Help! Engine suddenly Revving at 4-6000..
#1
Help! Engine suddenly Revving at 4-6000..
Need some advice / suggestions please.
This has me stumped, did a full track day 3 days ago (saturday) without missing a beat, then drove it back home 50min trip.
Went to move the car out of the garage tonight to help my nephew on his car and the car backfired in the intake on turning on ignition, ran on 3 cylinders for about 2 mins and then settled evenly on 3-4000rpm idle.
I gently drove around the street thinking that would sort it out and it hasn't.
Left it for 2 hours, started it again, idles straight up around 4000rpm...
Anyone have any ideas where to start?
This has me stumped, did a full track day 3 days ago (saturday) without missing a beat, then drove it back home 50min trip.
Went to move the car out of the garage tonight to help my nephew on his car and the car backfired in the intake on turning on ignition, ran on 3 cylinders for about 2 mins and then settled evenly on 3-4000rpm idle.
I gently drove around the street thinking that would sort it out and it hasn't.
Left it for 2 hours, started it again, idles straight up around 4000rpm...
Anyone have any ideas where to start?
#7
Okay, so it looks like I may beed to pull IM and check some ---- out. As such I have some questions...
- Are there any mods I should do while IM is off?
- There is a mod to the fuel rail soemwhere around here, at 6, soon to be 8-9 psi is it worth doing?
- Car frequently backfires on ignition, is that likely a leaking injector?
- Is the IM gasket reuseable or do I need a new one?
- Are the supports for the IM required, was there any concensus on the butterfly shaft screws breaking being related to IM support removal (can the 1600 IM even remove the runners..?)
- Is there any point in port matching or flowing the IM while it is off?
- Are there any mods I should do while IM is off?
- There is a mod to the fuel rail soemwhere around here, at 6, soon to be 8-9 psi is it worth doing?
- Car frequently backfires on ignition, is that likely a leaking injector?
- Is the IM gasket reuseable or do I need a new one?
- Are the supports for the IM required, was there any concensus on the butterfly shaft screws breaking being related to IM support removal (can the 1600 IM even remove the runners..?)
- Is there any point in port matching or flowing the IM while it is off?
#11
I'm going to go with harmonics. Because it seems like cars that must keep the brace on to be legal almost never break shafts but ones that take it off break them. The intake vibrates, its cantilevered off the vibrating engine and it vibrates from the air inside it, so the extra stiffness and weight provided by the brace changes the natural frequency of the manifold and tb.
#12
Thanks guys.
Older guy, the harmonic thing was a theory develping in the thread re broken throttle shaft/screw issue, which was why I asked. I don't know if it was ever proven or disproven but wanted tosee current reaction...1 for and 1 agaisnt is a bit inconclusve though!
anyway, leaves a couple of questions if people could jump in.....
- There is a mod to the fuel rail somewhere around here, at 6, soon to be 8-9 psi is it worth doing? (my search capability on this site is terrible, any links welcomed!)
- Is the IM gasket reuseable or do I need a new one?
- Is the result worth the effort, in port matching or flowing the IM while it is off?
Older guy, the harmonic thing was a theory develping in the thread re broken throttle shaft/screw issue, which was why I asked. I don't know if it was ever proven or disproven but wanted tosee current reaction...1 for and 1 agaisnt is a bit inconclusve though!
anyway, leaves a couple of questions if people could jump in.....
- There is a mod to the fuel rail somewhere around here, at 6, soon to be 8-9 psi is it worth doing? (my search capability on this site is terrible, any links welcomed!)
- Is the IM gasket reuseable or do I need a new one?
- Is the result worth the effort, in port matching or flowing the IM while it is off?
#14
Thanks Leafy. Some gaskets are reuseable I just wasn't sure if it was or not, sounds like not. Will order one. I'm going to pull the injectors this weekend, I presume that can be done without much associated dismantling...
SO much info here, hard to know whats relevant or not...The fuel rail thing (from memory) was opening up the closed end and looping it around to even fuel flow/pressure across all cylnders ....I may have that totally wrong...?
But while everythings apart I was just trying to do what should/could be done to improve.
If it's not required I won't waste my time. Ideally I would be running 12 psi boost but i'm doing it in slow planned stages..8-9 is next and will be it for the next year or so at least. (famous last words...)
Cheers.
SO much info here, hard to know whats relevant or not...The fuel rail thing (from memory) was opening up the closed end and looping it around to even fuel flow/pressure across all cylnders ....I may have that totally wrong...?
But while everythings apart I was just trying to do what should/could be done to improve.
If it's not required I won't waste my time. Ideally I would be running 12 psi boost but i'm doing it in slow planned stages..8-9 is next and will be it for the next year or so at least. (famous last words...)
Cheers.
Last edited by mx5-kiwi; 08-09-2012 at 06:57 AM.
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