Another wave of running problems

[sirRhodes]

You're probably sick of me constantly posting problems on here but it needs to be done

Basically my engine is running much better than it was but is still not right.
The idle isn't THAT bad now its at around 8 or 900 rpm (still rather low but getting better) the problems are inconsistent so probably electrical? yesterday I started it and it was completely normal, it revved up to about 6 or 7000 rpm (it did backfire when I let off the throttle after revving, is that normal?) but today it only revved up to about 3000 rpm.
When it is idling it still struggles to rev up and if it has been left for a while idling it just will not rev from that.
It doesn't like to hold revs either if that makes sense, if I try and hold higher revs it makes an awful screaming noise and slowly dies.
also there is a slight whining/whistling, it is only really obvious when the engine is slightly revving and just above the engine/around the inlet manifold.

[parker455]

Alternator belt slipping/worn? Sounds like it to me


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[chefey]

+ 1 with alternator belt, whistling noise sounds like an air leak, which could explain bad running.

[Protok]

BTW 800-900rpm is about right for a 3S engine.

[jimi]

BTW 800-900rpm is about right for a 3S engine.

But is it for a 4A-GE ?





As it happens it is ............. but pay attention ! this is the MR2OC not the MK2OC

[Protok]

BTW 800-900rpm is about right for a 3S engine.

But is it for a 4A-GE ?





As it happens it is ............. but pay attention ! this is the MR2OC not the MK2OC

I believe it is the same for the 4AGE.

I cannot see which forum on my phone.

[adamstanford]

My 4age idles at about 1100rpm usually, 800rpm after being driven a looong distance, like over 150miles.

[jimi]

My 4age idles at about 1100rpm usually, 800rpm after being driven a looong distance, like over 150miles.

Sounds like your AAV is sticking open slightly and only closing after a sustained period of running at temperature hence the idle dropping to 800. MR T's 4A-GE engine manual and MK1 BGB say the standard idle is 800rpm.

[sirRhodes]

The alternator is new and the belt is new, it could be that I haven't properly tensioned it.

I'm going to be removing all the intake manifold throttle body etc, replacing the gaskets and possibly cleaning inside them, on that note is carb cleaner alright just to spray in all of the throttle body and manifold just in case there is some clogging?
Also maybe spraying that in the injectors in case they are clogged, will that do any good or is there a better way to clean the injectors?

[adamstanford]

Im going to have mine terracleaned next month i think. Seems to make sense for such an old engine etc. Apparantly ill feel no end of benefits (but that was the bloke trying to sell me the product to be fair) however it seems decent, its only £100 and it does the injectors.

I wouldnt just simply spray carb cleaner in the inlet if you intend to remove it all anyway to replace gaskets and all that jazz just clean it all up good when you have the parts off the car.

[sirRhodes]

Well I'm thinking of using the carb cleaner when it is off, I'm just thinking it could be possible that some smaller parts are clogged, also I've got air flow sensor cleaner so I'll be cleaning that too.

[adamstanford]

Ah yeah. A soaking and a good scrubbing should bring them up nicely.

[jimi]

Well I'm thinking of using the carb cleaner when it is off, I'm just thinking it could be possible that some smaller parts are clogged, also I've got air flow sensor cleaner so I'll be cleaning that too.

There aren't any small parts to clog up other than a couple of small airways that bypass the throttle butterfly (for the idle up) Be very careful you don't damage the TPS (Throttle Position Sensor ) or change the position of it, if you do then you will have to set it up again.
Air flow sensor cleaner won't do you any good ... you don't have one UK MK1's use a MAP sensor instead (which measures vacuum not airflow)

[sirRhodes]

oops, there is something on one of the intake pipes that looked like an air flow sensor, underneath that big black box (don't know what that is either).

Well I've just started it up again and once it had been running a while I noticed small a metallic knocking/clicking whilst running, could that be timing?
Also the same problem where if it is left idling for a while it will not rev up easily and I just can't figure out why