4age Smallport Low Topend power.

[ca5pa]

Im running an ae82 Twincam with a 4age smallport. I have done services and stuf on it regularly since i bought it and not thrashed it.

All of a sudden I have power down low but as im reaching say 4500 rpm through to 5500-6000 the car just has no go. So low down im all good, though 4ages being a revy engine. I noticed power loss at the top end.

I believe i have a fuel delivery issue i think in the throttle body. Though the car is not hunting for rev at idle and doesn't miss at all. No smoke even when I give a go. In my mind its not gettng enough fuel at top end. BUt Im wondering if anyone here has had this issue before.

I've checked the electrics for starters, air intake, the idle and the butterfly are fine. THough it tends to idle a bit high at about 1200rpm. I know it not ment to be that high but it seems to run better. Possibly fuel/air mixture?

Cheers for input.

[oldeskewltoy]

Hmmmm, sure it is a smallport? AE82 came with largeport and TVIS... TVIS could be none functioning....

[Hiro]

Hmmmm, sure it is a smallport? AE82 came with largeport and TVIS... TVIS could be none functioning....

That's what I'm thinking, TVIS is supposed to open at 4400rpm, if it doesn't then the engine is going to be extremely strangled up high.

[The Last Streetfighter]

all 4ages have a dip in power at that RPM. It is the switching point for VVT on a silvertop even. But if you have noticed a change over time, then I guess you could say that something is wrong.

[Hiro]

all 4ages have a dip in power at that RPM. It is the switching point for VVT on a silvertop even. But if you have noticed a change over time, then I guess you could say that something is wrong.

A dip at a particular rpm is different to a loss of power over a large rpm range.

[ca5pa]

Im positive it's a smallport 100kw. Not original motor. Yer it's over a large rpm range. Mid range is good but lack topend power. Im still guessing fuel delivery.

[Hiro]

I'd be checking fuel filter first then, if you think it's a fuel issue.

[benjamin]

Is there a vacuum hose that goes from the FPR to the inlet manifold? If it has come off it MAY be causing issues with fuel delivery at top end. And if the hose has come off it will be taking in more air which would also be causing the higher than normal idle.

Maybe your fuel pump is failing... or fuel filter

[ca5pa]

Thanks for your input guys. I checked the filter and it seems ok but i probably will replace. They are cheap enough to just replace and eliminate. I'll check that vacum hose to the intake. I think you might be on too something there.

I'll check all that stuff out and keep you posted. Cheers

[The Real Roadrunner]

Is the exhaust loudish or quiet? if its quiet chances are the cat or muffler have colapsed, my rolla had the same symptoms and when i changed the muffler it went from 52rwkw all the way up to 84rwkw (but now the sound drives me nuts).

Cheers
Linden

[Hen]

I seem to remember seeing a smallport dyno graph (Maybe Witzls old beater??) with a big dip in the middle due to a dodgy knock sensor. The ECU was "detecting" knock and pulling timing out.

Another possibility. Also check for error codes from the ECU, they can give you an idea where to start.

Hen

[ca5pa]

I found a small exhaust leak between the manifold and the head. Im gonna fix it up tomorrow morning with new gasket etc. But do you think that could be causing my issues.

The leaks not bad and there is no carbon build up around the area. Though its could be a loss of back pressure maybe? not sure. I connect the afm back through to the air intake. Didn't solve it though it does idle better now. Im also gonna check the noc sensor and see if thts running alright.

Cheers

[Cameron_Datto]

Check the Cam Timming , also check that the TDC Reference mark on the Balancer is Correct

[Twinky16v]

the leak will take a bit of power best to start with that.

also check your timing? make sure your dizzy is not bolted loosely as i have seen acouple that havent been tightened lol but usually when the timing is played with you will notice a change in idle revs

bridge the terminals and check what faults come up?


does your intake manifold have TVIS writen on it? show us a photo?

[Hiro]

I found a small exhaust leak between the manifold and the head. Im gonna fix it up tomorrow morning with new gasket etc. But do you think that could be causing my issues.

The leaks not bad and there is no carbon build up around the area. Though its could be a loss of back pressure maybe? not sure. I connect the afm back through to the air intake. Didn't solve it though it does idle better now. Im also gonna check the noc sensor and see if thts running alright.

Cheers

AFM? This engine just gets stranger and stranger, I've never seen an AFM smallport before....bigport yes (not ADM though, although can't remember what AW11s are), smallport no. Or maybe you were referring to the air-temp sensor, not the air-flow meter.

Photos of the engine could go a long way to clearing up the confusion here