My Rex is Misfiring really badly Please can u help

[johnharris]

Hi there,

Firstly i would like to introduce myself, my name is john and i have a 93 fd type R.

Again im sorry i havent introduced my self propely but unfortunety i have a big prob and really need some help.

my rex has had a new engine and turbo pack approx 14k ago and since with a apexi. the car has always had its little prob but now i have a big one and not sure what it could be

the story starts  2 weeks ago i was using the car and had to show up a prat in a 911 then when i finish playing i started to cool her down and then came to a junction, the car stalled so i restared but she sounded like a tool box full of spanners ( major mis fire). panicked pushed it to the side of the road and got a truck to get me home. After thinkin and crapping myself that i may have blown another engine i thought i would have a look at the prob and got some advice.

SO FAR i have changed all 3 coil packs (twice as one was bought on ebay) leads for some 11mm and some new plugs. Put a couple of cans of v power and then ummmm, same dam thing. made sure she isnt flooded but she wasn\'t.

i have been scared to even start her and the bat went flat so bought a new one and tried again she then started to sound and idle so much better but not right 2 days later tried again and back to square 1,  but now there is blue smoke had to move the car as neighbours were gettin peed off, and she drives like she is not getting any fuel. i cant do a diy compression test as she wont hold idle i have had to adjust the idc. and cant get it to a rx specialist as too far from the nearist one.

Just wondered if u guys can give any advice about this, for example could it be the injectors or the ecu maybe.  Any help would be greatly appreciated.
regards
John

[BlitzBoy]

sounds like you have blown it im afraid, did you have it mapped when you fitted the Apexi?
Have you checked the Map sensor? the vacuum line to it may have broken which will cause a misfire and overfueling

[Kieron]

14K is a bloody good innings :Thumbs-up well done.

[johnharris]

blitz thanks for the reply yer the ecu was remapped and then checked over when i did a rolling road and apart from running abit rich all was great. As for the map sensor sorry to sound dumb but it that the little black box on the pass side above the abs...

[BlitzBoy]

yep its near the ABS unit, a vacuum line goes from there to the Plenum

[Aceman]

Mine had a missfire (before the engine gave up the ghost with water seal failure..)

Used to occasionally stall at junctions. Similarly, at random times it would bog down while driving and then once the spark kicked in again you\'d have a huge bang. Neighbours loved it.

Changed plugs, leads, etc etc. Eventually decided it must be a short somewhere in the loom. We bypassed the loom running a direct power supply to the standard ignition amp (using a relay running off the ignition to cut the feed when the car was off!) and this solved all.

Just trying to give you some hope...  

[johnharris]

thanks, the wiring loom was rewired and the rats nest was changed so all pipin in 3.5 mm silicone hosing, any ideas how i can check the map sensor guys

[Warthog]

Is it in anyway over fueling mate.

The reason I say this is it may be like a problem I had, bit of a blat and play on the way to Silverstone and she just started popping and banging and chugging and kicking out heavey exhaust smoke, first thought was the pipe off the map sensor but it wasn\'t.

It was the Air Sensor.The Air Temp sensor is situated under the plenum sort of in the middle of the bends. It just unplugs and unscrews. I got a second hand one from a scrap yard. Changed it and the problem was solved. If, as in my case the sensor was reading extra cold (I believe as was not able to test it just change it) the ECU was dropping fuel in it like hell. if it is reading too hot then you will get the ECU going into limp mode.

If you have a mate with a Rex then just check it by nicking your mates one for a test. HTH.

[johnharris]

thank u all for your help i will have a play tommorrow and see whats what, will report on the issue tommorow, thank u once again

[johnharris]

hi guys just wondered if u could give me a bit more advise, i wondered if u could help me by telling me how i check the above mentioned sensors

[JBerg]

read the owners manual, it tells you the procedures to check all the sensors.
 
Also look at pulling the stored codes from the ecu. Gives you an idea whats going on
 
http://www.rx7city.com/ecucodes.htm
 
Lastly, do a compression test. (you dont need the car to start/idle)

[gsb876]

Map sensor is behind the plenum on the passenger side of the car just about, if its unplugged you will see it hanging down bud.

If all fails get it compression checked as it eliminates the possibility the engine has blown, but the MAP sensor disconnected will make it idle crazy and feel like you are running on 1 rotor.

The Apexi PFC unit also has a safe mode where if it feels the engine could be in danger it sets it to limp mode, this happened in my purple rx7 on the tunnel run a few years ago HOWEVER it did reset itself once the air temps and water temps got cooler.

[needham]

hi guys, just a quick question regardin the compression test, are you able to use a standard comp tester to see if the engine has gone....if so whats the best way do i have to disconnect the coils or anything..

[m1tch]

hi guys, just a quick question regardin the compression test, are you able to use a standard comp tester to see if the engine has gone....if so whats the best way do i have to disconnect the coils or anything..

There are certain compression tests you can do without a tester, unfortunatly compression testers are ment for piston engines and its best to get it checked out at a specialist, won\'t cost much and will give you peace of mind, plus the specilists will be able to give an indication what might be up with it whilst you are there

[gandyRX]

mine 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