Leon 24 Posted March 14, 2008 I have a pile of Megajolt bits that I bought a while ago and never used because I didn't have a suitable car to try them on. It's the TPS version. Is there any reason why it wouldn't work on a stock 1.9 8v? I'm quite keen to get rid of the coil and distributor on my 205 and this seems the ideal way - but I my only knowledge of Megajolt is when fitting it to non EFI vehicles - so I'm concerned that by splicing it in with the standard injection/ignition system it wouldn't work. I've had a good think about it and can't really see any reason why this wouldn't work though. Any thoughts? Share this post Link to post Share on other sites
MartinM 0 Posted March 14, 2008 It'll work perfectly. The only thing I did was to leave wiring to the coil primary as the ECU and rev counter take their feed for their rpm values from the coil.... I actually left the king lead to the dizzy and the normal leads on the dizzy but then cable tied them to the strut brace so if the MJLJ/EDIS system failed I could revert back to coil and dizzy very easily.... ...but I never had to.... Share this post Link to post Share on other sites
Leon 24 Posted March 14, 2008 Excellent - that is exactly what I wanted to hear So to get this ironed out in my head: Get a toothed wheel welded/fitted to the crank pulley (space tight here on the 205!) Mount the crank sensor on a suitable bracket so it reads from the toothed wheel Disconnect the factory TPS and leave the factory wiring unplugged - wire the factory TPS to the Megajolt/EDIS setup instead Leave the factory coil powered up so we still have rev counter working properly. Leave all 4 coil connections on? Unplug and remove (if you want to) the standard distributor Fit coilpack and leads and connect to Megajolt/EDIS setup Leave ECU connected Leave SAD connected What about the ignition amp mounted underneath the coil? Does this need to remain connected... if there is no distributor any more it won't be getting "information" from the dizzy any more so does it now become redundant? Sorry for the questions, I just don't like hacking wiring up without being sure that I'm doing the right bits Share this post Link to post Share on other sites
Tom Fenton 1,519 Posted March 14, 2008 You'll need to change the TPS as the standard one is not a throttle "pot" it is an "off-idle switch". You'll also need to retain the dizzy as this sends the cranking information to the ECU for the injection. Share this post Link to post Share on other sites
welshpug 1,620 Posted March 14, 2008 how does the ECU then get its "idle" signal? Share this post Link to post Share on other sites
Tom Fenton 1,519 Posted March 14, 2008 Good point, I think you may need to have 2 TPS, the standard, and one other. Unless you use a MAP MegaJolt to sense engine load? Share this post Link to post Share on other sites
Anthony 1,000 Posted March 14, 2008 how does the ECU then get its "idle" signal? Without some jiggery-pokery, it won't basically - nor will it do WOT fuel enrichment for that matter PS. It's not really an "idle" signal per-se, but is really just fuel cut on overrun - with the TPS disconnected everything will idle and run exactly as it did before, just fuel economy will be a touch worse (due to lack of fuel cut) and you might lose a little top end power due to the lack of WOT enrichment. Share this post Link to post Share on other sites
Leon 24 Posted March 15, 2008 You'll need to change the TPS as the standard one is not a throttle "pot" it is an "off-idle switch". You'll also need to retain the dizzy as this sends the cranking information to the ECU for the injection. I can live without fuel cut on overrun - but I'd rather not have the hassle of fitting 2 TPS in all honesty So the distributor is sending a signal to the ECU and nothing else - basically acting as a sender unit for the crank signal? Makes sense - it wouldn't need to remain connected to the coil though if it is not being used to distribute sparks? Share this post Link to post Share on other sites
MartinM 0 Posted March 16, 2008 (edited) A MAP-based MJLJ is highly recommended on a 205 - you've got a huge great plenum chamber giving you a nice source of "average vacuum" and the anoraks will tell you that MAP is better as a load sensor that TPS. Far easier than fitting an analogue TPS too. You could piggy back the MJLJ into the car and then start taking bits off one by one until it stops working (maybe that's what I did... ) Edited March 16, 2008 by MartinM Share this post Link to post Share on other sites
