Originally Posted by
chilla
... However the boost doesn't hit the 1.25bar max every time I keep it floored and when it does, after the initial peak of 1.25bar, it decreases to around 1.16 bar and then floats between 1.16 and 1.25, all while throttle is pinned and speed increasing.
Is it normal to see under full throttle, max boost or near to max boost achieved, then a roll off, and then it hovering around but not hitting max boost while it is still under full throttle?
Or is it more normal to see max boost achieved and and boost held constant at max while under full throttle?
....
I dont' think so.
forewarning tho: I'm no Td5 (or ay engine type!) expert ..
But, from experience with the brothers TD5, boost should stay relatively stable on full pedal.
That is, if you see 1.25Bar, then it should remain close to that number as the engine revs increase.
Note I never rev engines needlessly, and I maintained a self imposed 4K RPM limit on most engines.
Anyhow, brothers had the boost on, boost of variance, and with help from here, determined that the WGM(waste gate modulator) was acting up.
There's a bypass trick, which lowers overall boost pressure(mainly power) as the ECU does this default fuelling mode.
But with the WGM bypass, it was determined that the WGM was out of order, new WGM fitted, and boost happily and steadily maintained 1.4(something) kPa.
TD5 pulls like a V8 now .... actually I have a V8 and that last superlative is doing the TD5 a disservice!
with 1.5K RPM up, the TD5 pulls much harder for longer than a std V8.
Brother's TD5 came with a TRS stamped ECU too tho(ie. already remapped).
Where the V8 excels is off idle up to about 2K rpm, where it shoots way ahead of the TD5.
BUT! Bros TD5 came with no mufflers, and it's way too gruff for a refined vehicle like a D2.
I told him to get a rear resonator fitted(like DazzaTD5 did), but he had a central muffler of some kind fitted. Still too droney(even compared to the rough as guts 300 Tdi).
So be warned about the exhaust system .. get a remap, make sure you have an EGT gauge to keep a check on heat build up.
If they remain high, do a intercooler mod. If that still doesn't help, then a freer exhaust will .. and try to maintain a balance between power refinement cost .. etc.
Arthur.
'99 D1 300Tdi Auto
'03 D2 Td5 Auto
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