6G Celicas Forums

Ok so i just performed an oil change on my 7afe. The first couple of weeks the car was fine but now when the engine is at normal operating temperature the rpm idle drops to about 600-700 rpm and the car feels like its about to die. Anybody know why it does this? nothing is wrong with any vacuum lines, everything has been kept up to date.

mine does something similar, stop lights and traffic especially make it noticable....havent found a cause or a fix yet!

not sure if the 7A has a throttle adjustment screw above the throttle body or not.

what i did was add about half a quart of oil to it and after about 2 days driving the car, the idle problem stopped. i dont know if its a low oil problem or not though.

mine definitly isnt low on oil.....dirty IACV maybe?

my 7a has always idled low like that once its warmed up.. maybe not down to 600, but usually 700-800 rpm

^ This.

I think it's a natural problem that plagues our 7As. What I do when I'm stopped is just bump up the revs to about 900 and that gets rid of the roughness and shaking.

The funny thing is: when I introduced a vacuum leak to the system when I was trying to figure out what was going on, the rough idle stopped.

This post has been edited by HectortheRican: Mar 29, 2012 - 12:49 PM

i see that you have a 95 7a, (OBDI) low idle speed can also be caused from the ingition timing being set a bit low aswell.. if the dizzy was backed up a bit (lose, and bumped or vibrated back).. since the car idles higher until warm you may not notice it upon start up.

check your timing.

the idle RPM is not that far off.. IIRC should be 850-900.

theres nothing wrong with the timing. before it would stay at 800 rpm and feel fine until i did the oil change. this happened before but i never paid attention to it until yesterday when it got really bad. my steering wheel started vibrating like crazy at a stop light. ill probably clean the throttle valve again and see what happens after that

hmm, and you checked the base timing with a jumper in the "E-1" and terminal "Te-1" in the dieg port?

well.. not saying that you have not checked it right, but its an easy thing to over look..

and after an oil change.. same oil type and filter as b4? defiantly odd..

good luck

nope , yeah same oil except i put alittle less of it this time. i usually put about 4 1/2 quarts of 10w-30 castrol high mileage but this time i only put 4 quarts.

Was there any solution to this issue.
I'm having the same problem with mine.

Idle speed is supposed to be 750 +/- 50 RPM, so 700-800 RPM is a perfectly correct idle speed, if it feels rough at that speed then you need to look at engine mounts or at the ignition system and check compression for a weak cylinder. Likely the passenger side mount is worn out and needs to be replaced, I can't promote any part for that except the dealer mount since most aftermarket mounts use the wrong firmness of rubber and the wrong fluid inside and cause a booming or rough idle, the dealer part is built right and will work right and last another 90,000 miles again.

How do you check the timing on 7AFE engine. My car at times idles rough when warmed up but only when sitting at stop light. I have tried to clean IAW and it does get better for a couple of days.

Jump E1 and TE1 in the diag box and then start the engine, the engine should be warmed to operating temp before starting and all accessories should be off. This places the engine into base timing mode with no advance or retard, do not drive the vehicle in this mode. To check timing allow idle to stabilize and then check timing off plug wire #1, snap the throttle a couple times while checking timing to ensure it always settles back down to the correct position. It should be 10 degrees BTDC, only non OBD2 are adjustable, later models are fixed timing even if the distributor is rotatable as the ECU uses crankshaft and camshaft position to set ignition and fuel injection timing. Timing set too advanced will cause a high idle and possibly preignition or ping under load without the use of higher octane fuel, ignition timing set too low will cause sluggish acceleration and high emissions as well as a low idle. The 7A with adjustable timing runs very well with 15 degrees timing and 89 octane or better fuel, pairs well with bolt ons such as an air intake and ebay header+exhaust.


But if you're idling at specification and it still feels rough either you have one or more cylinders not running correctly or worn mounts or both issues going on. The passenger side mount is responsible for most of the idle quality issues reported. Assuming your engine is running perfectly with good compression across the board and all cylinders contributing 100% the mount is the cause of a rough feeling idle, it's not that the engine is running roughly it's that you're feeling it in the cabin due to a worn mount transmitting too much vibration. If it feels 'boomy' in the cabin at idle it's the mount worn out.

Thanks Bitter. My car is 1996 ST so OBDII.

You can check timing but you can't adjust it, too bad cause that 5 degrees extra timing really wakes up the 7A.

Thank You Bitter. Appreciate your input and help.