Chip tuning well used diesel

The lag is tolerable, but is noticeably longer than my old Escort TD. Could this indicate a problem somewhere? I've fitted new air and fuel filters.

The Dervboy

You're mis-understanding what "lag" is. Fit a boost guage, and I can assure you that your spool-up time will be minimal.

Like you say, I suspect that the lag is perhaps the fault of th ECU rather than the blower. Perhaps it deliberately delays the increase in fuelling until the boost is well in excess of what's required in order to minimise the risk of smoke. Will the ECU tuning (chip) help to reduce this delay?

Once it has come on song it goes very quickly, but even at 2500rpm, there is noticeable delay to throttle response. The escort responded much more quickly at the same revs, unless my seat-of-pants has become rose-tinted with age :o)). Vauxhall quote max torque of 230Nm at 1950-2500 rpm. I don't see how this is possible to do this at 1950rpm when it doesen't really come on song until about 2200rpm.

As for you comment about the gearing, I think it's great. 2400rpm at 70mph is very peaceful. And it accellerates well from that, lag aside.

Perhaps not the ideal unit for a 2 litre diesel then, but as people have pointed out, a larger blower will only increase the lag further. Would I be right in saying that a larger blower will only improve the power at high revs? if so then I'll leave the blower alone. I didn't buy a diesel so I could drive it at 4500rpm all the time!

The Dervboy.

My fears are clearly unjustified, so I think I'll go ahead with the tuning.

That is my belief too. I followed this servicing regeime on the escort. I drove it hard for about 40k. It's now done over 100k and still starts well , runs faultlessly and sounds good as it ever did. It is starting to use a little oil now though - about 1 litre between 5k services.

You're right, I'll leave it alone. I would still be interested to know what the above terms mean though.

I think my understanding of the term "lag" might be confused. There are two characteristics of turbo's which I am aware of. The first being the engine speed at which the turbo charger reaches the max boost when full throttle is applied. In the case of the Escort (i had a gauge here) this was 2100rpm. Below that speed little boost was achievable. The other characteristic is the amount of time taken for the turbocharger to reach max boost on the transition from closed throttle to full throttle, when the engine speed is already at or above the required value (eg for the escort, over 2100rpm).

I assumed that the term "lag" covered both of these characteristics. Am I mistaken?

Indeed they do. With the plug-in module from Bromleys;

figures are 100 bhp > 125 bhp and 152 lb-ft > 181lb-ft.

All I would like to ask now is what is better; a plug in unit like the above or an ECU reprogramming, such as Superchips would do?

I know there are other companies out there doing this sort of stuff, does anyone here have any recommendations?

cheers The Dervboy

I would /expect/ an aftermarket tuning chip for a diesel to concentrate on providing extra torque at lower revs. Obviously that's something that you'd have to do some brand research on (i.e. don't trust a behind the counter salesman who just wants to sell you something).

Escort is an older design so probably will feel quicker. I get the same sort of thing with the Sapphire Cosworth I run alongside the Ti - it

*feels* much more aggressive and quicker, but side by side there's absolutely nothing in it.

Same with my Turbo Petrol tho, peak torque is at 2,100rpm but boost doesn't land until 2,750. Must admit, I could never get my head around that one either :/

Bit of a generalisation, but for the main the answer would be yes.

There are two different "lag"s as you correctly describe. If you're above

2100rpm in the Escort, and you floor it, it will take half a second or so for the boost to rise to max. This is one lag, and is dictated by the size of the turbo, and the time it takes to spool up. Your Vauxhall one is very small and quick-spooling so this shouldn't take long at all.

The other "lag" is the off-boost time when you're below 2100rpm - if you floor it from 1000rpm, it takes time for you to reach 2100rpm and make full boost. You can remove this lag, by staying above 2100rpm at all times. The other one is dictated by the Turbo, and you can't do anything about it without changing the Turbo.

are the masters. Speak to them, and buy whateverthey recommend. It'll be well worth the small price premium, if any. also have a good reputation. AVOID SuperChips, or any other non-diesel-specialist.

How can a guage reduce the spin up time of a turbo? After all that's what turbo lag is...the time it takes the turbo to get up enough speed.

Something's not been right for a long time - I have the rattly loose wastegate, remember. It's a lot slower than it should be due to boost leakage (I reckon 60 is taking well over 8 seconds at the moment). Never could be arsed to take the turbo off to fix it.

My plan is to sort it out after christmas.

Erm, I think he means fit a guage in order to check the time the turbo is taking to spin up :)

It's "gauge" BTW. (I should have a doctorate in pedantry)

It can't. But as I said, it will allow him to see that his lag is minimal.

...and also the time it takes for the engine to reach the point where it begins to make boost.

And you thought the Turbo bolts looked bad ;)

...I pray that nothing goes wrong with my Turbo or manifold before I sell the car :)

No hurry at all then :) Don't bother with the expense of a new Turbo - just chop the car in against a Legacy :)

I can't make up my mind, it changes every week :( I'm torn between getting something new, or doing the ti up a little (i.e a T28 minimum, possibly a T3 - not bothered about lag). At the moment I'm leaning towards doing it up as I want to get a deposit together for a new house.

Ditto. I too am looking to buy a house, so money is tight. I want more power, but it's false economy to spend big money on the TI I rekon - all the cash you need to spend to make the engine take-the-pain, is money down the pan :(

I reckon a grand should see somewhere between 235 to 250bhp. It's been running 'off' for so long due to the leaky wastegate that that much power is going to seem like a huge jump. Perhaps keep it for another year after that and run it into the ground, £1K isn't worth worrying about too much for a bit of fun.