20v raised idle + backfire

[hachi_dk]

Car - ae86

motor - 20v ST running blacktop ECU, open trumpets (currently no filter), oil cooler system + oil filter relocation kit, dizzy relocation kit on front of head.

use - daily/drift

problem - after installing oil cooler, car now idles at about 1900 on start up and drops to about 1500 when warm. also, car backfires (never ever backfired before regardless of the thrashing)

occurs/started when - after installing oil cooler

so i've just put an oil cooler system and oil filter relocation kit on my 20v.
after i hooked all this up, turned my car on and the idle hit about 1900.
after letting her warm up a bit (assuming the idle would drop to about 700-800) but it didnt. it only dropped to about 1400-1500.
the car also backfires now. under revs you hear "pop pop", under high revs spits fire out of the exhaust. so its not burning fuel at some stage. but how? i havnt touched anything to do with the timing/dizzy/cam gears.

i have:
-topped up the oil because of the additional oil travel through the system.
-checked all fittings for leaks, there are none
-oil pressure is good

could the timing have skipped foreward or back somehow?
which would explain for the backfires, i really dont know.
any help would be greatly appreciated.

[DR86TY]

u have flames that just equals bonus points, my 20v used to do this, it was sick.

Sorry that doesn't help your problem tho.

Did you happen to bump a vacuum hose off or nick one, as this would be a good starting point for a sudden increase in revs and the car running rich.

This would be my first point as its very easy to do when working in a tight engine bay

[Twinky]

The vvt operation will not work with an oil cooler on the 20v (either bt/st)
The oil pressure should have changed. Just take out the oil cooler, run the car and see how it goes. Also I have heard using the bt ecu makes the st run a little rich. I'm no pro but i have a st myself and have looked into using an oil cooler but was told not to do so. Just wondering with your quads, are you using bt or st? if you are using st how have you connected the map sensor hoses?

[ONCHRG]

why wouldnt the vvt work with an oil cooler???

[Twinky]

The vvt is controlled by an 'oil controll solenoid/valve' that works on oil pressure. with an oil cooler i would assume oil pressure decrease thus not properly functioning vvt. But i don't think the vvt would be the problem he is seeing. unless ofcourse he has higher oil pressure thus triggering vvt operation early.

here is the info

[hachi_dk]

oil pressure is the exact same.
havnt thrashed the car since putting it in so couldnt tell you if vvt is working or if the car feels different in any way.

i agree, flames are very cool but since it happened randomly, i just want to know why and the raised idle is not cool.

also, I only worked on the exhaust outlet side of the engine, spent no time (not even a second with my hands near the inlet) anywhere near the inlet but i will have a good geeze to make sure all the vacuum hoses are good.

[Sam-Q]

ok so how is the temperature of the engine now? could it be possible your engine is now running too cold because of the oil cooler?

The VVT should still work fine because it doesn't need much oil pressure to work, or so I hear from the reports I have been given. Either way it would be off at idle. So what did you use to check the oil pressure anyway? the factory gauge?

show us a pic of this combination

[lolwat]

check vacume lines, get a can on carby cleaner and spray around them if the idle raises when you spray on a certain point, that point is leaking

[hachi_dk]

thats the engine with the cooler just infront of the radiator support. just under where the battery sits, is a thermostat for the oil so it doesnt cool, cool oil, it waits for it to get to a certain temp etc; as you already know before it cools it down.
i am using the factory guages to tell me temperature and oil pressure also. (soon will be getting a set of aftermarket though)

-also, i drove her for about 15minutes and the temp was at the middle (optimum) just like before i put the oil cooler in.
-i checked all vacuum hoses and they are all fine; but will be trying what KE slider mentioned.
-changed the oil and replaced oil filter too

seems really odd as it sounds timing related because of the idle going up and the backfiring.

hmmm.....

[lolwat]

try disconnecting the batterie, reconnecting, starting and le it sit there and idle like shit, and let it sit there, it might need to learn idle (yes it will learn it itself)