July/August Update
So after the calamity that was June and July, I’ve been trying to enjoy the car and getting some miles on it to shake it down and tune it decently before I take it to a dyno for a proper tune. I did try and take it to a dyno that’s semi-local to me and they didn’t want to put it on in its current state. Main issues for them was a persistent oil leak and a misfire.
It’s not a serious oil leak at the moment, but it is coating everything under the engine in a light film of oil, which includes the exhaust manifold. The oil leak has been a constant issues that I’d been chasing on the old engine but seemed to be changing it’s location but I think I know what’s happening. On the old engine, I replaced the sump gasket 2-3 times and couldn’t fix the oil leak fully as I had two leaks when I thought I had one and the second oil leak was coming from a weeping oil line connection.
The problem with the sump gasket is that I’m not using one

, I’m only using gasket sealant as the mating face of the sump isn’t very flat and as I’m using ITBs for the intake, the existing Jaguar Crank Case breather doesn’t have a vacuum source to operate properly. There are intakes for the crank case on the cam covers but I think they’re too segregated from the crank case to work effectively. Now that my old engine is in my workshop, I’ll have a look at the crank breather system and see if I can bodge it into working without a vacuum source and just run it into a catch can. Hopefully this will reduce the likelihood of a leak. If I still get one, I’ll try and redesign the intake manifold to add a vacuum port so that the crank case is under slight vacuum which should stop any oil from leaking out.
As for the misfire, that was coming from the ignition coils. Turns out that the stock form of the VW 4 pin coil-on-plug coil packs just aren’t compatible with the Jaguar spark plugs. The VW coils have a metal shroud that go around a rubber insulator which goes partially over the head of the spark plugs. The metal shroud is grounded through the coil pack. Originally, I had trimmed the shroud down as it was quite long and would rest on the hex part of the plug so would be an alternate path to ground after the spark. After I had trimmed them down, I still had the occasional issue with the spark jumping to the shroud so I had wrapped them in electrical tape to prevent this. Turns out that it wasn’t enough to prevent it from arcing to the shroud instead of the spark plug… so I removed the shrouds entirely. This has completely removed the misfire which has also removed the odd engine stumbling I was getting at low RPM.
I’ve also made a load of changes to the map in the ECU as well as getting my hands on a really good map from a guy called Dave who has the same engine fitted into a MK Indy Roadster/Caterham-esque car. His map made around 270hp on a standard Jaguar engine with the Mondeo ST intake manifold, so unsure how compatible that is to my ITB arrangement but it’s a good start. I’ve taken his map and dialled the ignition timing back a touch just to reduce the chance of knocking until I can get the car on the dyno.
One other issue I’m going to resolve is the problem of voltage. I have the standard voltmeter fitted to the dash and the ECU also measures the voltage to add in correction factors to the injector and ignition timings. For some reason, these are different. The ECU reads it at around 13.8-14V and the gauge seems to be reading around 15-16V and is sometimes reading off the gauge. When I use an independent meter on the battery, it’s about 13.5-14V when the engine is running. This change in voltage is also changing the water temp and fuel level gauge readings (I know the fuel sensor has the voltage regulator but I don’t entirely trust it to work amazingly). The temp gauge isn’t much of an issue as I can just mentally adjust what is “operating temp” but the fuel one is annoying.
When the cars on flat and level ground, it will start to fuel surge/start with just under 1/4 of a tank showing in the gauge. If I start the car, this changes the reading from 1/4 to 1/3-1/2 of a tank so I never know if I’m too low on fuel. If the car is angled either forward or backwards by a few degrees like on a decent hill or under hard acceleration, it will have some problems running and absolutely will not start. I have had it happen 2-3 times now where I’ve stopped to check why it’s not running well and then it’s refused to start due to lack of fuel even though it said I had 1/2 a tank.
I think that I need to either modify the fuel tank to add some baffles or move my fuel pump to a surge tank as well as sorting out the voltage issues. I’ve found a small 10-20A voltage regulator that I’m going to fit between the battery/alternator post and the main voltage bus for the car wiring loom so that only the engine sees the higher voltage and the original dolomite loom and equipment sees the regulated 12V.
Anyway, enough of me wittering on, hope all of you who read my ramblings are having a good summer and hopefully I’ll get around to some of the Dolomite meets and see you all soon.
So many ideas... So little budget... So little time.