Some days I reckon I have the best job in the world, but then again on other days I just despair. It’s the fashion industry that drives me crazy, not the idiots on the catwalk or the people paying thousands of pounds for a bit of rag shaped like a dress, I am talking about the customised car industry.

Current fashion, or so I am told, is to make your car look really “cool” by lowering the suspension to the point where the bumpers hit the ground, fit the biggest rims you can find but you have to have very narrow tyres stretched as far as possible to meet the rims. The “best” cars are so low and the tyres so stretched that you can’t actually drive them on the road. What you do is drive to the showground, fit the big wheels and drop the suspension with air jacks - then spend the rest of the day polishing the paintwork.

I know I am a grumpy old git and these youths are just having fun but there is a chance it will impact on the rest of us. If enough idiots (sorry, I mean youths) modify their cars so that they are dangerous there are going to be accidents. This could be followed by our responsible press screaming for “something to be done” and the next thing you know we are like France; where it is illegal to modify your car – in any shape or form. You can’t even change the tyre size, let along the wheels.

At the moment my biggest gripe with the customised car youths is that they expect me to set up their engines to make as much boost as possible, regardless of the power output or the ability of the chassis and brakes to handle the power. The numbers are everything. I had one lad recently with a face as long as next week because he only had 296 bhp where he had to have 300bhp. It didn’t matter how much I explained the reality to him, he just had to have a bit of paper showing 300 bhp. I suggested I cheat the air temps (which I did) and he went away happy with his graph showing 300 bhp. Like I said, I despair some days.

Injector problems

On a brighter note I also get to see some proper cars with serious engines. I do a lot of Caterham 7s, usually with K Series engines, or more lately Duratecs. The point of the Duratec is that you can get big power without stretching the engine or the budget as much as a K will cost you. On the down side the engine is a little heavier and also a fair bit taller. To people who value handling these things are important.

ppc-aug-10aEqually important is an engine that drives nicely as well as making the numbers. I have had a couple of Caterhams in recently with interesting light-throttle running problems and I only found the answer with a bit of luck. On a Caterham the lambda sensor is fitted into number four branch of the exhaust manifold so you only read the mixture on number four cylinder (sorry for stating the blindingly obvious). As long as the bodies are balanced this isn’t a problem.

Running on light throttle I had a misfire when the mixture was set correctly according to the lambda, but this went away if I added fuel. As a double check I always look at the power output. If you add fuel and the power goes up then it was running weak – whatever the lambda is telling you. With the fuelling correct I could gain good power by adding fuel, right down tot 11 to 1 AFR where it should have showed 13.5 to 1 AFR as best power. I swapped the lambda sensor as a precaution but got the same result.

ppc-aug-10bOut came the injectors and we tested them on the ASNU machine. Everything looked okay on 100% injector time but if you dropped the pulse back to idle the low flow test cycle showed number four injector was flowing about 10% more fuel than the other three. I had no new injectors so we swapped the lambda into the tail pipe to read all four injectors and mapped it with number four running slightly richer than the rest. That dodgy injector will get replaced later and the mixture will be a fraction weaker than we set it on the day.

Injector problem 2

This was another Caterham but this one had a misfire on light throttle where it dropped one cylinder. By pulling the HT leads off one at a time it was identified as cylinder number four not firing – but it came back on song with heavier throttle application. We tracked it down as an injector problem confirmed by swapping the injectors over on 1 and 4.

Again the ASNU showed no fault on wide open but the injector pretty much stopped flowing at light throttle duration. The answer in this case was another set of injectors.  It’s been years since I have seen an injector problem and then two came along in the same week.

Astra 4WD

ppc-aug-10cI see all sorts of interesting cars here but this was the first Astra four-wheel-drive that I have seen. The car was built using Calibre running gear and featured a turbo XE engine.  It was very nicely done but on the day of mapping we had a turbo over-boost problem. The external waste gate seemed to have the wrong spring in it. Rarely do I get a turbo car that goes right on the first attempt. So many of them have boost pipes blow off, overheating problems or dodgy dump valves. Apart from the waste gate spring this one was good.

Astra RWD

Just like buses and injector problems, interesting Astras seem to come in pairs. This example was very different having rear-wheel-drive and a Mercedes 2.3 aspirated engine. No real problems with the mapping which was a bit of a surprise because the engine had sat around for years without being turned over and was installed in the Astra untested.

I asked the owner why he had gone to so much trouble to fit the Mercedes engine when an XE would have made the same sort of power. The answer was that he had the Merc sitting on the drive doing nothing and he had always wanted an Astra that: “handled properly”. Fair enough.

Cars of interest

Thought you might like to see a few of the other interesting cars we have had in this month. Then there was a stunning Capri with a BOB Cosworth V6 engine. The BMW we have featured before but this time the supercharger from the BMW Mini was swapped for a Rotrex which makes it a very different engine. The Mini supercharger gives good low speed torque but runs out of breath at higher rpm.

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The Rotrex is the opposite, not much low speed boost, but big boost as the revs climb. Rotrex engines tend to feel more like a tuned aspirated motor. Then finally there was a nice aspirated Cat 7 2.3 Duratec. Home built engine using the big direct to head throttle bodies and other parts from Ammo at Raceco.  This one made 285 bhp with a rev limit of 8500rpm. The owner was more than a little chuffed as they say. The Duratec really is the engine of choice these days if you can fit it under the hood and if you can find a bell housing to fit your gearbox. After several decades that went from the pre-crossflow engine to the Zetec Ford retained the same bell housing pattern. Sadly the Duratec was a Mazda design and the pattern was changed as a result. I wouldn’t mind a 285 bhp MX5 with a six speed gearbox for a bit of a fun/track day car. It won’t happen though – too many unfinished projects as it is.