Please explain the wonders of chipping

[kalniel]

Absolute novice to modding here, and also very unlikely to actually go and do anything. But I am rather curious at times, and I wondered if people could explain in very clear, scientific words exactly how chipping works and the real benefits/disadvantages it brings?

From rather simple searching there seems to be different pictures about it even within the Hexus forums - posts a couple of years ago indicate that it's really something you want to do after you've done a bunch of other mods, so that it's tuned for the new airflow etc. that you're getting. However more recent posts have hinted that it's something you can just do to a modern car with no mods to get more power out of it.

Sites that sell chips are absolutely useless, giving no information about what their chips are actually doing - some even seem to say you have to give your car 48 hours to 'learn' the new settings.

Anyway, I'd be grateful for a Hexus guide to chipping

[Moby-Dick]

In most cases , "chipping" a car involves modifying the MAP that the ECU uses. This is the method that the ECU uses to control the fueling and the ignition for different combinations of engine speed , throttle position , and a number of other variables.

However , some turbo chraged cars will also store vary the level of boost pressure as parto f the the map , so that a re-map can be used to raise boost pressure , thus gaining more power.

My car is less sophisticated than that , with a seperate boost controller. My map had to be adjusted to take account of different cams , injectors Air Flow meter etc. so it was needed to complete the mods that I had and allow me to take advantage of them so doesn't actually give more power in itself.

The other end of the scale woudl be the golk turbo diesel where a piggy back ECu is used to modify the map and increase boot pressure considerably.

[kalniel]

Right, so you can adjust the amount of fuel you put it, when you put it in, when you ignite it (if you're a petrol runner), and sometimes the turbo boost information.

Do you need a vairable geometry turbo to change the boost pressure? If not, how can you vary boost pressure? Hmm, maybe if there's a cap which lets pressure out when it hits a preset value and that is software controlled rather than mechanical you can do it, assuming that your turbo mechanicals are creating more pressure than you need, but that wouldn't be very economical.

For eg. I've got a 1.7dti astra (izuzu lump), which has a low pressure turbo - how would I find out what controls the turbo pressure?

[Moby-Dick]

Do you need a vairable geometry turbo to change the boost pressure?

no

Turbos use the wastegate ( internal or external ) to allow gases to bypass unit when a certian boost pressure is reached. If you didn't have a watsegate then you'd blow somethign up.

On an internalyl wategated turbo , the control of the wastegate is done by the acutator , which opens up the wategate when a given level of pressure is seen.

If you fool wate wasegate actuator into thinking that the pressure is lower than it realyl is ( by bleeding of a little of the pressure that it can see ) then you can ensure that it opens a bit later , thus building up a higher boost pressure )

If the pressure hose that comes of the actuator just goes back into the pressured part of the hoses then it'll just be mechanic boost control ( depends on the spring in the actuator ) . If it goes to a solenoid first then you may well have some extra boost controlin place ( this may or may not be from the ECU - eg later model 200sx's have a solenoid that restricts boost in low gears to prevent wheel spin )

I may well have over simplified things a bit here for the gurus

[Golden Dragoon]

I would imagine that it would be possible to wire in a switch connected to the solenoid under the throtle of a turbo car (similar to the kickdown in auto's), so that you could bumble along at low boost most of the time (and benifit from lower fuel consumption), and only get the increased boost when flooring it, for example when overtaking.

[Lowe]

Bleeding away a little bit of boost using a bleed valve/grainger valve set up is quick and easy, but isn't really the most reliable way of doing it. After all, should the valve fail and permenently open, your engine will be in a world of pain since the turbo will literally overboost it to pieces. I've seen R5GTT's hitting in excess of 60psi! For 30 seconds this turned them into absolute animals, but it usually ended up with a melted liner (or worse)....

Yes use a bleed valve to check your boost and have a play about to see how the car drives. But for the love of God, please then lose the valve and adjust your actuator by winding it in and do it properly.

Golden D - it's not really worth wiring up something like that. Remember, you don't produce big boost unless you boot it anyway, so why would you ever want to boot it and not have all the boost you can produce available? The economy gains via your system wouldn't be worth the effort where you can simply just not use full throttle and get the same effect. You just have to stop using a binary throttle position (difficult when you've got the turbo bug though I admit!).

[Butuz]

Yep you can do that. Or you can just use your throttle foot to do the same

Butuz

[Lowe]

By the way before this thread derails onto turbos and boosting, Moby's pretty well covered it.

Chipping or remapping is simply taking the standard fuel and ignition map provided by the manufacturer and improving upon it. Standard maps for cars are usually have a certain amount of tolerance built into them. This is because the manufacturing process for each car is never 100% the same; casting problems lead to differences in the inside of the engine, and all sorts of other minor niggles such as fuel ratings for a particular country. If you were to set up an engine 100% perfect, then apply that map to another (same) car, it may not run very well, or in worst case it might blow up....

So - we have a certain amount of tolerance in our map. If you remove this tolerance, you have a car that's set up on the cutting edge of its limits. This might gain you a few horses, and a few pounds of torque. It usually improves the throttle response makes the car more fuel efficient as a rule, but you don't often feel the difference in power unless the car is turbocharged (since as Moby points out, they often up the boost - look at the VAG car chipping results for example).

Most of the time on normal cars it's not worth it. However, if you've just blown a few grand on an engine rebuild with bigger this, wilder that and the other, you'd be silly not to have the engine set up to make the most of your new shiny bits. It's also worth noting that a remap is something insurance companies don't often approve of without charging you a few more quid for too.

[dangel]

I have a boost controller in my car and it's wired to the ECU and just adjusts the value of the 'requested' boost that the ecu makes. It's bloody useful when it snows and you don't really want the front wheels to 'snatch' or when the car goes in for work and you don't want the monkeys to play..

[Zak33]

also to consider: many manufacturers have forgotten to mention to the public that they build in a very low fueling, ultra economical area of the rev range so that certain road speeds in top gear produce favourable fuel consumptions for certain governement set mpg tests.

In essence, they cheat and give you a bleedin great flat spot in your power band where iut happens to sit in top gear on a particular euro mileage per gallon test.

Mid range torque is normally the biggest improvement from a remap, but also improved throttle response. With a lot of cars, when you lift off the throttle the fuel is cut totally to help with fuel consumption and also to allow emmisions to be lowered, BUT it makes the cars a tad jerky (perosnal experience....almost everything Vauxhall made in the early to mid 90's with fuel injection) and when the loving hands and mouse skills of a re programmer are borugh to bear on the mapping of that ecu you can get much sharper and also smoother power delivery, with less snatch.

Its sometimes possible to reprogram the rev limiter, and with a set of bottom end bolts, that does it's own magic too.

Putting lots of emphasis on bhp performance is often where they go wrong though....take boost pressures for example. Some just needs smoothing, not monstering up.

[CocoPops]

My VX has been remapped.

One of the best points, is the raise and softened rev limit.
The engine originally hit the Hard (on-off-on-off style) rev limit at 6,500rpm which is fine for a motorway crawling rep mobile, however not for a sports car.

So my rev limit is a soft (less noticable limit) at 7,250.
Now, I don't regularly hit the limit, but it does mean you can reach 60 in 2nd now, and hold the gears for longer rather than wasting time changing just before a corner on a track etc.

Also, you have to rememer the manufacturers build cars to be run into the ground, run on poo petrol and oil etc. Where as those of us likely to get cars remapped (and so remove some of the tolerance) are more likely to use decent petrol, make regular oil changes etc.

Hope that helps.

[Zak33]

/\what he said.....with brass knobs on

[Neo_VR]

In perspective kalniel its *alot* easier to get more power from a turbo diesel than a petrol/turbo petrol engine.
Theres only one rule with a diesel... more fuel = more power!
but if you just chuck more fuel into the engine, youll get more black smoke, which is why the turbo boost gets upped a bit.

My Fabia vRS (originally a 130bhp tdi) is remapped to circa 180bhp... it smokes a bit when its being pushed..
When i had NOS on it, the engine management program for that was to just inject as much fuel into the cylnders as possible.. which gave a small improvement but lots of smoke when not using NOS (it couldnt burn all the fuel quickly) but a huge improvement and virtually no smoke when NOS was on (smidge over 200bhp)


Depending on specifically what technology your 1.7dti engine uses (older injector pump probably) you may not need a chip to get more power... most injector pumps can be "tweeked"

[Konan555]

also to consider: many manufacturers have forgotten to mention to the public that they build in a very low fueling, ultra economical area of the rev range so that certain road speeds in top gear produce favourable fuel consumptions for certain governement set mpg tests.

On the flip side, many 'performance' chips alter the map to get good readings from the back-side-torque-meter. The car feels more lively, but in reality it's a bit of trickery.

It's a bit like carb enthusiasts confusing a less progressive throttle response (twin 40's leaping off at a touch of the throttle anyone? ) with more power.

There's a load of other stuff to do before chipping an N/A engine. And even after that, you'll get better value if you remap it to suit the engine rather than use an 'off the shelf' chip.

[badass]

Yep you can do that. Or you can just use your throttle foot to do the same

Butuz

Except you'll get even more fuel efficiency for the same power output if you reduce the boost rather than use your foot.

Its all about the pumping losses......

[wazi]

just had my 1.9 dci done its like $hit of a shovel now, fule economy is better , but i have a clutch slip now ;(