Help with engine questions

[Shawn]

Hey everyone, I will try to be brief but this is fairly involved. My brother and I are trying to get our recently rebuilt TT running. Lots has changed with the engine and need some advice before we do something bad. The engine was a mostly stock 1.8L turbo engine from Audi (the higher output (225) version) when we broke it a few years ago, I think only the diverter valve was replaced with an aftermarket unit. To fix the engine after over revving it and hitting the valves and pistons together, we have replaced the bottom end with a short block from Integrated engineering (now a 2.0L engine), the head was reworked and set-up from local company Classic Motorwerks and we had to go to a standalone engine management from AEM. We have replaced a few additional bits like fuel lines, engine mounts and performed a delete of the secondary air intake (a common mod on these cars) but everything also is stock (turbo, injectors, fuel pump, etc).

We had a resource that sold us the AEM unit (he is an authorized dealer for AEM) that also has a similar TT build to ours. He provided us some basic information and told us at first that the base tune provided for the 1.8T was enough to get the car to fire up and idle, all we did was change the displacement setting to be 2.0 up from 1.8...again we are just trying to get the car to idle. So we loaded the tune and tried to fire up the engine but it would not idle. We thought that maybe it was the stale fuel so we pumped out as much as we could, changed the fuel filter, put in new spark plugs, and tried again. Car will eventually catch but to get it to "idle" you have to pump the throttle. We reached out to our AEM contact and he suggested changing the VE table values, which we did and tried again...same result. The video link below is of this attempt. Since then, we have not been able to reach our AEM contact.

We made a change to the injector set-up but are hesitant to try to run the car again because of the snapping/popping sounds. And that is where we are at, before we try again does anyone know or have an educated guess what the snapping/popping sound is in the following video? I have an idea what it might be but I want to see what others might say before I pollute the waters.

https://youtu.be/mqmGC2zVAkc

[________]

In my experience it has usually been lean mixture.

I'd check the fuel pump pressure/flow and the injectors.

Are the valve trains properly aligned? Since this car has 3 admission valves (if I recall correctly), that could make it run lean if out of sync.

However, since you are now running a standalone ECU, I'd probably try to see what other maps could make it work as well.

Best of luck

[Beau]

No clue Shawn. I have hardly any experience with engine tuning, esp with a standalone ECU.

I don't know what that popping sound is but it doesn't sound good to me.

The only thing I will mention is that if your engine is able to fire and run, but won't idle, you know that you have compression, spark, and air/fuel. Just maybe not in the right amounts or at the right time. It could be something simple like your mass air flow (MAF) sensor not being connected or a vacuum leak drawing in way too much unmetered air.  I've had both of those issues before and both of them resulted in a similar thing - the engine would not idle, but if you opened the throttle it seemed to run okay at like 4000 rpm. One time I had forgotten to connect the MAF altogether, the other time I had a massive vacuum leak after the MAF, which is pretty much like not having the MAF connected at all.

I might be way off base here. That's all I got. 

Best of luck!

[Magner]

Quickly:

If you don't already have a wideband o2 installed and working. Stop everything and get one first, you're blind without one. Can't tune fuel reliably.

Popping soundsld like a lean condition. Increase your base fuel calculation. From my experience with other systems the theoretical fuel calculation for engine, injector size, fuel pressure is never accurate. Don't be shy to deviate. 

It's also not uncommon to have a poor idle on first start up with a new tune that's off. Step one is get the car at operating temperature first, then start making changes. (once you have a wideband). Note vacuum leaks and ignition timing set too high or too low will screw with idle. If you are at the events this weekend I could chat with you in detail.

I doubt a tune for the 1.8 is going to work well on the 2.0 without significant changes. it's not just a displacement change, you run into bore/stroke ratio, cylinder head flow, variables to name a few.

[Brian_Earl_Spilner]

I don't know those engines very well, but do they have some sort of variable valve timing/lift?

Those are always a bitch to program with aftermarket ECUs, and oftentimes aren't programmed correctly. i.e. kicked on at low RPM or idle when it shouldn't be, throwing everything off.

[Shawn]

We did do a wideband O2 sensor conversion on the car, but that too could be a place where something is not working correctly. When we connect the ECU and just get static values, the lambda jumps around from ~0.9 to ~1.3. We are not sure that is normal, does that sounds normal? It is a brand new harness and O2 sensor although we did have to add the pins into the harness to make the conversion.

We knew the tune would need a lot of work however it was suggested that getting the car to idle would almost work right out of the box, a few tweaks would be all that it would need. Getting it to drive and make solid reliable power was going to take a decent amount of work. Again, the resource that said he'd be helping us with this has basically gone silent and we are not sure why. He is a huge resource on the TT forums not some fly-by-night kinda guy. It's unfortunate and frustrating as we went into this telling the guy we have no experience with tuning an engine and he assured us it was easy enough to do and he'd help us through it. We knew going this wasn't plug and play and that we'd have to learn a lot, we just thought we'd have a little more help early on. Live and learn...emphasis on the learn part.

Regarding the fuel, we disconnected the fuel return and cranked the car over and the fuel flow seems decent but I do not have a flow meter to get actual numbers.

I appreciate the feedback guys, I will looks at a few things and yes, this weekend I'd love to chat further Chris.

[nopistons]

I struggled with a very similar sound/issue with the TT of another club member.

Turned out to be a bad intake gasket seal. However, It used an OE ECU with a mail order tune. It was easier to diagnose.

it could be your Initial timing, could be VE tables etc.

if your running speed density, you can try starting it up with brake clean sprayed into the intake. If it runs better, spray around the intake to head.

what EMS you running? EMS 4, infinity?

you can open the cold start enrichment tables and make sure you have the correct vacuum, coolant and intake temperature values.

if the values are not calibrated, they'll play with the VE and timing tables

[funkejay]

I don't pretend to know as much as Darin or the other guys, but I know when Darin and I had a similar problem getting my TT to fire up one of the issues we encountered was a small gap between the intake manifold and block when the manifold got hung up on a bracket that prevented it from seating properly.

seems like an unlikely problem to repeat itself, but the symptoms you're having are eerily familiar...

might be worth your time to give it a quick check - everything looked good from on top - wasn't until we looked underneath we noticed the small gap.

hope you guys get it sorted out!

oh, and let me know who your AEM guy is, I think I'm going to ditch my OEM ECU and go aftermarket at some point - stock unit is a bitch to work around (huh Darin?!?)

[Corey]

I recall doing a pressure test on my Subaru long ago - some cobbled together fittings on the MAF inlet and I put 5 psi or so into it. A leak became obvious. 

Though I think the brake cleaner would do the same thing without buying parts. 

[Shawn]

Thanks for all the suggestions guys. Tonight is the first night I will be back working on the car we are going to try to figure a few things out. I think the key piece is the Wideband O2 sensor and grounds. then move on from there. I'll post some updates as we go along.

[Jim Eh.]

Pictures. Talkies are even always more fun!

[nopistons]

A wideband is good at telling you that it's rich or lean, but won't tell you why.

I'd suggest spending a bit of time looking for vacuum leaks and making sure everything is sealed right before spending time on a wideband.

[funkejay]

No doubt - your symptoms are identical to the ones I was having. A vacuum leak is definitely the most likely suspect - and the fix won't cost you much other than your time. 

Oh, and BTW - Darin is the one who solved the issues with my car, so he knows from whence he speaks. 

Ignore his advice at your peril!!

[nopistons]

Hahaha wow Jay! Talk about pouring it on thick!

While your confidence in me is appreciated, I'm merely helping to diagnose over the internet like everyone else. 

[funkejay]

Hmmmm... I was trying to be humorous, apparently that didn't come across.

But seriously - Darin understands these Audi's better than most. 

[Shawn]

Just wanted to drop a quick update here. We discovered a wiring issue that was the cause of the wideband O2 sensor's erratic behaviour. Basically the connector we added to change from narrowband to wideband was either damaged to begin with (less likely) or we damaged it when installing it (much more likely). When we connected it to the harness it actually displaced the pin and forced it down. It was really hard to see until we pulled the harness out and looked at it with a magnifying glass under good light. Looking at some pictures of the back of the harness (we can't open it up as it is a sealed unit) the pins are not insulated from each other besides the fact that they are "rigidly" held in place and there is an air gap. Possibly the one pin was touching one or more of the other pins within the harness. We rewired the connector and pulled the pin back into position, tried a few test fits to ensure that we weren't pushing the pin down, and tried again. The lambda fluctuations are basically gone, it hovers right at 1, you see a tiny wiggle of the digital gauge but it appear to be in the hundredths.

Car starts and the popping noise is gone, but the idle is way too high, like 3700 RPM. We think we have a vacuum leak and we think we know where. Tonight we will fix it and hopefully post a video of the car actually idling properly.