My Rex is Misfiring really badly Please can u help

fil_auto · January 09, 2009, 05:11:25 PM

Nope - the banging your getting on let off is un burnt fuel - that\'s all good :driving

Quote from: gandyRX;572927mine was compression tested by karl at heyward rotary and he had a digital 3 way type tester that meausred each stroke of the rotor, just aquick question what do you count as a missfire? coz after boosting it, if i let off it pops and crackles (sounds like a gun shot!) quite abit, and if i accelerate quick and totaly come off it bangs massively again like a gun, is that it missfiring? or is it before you accelerate? sorry its my first rotary engine so im still learning bits

gear1275 · February 10, 2009, 07:50:25 AM

hi guys, i have had the same problem since sunday, i have just taken my map sensor off and taken the vacuum line off too. would i be right in saying it has a one way valve in it? if so, i shouldnt be able to blow down it both ways should i? because i can, would this maybe be a contributing factor to my problem? thanks

gear1275 · February 10, 2009, 06:18:58 PM

hi again, i have spoken to mazda and they say that what i thought was a one way valve, is actually a filter. i have also removed the plugs today, and they were black in colour. only carbon deposits though not oily deposits.
i gave them a quick clean and put them back in and it seemed to improve things a little but its still no where near sorted. any ideas??

trotter · February 11, 2009, 09:04:49 AM

\'A quick clean\' might not be enough mate. If the electrode has been contaminated enough the spark will still be crap. Best whip them out and clean them up properly or better still get a new set.

Other problems I can think of: HT leads might be knackered/split/corroded so the plugs aren\'t getting a decent hit of volts. Any one of the coils could be knackered - same outcome as HT leads....

All relatively simple things to check - would def be worthwhile spending an hour doing that before jumping to bad conclusions!!

HTH

graeme

hairyhoover · February 11, 2009, 09:48:56 AM

if you take ur plugs out and turn your engine over manually you should be able to hear six even compression strokes.

gear1275 · February 11, 2009, 01:25:45 PM

ive got a set of plugs for collection on friday
i was looking at a plug thread on here yesterday and they were saying to run 7\'s leading and 9\'s trailing but my local brights autos say that their listing for and rx7 is just a set of 4 9\'s (part number being bur9eqp (ngk plugs)) would this make any great difference running a colder plug in the leading?
also, does anybody know how to test coil packs?
thanks for the help

hairyhoover · February 11, 2009, 02:00:23 PM

they will be fine!!

trotter · February 11, 2009, 03:06:19 PM

Its open to interpretation what plugs you use, but for a standard or mildly modded rex, 9\'s all round are fine.

Asfor testing coil packs im assuming you can still use the standard technique - take one out and hold it using insulated pliers and crank the engine. You should see a decent voltage on the end. OR, take out the plug as well and you should see the spark.

Anyone any better ideas?

gear1275 · February 12, 2009, 07:32:59 AM

thanks guys, i will get the plugs on friday and ill get a set of leads too.
ill report back my findings when they are fitted

gear1275 · February 13, 2009, 01:04:47 PM

guys,
i have just changed the plugs and it has made next to no difference.
i have just been out for a bit of a longer test drive and have had a little play around.
if i drive along putting steady pressure on the accelerator, the car will pull fine all the way through the rev range, but if i put my foot down at low revs, the car seems to stop revving and pop and splutter at about 2.2-2.5k rpm?
im very confused! am i right in saying that is about the revs that the first turbo comes in at? it just seems that when there is a real demand for fuel it just doesent want to go there?
any ideas would be greatly recieved
james

trotter · February 13, 2009, 01:57:51 PM

First tubby kicks in at around 1500 or so IIRC, and is definately well in by about 2500. If the cars is popping then at least some fuel is going in. If its popping it sounds like TOO much fuel is going in.....

gear1275 · February 13, 2009, 05:14:03 PM

...... so maybe an air temp sensor telling the ecu its still cold so chucking too much fuel in?? mite be worth swapping it with the one on my mates fd. im taking it to get it put on a computer tomorrow hopefully to give me a bit more direction. am i right in saying that i have to remove the plenum to get to the sensor? might aswell replace all of the vacuum hoses if ive got the plenum off!
thanks for the reply trotter

a.tapos · February 13, 2009, 09:00:48 PM

check for exhaust leaks this may cause it to overfuel,check the earths aswell the coils may be struggling under load,mine had a similar fault turned out to be fuel pump cutting out so maybe worth checking pressure will driving,

christmas · February 14, 2009, 10:55:36 AM

i had this problem...the boosting problem at least. i reset the ecu and all was good again. but mine is still a standard ecu.

Cleggy · February 14, 2009, 11:47:46 AM

Boost leak perhaps. Check the intake system for any loose joints. The blue smoke will be excess fuel.