What is so special about stand alone vs. piggyback?

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Lextreme II

Active Member
Lots of talks about standalone and little respect for the piggyback. Can some experts explain in details why would someone what to spend $1,500 to $2,500 and massive amount of wiring. Piggyback have about 7-10 wires and cost about $400-$550.

Would the functions justify the cost?
 
piggyback ecus usually have lkimitations

they suk ass and should only be used by people who are tight asses

u usually cannot get rid of the air flow meter with a piggy back

and if u use std injectors then u are lmited to how much they flow

anyway ive always had the theory of doin things properly so i dont really like piggy
back ecus

the only reason u might piggu back is if the engine ecu also controls the auto gbox

some ecus control the air con and the cruise control too but i usually can get around those small problems from doin alot of testing so this can also stop someone from goin to a full aftermarket ecu
 
Piggybacks are okay for certain applications. You can definitely make a 10-second car with them. But for accuracy of tuning, stand-alones are better.

Oh, and by the way, you CAN remove the AFM with a piggyback.
 
There is one huge difference between a piggy backs (not talking about addtional injector controllers here) and a stand alone: The piggy back changes the fuel mixture and timing by altering the -inputs- to the stock ECU. It interecpts the singals on the MAF and timing sensors and alters them, tricking the ECU into thinking something else is going on. By doing this, the ECU will richen/lean the mixture and advance/retard timing. The big problem with this is that stock ECUs tend the learn and change their tune -this is unpredictable, and your tuning bay be good one day, but bad another day. Other problems are that piggy backs can not raise rev limits either.

Stand alone ECUs have 100% control over your motor. They control the outputs directly. It is much more difficult to tune a stanalone, but IMO you will have a much more consistent motor.

There is probably some threshold that determines which is best: piggyback or standalone. If you bumped the HP just a little, then a piggy back might be OK. If you are making 2x or more power, and you went to huge injectors, etc, a standalone will be much better.

The onyl other thing I can suggest is a standalone -with- the original ECU. Let the original ECU control the tranny and misc stuff like A/C, etc. Stock ECU would still be reading most of the inputs to operate, but the standalone uses inputs as well, but just controls the injectors and coils. This seems to becomming more popular on recent cars, as you just can't remove the stock ECU anymore because it is integrated with way too much stuff now.
 
That was some great points. I also liked Chrisman method of providing more fuel to the FI system. If the stock ecu is left alone and it control the stock injectors and have a huge extra injectors system to dump massive amount of fuel for high boost and at the same time alter timing also.

The above method Chrisman did basically the stock ecu doesnt change at all. Idle and driveability would be the same as stock and add fuel as need with boost. An example i can think of would be the Split Second FTC1 controlling the extra injectors and alter timing. The stock ecu controls the engine, ac and transmission. Piggyback on the stock ecu might be hard to get consistancy due to ecu learning.

What if we leave the stock system alone but add large extra injectors for high boost demand. What do u think?

Here is a picture of Chrisman's Work:
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Here is a spread sheet I created with stock injectors and extrat injectors with final equivalent flow rate. Extra Injectors Spreadsheet
 

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There is a new piggyback that allows you to convert your MAF system to a MAP system. It is rather expensive for a piggyback but a bargain compared to a full stand-alone, especially if your mainly wanting to ditch the MAF.
 
1100 bucks retail for a microtech is not expensive

if i had to chosse between 700 or 800 for piggy back id rather go the 1100
 
I think greddy emanage will convert maf to map, but I am not sure if it will control additional injectors. If I were to use a piggy back, I would probably try the emanage, convert to map, and use larger injectors.
 
Yeah, the new emanage does it too. It's also a bit more expensive but it's probably one of the best piggybacks you can buy.
 

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The piggyback I've been using for some three years or so isn't in any way over-ridden by the self adjusting capability of the stock ecu, in fact it's more like a carbed/mechanical advance timing setup now with the mixture/timing signals clamped by the piggy back the way that they are.
The stock ecu still handles tuning all of the normal driving functions by self adjusting, but at any larger throttle openings, the piggyback takes over.
My limits now are from the stock injectors, if which were changed, would not allow for annual visits to the smog test w/only a bypass plug, may try it without it this time, just for the heck of it.
I like the setup because I'm able to remove the piggyback entirely and run the car closed loop w/out any problems.
The factory ECUs are largely more sorted out than the aftermarket ones,(except for Motec) which makes them more reliable.
So unless I spend huge $$$ on an all-out motor, it would be a waste, as well as a great tuning nightmare to use a standalone.
 
But one simply cannot dispute a 50-70 horse increase when going from a stock ecu/piggyback to a well tuned stanalone on a bpu mkiv supra.
 
Yeah. If you want to maximize the setup, a standalone is a must. But at the same time, a piggyback is a great way to get your feet wet.
 
Personally, there are a few things I believe in that I've always found true.
1) most piggybacks themselves are not very useful because they simply can't control much. Because of that, you wind up chaining several together when you could buy a cheap standalone for the same price
2) Cheap standalones suck<PERIOD>. Either go all out on a great system, or don't do it at all. There are too many important compromises to go 50%.

To me, it comes down to what you can get the stock ECU to do.
If you buy an advanced piggyback that can control, for example, the air meter data, the ignition timing and/or coil<s> outright, extra injectors/lambda output/triggering devices/controlling extra devices - while tuning & logging information live, all at a reasonable cost, there is NO reason to buy any standalone!

Where people screw up is that they go out and buy some cheap, half assed $700-1000 stand alone. To get a top quality tune out of it you wind up with a little box that you either spend tens - hundreds of hours getting it to work right yourself, or paying hundreds/thousands to have done for you. Even then, it may, or may not have many capabilities you might want, and definitely won't have the wide conditions & safety features built into the stock computer. Buy a great standalone you're just left with paying for it in both time & money but not enough people actually do that.

What they wind up with, is spending all the time & money on it that someone smart with an advanced piggyback could get the same results with by spending a few hundred dollars, cutting the tuning time to a small fraction of a standalone, all while having many times the reliability & running conditions, AND still make the same amount of quality power.

Again, that assumes you can get what you need to happen, to happen with a piggyback. Most people SEVERELY underrate what advanced piggybacks can accomplish to begin with... If you can't get a reliable idle & part throttle running, or keep the A/F ratio in check by simply dropping in huge injectors & handling the air sensor, that's a problem for something like an AFC...
Something more advanced, you can do that, AND/OR add injectors to cover up any part throttle, or closed-loop fueling holes. OR modify the stock o2 sensor output to make the stock ECU cover up the fueling hole by itself!

There are also many tricks for most cars to get out of closed loop that no one takes advantage of. My favorite example for Toyota's is that if a car has an air meter, the TPS doesn't control anything tuning wise other than the ECU giving some light tip in ignition advance, or tip out retard... In reality, they do nothing more than trigger when to go from closed-loop, to open loop.

For example only, but I have used this on a few various OBD-I, and early OBD-II Toyota engine's.
Let's say the TPS sensor is a 0-5v scale, with 5v being 100% wide open throttle. Open loop mode is triggered at XXXX rpm, and/OR 80% of wide open throttle.
It's just as easy as wiring in a single throw, double pole relay into the TPS signal that breaks the TPS signal, and applies it's own voltage (Higher than the trigger point, say 80% of 5v is 4v, so you would obviously need something between say 4-6 volts. Not so high as to burn out the ECU tho!). Then you simply have the piggyback throw the relay by whatever means it can.

Be that RPM by throttle angle, or in our case, off a MAP sensor / boost switch. As soon as whatever trigger is hit, the relay throws and we're now in open loop mode running live instead off of oxygen sensor<s> that could lead to catastrophic lean-outs before the engine would normally reach open-loop mode. We also just threw the difficulty of part throttle tuning / ECU corrections out the window... There is nothing to tune out if the ECU is disregarding the o2 sensors to begin with!!!

What did it take do accomplish that? Maybe 10-30min depending on how slow you are at reading a wiring diagram to find the TPS sensor output, then splicing the new connections in. All at the cost of cheap wire & a relay.

On the downside, yes... There is another function modified by the TPS signal. That being the transmission logic. It will believe it needs to shift more aggressive for the same amount of throttle you give it when you've triggered open-loop than it would normally if you're under conditions that would be closed-loop. Ask yourself... Is that really a problem? No that's another BENIFIT!!!

This works on the few Toyota ECU's I've tried it on, but may, or may not depending on the application. One notable problem is drive-by-wire. You wind up in theory either confusing the ECU as to where the throttle actually is, or you inadvertently move where the ECU moves the throttle! Obviously in either case you're **** outta luck! Personally, I've never trie dit, but I don't see it working on DBW.

There is also no reason to need a separate unit to control timing / coil<s>. A good piggyback can:
intercept the cam & crank signals making the ECU advance/retard the timing intercept the dwell ignition signal to modify the ignition signal sent to the coil
simply control the coil<s> outright...

Advanced piggybacks should have modifiers for everything they try to do. Examples being make the base N/A air meter, and/or fueling maps run perfectly for a turbocharged engine while out of boost, but modify it by a MAP sensor run correctly under boost (or vice-versa, make a boost map, then detune for N/A).
Another would be having the same setup, but then scaling it to a temperature sensor. That way, you could either have it run rich while cold for emessions, or run rich while hot to save pistons. (Or both if you can completely program the algorithm)

In essence, a real advanced piggyback doesn't just quality as a piggyback. They also qualify as a cheap stand alone, as most advanced piggybacks can run an engine as a stand-alone.

I feel like I just wrote a dissertation, but people that don't have first hand experience using an advanced piggyback don't need to be telling people what they can & can't do. The possibilities are only limited by what problems actually arise, and how you choose to solve them.

Now personal opinion. I swear by Perfect Power's SMT's.
The kick the pants out of the same technical level e-manage, at 2/3 the price of a fully upgraded e-manage.
They kick the crap out of split second's stuff as they do much more, and tune/log live.

They also have multiple sets of maps. Want an economy/power setup? What about a power & more power setup?
No problem. Install a swithc to ground (Ooor if you're smoothe, take the ECT/Power button for the transmission on some models, have it also trigger a relay that grounds the SMT's map switch wire.) Push the ECT/Power button, and it swaps over.

I love my SMT-6. I setup one OBD-I (i.e. they don't throw/store codes for any reason because they're stupid) 3.0L v6 turbo (200cc stock) to run reliably with 680cc injectors by nothing more than tuning the air-flow meter. If I recall, it intercepted the small airflow-meter which we created a bypass for, ran the ignition timing . We set it up to run 100% N/A, but used a pressure switch to swap the unit over to it's second set of maps which contained boost friendly fuel. If I remember correctly it wasn't a boost pressure switch sensing positive pressure, we installed a vacuum switch taking manifold vacuum that would trigger at very low vacuum like 2-3 in/hg (i.e. high throttle). (We had to invert the signal with a relay)

That way, the SMT would be swapped over as the engine was about to finish spooling, instead of all-ready creating positive psi.

I had fitted 720cc's on it with a buddy, but we took them back off. Yes... They did work also.

AFA OBD-II, you don't get the "wide birth" freedom of tuning that older OBD-I cars have, but as long as you either KEEP the stock ECU reading acceptably normal ranges, or SIMPLY MAKE IT THINK that it is still close enough to normal ranges.

You can accomplish anything.
 

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I could go on & on with a hundred thousand neat little things you don't normally expect things to do.

If you think outside of the box, what you can realy do with a great piggyback, or anything else for that matter, is nearly limitless.
 
What would you class as a 'cheap' standalone?
I realise that prices differ hugely Aus vs US, but the $700USD ecu's do pretty much everything that the $1500+USD ecu's do, without the extra things like traction control, launch control, antilag, etc.

They don't require any extra costs, and most of the time require less tuning.
 
It doesn't take much tuning to get an engine running.
What takes hours, upon hours to do is get one running reliably under the majority of the conditions it can see.
Cheap stand-alones don't always have the programmability, or ability to do this to a good affect.

There is no substitute for experiance. If you buy a good unit & have it done by an experianced tuner (For it's application) shop, they all ready have 90% of the work done. Nothing more than plugging rough numbers, doing a fine tune (or a few), and putting in the modifying parameters for the varriable conditions it might see to keep it safe.

I'm not reffering to the extra features, like transmission control, spooling/antilag control, simple traction control. All of that is just candy. When I say a good tune, I mean it will run under any concievable condition A-OK. From taking a trip up & down a mountian range, to driving from say Mexico to Canada under any engine load combination without a problem. Then if a problem does come up, it needs to not only be able to tell you what has happened, but it needs to have enough failsafe tuning to keep anything it's being used on safe.

Cheap standalones don't fare so well because a lot of them simply can't handle enough parameters to tune by.

My definition of a good piggyback, is fairly wlel the following:
one that can handle nearly anything it needs to by itself, without extra boxes, or parts to buy.
The best example is a Unichip. If youre' willing to pay them the $800-1100usd, plus whatever it costs for them to set one up, you can accomplish nearly anything with a Unichip on nearly any stock computer, if you give them the time to accomplish your goal.

My definition of an advanced piggyback is one that is far cheaper than a Unichip $300-$600usd range prefferable, while having all, or most of the function a Unichip is capable of.
Supporting logging & live tuning.
All by the end user, with no special equipment needed to accomplish anything done.

Something else many people tend to forget is that many Toyota sensors simply don't work, or are flaky at best with stand-alone systems.
Offhand, Toyota/Denso cam & crank sensor range from being notoriously hard, to impossible on many engine's. Some of the other sensor's also tend to be hit & miss.

Personally, of the cheap standalones, I think the common Haltech's are way over rated, I do like AEM a lot. It has a lot of bang for the buck, easy enough to use.

For expencive stuff I like Perfect Power's XMS. Very advanced, but not quite as expencive VS what it compete's against. Unfortunately, it tends ot be fairly flaky with the Denso cam & crank sensors. They should be changed out (Not a hard thing to do, but just more **** most people don't think about when they start)
Motec's are great, but can get hella expencive.
 
I'm going to have to disagree on some of those points.

I have probably one of the cheapest ecu's on the market (Microtech), and I also have a 1UZ on factory management.
For the most part, the drivability between the 2 ecu's is pretty much identical.

Yes, my cold start leaves something to be desired, but I never really got that tuned properly, because like most people, I wanted the car back now, and didn't leave it the long enough to get a couple of decent goes at a cold tune.

Granted I haven't been to anywhere with high altitude, but where I live I don't get much oppurtunity to do that.
But I have driven long distances, and driven at temperatures from freezing to boiling, and its performed flawlessly (after all my wiring bugs were sorted out)

I get better response than the factory tune, more power, and only slightly worse fuel economy.

All of this and only 3-4hrs on the dyno.
Another 2 hours and I would have gotten better fuel economy than factory without a doubt.


It does definately depend on the tuner though.
I was lucky and happened to get probably the best tuner in the state (it was the only place that wanted to dyno on a saturday, so I went there).
So had it been someone else tuning, I'm sure it would have been a different story.
 
I don't think Haltech is overrated, rather, I think a lot of people use them so there's more incentive for other people to use them. That is, just about everything under the sun has been ran by a Haltech, so there is already information out there.

I have heard nothing but bad things about the E6X though. I think I'd stick to the E6K if I were going Haltech.

I do think there are some great standalones that get overlooked because of Haltech. Autronic in particular doesn't seem to be very popular in the US, and yet from what I hear of it it's a great standalone. I think the US in particular mods their cars according to what's cheapest, and that's why Haltechs are so widely used.
 
Toysrme - With regards to the TPS signal modification how do you find the transient fueling afterwards?? The TPS controls power enrichment and with out it connected id have thought a hesitation and lean-out on throttle tip in would be present. Also does the ECU set an error code? Most ECUs look at the signal and if it is too high (higher than about 4.8v) it sets an error or if there is no change in TPS for a few seconds sets a code.

PS: you type too much :omfg: :)
 


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