Chipping my MK2

**NeuSpeedGTI** · 28-12-2010, 10:00 AM

So the engine is done!! The bigger cam, exhaust header, valves, springs, lifters, rings etc all replaced and its sounding fine, very happy. However, with all this increased air flow I am finding it running a bit lean. After monitoring my wideband Air/Fuel meter over a series of drives I have noted my readings to be anywhere from 12-16, but more so around the 14.5-16 mark.

So what does this mean? For a reading of 14.7 (which is supposedly the optimum ratio for combustion and effiency) there are 14.7 parts air, to 1 part fuel. For performance you are most likely looking for something a little bit lower. From reading I have discovered that old school mustangs etc will run mixtures in the 10's, 11's and 12's, but I dont want anything that rich running through my 1.8l 8V!!!

Anyway Im running lean so its time to get those injectors working a bit harder and chip the Digilean. (Digifant)

The process is pretty straight foward.. (or so I thought) and I thought I would attempt a write up.

Stage 1 - Locate the ECU

In the top left hand corner underneath the rain tray is where the ECU is located. See below:

Stage 2 - Disconnect the battery, remove the rain tray, then remove the ECU.

Before we go any further it is important to disconnect the battery, both the postive AND negative terminals. We certainly dont want to damage the ECU!!

Next step, peel back the rubber seal on the front of the rain tray and gently pry the clips holding the piece covering the ECU up. Now you can remove this, exposing the ECU and ultimately giving you access.

The ECU is held in place by a series of clips and one bolt. First thing is to disconnect the terminals, then get started on unscrewing that bolt which we can see below.

Once the bolt is removed it is just a series of clips holding the ECU in place. To unclip take a firm hold of the unit and push away from the engine bay (a small wiggle doesnt hurt) and it will come loose. We can see it removed below.

Stage 3 - Remove ECU casing and cover.

Now that its out of the car we can take it over to the bench and get started on opening it up. The case surrounding the unit is held in place with 3 very stubborn screws, we need to unscrew these first.

After struggling with a screw driver for awhile I fell back on the old trusty phillips head drill bit slotted into my wrench for a bit of extra leverage.

Now that the casing is off we can see the unit....

Now to take the cover off... At each end there are a series of screws, both of these must be unscrewed. Set of 3 on the black plastic end and 4 on the metal end from memory. Once these are off we can remove the case and expose the chip boards.

To get access to the chip we want to change we first need to unscrew to the two screws on the right hand side (you can see one on the top right is already done) and gently pull off two black plastic heads (you can see one on the top left is already done)se we can split the two boards.

Now at this point I do not have more pics, upon opening everything up I discovered that my chip is in fact soldered into place. My understanding was some units have a chip terminal and some are soldered in, unfortunately mine is soldered in.

Rather than attempt to remove the chip and solder in the new one I have been advised to get down to Jaycar and get myself a terminal which i can plug the chip straight into. When soldering in a terminal as opposed to a chip you minimise any damage that you may do to the chip. The reason is; when they are soldered in originally, it is done by machine, thus the chips exposure to heat via the solder is minimal. In doing it by hand it is likely that you will be exposing the chip to excessive amounts of heat thus frying the inside!!

So the outcome... well I had to put everything back together, plug it all back in and now arrange a time to get down to Jaycar!!

Anyway stay tuned, for the remainder of this project. Any feedback, corrections ect would be appreciated.

Cheers.

**benough** · 30-12-2010, 12:46 AM

Nice write up... so far!

With my car the stock chips pried out and in they went. Make sure you disconnect the blue sensor and rev it over 3000rpm 3 times to reset the ECU.

**Jarred** · 30-12-2010, 09:18 AM

Hopefully this will unleash the beast inside! hah

**mikinoz** · 30-12-2010, 09:28 AM

What chip have you chosen? I've had 2 chip types for the same digi2 ECU as yours, but none required solder?

**GoLfMan** · 30-12-2010, 10:26 AM

nice write up fella! Looking forward to results!

**benough** · 31-12-2010, 02:09 PM

Originally Posted by mikinoz

What chip have you chosen? I've had 2 chip types for the same digi2 ECU as yours, but none required solder?

I've heard of ppl with the same ECU having to de-solder.

**8v ggggti** · 11-01-2011, 02:29 AM

im pretty sure the chips plug in are your sure your looking at the right chip this is a pic of mine

**NeuSpeedGTI** · 25-02-2011, 04:55 PM

So just an update. After a few ECU troubles which I will not go into too much detail about.. the chip project is finally finished. The original chip I sourced of EBay turned out to be a dud, however after getting in contact with a fella by the name of Colin (thanks JJ and Matty from Camden GTI) from Techtonics USA I sourced a chip suitable for a 1.8L with head work, extractors and cam.

After fitting it, disconnecting my blue coolant temp connector and reving the engine to 2700RPM 3times to reset everything and plugging it back in I was treated to garage full of blue smoke!! Yeah!!! Finally those injectors are working as they should. The next step was getting the ignition timing setup to match the new programming in the ECU and the new fuelling curves.

It is mildly agressive and we set the timing foward 10 degrees to match the new ECU requirements. Also added an aluminium knock sensor bushing and a longer bolt to match. At the same time made some adjustments to the cam timing also which is made super easy with an adjustable cam gear. So moving away from top end power in the negatives, I now have the cam set at +2 degrees (perfect for that low end torque and those cheeky mountain runs!!)

So what did the lambada meter have to say about all this... well it is giving me 12.5-15's!! Perfect! Averaging 13-14's under load and 14.5-15 at idle and cruising. A great result.

In addition the readings are very consistent and constant. In the past they have fluctuated wildy!

* Side note: The stock 1.8L engine in the MK2 is built to run a bit lean. After a brief chat with Matt from Camden he said that anything around 14.5 -15.5 air/fuel ratio mark is pretty normal and is one of the reasons fuel economy in these cars is so good. However under load it is a different story and will require more fueling especially with modifications.

I dare say this is about as close to finishing what is a never ending project I will be for a long time. Engine, transmission, clutch, tyres, suspension all done. I would like to thank everyone who has helped me though this with their advice etc. All the boys on here, the guys at J & F motors in Richmond have been sensational and an absolute pleasure to deal with and of course the fellas from Camden GTI for their advice and parts over the past 18 months.

Whilst Im thinking about it also. I have just swapped tyres. I have gone with the BF Goodrich G-Sport again (very happy with the longevity of the tyre and the performance factor also) I found after lowering the suspension my initial tyres were rubbing the inside of the guards at the front when doing those tight U-turns and the clearance between the rear springs and the tyres was a good CM at most. So to the dismay of my fellow dubbers I am sure.... I have moved from the 205/50's to the 195/50's and the fit is perfect.

Thats all for now. Time to get driving!