Jump to content
SAU Community

Recommended Posts

Hey Guys

Heres the story after 10 mins of driving and i come to a set of lights feels like my car has a heart beat or a pulse the revs go down then back up again. keeps on doing this. Feels like its going to just die on me do u know what is probally the cause of this???? i was thinking the fuel pump??? has any of you guys had this problem its 96 r33 srs2 N/A. and if so is it expensive to fix.

Link to comment
https://www.sau.com.au/forums/topic/282798-car-revs-drop-and-come-back-up/
Share on other sites

Get the fuel pump tested, you can test for fuel pressure and flow. Sounds more like you have a 'clean' problem to me, dirty plugs or sensor [o2,tps etc] somewhere.

Don't replace the fuel pump without testing the whole fuel system. Cost, sub $200, probably what ever a service is worth.

Fuel pump, being an N/A, a Walbro will do it easy, around $250 fitted, but get it checked first.

And get your fuel filter cleaned/replaced, could have dirt/water in it.

yeh i changed all of my spark plugs and replaced the fuel filter which was dirty as and still having the same problem? so im guessing would it be just the fuel pump or coil packs? and whats the o2,tps as you quoted????

atmo bov?

if u have a standard ecu try ressetting it (unplug battery and pump the brakes or turn stuff on and off to drain all the residual power from the wires) then plug battery bak in

easy thing to do and doesnt cost anything

if not start looking elsewhere

Hey mate, I think I'm having exactly the problem you are. I posted about it, it's only like the 10th post down lol... still haven't solved it though. There's a link to my youtube video of it as well, have a listen and let me know if the noise is the same.

Happens when my car is idle, warmed up.

My mechanic has told me my AAC valve needs replacing so I'm waiting for someone else to verify that this could be causing this noise? If so, then it could very well be your problem too.

CLICK HERE LINK OMG CLICK CLICK <== Link to my post, containing youtube link.

yes, most lumpy idles are caused by either the AAC or IAC. mostly the IAC (idle air control). this will happen when you put your foot on the clutch and it idles like a drag car. do a search on here, it has been covered many times before. it is reasonably easy to do. all you need is some carby cleaner and (from memory) a 12mm spanner. the IAC is situated on the back of the plenum near the firewall.

my car did this.

i had a power FC and it happened when i turned the air con on, and it happened randomly - not all the time.

could be completely unrelated to your problem, but when i turned the air on - revs dropped to about 300 and then it kicked itself back up to 1000, then dropped back down - kicked itself back up - etc.

was a power FC setting problem.

Check: IAC or AAC ( by that I mean clean it out) couple of bolts and some time with petrol or carby cleaner.

AFM. Clean with electrical cleaning spray. I think around $10 so just spray it into the AFM, no need to remove.

If you have a BOV other than standard or GTR then remove it.

Drive the car and see if it does it when you back off in gear then put it in neutral or if you are cruising along and suddenly push the clutch in. Won't be the coils as they would be acting up under boost before they played up at idle.

Always start with the simplest things first.

Ok can someone explain the difference between the IAC and AAC? By the difference, I really mean where both are located? I thought I'd had a go at removing the AAC from the back of the plenum... is that the right one? So where abouts is the IAC?

I always (stupidly) thought they were the same thing..... d'oh!

IAC and AAC are located very close to each other. if i remember correctly, the IAC is located above the AAC. IAC = easy to get to. AAC = not so easy to get to. i will have a flick through my workshop manual and see if it has any pics

IAC and AAC are located very close to each other. if i remember correctly, the IAC is located above the AAC. IAC = easy to get to. AAC = not so easy to get to. i will have a flick through my workshop manual and see if it has any pics

Could the AAC cause boost spike?? If it was failing?? I am working on an R33 at the moment and it seems to idle rough on and off. Get it idling smooth then 10 minutes later its idling like balls.....along with the rough idle I also have intermittent idle hunting after boost. Comes down to almost stall and then picks up again. Does it about 2 times then idle sets again. So couldthe AAC be a possibility?? when I say boost spike too I mean I get alot of lag then all of a sudden a major boost. Very hard to control and very unpredictable.

Could the AAC cause boost spike?? If it was failing?? I am working on an R33 at the moment and it seems to idle rough on and off. Get it idling smooth then 10 minutes later its idling like balls.....along with the rough idle I also have intermittent idle hunting after boost. Comes down to almost stall and then picks up again. Does it about 2 times then idle sets again. So couldthe AAC be a possibility?? when I say boost spike too I mean I get alot of lag then all of a sudden a major boost. Very hard to control and very unpredictable.

the AAC shouldn't affect boost at all. it only lets in a tiny amount of air. it could be causing the hunting idle after boost but there could be other causes too. when i first got my 33 it was pretty much stock, but if you gave it the beans then lifted off it would nearly stall. it was caused by worn spark plugs. if you have an atmo bov this can be made worse. i only had the stock bov though, so it isn't just atmo bovs that can make this happen if the plugs are crappy. what happens is that when you lift off and the bov opens, with an atmo bov all the air in the cooler piping is released out into the engine bay and this sucks a bit more air through the afm so the ecu puts more fuel in, making it too rich and the spark plugs aren't able to ignite all the fuel. with the stock bov a similar thing happens although it doesn't suck as much air through the afm, but you get some of the air that is being recirculated passing back out the afm, and since it doesn't know which way the air is travelling it dumps in extra fuel also. the fact that your idle drops after lifting off then comes good again makes me think that your problem is like mine and there is a very good chance that new plugs should fix it. and if you haven't replaced your plugs in a while it wouldn't hurt doing it anyway since it will only cost you about $30 for a set of plugs. the part number you want is BCPR6ES. don't bother with iridiums. i was getting similar life from copper plugs as from iridiums with a $100 price difference.

as for the lag, don't really know about that one. that could be caused by a lot of things. could be to do with the wastegate or the boost controller.

as for the AAC valve location, i looked it up again (it's been about 3 years since i had my 33 so i'm a bit rusty on locations of things). the AAC is attached to the side of the IAC. if you look at the back of the plenum you will see a round cylinder about 1 inch wide pointing towards the passenger side with a plug on it, and just behind it what looks like a really long nut with a plug in the end of it. the round cylinder is the AAC solenoid. the other is the IAC. you remove the whole unit with 3 bolts (i think they are 12mm, maybe 13mm) and 1 or 2 of them are located under the unit. then disconnect the plugs and hoses. the AAC i think is held on by 2 small phillips head screws. give the whole unit a good spray with carby/throttle body cleaner. then stick it back together and install the unit back in the car. after doing this it is best to readjust the idle which you need to lock the car into base idle mode. this can be done without a consult but i can't remember how. has something to do with bridging 2 wires in the consult plug.

Too late for the irridiums. Replaced with platinum plugs gapped at .6mm and new Yellow Jacket coils. AFM has been cleaned and a million other things have been tried.

I have a feeling that the lagging, idling, and boost spike are all to do with the same thing. I am doubtful that there is more than one issue causing these issues. The ECU is a Garage Saurus complete replacement plugin. Unfortunately no one here in Perth knows anything about the Garage Saurus gear. As in no body knows how to access the ecu to re map. I have a feeling thats what it needs.....

Thanks for your help anyway. I will have a look at a few more things. Do you know of anyone anywhere in australia that I could call to pick brains?? I have called most performance places here in Perth.....they all say the same thing, get a Power FC.....but I am not confident on spend $1500 on a Power FC until I know that the turbo or motor aren't shagged. Low compression can cause rough base idle.....yet to do a compression test. Pffft.....stupid R33!! Goes hard but this is frustrating!! :huh:

atmo bov?

if u have a standard ecu try ressetting it (unplug battery and pump the brakes or turn stuff on and off to drain all the residual power from the wires) then plug battery bak in

easy thing to do and doesnt cost anything

if not start looking elsewhere

I'll have to give that a go, mine has been doing it and it has an atmos + plumb back bov.

My car is known to die though while driving but only when braking quickly after a boot.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Major thread necro but how bad of a job is it to DIY? Looking at it online it looks like if you reuse your ring and pinion as long as those are in good condition it should be fine to just pull the axles/front cover and replace the diff that way? Or should I be replacing everything and doing preload measurements/gear mesh testing like the factory service manual mentions for the rear diff?
    • in my list I had the R33 GTR as the best Skyline. Infact I had all GTR's (33>34=32), the NSX, the GTO, the 300ZX, the 180SX, the S15 better than the FD RX7. I had the MR2 and the A80 as 'just' better. I also think the DC5R Integra looks better but this is an 01 onwards car. I also think the FC>FD. It's almost like aesthetics are individual! The elements @GTSBoy likes about the FD and dislikes about the 180 are inverse in my eyes. I hate the rear end of the FD and it's weird tail lights that are bulbous and remind me of early hyundai excels. They are not striking, nor iconic, nor retro cool. The GTO has supercar proportions. I maintain these look much better in person (like the NSX) especially with nice wheels and suspension which is mandatory for all cars pretty much. Some (or all) of these you have to see in person to appreciate. You can't write a car off until you see one in the flesh IMO. Like most people we probably just like/dislike cars which represent certain eras of design or design styles in general. I also think the 60's Jag E type looks HORRIBLE, literally disgusting, and the 2000GT is nothing to write home about. FWIW I don't think the Dodge Viper Gen1's have aged very well either. You can probably see where I rate bubbly coupes like the FD. I know we're straying now but the C4 and C5 absolutely murder the Viper in the looks department as time goes on, for my eyes. Wouldn't surprise me if people who love the FD, also love the MX5, Dodge Viper, Jag E Type, etc etc.
    • I used to hate R31s, and any of the other Nissans that led up to it, and any of the Toyotas with similar styling, because of the boxiness. They were, and remain, childish, simplistic, and generally awful. I appreciate R31s a lot more now, but only the JDM 2 door. The ADM 4 door (and any other 4 door, even if they are unique compared to our local one) can eat a bowl of dicks. The Aussie R31 is also forever tarnished by their association with stereotypical bong clutching Aussie R31 owners of the 90s and early 2000s. I think the Nissans of the 70s (other than 120Y/180B/200B) are far superior looking to the 80s cars. The 240K era Skylines are boss. The same is broadly true of Toyotas. Hondas don't ever register in my thinking, from any era. Mitsus are all horrid shitboxen in any era, and so also don't register. Subarus are always awful, ditto. Daihatsus and Suzukis also don't generally register. They are all invisible. I think the SW20 MR2 looks fiddly. The 3000GT/GTO is like that but way worse. Too many silly plastic barnacles and fiddly gimmicks ruined what could have been a really nice base shape. Kinda-sorta looks like a big heavy ST165 Celica coupe (and I'm not sure if that's a good thing or a bad thing). I think the 180SX is dreadfully bland. It's not bad looking. But it has no excitement to it at all. It's just a liftback coupe thing with no interest in its lines, and bad graphical elements (ie wide expanses of taillight plastic on the rear garnish). The S13 Silvia is a little better - getting closer to R32 shapes. But still....bland. S14? Nope. Don't love it. S15...a little better. Probably a lot better, actually. Benefits from not being like a shrunk in the wash R34 (where the S13 was a shrunk in the wash R32 and the S14 looked like a Pulsar or something else from the stable on Nissan mid 90s horrors). The Z32 was hot as f**k when it came out but hasn't aged as well as the A80. Keep in mind that I think the R33 is the most disgusting looking thing - and out of all the previous cars mentioned is objectively closest to my precious R32. It's just....real bad, almost everywhere you look. And that is down to the majority of what was designed in the 90s being shit. All Nissans from that era look like shit. Most other brands ditto. In that context, the FD absolutely stands out as being by far the best looking car, for reasons already discussed. Going behind the aesthetics, the suspension alone makes it better than almost any other car.  
    • If they just called it the "Mazda Tiffany", it would have been spot on.
    • Yup but for me its the HR ! Cut my teeth on the old holden 6s in the day ! And here's me thinking in the day it was also the 300ZX and the Mitsubishi GT3000 ! All, as well had good lines, but always seemed to need finishing off, style wise.
×
×
  • Create New...