2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

RPMs goin whacko

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Old Jul 18, 2003 | 08:33 PM
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RPMs goin whacko

Hey all, I fixed my idle and it's at around 800 now, which is good for me -- problem is now, when I am downshifting for a stopsign and my RPMs go to 3500 or so, and then I press the clutch in, my RPMs fall to 0 and jump back up to like 800 where it should be...

I was wondering if this could be the fuel injectors, or the streetport maybe? Vac leak?? If it's the streetport, that's normal to have RPM things going on like that.. but I'm not sure...
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Old Jul 18, 2003 | 08:48 PM
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Could be just the effect of the lightweight flywheel. (I think flybye had a alum flywheel right?)
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Old Jul 18, 2003 | 08:58 PM
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Lightened flywheel was going to be my guess too.
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Old Jul 18, 2003 | 09:02 PM
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hmm... yep, it's a lightweight alright... but it would really cause the rpms to go to "0"????? I mean its like it is like the engine is dying, but not roughly.. it's smooth -- I guess I don't have anything to worry about huh?

If ya wanna check out my latest polish and waxing pics, go ahead and look at my website in my signature, it's nice
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Old Jul 18, 2003 | 09:08 PM
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Try setting the idle slightly higher, maybe 900-1000 rpm. With the lightened flywheel, when the engine is spinning down from higher RPM, there isnt enough mass in the flywheel to slow the engines decent, so it can pass up the idle point and almost stall ( I have heard of it actually stalling sometimes as well..) Basically it has the same effect as revving up as it does in revving down..
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Old Jul 18, 2003 | 09:14 PM
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on a side note, blip the gas when you downshift so your revs are raised to the right spot.
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Old Jul 18, 2003 | 09:19 PM
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i dunno about you guys, but when im coming to a stop i never down shift... if the gear im in is low enough ill let it slow me down for a lil while, then both the cluch and the brake go in....

personaly id rather change my brake pads more frequently than my clutch

but yeah, id try setting the idle a lil higher... and make sure your tps is right on the money too
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Old Jul 19, 2003 | 12:04 AM
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Originally posted by bingoboy
on a side note, blip the gas when you downshift so your revs are raised to the right spot.
I used to do that all the time in the car and yea they do have a goodpoint about the flywheel....I was thinking that to when I had it but wasnt sure.... but the rpms going to over 3000 rpm never happened lol.

Nick
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Old Jul 19, 2003 | 12:39 AM
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From: Oklahoma
I was talking about the rpms going over 3000 like when I shift from 5th to 3rd going 45mph or so... But I'll probably stop downshifting now, good point about the clutch/brake pad thing...
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Old Jul 19, 2003 | 12:40 AM
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wtf???
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Old Jul 19, 2003 | 01:21 AM
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Why would you downshift from 5th to 3rd? And when you do downshift your rpms of course will go up because your engine speed still remains the same while you are in a lower gear. You better watch out for overrev.
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Old Jul 19, 2003 | 01:22 AM
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From: Oklahoma
overrev?? what like 9000-10000rpms?? 3500 won't hurt when downshifting, no big deal, I'm not stupid...
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Old Jul 19, 2003 | 01:28 AM
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Originally posted by Driv300mph
...no big deal, I'm not stupid...

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Old Jul 19, 2003 | 01:31 AM
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haha
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Old Jul 19, 2003 | 01:41 AM
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From: Oklahoma
Ok 1987, are you having one of your moments again? I'm not stupid enough to downshift it say into 2nd gear while going 80mph and blow the engine and **** up the tranny!
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Old Jul 19, 2003 | 01:43 AM
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From: Laredo, Tx
It was just a joke man. Your not a retard just slow or something


Anyways the onlything that is wierd there is the going to 0rpms not 3500 that would be what you call NORMAL.
You can probably adjust the idle a bit to help prevent stalling and also get the hang of downshifting properly.


How is the lean problems going? did you ever fix it?
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Old Jul 19, 2003 | 02:09 AM
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No... I am saying that when I downshift and it goes to 3500 or so (Where it should) and then when I press the clutch in the rpms drop quickly and fall to 0 and then go back to normal idle... I know how to downshift

I went to Noble, OK to have it checked out and he said it looked great -- he was almost positive the a/f guage wasn't working though, considering the air flow screw was all the way in which if anything, it should be reading rich -- I'm going to check the ECU tomorrow if I can get the damn housing off of it!! Damn bolts are giving me a hard time...
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Old Jul 19, 2003 | 02:13 AM
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lol! your having a hard time with 10mm bolts??? ahahahaha

Well if your A/F guage isn't working check the O2 sensor.
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Old Jul 19, 2003 | 02:20 AM
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Driv300mph- "10 mm bolts are hard when you are trying to get them off with your fingers..., because you have never worked on a car before and you dont have tools"


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Old Jul 19, 2003 | 02:22 AM
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nah I have tools... I just don't have the right fitting for the bolt... where are the o2 sensors located?
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Old Jul 19, 2003 | 02:30 AM
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the o2 sensor is on the header. Nice was telling me that it is probably what was giving you wierd readings earlier. BTW buy some good metric stuff. You can just throw away your SAE crap.
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Old Jul 19, 2003 | 02:52 AM
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Oh damn... so the sensor is hard to get to then huh??? If you happen to have a picture of the sensor that would be great...

Ok, raise the newb flag if you must, but what is SAE? Standard Equipment or something? What kinda metric stuff? I'm off to bed, I'll post more in the morning...
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Old Jul 19, 2003 | 03:42 AM
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Why does your car drop in rpms and then bounce back, at idle? It's called having an s5 NA. Most of them do that...it's an effect of the lightweight rotors, amplified by a big port and a lightweight flywheel. Most s5 NA's hunt between 700 and 900, I consider this to be normal for our old cars with poor electronics...not desireable, but normal.
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Old Jul 19, 2003 | 09:21 AM
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Originally posted by hypntyz7
Why does your car drop in rpms and then bounce back, at idle? It's called having an s5 NA. Most of them do that...it's an effect of the lightweight rotors, amplified by a big port and a lightweight flywheel. Most s5 NA's hunt between 700 and 900, I consider this to be normal for our old cars with poor electronics...not desireable, but normal.
Having an S5 lol Goodcall Hypntyz7
And Troy the O2 sensor is right on the header. Very easy to get to. Just look at the header and you will see a little wire coming from the header hooked to a round peice hooked to the header. Thats the O2. (Did that help? lol)

Nick
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Old Jul 19, 2003 | 09:48 AM
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Well, I can say with my Aluminum Flywheel, at times my Idle would drop to 500rpm (causing all the dash lights to go on) and than right back to 750, when I put It Into Neutral approaching a Stop Light or Sign. From there, It would bounce back to the sweet 750 I adjusted It too.

Since, I've adjusted It to 800 rpm's I've had no Indication of any Idle problems or fitting Into the clitche "an aluminum flywheel Is not streetable:.

The latter point Is for another thread, on It's own.
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