idling and jerking when take foot off gas

[topcat_666]

Hi all (great site). Please can someone help me with this.

I have 1990 RX-7 Turbo II and am experiencing a number of problems which the Mazda dealership (v very expensive for me) cannot fix/advise on.

1) When the engine is warm and idling the revs are bouncing all over the place - sometimes it even just cuts out. The dealership suggested replacing sparks and cleaning ignition timer - no joy at all.

2) When I am just cruising along at any speed if I am not accelerating the car starts to jerk as if I was in 4 or 5th and was doing about 10mph. I have to depress the clutch to stop it getting worse. This happens a lot

3) The cat is blowing. According to the dealer the car doesn\'t require one by law. Since they want to charge me over £700 for one they suggested putting a \'through\' pipe on. I\'m scared this will make things worse and give me illegal emissions. Reading the threads on here I am convinced it will if I don\'t get it sorted properly. Which leads me onto my final question...

4) Can anyone suggest somewhere I can take my RX-7 in/near West Yorkshire where I can get it tuned / checked out etc ?

Many thanks in advance for a great site and for anyone who replies.

Cheers and keep turning !

[t2rew]

both mine do that.   cat, take it off http://www.home.rmci.net/panther/89_91ecu.htm i have just tryed to use this and it didnt work, it is a site though so just have to type it out.

[Ultraman_Cosmo]

Our 84 Series 1 and 89 Turbo 2 both experience the jerking you have described, it\'s a problem I too would like to see the back of! Jason, I cant get your link to work whatever I try, is it a remedy for this problem? As far as the Cat is concerned, our T2 is fitted with a cat replacement pipe and has just passed the MOT so one would assume you can just whip it off! Makes it more free revving too

Phil

[t2rew]

sorry that thing didnt work. i have it on my favorites, you\'ll just have to take my word for it that is was interesting...... anyway try this instead //www.teamfc3s.org and go to trouble shooting about idle....


 also try
//www.fc3s.pro.com    goto problems, then components, then tps  otherwise known as throttle position sensor. ithink this is what i need to do but never have time. hope this works

jason

[t2rew]

hi all.


 i went on a track day around the begining of march and i think i have a cure for the jerky problem. i didnt post up sooner because i wanted to see if it was just a fluke are there was some real truth in it.


 as i said my car done this jerky thing where you had to put the clutch down so as not to break your neck. i went on the track day with a full tank of optmax and some octain booster and some 2 stroke oil in the tank. (nice little cocktail ) . the fan belts came off and i cooked the engine for good measure.

 the car was thrashed all day and the ends of the exhausts were showing white carbon to say it was burning all the cocktil properly.

a couple of weeks past and i realized that i wasnt having to dip the clutch when slowing down as i was before. i carried on driveing around like this and thought what have i done here.

my conclusion was that my engine and inlet track must have been choked up with carbon , and the good caining it got cleaned out the inside of the engine.i think there is some logic in this idea and maybe everyone should go on a track day.

for the interest of science of course.........

[grinder]

not sure if this is the same thing BUT

about a month ago i thought i had broke my engine ( ekkk )

at idle the revs were all over the place , 400 - 1500

bouncing all over the place

instant panic set in !!!

the car ran ok though

got the car home , once i had finished crying over my car , i though i would investigate

i found the oil filler cap lid on the battey ( oppps ! )

put it back on , and straight away the revs calmed to a normal level

i assume it uses some sort of back pressure to regulate the revs

hope this helps - or points you in the right direction

thanks

Stu

[Mark Ide]

I\'m interested in your optimax comment... I used it for a while last year (admittedly only on the road....not on track) and didn\'t notice a whole lotta difference. I have an EGI with a rebuilt engine 2.5k ago and new downpipe
I was under the impression that it was only helpful in piston cars (especially VVC\'s and the like) at the top end of the rev range and wondered if it helped rotaries to the same degree. Perhaps it\'s a T2 thing.......
All the best
Mark

[t2rew]

hi

  i didnt notice a performance gain at all.  i used it because the high octain holds off detination. what i was thinking is that a good thashing for a long period with some good fuel seems to have elininated a problem. when i got my car it had knackered turbo bearings so couldnt boost properly . i dont know how long it was like this but i bet everything that was in contact with exhaust gas was covered in soot. including the lambda sencer. the thrashing has cleaned up everything and now seems to be ok.

the interesting thing would be to take all the t2\'s with this prob to the track for a day and see if they get cured>

[Mark Ide]

sounds good
Sorry to sort of stay OT but I wondered what you used in your T2 now? I was under the impression that N/A cars could use normal unleaded (originally used 2 star in 13B\'s) but that the turbocharged cars were supposed to use higher octane fuel all the time. Would explain why Optimax did little for me without further mods.
What do you think? have you heard this before, or I am living in my own little world here?
Regards
Mark

[t2rew]

Originally posted by Mark Ide
sounds good
Sorry to sort of stay OT .....what?


               but I wondered what you used in your T2 now?


                       if im near optimax i use it  


                                                                                                  I was under the impression that N/A cars could use normal unleaded (originally used 2 star in 13B\'s) but that the turbocharged cars were supposed to use higher octane fuel all the time.  
What do you think?  




                i agree