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Improving throttle response in a Sport 350.
Posted 03 September 2009 - 01:04 PM
Is this what all the new tools are for Bibs?
Professionals built the Titanic
"I haven't ridden in cars pulled by cows before" "Bullocks, Mr.Belcher" "No, I haven't, honestly"
Posted 03 September 2009 - 01:09 PM
The easy ones:
check throttle adjustment is correct
SportCATs or cat-free (dare I say that?)...
K&Ns or equivalent non-paper filter elements
Not so easy:
Posted 06 March 2010 - 02:57 PM
I'm not sure if this thread is "out of use by date" but I try a small input:
Supposing that everything with the engine and its controls is working as intended (and that you don't want to throw out a lot of weight from the car), this kind of changing the "behaviour" of the engine is normally down to the maps of the ECU. They have been programmed by the factory to make the best possible compromise of low emissions, quick responses and power.
There are several functions that the factory programmers use to better the emissions, that take some of the edge away from the engine at the same time.
When you blip the throttle on an old carburettor engine, the sudden wash of petrol from the accelerator pumps sends the revs up immediately, and when you back off, the closed throttle ports cuts the revs. Of course the lighter the moving parts of the engine - including and especially the flywheel - the quicker it will react to input.
When it comes to more modern engines with managements, it's no problem to "mimic" these reactions, but the factories have chosen not to. On the contrary, there are specific parts of the programming that sends the acceleration of the engine through a smoother curve, because this is creating less emissions. The old carb engines reacted quickly, but didn't manage to burn all the petrol in the process, so pushed lots of un- and half burnt petrol out with the exhaust making a high emission.
This is maybe most noticeable on a modern car when listening to the engine note/revs as you first rev up to let's say 3k and then immediately let go the right pedal. You will often hear that the engine keeps the revs high for an instant before slowly lowering again. I have this with my "civilian car" a normal BMW E39, and the first time I wondered if the wire was sticking and started to investigate. The answer was that this is much nicer to the environment, and won't make much of a difference to the normal car driver.
Us hotheads have a different approach of course, and as you may be know I'm starting with blank sheets in my project and will have this particular item available in the back of my head when I set up the new engine and the free standing (non factory) ECU.
As I mentioned it's not difficult for a programmer / rolling road expert to set up an ECU to behave like the old carbs in this matter (and still keep the driveability / tractability of a managed engine) but he has to balance it towards the MOT and emissions control. In my case the car is from 1979 so it's an easier matter with emissions :-)
Edited by saggitarius, 06 March 2010 - 03:05 PM.
Posted 26 March 2010 - 08:41 AM
Sports cats will give BHP but not always better throttle response. I've put original CATs back on mine as low down the back pressure must make a difference. Yes the Sports cats breath easier but to get the turbo to spool up quicker, I've found the standard cats better low down. Oh, I have a Blitz boost controller on mine which may on may not help the equation. The Blitz boost controller, you can program how quick you want the boost to come on and how long. So car feels a lot quicker without increasing top end BHP. Good for insurance too!
K&N's or Green cotton filters will help things out at intake end. I thinks this makes a little difference.
As for chips, I supply PUK to a lot of UK customers. They like dealing with somene from UK and sometimes even drop off their ECU with me. This way there's less risk of ECU going missing. As they are obsolete, most people would consider this as a big risk.
Also check your TPS using laptop and make sure your throttle cable is adjusted right and there's not a load of slack left i.e your foot is on the floor but you are only opening the throttle say 80%.
You can also strip or just lubricate the throttle linkages. On the V8, there's quite a lot of linkages and springs, all of which get stiff and clogged up over the years. After about a year of ownership on my V8, I discovered that my throttle pedal was gradually getting heavier. So I decided to spray the linkages with WD40 first then wipe the old grease of and spray some more then spray with spray grease to protect the linkage. I also tweeked the main spring a bit to make it a tad lighter.
Hope some of thie helps,
Posted 18 April 2010 - 11:38 PM
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