captain venners called over to finish off the welding on the fugly so while he got stuck into that i did some quick electrical shopping at maplins…

ten minutes later and i’ve got enough cable to plug the laptop into the ECU brain on the fuelinjection and secure the laptop into the harness on the passenger seat so i can monitor what it’s doing in real time as i’m driving around!
how cool is that ?

what i’ve been trying to track down is an ‘episodic’ kind of thing. after a time of driving the engine loses power, if i try and increase revs the engine chokes up and power drops off. switching the engine on and off restores normal service and off we go again so i’ve assumed it’s an engine management thing.

after dumping the logs and checking the diagnostic with martin taylor at the weekend it seemed that the air temp sensor was giving wierd readings (120 degrees c!) so the compensation effect of that was switched off but it’s still doing it…

after blatting about and checking everything (even dumping the log files into a spreadsheet and making very pretty 3D charts and graphs with the data) it seems that the ECU is behaving as it should and also that it is unaware of what the engine is doing….

which leads me to suspect the fuel system..

paul venners suggested a chat with ritchie webb who runs the DTA injection system in his VERY cool wheelie standing 11 second cabriolet beetle.

ritchie was very helpful and suggested the fuel system also, with much more clarification and some useful anecdotes about potential problems. number one being inadequate venting of the fuel tank causing a kind of vacuum lock in the tank

(the fuel injection runs a fuel circuit out of the tank and back into it so that the fuel rails passing the injectors are always supplied with LOTS of fuel -if i remember rightly Martin told me that the system runs at 60PSI !- )

ritchie told me he’s seen racing fuel pumps like the one i’m running collapse beetle fuel tanks where the vents got blocked… also he suggested checking that there’s adequate power the the pump. under full load the engine needs LOTS of fuel. at bug jam i used 20 litres of fuel (about five gallons) over the weekend in qualifying and eliminations. i covered a total of about ten miles…

YES i’m not kidding !

that is about TWO MILES TO THE GALLON !

so, a blast up the m32 with the fuel cap off the tank. let it cool and repeat with the fuel cap on.

no difference.

doh!

ah well, twiddle with some more stuff, clean some bits. scratch my head some more.

at the end of the day i’m not much further toward tracking the problem but i have a much better understanding of the whole system and potential issues.

i did get a few other jobs done though, i mounted the new AFFF fire extinguisher i got from jimby kellas (the old dry powder extinguisher i had is illegal to race with and very messy), i fixed in the rear seat back with some velcro and even fixed the passenger side windscreen wiper spindle so it no longer slops about like some useless broken appendage!

MEANWHILE back at the ranch…

mr. venners finished the welding and has made a rather good job of it. although i’ve got a busy week ahead with luck the fugly could be MOT’d and running properly by the end of the week.

oh happy day !