Ok , first of all I've got a JDM S5 TII with a rebuilt motor about 5000kms ago. Everything is stock except for a street/extend port and pod filter.

I've replaced then spark plugs and ignition leads recently so highly doubt they're the problem.



Occasionally when I'm driving along at a constant speed the car starts to jerk violently. The only way to stop it is to accelerate or take my foot off the throttle.

It feels like I'm stabbing my foot on and off the throttle.

It seems as if there's an intermittent ignition problem in one of the rotors so it will fire, then not, then fire, then not etc. all within a moment. It had slowly been happening more often.

I've checked to see if the connections of the leads to the spark plugs and coils were loose.



Any help please guys. I'd rather fix this myself than take it to a shop to get fixed.

bad igniter box?

i think its more likely to be a bad o2 sensor, or tps

Really would and o2 cause it to be that bad?

I've been having the same problem with my car for a few months. so bad now that I have to pull over on the highway. it would jerk and jerk to the piont that it would travel so slow I'd have to pull over and let traffic by me. you sound like me about two months ago. hope you aren;t headed where I am with it.lol......I think. I'm in the middle of a major overhaul I'll post pics soon. https://www.nopistons.com/forums/pub...IR#>/smile.gif

crusing is the only time the ecu really uses it, so if its off, it can do weird things.

just for the hell of it play around with the tps and see if it goes away... and if it changes or whatnot set it at the proper setting and you should be good to go...

It's stopped doing it now. I'm waiting for it to come back and get worse. Then I'll have a look at the oxygen sensor. I was thinking it could be the TPS but that should have been set correctly when the motor was rebuilt.

I bought a Bosch oxygen sensor to put in but haven't installed it yet. Is there any difference between the mazda and bosch O2 sensors? Is installing it just a matter of disconnecting the old one, unscrewing it and putting the new one in?

personally i wouldnt use anything that was stamped Bosch i have seen their spark plugs just fall apart (ceramic part in it gone) in someones engine

I'm assuming all this has been said but its most likely either a lean surge or boggin. Check your o2 sensor, fuel pressure, voltage at fuel pump, and connections to fuel pump, fpr then worst case an intermittent ground on an injector line.

The problem has got worse so that it jerks back and forth even when accelerating now. It used to just be when at a constant rpm. I changed the oxygen sensor but the problem is still there. I'll check the fuel pump voltage, fuel pump connections and then look for a grounding problem tomorrow.

Any other suggestions?



p.s. also it bogs down when accelerating hard in the higher rpm range. It goes hard, bogs, goes hard again, bogs etc. but is intermittent. Sometimes it's terrible, others there is no problem at all. https://www.nopistons.com/forums/pub...IR#>/angry.gif

I'm having this problem with my gsl-se though not as severe as you describe. I'm not sure if this will help, but read it over and see if any of it makes sense to you. Not much of it does to me w/o looking at a manual.



https://www.nopistons.com/forums/gsl-se-idl...p;hl=gsl-se+won

Before you go chasing random stuff and getting into a hopeless loop, Have you confirmed that the TPS is good? Have you confirmed you do not have any bad mounts (trans, diff, and or engine?). A out of spec TPS combined with broken mounts will cause the car to resonate as you experience.

I had a fuel flow test done. It came back reading at about 1/6th of where it should be so had a Walbro pump, relay and new plugs put in. The problem is still there but now I know that it is not a fuel issue.

The cat had collapsed inside so I gutted that but that made no difference to the problem.



The shop I brought it to believes that is most likely a wiring problem causing ignition to be intermittent. I'll have a look at the TPS and try and pin point the problem down to one rotor/coil and one sparkplug.



Any other suggestions? Is there any point seeing if there is any problems the ECU has picked up?

o2 sensor?



if you can find the code reader, it will give you codes?

Unplug the O2 sensor and drive around and see what happens. The car will just stay in open loop using more gasoline, but there would be no feedback loop that might cause the ECU to go rich and lean on wild swings.



Personally I think your TPS is bum, or your CAS is in rough shape.

yeah its his tps... I just an FC last week and I got the and paied for the car with a bad tps and i still been driving it since for a week now with a bad tps.... so yeah its the tps that is casuing his jerky problem and such.

its your tps? how does your car shift in low rpm does it shift jerky,hard, or what?

I can't find the green 3-pin connector near the air filter. My car is a Japanese Import. Is it possible that it isn't on the JDM models? I ran a code check but no blinking of the check engine light. I actually don't think I have a check engine light in the center console of warning lights. Could this be a JDM difference as well?



FC MidNight Blue, I don't understand what you mean about shifting jerky. My car's manual as it is turbo so the car shifts how I shift it.

The North American cars are the same as the JDM cars. The only difference is that it is RHD, and some parts are different (steering rack, and other bits). The core of the car ist eh same.

Had to drop it off at a work shop to get it fixed since I couldn't work the TPS out. He had it half a day and said it was the full range TPS that needed to be replaced. Now it's apparently running sweet, picking it up this afternoon.



Damn you guys are good! Thanks

well now anyone who has a problem like this will know

it took you 6 months to believe us?

i guess its hard for some people to believe others