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Old 01-23-2021, 12:32 PM   #21 (permalink)
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Originally Posted by hayden55 View Post
If I was you I would do the egr delete kit. Thats the number one killer with those engines. Efficiency will go down a bit but not much. Or since its a VW I assume the carbon cleaning is basically scheduled maintenance on those cars since its so common. :P
The early TDIs were known to suffer from carbon buildup in the intake but much of that happened before low sulphur diesel was available in the US. EGR contributed to carbon buildup so people removed the EGR circuit and replaced it with a straight pipe. This also affects engine heating from cold starts. My buddy did this to his TDI and his biggest complaint is how long it takes to get heat into the cabin.

The EGR cooler helps get some heat into the coolant loop so I did not want to remove mine. I did load a tune that allows EGR when the engine is cold to help the engine warm up more quickly but does not add EGR when the engine is up to temperature. FWIW my car is 16 years old with 110,000 miles and I have not needed to do a carbon cleaning.

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The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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Old 01-23-2021, 01:04 PM   #22 (permalink)
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My buddy did this to his TDI and his biggest complaint is how long it takes to get heat into the cabin.
Oooofff! I remember how terrible the heat was in my non-turbo non-tdi 1.6L VW diesel. I could warm up the engine (only took like half an hour) and then go turn on the heater and just watch the needle slowly drop and after a while the heater was blowing cool air. And that was even driving around town with a new high-temp thermostat (that I had changed several times thinking it was the problem). Only cruising along the highway would keep the engine warm enough to warm the inside of the car during the winter.
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Old 01-23-2021, 02:30 PM   #23 (permalink)
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The Dasher experiences thermal runaway. I think it's the sensor at the bottom of the radiator. Water cooling is so complicated.

Maybe I should try turning the heater on.
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Old 01-25-2021, 04:10 PM   #24 (permalink)
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Quote:
Originally Posted by COcyclist View Post
The early TDIs were known to suffer from carbon buildup in the intake but much of that happened before low sulphur diesel was available in the US. EGR contributed to carbon buildup so people removed the EGR circuit and replaced it with a straight pipe. This also affects engine heating from cold starts. My buddy did this to his TDI and his biggest complaint is how long it takes to get heat into the cabin.

The EGR cooler helps get some heat into the coolant loop so I did not want to remove mine. I did load a tune that allows EGR when the engine is cold to help the engine warm up more quickly but does not add EGR when the engine is up to temperature. FWIW my car is 16 years old with 110,000 miles and I have not needed to do a carbon cleaning.
Sounds like yours is a bit different with your tune. Not sure what you mean about low sulfur diesel. Had a friend with an 06 tdi that was clogged up in 2010 at 90k miles and it gave up the ghost. To be fair it was probably the cheater tune they had from the factory. They rolled coal so hard i thought it was a factory option for them to have a big black rear end. :P
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Old 05-15-2021, 12:29 AM   #25 (permalink)
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Quote:
Originally Posted by COcyclist View Post
My buddy did this to his TDI and his biggest complaint is how long it takes to get heat into the cabin. .
I could see that on a stock tune, with after TDC injection.

This one got a DIY EGR delete, cutting and welding factory parts. Also tuned for more SOI, this seems to have helped the warmup, I noticed only a slightly longer warmup time after this.

Edit: I should add that it did need a clean of the VNT recently. I attribute this to the combination of a tune with stock SOI table, EGR physically disabled (which wants more SOI), lots of driving, and I guess different fuel chemistry. Hoping the car is good for a while, I actually took some out of the low rpm of the torque limiter, having injectors and hearing loud, deep roar at 1200rpm and wot.

Anyways, more stories about <2000rpm shifting? There is a lot of good evidence here already to suggest it is fine. I do believe the PD engines have stronger bottom ends that would be less prone to lugging-related failures.

Last edited by ssullivan; 05-19-2021 at 09:24 PM..
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Old 08-16-2021, 08:53 AM   #26 (permalink)
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PD driver here.

I have a 2003 Seat Ibiza, in the UK.
PD130, 130hp stock, and 165hp with an ECU i bought off ebay.

The torque is immense, this is a car as big as a Honda fit, with almost 3x the torque!

I've found that off boost it can be efficient, also on boost surprisingly efficient.. But inbetween those it's not great.

Accelerating up hills where you need to hold the gear, but not actually need the torque, it can drink diesel.

I'm a delivery driver, and so i've found lots of tricks to help get as much economy as possible, despite town traffic.

Under light load, I can shift up as low as 1400rpm. Into 4th gear at 25mph. Feathering the throttle, the car will accelerate with the flow of slow accelerating traffic even pulling from just below 1000rpm.
This is more economical than just being in 3rd and risking coming onto boost un-necessarily.

Lugging the engine is no good, there are often times where being in too high a gear is not efficient, just got to find the right balance. Took me a long time on a PD engine to learn where its most efficient.

Oddly, I find sometimes it's most efficient to accelerate using low RPMs, but sometimes maintain speed with more RPM.
Feels like the PD has sometimes an efficient zone / 'lean mode'. Eg if i'm pulling up a slight hill i'll be in 6th gear at 40mph with the engine doing around 1000rpm, under load but no boost.
However once i've climbed that hill, it can be better to shift down into 5th gear and use as little throttle as possible to keep the car moving along at around 1200rpm. Perhaps here the ignition timing is more advanced (just a guess), If I climbed the hill in 5th i'd come onto boost, and would use more fuel.

Overall though, i'm very happy with how flexible the engine is.
With AC off I can average anywhere between 42-47 US MPG. Best nearly 50mpg US!
A lot of smaller engine petrols (albeit without hypermiling techniques) average 31-35 US MPG.

Before I learnt the engine I was averaging around 37-40 US MPG.
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Old 11-30-2021, 04:25 PM   #27 (permalink)
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I have an '02 Jetta TDI, with the 5-speed manual gearbox. I bought it in 2015, and drove it daily until last month. The car is mostly stock, with all the emissions equipment still intact.

When I bought the car, the intake manifold was caked with carbon deposits. It's a common thing with these engines. Soot from the EGR mixes with oil vapors from the PCV system to make black sludge in the intake manifold. I was told that driving more aggressively can mitigate it. So I learned to accelerate briskly up to cruising speed. I also added a catch can, to reduce the oil vapors going into the intake.

Diesel engines also use very little fuel during idle. So if you can get up to cruising speed quickly, then start using P&G, the car should reward you with good fuel economy.

That said, I don't rev the engine very high. The engine's torque curve is similar to the boost curve posted on page 1. So going past 3000 RPM (on a stock engine) is basically pointless. When accelerating, I prefer to upshift around 2500-2700 RPM, which puts the engine at peak torque in the next gear.

I have to admit, I get lazy when it comes to hypermiling. But I try get up to cruising speed quickly. Plus I get off the throttle and disengage the clutch as much as possible. With this half-hearted hypermiling, the car averaged over 40 mpg. I'm sure you could do better.

I should also add that on a modified engine, the situation could be totally different. It would depend on the nature of the mods, and the tune. For example, with an EGR delete and a catch can, you don't need to worry about the intake clogging anymore. And a custom tune will shift the torque peak higher in the RPM range.


Last edited by Blacktree; 11-30-2021 at 04:37 PM..
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