Engine management and tuning, stock and aftermarket systems can be discussed here. Information found here is mostly of very advanced nature and as such should not be approached lightly.
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I'd like to interject something here...fuel cut rev limiters are actually the best method. They do not cause an engine to run 'lean', for the very definition of 'lean' is insufficient fuel, not non-existent fuel.
Bear in mind: what do we typically fear from a lean condition? Detonation! But detonation still requires fuel...take away the fuel altogether, and you also take away any possibility of detonation. Air alone will not detonate!
Why is the fuel cut rev limit preferred? Well, once we understand the above, we can consider what 'interrupting' the spark (the other method of rev control) does to the engine. As we take away interspersed ignition pulses, we cause a very unstable condition to a very smooth-revving engine. The cylinder fires, then it doesn't, then it does, then it doesn't...mechanical parts are being jacked around, unevenly unloaded, then instantly reloaded...unburned/partially burned fuel causes all kinds of instabilities in the cylinder, as well as intake and exhaust systems...oddball pressure waves are caused in the manifolding...backfires often occur. Use your imagination and think about what's going on in there as the spark turns on/off repeatedly. It's just wrong on so many levels, and your engine HATES it, especilly when it's at its most tender condition...maximum RPM!
I stand corrected, and that is exactly the type of response I was looking for! Thank you for the info.
I'd like to interject something here...fuel cut rev limiters are actually the best method. They do not cause an engine to run 'lean', for the very definition of 'lean' is insufficient fuel, not non-existent fuel.
Bear in mind: what do we typically fear from a lean condition? Detonation! But detonation still requires fuel...take away the fuel altogether, and you also take away any possibility of detonation. Air alone will not detonate!
Why is the fuel cut rev limit preferred? Well, once we understand the above, we can consider what 'interrupting' the spark (the other method of rev control) does to the engine. As we take away interspersed ignition pulses, we cause a very unstable condition to a very smooth-revving engine. The cylinder fires, then it doesn't, then it does, then it doesn't...mechanical parts are being jacked around, unevenly unloaded, then instantly reloaded...unburned/partially burned fuel causes all kinds of instabilities in the cylinder, as well as intake and exhaust systems...oddball pressure waves are caused in the manifolding...backfires often occur. Use your imagination and think about what's going on in there as the spark turns on/off repeatedly. It's just wrong on so many levels, and your engine HATES it, especilly when it's at its most tender condition...maximum RPM!
The inertial load (the force on the rods and bearings when the piston accelerates/decelerates from a complete stop to maximum velocity) is the real issue here as the engine goes from full power to nothing at the rev limit. This happens regardless of fuel cut or spark cut. It's a huge shock load to the bearings and i bet the crank doesn't like it too much either
This is why manufacturers have moved to the fast acting and highly accurate electronic throttle as the primary method to control engine torque (and hence RPM). If you ever see an LS2 V8 hit the RPM limit you'll be quite surprised how civilized it all is, compared to the bucking fuel cut.
I used to have an old 383 SBC that could throw a 3ft flame from dual exhausts by cutting ignition at 7000rpm and holding your your foot to the floor, then keying on just before it stalled OMG what a noise!! A neat party trick Ahhhhh the memories....
It's not an electronic throttle car, but the SRT-4 has an interesting feature along these lines...the 'no-lift shift'. In this version, a unique rev limiting strategy is used to allow full-throttle upshifts. As hairball as this sounds, it works, and Dodge even touts it as a feature!
The way they make it happen is a 'soft' rev-limiting method. Rather than just hitting a certain RPM point where the engine suddenly begins to 'miss' to control revs, the rev limit actually sounds like one is modulating the throttle to 'hold' a particular RPM. Then, several tenths of a second later, the more aggressive 'limiter' engages, sounding much more like a conventional rev limit.
It's this 'soft' initial limiting where the engine is not 'missing' that allows the driver to just stab the clutch and pull the shifter without lifting off the gas. Of course, you can also attempt this on a conventional rev limiting car, but the odds of pulling it off successfully with every upshift are poor...usually, this will result in the occasional very violent missed gear, and can damage the transmission instantly!
Why does the 'soft' limiting work better for this no-lift shift? It seems to allow smoother engagement of the synchros since the engine is not vacillating back and forth on a 'pow-pow-pow' rev limit. I've done it many times on my own SRT-4, but I prefer conventional shifting. Even tho the no-lift shift works, at enhanced power levels (bear in mind, this car's been 11's on drag radials!), it just feels too violent for me!
Thanks for the soapbox, back to HPTuners features now.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
what kind of things can be done to the 4spd auto? any ways to get one into the 14's n/a
Probably with some bolt ons (I/H/E) on a 2.4 or eco. You can adjust all the shift tables you want, fueling, spark, etc. There is a list on the first post with the editable parameters for my 4 speed.
Damn for 499.00 I would think you should be allowed to do unlimited tuning without having to buy credits and such... NOT complaining though
You get 8 credits, costs 2 to do unlimited tuning to one car, so for $500 you can tune 4 vehicles.... I think thats a damn good deal.
It's a chunk of change, no doubt...but if one compares its capabilities to other options (such as piggyback controllers and other fuel items), it seems less expensive, especially in light of the much greater capabilties. Sure, it doesn't do EVERYTHING, but it does so much more than what you could access previously.
They have to limit the amount of cars you can do with one purchase, else they'd sell a few, then never sell another! In these days of peer-to-peer 'sharing' and the like, companies have to protect their interests if they want to be there tomorrow.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
I emailed Chris a couple days ago asking if there were any new developments on the issue of getting hp tuners to work with the ecotec gm s/c reflash or if there had been any progress, his reply was...
There's nothing much i can do about it unfortunately.
Chris...
So I guess the eco reflash guys are kind of out of luck. So I was wondering what everyone else in this situation is doing? Any other ideas? Going back to stock pcm then trying to use hp tuners? Anyone?
Got a question on the credits. year/model. means you can do work on any vehicle of that year/and model for a year. Then you need 6 more credits once the year is up?
No, its any vehicle of that model and year, forever. Its called a "single year license", but really what it means is a "single model year license". It does not expire after a year.
Well an update, Jimmy99Z at 607 tuning has been tuning my car with HP tuners in Corning NY. Two days ago the computer quit and nothing worked, so I got a new computer and now it is up and running again. The car will still be slower than shiot because of the damn lowered compression to 9.0.1, which was the supidest thing I ever did. So GM SC, 9.0.1 compression, 2.6 inch puley etc, and the car is struggling to get out of the 15s, I hate my car, lol.
i hear ya except i called my machine shop and they told me my comp was 9.2 not 9.0 so it isn't gonna be that bad
besides i am starting an m62 project on the car
hehehehehe
20psi here i come
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Why would someone want to disable the vats with hptuners. A quick search of vats came back with vehicle anti thefts system. Why wouldn't you want this.
Why would someone want to disable the vats with hptuners. A quick search of vats came back with vehicle anti thefts system. Why wouldn't you want this.
When you change the ECU programming to one that didn't come with the car, (IE the security code in the ECU doesn't match the code in the BCM), the car won't start. HPT doesn't give us the ability to relink the VATS (yet), so if you want your car to run with somebody elses tune, you will have to turn off VATS. VATS doesn't keep your car from getting stolen, its actually pretty ineffective, it just won't let the car run without a key in the ignition, or the correct PCM/BCM combo in the car.
^^oh. So someone can e-mail me their flash they have customized, And i can put that into my ecu. But only after i have disabled the vats. If i read correctly thats way you would want to turn it off.
I just ordered the hptuners program. But i am going to be running the protfueler. So all i need if for is to change
my close loop/open settings anyway. Maybe change my timing.
i only ordered it on Thursday and i already got an e-mail with instructions on it. so it shouldn't be long.
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