'01 Audi A4 1.8T quattro TDI Conversion

Mikkijayne said:

Confirmation bias. Still, at least you realised before it got back to Scott.

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That's exactly what it was. Everything else pointed to mismatched final drives, so I leaped to that conclusion without being thorough. It's really all on me.

But yes, there is *something* wrong there, and the transmission would've had to come out to resolve it anyways. I just feel terrible about the negative things I said about Scott.

Frank, nice to read that you've got the car up and running! I'm really overdue now for a short jaunt to visit you.

I need to speak with you about what you did to get a lift pump in your car. I'd like to install one too. Can we take up a conversation by PM or e-mail or phone?


Cheers,
Dave

well it WAS running... now it's sitting there in the garage again waiting on a transmission. Still haven't heard back from Scott Dewitt about what's going on with that.

An update: I started out busy since shipping the transmission back to Texas. Got all the Passat's sound insulation pads installed on my A4. They all fit perfectly. Also added some butyl sound damper in the transmission tunnel and a couple other places. I'm hoping all this sound deadening will help with the engine noise.

I drilled and tapped a 1/8" NPT port in the exhaust manifold to add an exhaust manifold pressure gauge. I have this neat 50psi boost gauge with 2 separate needles, so I can monitor both boost and EMP simultaneously on the same gauge. I was originally planning to use it to monitor boost/fuel pressure (which is its intended purpose), but I think boost/EMP is much more apt.

I'm in the middle of modifying my center vents to mount 3x 52mm gauges. I already had a 45mm APR boost gauge mounted there, but now I'm modifying all 3 vents for 52mm gauges instead. I've got oil pressure (with isolator), EGT and boost/EMP (with isolator) all ready to plumb into there.

And then I got a nasty virus, and I've been bed-ridden since then. Good times.

edit: oh, and I finally bought a beater car to drive around while I wait on the transmission. It's a 1999 Audi A6 Avant quattro, and it's in appropriately poor shape for a beater. Lots of barely-hidden rust under backyard body work and a fantastic spray-can paint job, tons of electrical gremlins, and a thermostat that forgot how to close years ago. Engine light comes on once in a while for lean condition on both banks, so I assume there's a vacuum leak in there somewhere too, or an aging MAF.

But at least it's a wagon and it drives!

good call on the beater car, greatly reduces the stress of a project car.

vtpsd said:

good call on the beater car, greatly reduces the stress of a project car.

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I made sure to get one that was really cheap and crap, but still runs ok. That way I'm still very motivated to get my own car done ASAP.

Just for clarity, 2001 Audi Avant Quattro 1.8t 5sp manual. What is the rear diff. ratio ? I keep reading it's a 4:11, no a 3.89. etc. What is really back there ? Thinking of a simple swap. AFN, 5sp tdi trans. Just thinking, would like to know so I can sleep on it.

On mine it's a 3.89, 100% sure. But checking the diff code on the housing is always the safest thing to do.

Throughout this project, my biggest concern was always the engine wire harness, mostly due to its age. Every time I messed around with it, something would crack or break and need patching. The insulators are dried up and brittle, and conductors are exposed in many places. I had to replace 3 of the glow plug connectors, and the 4th one cracked open during the last disassembly. There's electrical and friction tape all over the place from repairs I've had to make. Considering this is practically a brand new engine that I spent thousands of dollars building from scratch, it would be super aggravating to be stranded on the side of the road because the wire harness failed in an awkward location. Some of the sensor wires are easily replaceable (cam sensor, crank sensor, O2 sensor, etc) and I'm already running brand new ones of those anyways, but some are hard-wired and could fail at any point along the length of the harness (alternator, MAF, N75, glow plugs, injectors, etc).

With the engine out of the car again, this seemed like the perfect time to tackle this potential problem, so I took the plunge and ordered a new harness. Not a used harness from eBay, but a BRAND NEW complete engine wire harness from VW (technically through ECS Tuning). Had to be special-ordered from Germany, and it cost a small fortune. Hopefully, with proper care, this brand new harness will be reliable for years and years.

I ordered the harness almost a month ago and just received it today:



(I can't believe how expensive that thing is...)

Everything I needed is there, and it looks 10x better than the used harness I was working with. Now I have to repeat the whole process of modifying it to work with my car. Good thing I spent the time making that spreadsheet!

Today I got to drive TDIMeister's AFN-powered 1999 A4, and what a blast that was. If I can get my own car to run anywhere near that smoothly, I'll be over the moon. Granted, his was a European TDI right from the start, not a swap. But still, it's such a nice, clean setup and runs way smoother than I expected. Absolutely nothing like how mine ran. Even idle was smoother. Now I've got a goal to aim for with my own setup, when that transmission gets back.

Thanks again TDIMeister!

Mine is a 98. I only wish I could have mine so tight with the fresh suspension and driveline bits that your car has.

I can already imagine what your car will like once the transmission is sorted out and your car is back together and on the road again. Scott, if you're reading this, please, PLEASE get Frank's transmission fixed and sent back. It's been long enough.

QuickTD said:

I swapped a BHW and a 5 speed into a AWM 1.8T passat. It is a very complete factory quality swap with fully functioning ABS, traction control and guages. No fault codes in any modules.

Wiring was pretty straightforward. If I can be of assistance, let me know.

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Hey i have a passat 1.8t that i want to put an alh into. any guidance would be great. i have the opportunity to get the engine with all accessories and transmission and axels.

TDIMeister said:

Mine is a 98. I only wish I could have mine so tight with the fresh suspension and driveline bits that your car has.

I can already imagine what your car will like once the transmission is sorted out and your car is back together and on the road again. Scott, if you're reading this, please, PLEASE get Frank's transmission fixed and sent back. It's been long enough.

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Jesus man, you still haven't got the trans back? What's the hold up?

K1Cowboy said:

Jesus man, you still haven't got the trans back? What's the hold up?

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I do not know.

So while there is a lull in the action, may I ask an uninformed question....wouldn't it have been easier to swap a Quattro drive train into an A3 TDI?

Dcwhybrew said:

So while there is a lull in the action, may I ask an uninformed question....wouldn't it have been easier to swap a Quattro drive train into an A3 TDI?

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Easier? I'm sure it probably would be. But considering an A3 TDI alone would probably run you 15-20k, plus the added cost of the Quattro parts, I don't see that as a comparison at all. Not to mention the A3 is a common rail TDI and is subject to recall, we don't know what the fix will be for that and how it will affect the MPG and performance. Apples to oranges in my opinion.

I have zero interest in having an A3. Even the current A3 is smaller than my B5 A4, and my A4 is as small as I want to go. Sometimes I pine for the extra cargo and rear passenger space of an A6, but then I drive an A4 again and the outstanding handling brings me back to sanity.

Also, I'm not sure if this applies to A3's, but on Bx-chassis cars, the floorpan is completely different between FWD and quattro cars. The quattro drivetrain can't be retrofitted without cutting out the floor and modifying it. This is way more work than a simple engine swap.

In any case, the swap I did is about as easy and straightforward as it gets. The only reason mine took so long is because I rebuilt the engine from scratch and I'm also swapping in an 01E transmission. If it was just a matter of swapping in a running engine, it would be the simplest possible swap there is (BHW into a B5 Audi)

GoremanX said:

I have zero interest in having an A3. Even the current A3 is smaller than my B5 A4, and my A4 is as small as I want to go. Sometimes I pine for the extra cargo and rear passenger space of an A6, but then I drive an A4 again and the outstanding handling brings me back to sanity.

Also, I'm not sure if this applies to A3's, but on Bx-chassis cars, the floorpan is completely different between FWD and quattro cars. The quattro drivetrain can't be retrofitted without cutting out the floor and modifying it. This is way more work than a simple engine swap.

In any case, the swap I did is about as easy and straightforward as it gets. The only reason mine took so long is because I rebuilt the engine from scratch and I'm also swapping in an 01E transmission. If it was just a matter of swapping in a running engine, it would be the simplest possible swap there is (BHW into a B5 Audi)

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Thank you for the explanation. I appreciate it. I enjoyed reading your write up...even when I had to do a lot of google searching just to understand the technical details you were discussing.

I used to be a big Land Rover enthusiast (owned 7 of them) and considered doing a diesel swap with a 91 Range Rover or a mid-late 90s Discovery I. Most of the LR owners were swapping LR 300TDIs bought from the UK, or using small 2.8L Isuzu diesels. A couple even dropped in GM 6.5L because they ran bio and WVO fuels. It is cool to see people drop diesels into gas wagons. You're right, and all wheel drive, diesel, wagon, seems like the holy grail. I don't know why VW or Audi don't produce them.

Anyway, I look forward to reading more about the final product.

Dcwhybrew said:

It is cool to see people drop diesels into gas wagons. You're right, and all wheel drive, diesel, wagon, seems like the holy grail. I don't know why VW or Audi don't produce them.

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LOL! I have a 6.5TD lying around that I'm dying to put into a full size station wagon. The body of the truck it's currently in has rotted away, but the engine still starts and runs strong. I just haven't found a suitable recipient vehicle for it yet. I'm always on the lookout for a solid 90's B-body car (Caprice, Roadmaster, etc) to swap it into.

So as is often the case when I don't sleep well, I woke up with an idea this morning.

I wonder if the vibrations under heavy throttle and in 6th gear are being caused by the one-piece driveshaft I'm using. I bought it from Scott Dewitt mainly because it was cheaper than an OEM 2-piece driveshaft, and I figured the weight savings were an added bonus. But now I'm thinking such a long single piece might not be well-suited to a TDI application with lots of vibrations and soft engine mounts (compared to a 1.8T or 2.7T anyways, which I think is what this driveshaft is intended for).

That would just leave the loud howling in 5th gear to figure out.

You probably already know this,but are your U joints out of phase?

No U-joints on a one-piece driveshaft.

Oh,obviously I'm not familiar with these cars...lol
edit;looked it up,a CV driveshaft.
I know with a u-joint style,if it is straight without some degree of angle it will vibrate.

Hah! I couldn't have told you how it's made until I took it apart myself

You're correct, the one-piece driveshaft has CV joints on the ends. The 2-piece driveshaft has CV joints on the ends and a single U-joint in the middle, along with a center bearing right near the U-joint that's bolted to the underside of the car.

I don't think there's anything inherently wrong with the one-piece driveshaft I received. I'm not claiming it's out of balance or anything. I'm just wondering how suitable it is for use with a longitudinally-mounted TDI, especially at lower RPMs with strong pulses coming through. The 2-piece design is much better at handling and damping driveline vibrations.

They come with a OEM 2 piece driveshaft, must be a reason !

Col Sanders said:

They come with a OEM 2 piece driveshaft, must be a reason !

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Yeah but ALL B5 Audis came with a 2-piece shaft, and many people (with gas engines anyways) switch to a one-piece without any issues. I'm just not aware if anyone has done it with a TDI.

Looks like I'll be trading the one-piece driveshaft for a 2-piece part instead. Scott Dewitt is letting me trade for the difference in cost + shipping. Guess I'll see if that makes a difference. Now all I need is a transmission.

GoremanX said:

Yeah but ALL B5 Audis came with a 2-piece shaft, and many people (with gas engines anyways) switch to a one-piece without any issues. I'm just not aware if anyone has done it with a TDI.

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The two piece driveshaft was made for crash testing approval from what i recall. It's supposed to break away at the hanger instead of coming through the floor in a crash. It should have no effect on vibe issues in my opinion.

K1Cowboy said:

The two piece driveshaft was made for crash testing approval from what i recall. It's supposed to break away at the hanger instead of coming through the floor in a crash. It should have no effect on vibe issues in my opinion.

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hmm... now that's interesting and makes sense. I wish I'd known about that before, I would've picked a 2-piece driveshaft for sure then. My 2yo daughter sits in the back of my car most of the time, and one of the things I like about Audis is their crash-worthiness. Funny how we rarely take into account the safety aspects of simple modifications like this.

My new wheels arrived today! I ordered these way back in mid-February. They were supposed to arrive mid-April, and somehow got delayed by almost 2 months.

Now I'm debating whether I want to post photos of them now, or wait until they're installed on the car... whenever that will happen. Still no word on the transmission.

Fellow bhw swapped avant owner checking in.. Just read the whole thread and wow what a saga. Hopefully its all sorted once the trans is back in!