Getting out and about - again

I managed to escape the workshop again this month with a second visit to Clive Atthowe in Norwich. Clive was looking at a re-map for me on a Subaru WRX using his ECUTEK software. Previously we couldn’t complete the job because the pre-cat lambda had failed and the Subaru system relies heavily on the lambda sensor for its mapping.

With a new wide band sensor fitted, Clive and his buddy Dan set about taking a power run and logging the boost. Nothing wonderful by way of power was recorded - basically because the boost was too low. First step was to check the restrictor (what Clive called the “pill”) in the line to the boost valve. The smaller the hole, the higher the boost. It proved to be okay but then Clive realised that the plumbing on the valve was all wrong.

The car has been fitted with an aftermarket boost controller but this isn’t really the way to go. The stock ECU can alter the boost if the sensors report a problem, like pinking or detonation. Once you move control to an aftermarket system the ECU can no longer function properly. What we ended up with was a power level of 317 bhp but with the injectors running flat out. The car really needs larger injectors and probably a bigger fuel pump to keep up with fuel demand. It was interesting for me to see that Clive and Dan meet all the same problems that I see on a regular basis. I had always imagined that I am the only one who ever has problems on the rolling road!

Mystery misfire

The VW 1.8T engine is probably the most popular conversion for the Golf and I see no end of them here. This one was in for mapping and driving okay so in theory it was a straightforward calibration job. The owner had explained that he had previously had a misfire problem that was caused by the hydraulic tappets holding open on idle. New followers had cured the idle misfire albeit at some expense.

As it arrived the engine would not idle and I set about drilling the stock throttle body to add a simple throttle stop. We do this all the time so there was no mystery involved. We soon had a stable tick over but it wasn’t very smooth. These engines run like sewing machines normally so I went down the fuel rail pulling off one injector plug at a time and checking the idle speed. Sure enough, number four wasn’t doing anything on idle. However, when you picked the revs up it fired up okay. Was this the hydraulic tappet problem come back to haunt us?

No, it wasn’t. A simple check showed that the injector was getting the pulse from the ECU on idle but the injector was not reacting. You can confirm this by listening to the injector with a stethoscope (or a screwdriver pressed to your ear). When the revs picked up the longer injector pulse brought the injector to life.

I still mapped the car okay but the idle would need sorting out once the injector had been changed. What was interesting was that this engine was fitted with an LPG conversion. The LPG ECU simply follows the original ECU signal so in theory there’s no mapping needed on gas. This works really well with the Emerald ECU because you can switch to a second map when the gas is activated. Then you can map the gas as if it was just another petrol map. The lambda reading of the mixture stays the same so you don’t even have to think about it, you just map as per normal. The fact that the AFR reading says 14.7 to 1 (when in reality it isn’t) doesn’t change the fact that this is still the correct mixture for LPG even though it isn’t actually 14.7.

This is the system that our Will needs to adopt for his LPG conversion on this V8 Merc instead of playing about with outdated kit bought cheap on Ebay. With the cost of petrol only going one way I am seriously looking at an LPG conversion on my own Mazda 4x4. With our ECU I can map the LPG to get the mixture exactly right, run a little more advance on light throttle, and get the best MPG figure I can for the gas. LPG is cheap but it still isn’t free so I can’t see any excuse for wasting it.

Supercharged MX5

These are great little cars with excellent handling but most of them seem to lack a bit in the power department. This example in for mapping had a supercharger fitted which makes it a very different kettle of fish. All was going well initially but then the engine started to develop a squeak. A quick look under the bonnet showed that we had a second “belt” wrapped round the front pulley. This actually turned out to be a section of the supercharger drive belt that had sheared off. The pulley was not aligned properly and had cut two sections off the five rib belt. Nothing much you can do in that situation without a spare belt so that needs sorting before the engine can be mapped properly.

OBD

I was interested to read in a recent issue of PPC about OBD code readers and the fact that you can use this OBD information for things other than fault reporting. We had a request from an I.T. specialist who was running our ECU and wanted to use an “App” on his phone that needed an OBD output. Basically you have to buy a little module that can be wired into the ECU plug and this then outputs the data from the ECU in an OBD form, either Wi-Fi or Bluetooth.

What you end up with is a series of dials on your mobile phone screen showing all the data that the ECU is looking at, engine rpm, air temp, water temp, throttle angle, etc. This is all very clever but to my mind of limited practical value. Then it gets tricky. You can buy a programme to use as a data logger on a track day. The ECU adds its information to the GPS in your phone (or Device as some call it) and you can record a lap showing cornering G, road speed, braking point, corner speed, throttle angle, engine rpm. I am sure there are plenty of systems out there but the one we bought to test the ECU software was called “Harry’s Lap Timer” and it gives you an awful lot of information for not much money. I am not suggesting this will replace a professional data logger but it’s certainly worth a look if you already have a fancy mobile phone that can run these “Apps”.

CCC Shed

Readers with good memories might recall the old Fiesta Mk2 that I used to race under the Cars & Car Conversions banner. It was known as “the Shed”. I put it up for sale here a year or so back and had a lot of enquiries but given that it was a non-runner nobody ended up buying it. Since then I have fitted throttle bodies, an ECU and mapped the engine here on the rolling road.

So here it is again for sale. Being realistic I am never going to track day or race it again so someone might want to take it on. The basic spec is a 1600 CVH (+60) engine with individual throttle bodies, K6 ECU; flat topped (forged) pistons, big valve head, lowered wet sump with windage tray, polished and lightened rods with uprated big end bolts. The gearbox is a synchromesh close ratio five speed unit. LEDA suspension, standard brakes but Magnesium alloy split rim wheels: £2500. If anyone is interested then call Emerald on 01953 889110.