The Mother of All Troubles?

[Evan not Peters]

Good evening guys, this is Evan from Greece. 

I've been using my grandfather's Toyota Corolla (1996 1.3 xli) for over six months now and it is full of problems. 

It was immobilized for more than two years, and one day I thought, why have a car that does nothing but take up parking space, so I took it to a mechanic, changed filters, sparkplugs and oils, fixed the horribly loose brakes and cleaned the throttle body.

For quite some time the car worked perfectly, until a problem it had before my grandpa stopped using it reappeared. The problem? It revs up randomly! For no apparent reason it will rev up to 2000 rpms, stay there for a fraction of a second or even up to half a minute and then it will drop back down to a normal 800 rpms. The throttle will remain closed for while this is happening. 

Of course that's not enough of a problem to make this car the Mother of All Troubles, as the title suggests it might be. It also has another interesting issue, that is it won't start when it's hot. If I try to turn it on in the morning, before going to work, it starts immediately. When I try to turn it on after work, it also starts immediately. But if I dare go at a petrol station and turn it off for the two minutes it takes to fill her up then she's up to no good. It will cranck and cranck and cranck and if I incist for long enough it will start. Then for a few seconds it will sing the song of the belt people (the well known "scream" the belts make when they need replacement) and then it will go back to working normally (random power surges aside). 

So today I tried manually reading the troubles. I took a jumper cable, placed it in the E1 and Te1 slots at the Diagnosis panel and got absolutely nothing! The Check Engine Light just blinked repeatedly and steadily. Of course I feared this would happen since the CEL wasn't on. So now I find myself wondering that perhaps, even if I manage to find a mechanic with an old 22 pin OBD 1 scanner that he won't find any troubles either. 

Anyway, that's the magical story of How I Met The Mother Of All Troubles . Any suggestions would be much appreciated. 

Greetings! 

[flash22]

Does it have a throttle cable or is it drive by wire ? first thoughts is a bad idle control valve or a vacuum leak

[Aussiemarco]

Hi Evan! Good morning to beautiful Greece 😍🇬🇷
Your mother of all troubles you described is exactly what happened to my 1996 Rav4! In fact I could have written your post. I took it to two mechanics, one was a Toyota specialist who only works on Toyotas. Both had no idea what caused it. I’d fill up at a petrol station and have to wait up to 3 hours for the engine to cool down for it to start. It got to the stage where I’d fill up late at night, when nobody was around, keeping the engine running!!! Extremely irresponsible, I know - I shudder when I think of it now. It ended up being undrivable, the revs would soar suddenly then plummet so fast the engine would conk out and I’d be stranded for hours waiting for the engine to cool down enough for it to start again. It was a nightmare from Hell driving it. I ended up selling it for £300 for parts.

As I said, nobody had a clue what caused my nightmare. However, a few years after selling it I read on a forum somewhere that a heat sensor on the engine must have become unstable (or died?), so the engine would think it was cold while driving along and suddenly activate the choke, causing the revs to soar while driving. When trying to start it while the engine was hot, the engine thought it was a cold start, so it turned on the choke and flooded it with petrol. (I knew it was flooding because I could always smell petrol while staying to start it). When I waited for the engine to go cold, the choke would come on when it was needed and it started perfectly.

Your problem will only get worse, sorry to say. I hope that’s what it is. Good luck!