4AGE Running Rich??

[20vDan]

Hey there, recently i purchased a 92 Trueno with the 4age 20v engine.

Lately it has been idling quite high, from 1.1-1.5RPM and blows small amounts of black smoke when under heavy acceleration. Also i don't know whether this is normal or related or not but when i turn the car off it shudders as if it had just stalled.

I thought it might be running rich and thoguht the easiest thing to replace (if it was even the problem) would be the air filter so i bought a simota pod filter just waiting for it to arrive.

A mate of mine reckons it just needs to be tuned but im not sure.

So my question is can any one help me: 1) Is that idling too high or normal for this type of engine?
2)Is any of this normal has anyone else had problems with this sort of stuff?

3)Does anyone know what the problem could be / whether i was right in my assumption of the air filter?

Thanks heaps in advance, cheers.

[slighty_sykotic]

Bad injectors. The prefacelift injectors suck...

If that is the problem you will need to find facelift(~93-94) or blacktop injectors.

Black smoke can be injectors.

Idle is defintly high, I'd have a look for vaccum leaks (spray a can of ether around the vaccum pipes and lsiten for teh rpm to increase)

Check timing is ok. And replace fuel filter. Check codes from ECU.

[20vDan]

Any way i can check if its the injectors?
Is a vacuum leak the only cause of a high idle, also it idles kind of rough.

[Str8gangsta]

I agree with slighty_sykotic injectors and possible vaccum leak

It wouldn't hurt to replace the spark plugs if its idling a little rough.
I had a similar problem with my old 16v 4age a new set a plugs made it run sweet

[pc]

Maybe vacuum leak, TPS setting incorrect, O2 sensor not working.
also check spark plugs, leads, coil, dizzy etc.

I would be almost certain that it is nothing to do with the air filter.

[AceSniper]

does your engine temp sit at halfway?

[20vDan]

Engine temp sits about 1/4-1/3 ish. I thought poor air filter could cause it to run rich. Sorry im not that great mechanically haha. Thanks to everyone for your input might change plugs and injectors and see how that goes

[sergei]

Engine temp sits about 1/4-1/3 ish. I thought poor air filter could cause it to run rich. Sorry im not that great mechanically haha. Thanks to everyone for your input might change plugs and injectors and see how that goes :S.

Well if the temp is on 1/4-1/3 and takes ages to warm up (longer than 5min), and gets colder on motorway, your thermostat is jammed, which will cause it running rich. Replace your thermostat and enjoy better performance and fuel economy .

[20vDan]

So many possibilities haha.

[sergei]

Right, first fix the obvious problem (thermostat), then get some black-top injectors off Warwick (Mr Revhead), prefacelift silvertop are chronic with injectors, I have replaced them on so many (lost the count) including my own one to fix poor performance/black smoke. The thermostat will worsen the problem. By sounds of it you have both (injectors and thermostat problem).

[AceSniper]

sounds like your thermostat would be a good place to start... an pritty cheap

Im yet to pull a thermo housing off a 20v that has had its thermostat replaced

[20vDan]

Cheers sergei that sounds like a good idea, any idea of how much blacktop injectors are? Do i just email Mr_Revhead like it says in his thread?

[sergei]

yeah just e-mail him, he will not bite (although if you resemble a goat he might will... ), and they are around $150.
The reason why I told you to get black-top ones, as the wreckers have no idea if the engine is face lift silvertop, and might sell you prefacelift ones as facelift (happened to my friend).

[20vDan]

lright, cheers for the help! Hopefully will look into some injectors next week some time. Thanks again!