Rough idle - smooths out when I drive (going insane) Options

[stephen_lee]

if youre really worried about the internal condition of the motor, do a compression test...

both my 7a autos idled at 600-700 in gear once warm. its rough but its how itts supposed to run apparently..

but i got a fix

add a 330 ohm resistor inline with the ecus coolant temp sensor. its the 2 wire CTS on the water neck kinda pointing towards the throttle body.

this will raise idle to about 1000 in neutral, and 800-900 in gear. if you think thats a bit much try the next smallest resistor.

This post has been edited by stephen_lee: Mar 9, 2011 - 7:46 PM

[97Supra]

Compression test results:

Cylinder 1: 205 Cylinder2: 190 Cylinder 3: 195 Cylinder 4: 195

It failed emissions which is the only reason I'm even trying to fix it so I can pass inspection. Drive legal my friends

[stephen_lee]

motor should be okay then. raise the idle and it should be smooth sailing (err, driving) afterwards

i did it to my daily and its helped A LOT. takes a bit longer for the ecu to decide its ok to use 4th though. but i can live with that over the shaking...

[97Supra]

I'm definitely going to try this for the comfort of the ride if my fathers guy cant figure it out, because every time i stop i feel like the cars going to crumble into a pile of bolts. haha

[windowlicker]

do a cylinder leak down test.

[stephen_lee]

how'd this turn out?

[97Supra]

got the car back, it passed inspection and the shop couldn't figure out what was wrong.. all the owner .. a tech of 30+ years could say was:

"Adjust the hard idle setting with the screw, and change the motor mounts."

I already DID change the hard idle and somehow no matter how high I put it, it wont idle higher than like 700 with it way out where 1,000 should be and the mounts aren't causing the needle to fluctuate. When I start the car, the car is searching for an idle speed that it's hardly able to steady.. it doesnt jump a lot, but it fluctuates 200 rpms at least up and down for a few seconds and sometimes at lights it dips too far, or raises without throttle input. It's like a vacuum leak but I retorqued the manifold gasket, and sprayed carb cleaner all over the engine.. the rpms didnt change and I was using a timing light so I'd have a dead accurate reading of the rpms.

I have a set of cleaned up injectors I'm going to install with new rubbers, and I'll change the intake manifold gasket with a brand new one. If the new gasket doesn't have any impact, I'm going to probably give up.. I already have the gasket so I might as well.

[clownpRon]

I tried to solve this mystery, but gave up after a few failed attempts. Now I just throw it in neutral when I'm at a stop.

[97Supra]

If I figure it out I'll be sure to post it up because this is a pretty annoying issue, having to daily drive a car that literally is shaking itself to pieces is not something I can settle for. I put it in neutral also, but it still shakes just not as bad.

[clownpRon]

I'm pretty sure though it's the throttle body on mine. It started after I installed my SRI, I believe. I feel now it has to much play. So when it shakes it then shakes my hood and makes a lot of noise. But this is all in theory. I cleaned the throttle body out with a rag and deep creep and it shakes less. Random hard spurts. I just need to go back in there with a brush and go to town.

[stephen_lee]

raise the idle with that resistor guys. the idle is a factory spec 650-700 rpm. i induced a vac leak before to raise the idle (pulled that vac line of the top of the TB, closest to the front of the engine) it raised the idle...then the ecu "learned" and dropped it back down to 650ish when i plugged the line back in it dropped to 400 or so... then eventually raised back up to 650-700.. that resistor seems a permanent fix. 1 month so far

[Bitter]

you can't just change the throttle stop screw, you also have to recalibrate the TPS when you adjust it! Also, yes change the front and passenger side motor mounts to start with.

[delusionz]

You haven't unwittingly used Polyurethane engine mount bushes have you?

[brenton1919]

If I figure it out I'll be sure to post it up because this is a pretty annoying issue, having to daily drive a car that literally is shaking itself to pieces is not something I can settle for. I put it in neutral also, but it still shakes just not as bad.

dude i really think its your flywheel it may have came lose or lost some blots out of it your egr would make your car shake like hell if its bad but u said u changed it tho check your fly or check your harmonic balancer you might have a lose rod to i think your flywheel came lose tho my lil brother does it all the time he breaks the blots and the car shakes like hell

[zfjohnson07]

my car shakes like hell as well, today for some odd reason it stopped for about a min, once it gets to 900rpms its rough, so i throw it in neutral and rev it to 2000 rpms and it is fine, but like clownprob said clean your throttle body, someone recommended that to me.

[stephen_lee]

if theres a bottom end problem (balance, rod) it would get worse as RPMs rise.

[97Supra]

i still haven't found the issue.. but that shiny new alternator they sold me at advance auto parts failed already its grinding inside.. going back today to exchange it... man i wanna junk this car but i just gave up my truck and sold my Mr2 so I'm stuck with this thing until I save up enough for something else.

[zfjohnson07]

well not to jack your thread. been searching for it but how do you change the idle i know its a screw on the throttle, any pics

[97Supra]

The hard idle set screw is what the throttle pulley rests on, (half moon that the cable is attached to) comes to a stop at one end of the screw. There is a small nut to loosen it up and it is a small metric alan key which turns it if i recall correctly. The throttle position sensor will be out of sync if you change the hard idle.

[csscza]

Im following along mine just got back on the road and is now vibrating at idle a little once in awhile