these engines?

Can the rev limiter be raised safely and would it do any good? I raised it by 750 RPM on my Ecotec with no internal modifications and have had no problems in 2 seasons of drag racing and 40,000 street miles, and a few people though even raising it by 750 RPM was conservative for the engine. Yeah, I know, apples to oranges... Another thing is that my Ecotec pulls all the way up to the rev limiter, while my 3400 seems to taper off about 500 RPM before it shifts. I don't have a real dyno, I used a dyno app for the iPod, wideband O2 and datalogging to make a pretty good guess at what to change in the tune on my Cavalier. So I don't know exactly where I am from peak power when it shifts, but looking at the dyno sheets I could find online, I think it would keep the engine more in the powerband if I raised the rev limiter and shift points by a couple hundred RPM.

If I do decide to tune it, can the stock injectors deliver enough fuel at the current pressure? Is there a slightly higher pressure fuel pressure regulator that fits in the stock fuel rail? If not, I assume I could just add a low pressure FPR in the return line, say 5 or 10 PSI, and raise the fuel pressure by that much? Does the stock FPR raise the pressure beyond what it does at atmospheric pressure if pressure is applied to the vacuum port?

I also considered water/methanol injection, I built a full system for my Cavalier for about $20 (yeah, twenty $US) and I wouldn't have to modify the controller's program much to add one on my Impala. The pump and injectors were used and free (and I've got enough for a couple more systems). It helps a lot with the increased IAT on the supercharger, but I'm not sure how much on N/A. The websites that sell kits claim big gains on N/A (for example 16 HP on a Mazda 3L) just by bolting on the kit, but I'm not sure how much I believe that.

If anyone has suggestions for other cheap (not necessarily fast or easy) mods that might help with a good tune, I'd love to hear them. I'm an automotive technician, an electronics hobbyist and I'm pretty good at welding and fabricating. Very little is out of my grasp here, I just want to do this cheap because I'm planning on selling this car in the next year or two. I have as much fun building a fast car as I do driving it, so time is not an issue, just money. I know nothing I add will increase the value of the car much, and nothing (or very little) would swap over to the engine I will have in my next car.

Thanks in advance for answers to any or all of these questions!
Jason

[Google Adsense]

[mickaz]

the tuning will help you get more ponies but the main thing about tuning is efficiency you gain from a stock tune. the main problem with the GM v6 is the exhaust. They are very restricted. If you start with an header and you tune it you will a get substantial power increase. and your injectors are fine till about 210HP after that i would start to consider bigger injectors.

[SappySE107]

From what you have said, leave it alone.

[Merc6]

...I'm planning on selling this car in the next year or two...

*Spark plugs (OEM)
*Ignition wires (OEM)
*Cabin and engine air filters (OEM)
*Engine and trans oil change with filters

[J-Ri]

the tuning will help you get more ponies but the main thing about tuning is efficiency you gain from a stock tune. the main problem with the GM v6 is the exhaust. They are very restricted. If you start with an header and you tune it you will a get substantial power increase. and your injectors are fine till about 210HP after that i would start to consider bigger injectors.

Thanks, I'll give just a tune a try, and might try a set of headers depending on what I get from tuning alone. I'll post whatever results I get.

From what you have said, leave it alone.

What did I say? Could you please elaborate? The only thing I can think of that I said was that it was extremely cheap. It was so cheap because the previous owner didn't want to replace the lower intake manifold gasket, 4 wheel brakes, a fender and do a full tune-up. It's now in perfect mechanical condition, so while it cost me little more than the value of the 4 new tires it had on it, it's a very nice car, and in better shape than most other W-bodies I've seen (and I work on tons of these cars). I'm also not doing it cheap because I can't afford to make it fast, I'd just rather use the cars portion of my discretionary income on something that's not a 4 door sedan.

*Spark plugs (OEM)
*Ignition wires (OEM)
*Cabin and engine air filters (OEM)
*Engine and trans oil change with filters

Already done except for the cabin air filter. Still great advice, it's funny how often people put big money into add-ons while neglecting maintenance

[TGP37]

What about fuel filter? That is a big one. 3 times in 4 years I had changed a filter for a friend and twice it resulted in restoring top end power.

And if replacing the fuel filter really did help with top end, start preparing for a fuel pump swap. Cause the one you got is gonna die soon. They don't like fighting a clogged fuel filter and when they are free of it, they burn up/break in days/weeks.

Put seafoam in the fuel/oil and treat the intake as directed. it will help clean up the injectors, remove some oil coke garbage and clean up the intake valves some.

Spraying the MAF with cleaner helps. These sensors get dirty and then give a false reading, leading to poor performance. Avoid oiled air filters.\



Drive the car around while scanning it with the HPTuner. If you post a log with the basic parameters there are plenty here who can decifer the data.

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btw, Sappy is a straight forward guy. He said that for professional reasons.

You said the previous owner didn't want to replace the LIM. That means it is leaking coolant into the oil. The oil can boil off coolant but it leaves behind a gritty particle that chews into your bearings/journals etc.

Stoip driving it ASAP. Replace the LIM, drain and flush the coolant. Replace the T-Stat. Then check oil pressure when fully warm.




If you are serious about mild tuning, I can help somewhat. But you gotta make sure your sensors are working proper first. If just 1 important sensor is giving a false reading, the whole tune process is junked.

[J-Ri]

What about fuel filter? That is a big one. 3 times in 4 years I had changed a filter for a friend and twice it resulted in restoring top end power.

And if replacing the fuel filter really did help with top end, start preparing for a fuel pump swap. Cause the one you got is gonna die soon. They don't like fighting a clogged fuel filter and when they are free of it, they burn up/break in days/weeks.

Put seafoam in the fuel/oil and treat the intake as directed. it will help clean up the injectors, remove some oil coke garbage and clean up the intake valves some.

Spraying the MAF with cleaner helps. These sensors get dirty and then give a false reading, leading to poor performance. Avoid oiled air filters.\

Drive the car around while scanning it with the HPTuner. If you post a log with the basic parameters there are plenty here who can decifer the data.

-----------------------

btw, Sappy is a straight forward guy. He said that for professional reasons.

You said the previous owner didn't want to replace the LIM. That means it is leaking coolant into the oil. The oil can boil off coolant but it leaves behind a gritty particle that chews into your bearings/journals etc.

Stoip driving it ASAP. Replace the LIM, drain and flush the coolant. Replace the T-Stat. Then check oil pressure when fully warm.

If you are serious about mild tuning, I can help somewhat. But you gotta make sure your sensors are working proper first. If just 1 important sensor is giving a false reading, the whole tune process is junked.

The fuel filter looks fairly new. Around here they rust at least a little bit the first winter they're driven, this one is spotless. I checked both fuel pressure and exhaust backpressure to assure no fuel or breathing problems, neither changes as the power drops off. It's also not a big drop off, but I can tell it's going past the peak power, it's just the last few hundred RPM before it shifts. I'll do the fuel filter one of these days anyway, but I don't think it's plugged.

I completely agree about the fuel filter taking out pumps, the pump in most newer vehicles can build 120+ PSI if it's deadheaded, and I've seen 2 fuel filters so plugged that the engine would start if I let the pump run until the fuel rail pressure was up to spec, then the pressure would drop off at idle and the engine would stall within minutes. How they drove the car until it was at that point is a mystery to me.

I checked the fuel pump waveform and it is good, and the guy I bought it from never replaced the fuel pump. That indicates to me that he has replaced the fuel filter on a regular basis.

I don't believe in sea foam as a maintenance fluid. It is mostly ethanol, light hydrocarbon chains and a small quantity of water that is absorbed by the ethanol, you don't want alcohol and gas in the oil, and they are already present in the 10% ethanol blend fuel I use. It does work for intakes, but not that great. I have seen it used to free stuck rings on an engine once, but unless the alternative is tearing the engine apart, I would never use it in the oil. As an automotive technician, I have seen so many people use it (and other parts-store cleaners) and still have problems which were solved by an air induction flush kit from BG Products. It has a 12oz can each of fuel injector cleaner (you run the engine on it with a canister that has compressed air fed into it), a fuel additive, and an intake cleaner that is sprayed into the intake as the engine is run. It does a great job, and while a bit more expensive, is more than worth the price difference. I also cleaned the upper an lower intake while I had them off, and also cleaned off the intake valves while I had the pushrods removed for the lower gasket. They weren't that dirty, but are nearly spotless now.

I did clean the MAF sensor, but it lowered the reading by .1 g/S (close enough that I'd say it was unaffected by the cleaning), about what I expected from how clean it was, but I cleaned it while I had it apart anyway.

I meant to also say that I replaced the lower intake gasket before I drove the car, and the smaller problems in the first week I was driving it. The lower intake gasket wasn't leaking that bad internally either, when I did the gasket the insides had none of the whiteish-brown goo that you get with excessive water/coolant in the oil. I also clean what sludge I can out of the head/block area, then rinse it off with a few quarts of new oil, then after everything's back together, I drain and refill the oil before starting the engine, then get the engine up to temp, flush the coolant, then change the oil and filter. Anything that was in the old oil is out of it after that. Ironically, the gritty particles you get in oil when mixed with coolant is the carbon that's stuck to the walls of the oil passages that's cleaned off by the alcohol in the coolant. That's why I would never use seafoam in the oil except as a last effort.

I did take a quick look at all the sensors and they read what I expect them to. The LTFT is +2-5% for most cells, nothing above 10%. I appreciate the offer for help, and may take you up on it. I tuned my supercharged Cavalier with no problems (fake 2.5 bar MAP tune), but one never knows what they'll run into on a different project. I'll post the tune when I'm done. I was a bit surprised that there were none in the HP Tuners repository,

This paragraph isn't directed at any one person, and this isn't the first time I've said it on various forums. When I said I'm an automotive technician, I meant it. I try to say that anytime I post on a new forum so that people don't waste their time telling me things I know . I'm not a mechanic, not a grease money, not an experienced DIYer. I'm the one that fixes the drivability problem that a few other shops haven't been able to fix. Often times that comes down to maintenance that's been neglected.

I'm really only looking for cheap options to add a little power, not restore power that it's missing. It's slow compared to my built up street/track car, not slow for what it is. I do sincerely appreciate the time everyone took to give me maintenance advice (>99% of the time that would be better advice than how to add power), but unfortunately it's wasted on me.

[TGP37]

Good, it is easy when working w/ someone who knows their stuff.

What I forgot to add about the Seafoam treatment was time. I know that stuff isn't best in the oil but I use it just prior to oil changes. 1/3 can in the gas with a full tank, 1/3 in the oil and 1/3 sucked up. When the gas tank is near empty, I drain the oil and replace with fresh (no seafoam).

I am going to look into that product you mentioned, BP cleaner. But as of recently, my engine is pretty clean right now.

As far as tuning goes, finding the best AFR in PE Mode for power (12.5-13.2 area), more aggressive spark advance and fine tune the acceleration enrichment for the crispy throttle. If you are using HPTuners, they have a forum with a ton of info specific to your vehicle class. It is easier said then done but that's the basics of it.

You can tune the transmission some. Boosting line pressure slightly can net a faster, more firm shift with a little more grab and go feeling.

Opening up the exhaust and adding a CAI has done well for many 60v6's


Tuning is more effective gaining power when the mechanical parts were modified, changing the volumetric efficiencies, etc. The mods will net some power, the tune will make those mods more effective.

[Merc6]

BG is what GM actually uses right?

[Z3500]

This paragraph isn't directed at any one person, and this isn't the first time I've said it on various forums. When I said I'm an automotive technician, I meant it. I try to say that anytime I post on a new forum so that people don't waste their time telling me things I know . I'm not a mechanic, not a grease money, not an experienced DIYer. I'm the one that fixes the drivability problem that a few other shops haven't been able to fix. Often times that comes down to maintenance that's been neglected.

I have read this paragraph several times, and it makes no sense to me. An auto-tech who fixes cars by doing maintenance that other people have not done and other mechanics have overlooked. But you are not a mechanic, so you just tune the cars or change air filters?

Not trying to be a dork, but I don't understand.

And just doing a custom tune to get a little more HP is going to give you very little "seat of your pants" noticeable increases, marginal at best. I would bet that is why Ben said to leave it alone. If you are going to sell it in a year or two anyway, it would be more trouble than it is worth.