New, Seeking Some Advice

[ravecord]

Ahoy!

 

I purchased a nice AE92 corolla seca cs with a 4afc carby engine a few months ago.

It needed some work so i got it quite cheaply, but it was all fairly easily fixable things, mechically its excellent.

I put a new timing belt, brakes, wheel drums on the back wheels, muffler, tyres and replaced some seals/caps and oil filters n its lovely now.

It does have a few issues however, which i am trying to attend to, and i think the vast amount of knowledge of the people in this forum would be the best place to start. Ive gotten conflicting information from mechanics, the internet and my own knowledge.

Firstly, when i cold start the engine, it revs low and rattles.

If i give it a bit of gas it stops as the revs go up, but it still sounds a little bit clunky for a bit.

This lasts for probably 20-30 seconds.

I only started noticing this after the mechanic changed the oil/oil filter the first time, but this happened to coincide with winter starting (sydney australia, not too cold, would never get down to 0)

Ive sinced changed the oil myself, to castrol magnatech 15w40, and it hasnt really made a difference.

I figure this could be because oil isnt staying up in the head properly.. or because, being winter, the oil drains down after running hot, then becomes thick and can't get back up when i turn the engine on. I've also read that it could be the filter not holding oil up after the engine is off.

Next time i change the oil il try putting 20w50 in n see how that goes.

 

2nd issue: There is a metallic rattling sound as i accelerate past about 2k rpm. It doesnt always happen, usualy when I'm accelerating reasonably hard, but it is very noticable and quite disconcerting.

The mechanic said it was engine knock n to put some higher octane fuel in, which i did, and it hasnt solved it. I'm not sure if it could be engine knock tho, cos if i have it in gear and slow down, not giving it any gas, it still rattles as it goes down. I'm thinking something to do with the valvetrain?

 

Any advice would be greatly appreciated!

[strola]

Ahoy!

 

I purchased a nice AE92 corolla seca cs with a 4afc carby engine a few months ago.

It needed some work so i got it quite cheaply, but it was all fairly easily fixable things, mechically its excellent.

I put a new timing belt, brakes, wheel drums on the back wheels, muffler, tyres and replaced some seals/caps and oil filters n its lovely now.

It does have a few issues however, which i am trying to attend to, and i think the vast amount of knowledge of the people in this forum would be the best place to start. Ive gotten conflicting information from mechanics, the internet and my own knowledge.

Firstly, when i cold start the engine, it revs low and rattles.

If i give it a bit of gas it stops as the revs go up, but it still sounds a little bit clunky for a bit.

This lasts for probably 20-30 seconds.

I only started noticing this after the mechanic changed the oil/oil filter the first time, but this happened to coincide with winter starting (sydney australia, not too cold, would never get down to 0)

Ive sinced changed the oil myself, to castrol magnatech 15w40, and it hasnt really made a difference.

I figure this could be because oil isnt staying up in the head properly.. or because, being winter, the oil drains down after running hot, then becomes thick and can't get back up when i turn the engine on. I've also read that it could be the filter not holding oil up after the engine is off.

Next time i change the oil il try putting 20w50 in n see how that goes.

 

2nd issue: There is a metallic rattling sound as i accelerate past about 2k rpm. It doesnt always happen, usualy when I'm accelerating reasonably hard, but it is very noticable and quite disconcerting.

The mechanic said it was engine knock n to put some higher octane fuel in, which i did, and it hasnt solved it. I'm not sure if it could be engine knock tho, cos if i have it in gear and slow down, not giving it any gas, it still rattles as it goes down. I'm thinking something to do with the valvetrain?

 

Any advice would be greatly appreciated!

 

Too things seem a little out here.

 

1. being your fast idle

2. being timing.

 

the first one is that when on choke there is a secondary throttle screw which will increase the throttle and thus your idle (hence the name) this will be removed once the car is off choke and thus will return to normal idle.'

 

second is your knock issue. there are three different reasons which will induce the car to knock, 1. is timing (too much) 2. low octane 3. not enough fuel (lean) obviously it is not the second I suspect both lean and too much advance. I would start with the advance first then look at the fuel delivery if that does not help, when you do run the normal fuel you wish to run on. if that is normal unleaded then tune with that in the tank if it is high octane then make sure that is what you continue to use when you fill up.

 

Cheers

[AE92man]

i have the exact same car, only mines a CSX with a fair whack of mods.

 

Anyway.

 

no.1: what strola said. There should be an auto-choke that kicks in on cold start. When starting it up in Winter (Melbourne - sub 10 degrees) my car will always hit auto choke and rev to around 2-2500rpm. Mine does pretty much the same, start it up and it revs low/rattles/wants to cut-out. Give it a jab of the throttle and it'll warm up. I've noticed that by changing oil/oil filter it keeps the revs steady and prevents it dropping below 800rpm.

 

no.2 exhaust rattle? Maybe the rubber bushings in your exhaust mounts need a looking at.

 

good luck

[deri2k3]

Firstly, when i cold start the engine, it revs low and rattles.

If i give it a bit of gas it stops as the revs go up, but it still sounds a little bit clunky for a bit.

 

yup, my 1990 seca cs-x (no mods) also does this in the morning. but then i figured if i step on the gas pedal for 2-3 times before starting the engine, it would just starts first time with the rpm being in 1,5k-2k (auto choke maybe?)

[MYSTIK[RL]]

hmmm the rattle could quite possible be the lower heat shield on the manifold, which means you have to get under the car and remove the splash pan to have a look.