Anyone an expert on cars here?

I've decided that it would be fun to see what can be done to improve my car. It's a lovely hulking thing, capable of average speeds, but it's definitely built for comfort. I've been looking around on the interwebs and i've found that MPG and BHP can be improved by a chip remap which i'm not averse to.

Now there's a thing called the ECU. Or something like that. Reckon that this could be hooked up to a laptop to check what's currently going on in the brain of my car? I want to know everything there is to know about what Leona is thinking before I start anything. Obviously I know i'll need some sort of special software.

The car is a Renault Laguna II (Phase 1 - the one with the silver bit on the bonnet and the flippy-uppy panel in the dashboard) from late 2001, 16v 1.8.

I promise you I will post tomorrow about how to do stuff with the ECU. However, I'm tired and have to be up at 7am.

Wow that's so quick! Google was fruitless, except for in the case of buying one... which I don't want.

So thankyou in advance =)

You can buy a PROM programmer and re-map it yourself, but I'd leave it to a professional, you need the right software and you need to know what all the parameters mean and what new values are acceptable, what will improve the performance/fuel economy and what will ruin the engine...

You need to also inform your insurance company that the ECU has been modded (theoretically), otherwise you won't be covered if you have an accident and they check the car. That will boost your insurance premium - even if you just improve the fuel economy and not the performance...

Take it to a pro. You can get software to do it yourself, but you'll cock it up, I guarantee it. You want to be going to someone who'll produce you an original map using a rolling road, which should cost you around £400. You can get 'generic maps' for a couple of hundred quid, but they can be of variable quality and you're much better getting a custom one for your own car.

ECU remaps may be worthwhile for a turbocharged engine, but for a normally aspirated one the benefits are usually below a 10bhp improvement. It'll also put your insurance up. As Tombolt says, a rolling road is your best bet, or if you are feeling flush - induction kit, stainless steel exhaust and a more aggressive camshaft.

I'd second what Tom's said.
Dad had the Jag remapped - at the factory.
As a result, when the insurance people asked what the nature of the remap was, it was 'an improvement in the efficiency of the engine'. Which isn't technically a lie...
Don't forget, if you go down the induction kit/exhaust/cam route, it's compulsory to stick component manufacturers stickers down your doors, like a shopping list.

You may well find this, especially in cars which are derivatives of more “prestigious” models. From personal experience, my car is derived from the Mercedes SLK platform. However, Mercedes deemed the performance of the car to be too good, so it ha the ECUs programmed in such a way to limit the BHP. The result seems to be (from conversations with more learned folk on the subject) a richer mixture which affects the MPG. Having the car’s ECU remapped to original specs would up the BHP, but would also improve the MPG.

The ECU in your Laguna is a Siemens one, which are a pain in the arse for the end user to mess with. I didn't realize that, I thought they were just OBD2 like everything else.

You could get a SuperChip for it though. We had one in our little 1.25 Fiesta, and that gave it loads more grunt at the bottom end. Then, if that makes no difference, you can fit a throttle body off of a 1.8 Laguna onto it. It's just a bit wider so more air can flow through it. The injectors could need replacing though if it's already a lean burning engine.

Then, you can fit a aftermarket air filter/get rid of the plastic airbox altogether and fit a K&N or similar. De-cat pipes also work wonders for an engine, however you'll have to put the cat. converter back in come MOT time.

If you want to go wild, you can fit some higher lift cams in. These make the engine much more powerful at the top end, but run lumpier at the bottom end (like tickover -2.5k or so.). We tend to go for duration cams, because the engine runs much happier, and that gives it more torque. Individual throttle bodies are next. They make loads of difference, but are expensive and are kinda too exposed for a daily runner (You're supposed to run them without filters )

Either that or sell her up, and get a older one with the 2.6 litre V6 (IIRC).

Bally obviously knows his stuff, but I just wanted to add that increased MPG shouldn't be assumed with a remap. It's generally the result of having to use less throttle to drive at the same pace as you would've done. If you get some extra power and then decide to really use it all the time with spirited driving, you'll likely see a decrease.

Also, I would like to second the point that if your car is NA, don't bother. Chipping a forced induction car is a very cost effective way of increasing power, but with NA it requires a lot more money to see the same benefits.

Plus if you're intending to get different cams, exhaust and air filter (which is the base of any modding), the remap needs to be done last.

Wow... load of people who know WAY more about cars that I do! >.< Excellent... Heh heh.

With the plugging-my-laptop-into-the-car thing i'd never try and change anything myself, just interested in what's going on in there. I'll leave all the potentially car-destroying things to someone who knows what they're doing.

So from what I can make of the complicated words used, am I correct in thinking the following:

1 - No point remapping the ECU without a turbo?
2 - No point remapping the ECU before getting new cams, exhaust and air filter?
3 - I don't have a throttle body already...? (And what is one of those?)
4 - "Duration cams" will make my care much happier and will increase torque?

1. Other way round, carbouretter isn't worth mapping, injection and turbo will benefit, I think.
2. Correct. Filters and exhaust will increase air flow, for example, and throw off the ECU anyway - although many are self-compensating - so you would need to get it done again after replacing the bits anyway, therefore if you are planning on changing bits, wait with the ECU chipping and get it done with the rest.
3. For non-injected models.
4. Sort of. The high-end cams mean that the engine will need to run at higher revs to develop power. That means more clutch slipping, lumpy acceleration at low revs and the engine won't last as long - higher revs = higher wear. A low end torque or duration cam moves the power delivery down the rev range, meaning the engine generates more torque earlier. It puts the strain in different areas, but is generally better, unless you like hearing the engine screaming.

Personally, I'd always go for more low end grunt and top end scream. It is more usable on a daily basis (on the track it is a different matter)

Not always. It is quite common for mk2 Golf GTI 16v owners to strip out the Bosch K-Jetronic fuel injection and put a pair of throttle bodies in. After changing the camshafts, exhaust and air filter, owners would often outgrow the mechanical fuel injection system and revert to twin throttle bodies. They're not as efficient but the performance & torque gains can be quite impressive in the right situations.

Right so....

For efficiency i'd want a fuel injection system, but for power i'd want a throttle body? I definitely want it efficient and long-lasting and I doubt i'll ever race this thing so fuel injection then and that long-lasting camshaft thinger are on the table now.

Anyone know any place in or around Leeds I can get this stuff done?