My 20 Valver Won't Rev Cleanly

[Escy]

I've got a 20v 4A-GE engine in my Toyota Corolla Levin. It was running fine, took it for a good blast, (8,000rpm and it didn't hit the redline :)), 1st time i've driven it since i've had it / done the cambelt.

My mate went to use it the next day, he said he turned it over and left it to warm up, when he came back to it, it was tapping and wouldn't rev past 3k. It turns out the drivebelt had started to de-laminate and was hitting things everywhere. Put a new belt on it today but it still doesn't want to rev properly.

It's perfect at idle/low revs, on WOT, it's fine up untill 3k where it just holds back, if I back off, I can ease the revs up to say 6,000rpm and then when I put my foot to the floor it just holds back. It's like a mis-fire but without the pops and bangs. It seems quite smooth when it's holding back.

I thought the cambelt might have skipped a tooth, stripped it down and it's all bang on. The plugs in it are new.

It seems funny how one day it's fine and the next it's playing up.

Any ideas guy's?

[4ageae92]

did u try checking the ignition timing, condition of distributor cap and ht leads or if there's dampness around any of the ignition components.

[Escy]

How do you check the ignition timing?

It would have got wet today as I was working on it in the ****** rain. Wouldn't have been wet the 1st time it done it thought.

[4ageae92]

How do you check the ignition timing?

It would have got wet today as I was working on it in the ****** rain. Wouldn't have been wet the 1st time it done it thought.

you need a strobe to check the ignition timing. they usually clip on to the Battery and inbetween the distributor cap and ht lead for the no.1 cylinder and flash everytime that cylinder fires. you point the strobe at the pulley connected to the crank which usually has markings on it which should line up. you can then adjust the timing by losening the bolts holding the distributor in, twisting it and retightening them.

to be honest it more than likely isn't the timing unless u went fiddling with the distributor. it wouldn't get thrown that far out in a day.

it sounds to me like an ignition problem but i could be wrong. i'd suggest open up the bonnet when its fairly dark and get someone to check for a spark jumping to earth as u rev it. if nothing shows up maybe check the points on the distributor cap and the rotor arm or maybe the plugs. sometimes you can get duds that fail very quickly and cause a misfire but it shouldn't be anything as bad as you've discribed.

best of luck with it anyway

[Escy]

It revs fine when the engine isn't under load so checking the plugs for a spark won't really prove anything.

I'm thinking because the drive belt shredded, if there is any sensors around that side of the engine maybe they've been damaged.

I don't think there are any engine sensors around there though.

I'll check my distributer cap when I get a chance.

[Escy]

Had a look at the distributer cap, 2 of the 4 contacts inside look well mashed. I hope this is the problem, will try and get it swapped.

It seem strange though, started it up, drove in down the road fine, no problems at all, then all of a sudden it threw a hissy fit and won't idle, won't rev at all and just cuts out. If I left it 10 mins it'd start up, run fine for a few yards and then conk out.

Does this sound like a distributer cap at fault? I'm thinking it may be running on 2. That wouldn't explain how sometimes it's fine though.

[K20VFX]

Had a look at the distributer cap, 2 of the 4 contacts inside look well mashed. I hope this is the problem, will try and get it swapped.

It seem strange though, started it up, drove in down the road fine, no problems at all, then all of a sudden it threw a hissy fit and won't idle, won't rev at all and just cuts out. If I left it 10 mins it'd start up, run fine for a few yards and then conk out.

Does this sound like a distributer cap at fault? I'm thinking it may be running on 2. That wouldn't explain how sometimes it's fine though.

Put some new plug leads on it, when on the boat on the way here they fill up with salt water this kills the leads. When running cold they are ok but as they warm up misfires, could be your problem.

[Escy]

Had a better look at it today, the rotor arm is cracked near the tip and also 2 contacts on the distributor cap are mashed. I think this will be my problem.

Went to a few motorfactors and couldn't get the old cap matched up. Went to Toyota and they want £73 for both parts! Bit pricey. Anyone know how I can go about getting one other than Toyota?

K20VFX, where do you live? I'll have to keep an eye out for your car. :)

[4ageae92]

strange how it works fine sometimes and then doesn't others. you'd think if the points on the distributor were worn or damaged it would just be the same all the time.

could be a fuel filter but i've been told (not sure how reliable this source is) that the fuel filters on these dont go. the fuel filter got clogged on my brothers car b4 and it drove ok but if you put the foot down it would accelerate away fine for about 5 or 10 second and then just loose all power for another few seconds and then pick up again and go again and so on. it used to be fine when the engine wasnt under load, like you say with your car, but if you came to a hill it was ten times worse. don't know if this sounds like the problem you're having but it might be worth trying to bypass the fuel filter and see what happens. if the car runs fine then you know you need to get a new filter. if not atleast its one more thing you can rule out

could possible be the fuel pump on the way out too but again if the fuel pump was gone you'd expect the car to just not start at all

[Escy]

I've bought a new fuel filter but not fitted it yet. :)

I'm pretty sure the rotor arm will be at fault, there is a fairly big crack in the end of it, I think the metal contact on it has worked out a bit and hacked the inside of the cap up.

Also, it's got alot worse and now doesn't seem to want to start or idle. It seems like it's once it gets warm it plays up.

[Escy]

New distributor cap and rotor arm have made no difference :(

[St3ve]

Another option would be to try another coil pack. If it's dyeing when you open the taps, it's either there isnt enough air/fuel getting in, a Throttle position sensor / MAF is playing up thus not allowing enough fuel in or the spark it too weak and being blown out. Also worth checking the gap's on your plugs and the condition of the HT leads as these could be earthing out if they are damaged.

HTH

[Escy]

I'd like to try some new leads on it, but it's getting to the point where i'm throwing too much cash at it. I bet the leads are expensive and hard to get. Does the 20v use the same as other 4age engines?

Anyone live locally with some I could try?

Also, does the ECU have a self checking feature? On my old 200SX is had 2 flashing lights that would let you know if you had a problem and what it was.

I bet the airflow meter isn't cheap, will a squirt of carb cleaner be okay on it or is the hot wire fragile on them? When I bought the car, it didn't have an air filter on it, so it may have got mucked up.

[levin20v]

did you ever find what the problem was. cheers

[Escy]

2 capacitors leaked in the ECU. Seems like it's common on the silvertop ECU's from what i've read. :(

[levin20v]

2 capacitors leaked in the ECU. Seems like it's common on the silvertop ECU's from what i've read. :(

its manily the blacktop that blows the vvt capacitor. no silvertops blow but 3/10 bt 1s go

[beanman]

ok here is how to fix, unplug Battery, put pin in diagnostic box, should see 5 blinking check engine lights followed by a pause then 2 blinking check engine lights. this mean your knock sensor is fkn and will put the car into limp mode. to reset this unplug the Battery and it should work again for a while. to permanently fix get a new knock sensor. GL lads 

[FROSTYBALLS]

16 minutes ago, beanman said:

ok here is how to fix, unplug battery, put pin in diagnostic box, should see 5 blinking check engine lights followed by a pause then 2 blinking check engine lights. this mean your knock sensor is fkn and will put the car into limp mode. to reset this unplug the battery and it should work again for a while. to permanently fix get a new knock sensor. GL lads 

The topic is 13.5 years old.