Ae112 Rough Idle

[2001AE112]

Hi,

 

New member here. Owned many Corollas and they were very reliable, but my 2001 AE112 Ascent is suffering at present. Purchased in 2007 with 93k km, it's now done 135k km and has been great so far. A few weeks ago the idle became a bit rough. With the engine warm, at idle, there is a hiccup in the idle every 5 seconds or thereabouts. The idle was previously very smooth. The plugs were changed 10,000 kms ago. My new mechanic suggested some new ignition leads, so the 10 y.o. Sumitomo leads were replaced with blue silicone NGK leads which he sourced for me, and they didn't improve anything. Since the rough idle came in, the car suffers from a lack of power (-10%) at launch (manual trans.) and the car lurches once after about 1-2 minutes after I drive off to work in the morning from a cold start. I high road speed, the problem is undetctable. IIRC, the lurching was detected before the rough idle problem came about. I've since run 98 RON through it, which has made no difference, albeit a little more power, but still lacking where it used ot be.

 

So I'm thinking:

1) Spark plugs may be poor quality,

2) Dirty injectors

3) Not the fuel filter (checked 3,000 km ago)

4) Sensor(s)?

 

Appreciate some thoughts

Mike :)

[7shades]

Symptoms sound *similar* to problems I've had with an AE93RV and AE112R.

I think this might be something endemic specifially to the 7AFE as I've not encountered it in any 4AFE.

 

Carbon buildup.

 

I once picke up an AE93 that was idling terribly, lacked power and chuffed blue smoke. What I did:

 

Have a look down the guts of the throttle body and check that the butterfly is seating properly. As well as the carbon, the butterfly tends to corrode around the edge and it doesn't form a perfect seal. There's also two valves on the intake system, idle bypass and cold idle, that can sometimes get sticky and perform erratically. I took all mine apart and cleaned it up with carby cleaner and a toothbrush, soaking the valves in petrol for a while beforehand. Throttle butterfly might need a quick rub with emery paper if its corroded.

 

I also sprayed a metric f*ckton denatured alcohol into the intake and let it sit for a while, before starting the car and raping the hell out of the engine whilst spraying more carby cleaner down the intake. And by raped the engine, I mean revved the snot out of it for about 10 minutes. Several times.

 

Worked a treat :)

 

Of course you may have a different issue altogether, but I've seen it on quite a few 7AFE's now.

[ke70dave]

if carbon build up is the problem, a good product i found was "Subaru upper cylinder head cleaner" (could be made of the same stuff shades is talking about?)

 

only available from subaru, around $18 for can. apparently the boxer engines gets carbon build up worse than normal since they are on their side?

 

follow the instructions, it involves filling up your intake manifold with about half the can (engine off, the stuff comes out like shaving foam), then starting the car (quite difficult to start), and continuing to spray it in until can is empty.

 

when i used it on my Sr20, i started the car i had white smoke going everywhere for a good 3mins (ie looked like my engine was running on oil), cleaned it out real good! ran smooth as for ages, i think it might need another can again though.

 

i advise not doing this in your street, i went down to one of the back roads where no houses were, got some interesting looks from passes by.

[2001AE112]

Cheers, and thanks for the fast responses.

 

My mechanic suggested he could run a cleaner through the fuel injection system, similar to what Subaru do with the inlet manifold cleaning system. I've just sold a 2004 Suby Forester and I appreciate the carbon buildup problems in the 2.5L boxer engine... was a PITA having to get the mechanic to clean out the carbon buildup out every service... it would stop the pinging for a few weeks. I'll never buy a Suby again.

 

Anyway, I'll have a look at the Corolla's inlet body, as it sounds it might require a clean out 'somewhere' in there. If nothing stands out I'll get my mech to clean the air/fuel system out.... just trying to keep the cost of ownership down! Why I buy Rolly's!

[Hiro Protagonist]

Make sure your ISCV is plugged in properly too, and getting proper voltage at the pins I had a similar problem on my 7AFE a few years ago (resulted in inadvertant stalling and several sets of traffic lights, amongst other things like a lumpy unstable idle that was sometimes high and sometimes very low), fiddled around with the plug and never had a problem since.

[2001AE112]

Okay, I'll check out the ISCV too. Umm, where is the valve located on the 7AFE type engine? Thanks!

 

Edit: found the location of the ICV, measured the resistance as 19.6 ohm (expected). I then disconnected the plug with the engine idling and the idle speed dropped but the engine still ran. So I'm thinking it could be dirty injectors? The engine has a definite shake to it every few seconds.

 

I found some info on the ICV here:

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80380339

Edited July 2, 2011 by 2001AE112