TDS tuning options

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   Hi,

I've just bought a '96 E36 325TDS Touring as a general workhorse. One thing that's a little disappointing though is the turbo lag. It seems to need to get the revs to around 2.5k before any decent acceleration happens. So I was wondering if there's anything that could be done. 

I've seen a few places that offer plug and play piggy back chips like Van Aaken and Powerlink, also there's the UniChip which is programmed to the car. Of course these won't any effect on how well the turbo spools up but might help the fueling more at low revs.

Also how is the boost controlled on these engines? I'm guessing they have a recirculation system rather than the max power style dump valve. Is it possible to tweak that to increase the level of boost, if so what sort of boost level would be advisable? Obviously I'm not after drag racer performance  

Cheers,

Rob

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Robbus Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21-March-2004 Location: United Kingdom Status: Offline Points: 15	Topic: TDS tuning options Posted: 21-March-2004 at 20:03
	Hi, I've just bought a '96 E36 325TDS Touring as a general workhorse. One thing that's a little disappointing though is the turbo lag. It seems to need to get the revs to around 2.5k before any decent acceleration happens. So I was wondering if there's anything that could be done. I've seen a few places that offer plug and play piggy back chips like Van Aaken and Powerlink, also there's the UniChip which is programmed to the car. Of course these won't any effect on how well the turbo spools up but might help the fueling more at low revs. Also how is the boost controlled on these engines? I'm guessing they have a recirculation system rather than the max power style dump valve. Is it possible to tweak that to increase the level of boost, if so what sort of boost level would be advisable? Obviously I'm not after drag racer performance Cheers, Rob

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Peter Fenwick Members Profile Send Private Message Find Members Posts Add to Buddy List Bavarian-Board Contributor Joined: 27-August-2003 Location: Lost somewhere in time... Status: Offline Points: 6484	Posted: 22-March-2004 at 12:24
	Other than chipping not sure what else can be done. As far as I am aware all chipping does is increase the boost pressure, which will not affect low end power. What you want is the turbo to come in sooner, although I am not sure how you would do this. Best bet is to talk to one of the tuners.
	Entering an age of Austerity and now driving a Focus Diesel.

325captain Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21-March-2004 Location: United Kingdom Status: Offline Points: 25	Posted: 22-March-2004 at 17:29
	i would recommed adjusting the tie bar on the waste gate to allow the turbo pressure to build up higher. i reckon 4 bar is easily achevieable and should give a fine 0-60 time. i estimate low 6's. kiss the black top.

Peter Fenwick Members Profile Send Private Message Find Members Posts Add to Buddy List Bavarian-Board Contributor Joined: 27-August-2003 Location: Lost somewhere in time... Status: Offline Points: 6484	Posted: 22-March-2004 at 17:37
	4 bar is a lot of pressure. Before even attempting anything like this you need to make sure that every thing else would cope. It is easy to start blowing things appart on Turbo cars if you put the boost pressure up to high.
	Entering an age of Austerity and now driving a Focus Diesel.

Madrab Members Profile Send Private Message Find Members Posts Add to Buddy List Really Senior Member II Joined: 21-November-2003 Location: Scotland Status: Offline Points: 569	Posted: 23-March-2004 at 13:14
	Surely increasing the boost pressure only ups the inlet pressure into the chamber, it won't make the turbo spin up any faster? It will give higher performance once the turbo reaches the higher boost pressure but the only way to make the turbo spin up quicker (less lag) is a smaller turbine? I would also agree with Peter that 4bar is a large amount of boost and could lead to failures if the engine is not totally checked out that it could handle it.
	1990 E3o 325i Touring and she's definately a she! Pain in the ass sometimes but goes like a bunny :oD

dave 328 Members Profile Send Private Message Find Members Posts Add to Buddy List Really Senior Member II Joined: 21-October-2003 Location: United Kingdom Status: Offline Points: 835	Posted: 24-March-2004 at 13:32
	4 bar!! Thats 58 psi!! Most car turbos will only top 25-30psi which is a max of 2 bar!! Most diesels will be running at about a max of 14psi or 1 bar. If your getting lag, you can check the actuator arm for slackness which is basically bleeding off the exhaust gases before the turbo gets chance to spool. Adjusting the actuator arm won't increase boost pressure, it just controls it, it will be closed normally then opens when max boost is reached. There will be another control which monitors the boost (normally the ECU) and this controls the boost pressure by controlling the actuator, I think this is just for petrols tho. On diesels they have a rubber loop hose which controls the actuator and bascically the boost pressure is dependant on the actuator spring pressure. Check the air-filter as I have experienced lag from just a filter fault - dirty or whatever. Or it could be just the characteristics of that engine+turbo - I don't know I've never driven one, but turbo diesels do tend to pull well low down. It could also have a boost leak as diesels can be oily beasts and the oil can bugger rubber hoses - so check the boost hoses. Also intercoolers hav been known to have small holes that leak off boost. Call a good diesel tuner to see what they say. There is a little black box known as the Tuning Box which is suppossed to bo good and it plugs in between the ECU and the connecting loom. Van Aaken will be a better job as it is tailored for your car, but I think is more expensive. Just upping the boost on diesels doesn't work as they work in a different way to petrol variants. Diesels accelerate and thus spool the turbo by extra fueling as they have an open throttle at all times - so the fuelling is what needs adjusting aswell as some extra boost. Petrol engines use the throttle and fuel thats why its more dangerous to wack the boost up and not have extra fueling otherwise it melts the engine - theres more specifics on a petrol engine. I would guess at upto an extra 30ish bhp and more torque for your diesel - more than that, you'll be possibly be spending money on mechanicals to achieve more. Edited by dave 328

Alex Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member I SW Region Member Joined: 15-January-2003 Location: England Status: Offline Points: 148	Posted: 24-March-2004 at 17:16
	There wa san item about tuning the 2.5ltr diesel in last month's club magazine. I believe it concluded that there was much to be gained from tuning the older ones. There is no dump valve or recirculate valve on a diesel since the throttle is always wide open, so there's never any excess pressure to remove. Like Dave says, simply increasing the boost won't increase the power - you must increase the fueling. Too much fuel with not enough air = black smoke though. I agree with Madrab too - you can't cut lag by increasing boost. A smaller turbo would spin up faster, but ultimately pump less air. Increasing the fueling at lower revs would help, but may make it smokey.
	Alex Shirley 1990 E30 325i

Robbus Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21-March-2004 Location: United Kingdom Status: Offline Points: 15	Posted: 25-March-2004 at 16:58
	Thanks for the info guys. I never knew that diesels didn't have a throttle plate, so the loud pedal directly controls the fuel input then? That's all a bit simple isn't it! Think I'll take it to a specialist sometime and see about getting a custom map sorted and see if they can do anything with the turbo then. In the meantime I shall enjoy frugal economy and pleasing mid range accelleration Cheers, Rob

mollydog Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 12-June-2004 Location: United Kingdom Status: Offline Points: 4	Posted: 13-June-2004 at 15:14
	I bought a 00W 320 diesel a month ago which experienced the same lag at between 1900-2500rpm.I took it back to the dealer who diagnosed a faulty air mass sensor,they replaced that and the car now runs as quick if not quicker than the Ford Puma I had before it,try that!