4age misfire idle issue running rich

[ae92dude]

i have searched for days but not found anything that has helped me.

i have an ae92 gti that chucked a rod through the block at christmas. i have fitted a new engine recently. it took me ages to find a decent engine. i have got this really annoying misfire problem it sounds like a subaru impreza with a straight through exhaust lol.

i have checked everything in other threads i.e. leads, dizzy cap, dizzy, timing, tps, coolant temp sensor, plugs, air filter ect ect.

basically from when i start the engine i get a cold idle of 1500rpm and when it warms up it gradually drops to 500rpm and after about 20mins of being warm it will stall i will restart it and it will stall again. it just will not idle when warm. i have tried adjusting the idle screw however this will bring the revs up to 900rpm but the misfire stays there and this is the most i can adjust the idle screw.

so a fully open idle screw this certainly isn't normal. neither is the misfire normal.

the misfire will remain through the rev range with gradually pressing the accelerator (if i hold it at 3000rpm it will misfire constantly) however if i stamp the throttle the misfire goes but instead i get a huge cloud of black smoke coming from the exhaust.

its also using a lot of fuel i cant say how much more exactly but i know its using a lot more than normal.

im just out of ideas and i would really like to get this running right as i need the car next month for a car show.

[Hiro]

Believe it or not ~2000rpm cold/900rpm hot are the proper idle settings for a 4AGE.

[jondee86]

i have fitted a new engine recently. it took me ages to find a decent engine.

What engine was in the car... TVIS or non-TVIS ?? And was the replacement engine exactly the same as the one you had before ?? Were the injectors the same colour ?? Have to tried bringing the idle up by advancing the distributor ??

Cheers... jondee86

[ae92dude]

it was tvis in it previously i think mine was a red/silvertop second gen tvis. the one ive put in now has tvis and its blue top head and 7 rib block. its ment to have 4agze internals crank rods pistons. not sure how true this is tho.

the injectors was orange in this set up but they wouldn't fit my wiring loom so i used my old pink injectors. yeah ive tried full advanced to full retard and nothing changes much i dont get any rise in idle. if i retard it doesn't do anything.

hiro i know but its definately not running right its really rich but idling like a pile of crap. its getting worse if i hold it at 2k it sounds like rough v8. and if i slowly increase the revs it will sound like this up to 6k but if i quickly stamp the accelerator it won't miss i just get a puff of black smoke out of the back. i tried advancing one tooth on the dizzy and retarding one tooth but if i do either it wont start up.

[wiso]

advancing or retarding the dizzy should make a very noticeable difference to the idle. Once I had a 4agze that had a dizzy that did nothing when you adjusted it, turned out the base timing set on the belt was a tooth out. and I think dizzy was also out a tooth. so somehow it ran fine. but could not adjust the timing to spec after shorting the T1 and E1 connector.

if it does have 4agze pistons if they are first gen that will be heaps lower compression than the 4age ecu is used to, it won't feel like a revving powerhouse like a normal 4age. will feel a bit sluggish up higher when revving.

is your car using an air flow meter or map sensor? so I guess your using all your previous ecu and electrics? did the engine have any running issues before you changed it on the old motor?

the only times I have ever had issues with a 4age running like ass its always been either, vac leak, o2 sensor, bad ignition components, fuel system issues, timing. I have never even had any air flow sensor issues, ever.

[ae92dude]

advancing or retarding the dizzy should make a very noticeable difference to the idle. Once I had a 4agze that had a dizzy that did nothing when you adjusted it, turned out the base timing set on the belt was a tooth out. and I think dizzy was also out a tooth. so somehow it ran fine. but could not adjust the timing to spec after shorting the T1 and E1 connector.

if it does have 4agze pistons if they are first gen that will be heaps lower compression than the 4age ecu is used to, it won't feel like a revving powerhouse like a normal 4age. will feel a bit sluggish up higher when revving.

is your car using an air flow meter or map sensor? so I guess your using all your previous ecu and electrics? did the engine have any running issues before you changed it on the old motor?

the only times I have ever had issues with a 4age running like ass its always been either, vac leak, o2 sensor, bad ignition components, fuel system issues, timing. I have never even had any air flow sensor issues, ever.

i was thinking its maybe a tooth out on cam timing as well but all the marks line up. should i drop a rod down cylinder 1 and see if is true tdc?

it does have a map sensor that i managed to snap the plastic vacuum nipple but i glued it back on and sealed it maybe some glue got inside? i did check inside to see if any glue got in and i couldn't see any but maybe its seeped through?

i don't have an o2 sensor on mine as my car never had one from the factory.

i did have a problem similiar on the previous engine but it was no where near as bad and it seemed to go away after a while of driving. so do you think maybe its this problem come back i.e. ignition compents damp or worn? (ignitor or worn out dizzy)? fuel filter blocked? (but i thought a blocked filter would make it run lean not rich?)

i will describe it a bit better. basically when i hold a steady cruising speed i.e. 30mph in 5th gear at very slight throttle the car will start chugging and shakes me backwards and forwards in my seat until i either give more throttle or push the clutch in. if i set off at low revs in first it will violenty jump around until i floor it. it just doesnt like slight throttle inputs its either go flat out or be shuck to death lol.

like i say it did do this before with the old engine but not quite as bad and the problem went away on its own. it would sometimes come and go but i could live with that but i cant live with it now as its running so rich i cant breath properly when im near it and its using so much fuel i cant afford to keep up with it.

as for the sluggish thing its not that sluggish it just doesn't like low inputs. when i put my foot down it pulls like a train. but still runs rich. it doesn't misfire when i floor it.

[wiso]

well something from your previous electrics is on the way out and is radically affecting you new engine.

You said you reused injectors, when were they last cleaned properly taken out and cleaned? if a long time these could possibly be blocked up cause the fuel to drizzle rather than spray. sometimes the engine can run shit from this with the engine running lean then rich as the fuel runs into it.

Is your fuel pressure reg fine? have you had a fuel pressure test?

if there is no o2 sensor then there is not many sensors left to check to eliminate the running of the engine. Fuel pressure VSV, TPS, Map sensor, ignitor. have you checked the pin values of all these against that in the BGB? make sure they are all within spec?

otherwise, your have an AE92 gti do you? do you have the right ecu to go with the 4age? I thought AE92's nomally had smallports, but you have a t-vis bigport. your not using a smallport ecu and electrics on a bigport are you by chance? Bigport 7rib injectors are normally beige and 3 rib were a differant colour I thought. I am honestly not sure whate 4age came with pink injectors normally.

[ae92dude]

injectors are clean double checked. fuel pressure reg seems to be ok. i have deleted the fuel pressure regulator vsv valve and ran vacuum for the fpr straight to the 3 way vacuum connector on the inlet manifold. tps is spot on, map sensor electric wise is fine but im not sure if glue has got inside it as glue was clear as hell and the hole is kind of hard to look in lol. i know the map sensor is working at hard throttle cause i accidently ran it with the wire off on the first test and the car wouldn't rev i hooked it up and then it was fine. but if the glue got inside would this cause an issue at slight throttle?

im yet to check ignitor pin values and also dizzy values. dizzy looks ok inside the cap side there is a slight bit of oil in the actual dizzy but its only slight. are any of the other parts of the dizzy affected by oil other than the cap side?

yeah its an ae92 gti. its the right ecu. over here the gti's came with bigport and smallport mine was a bigport 7 rib with red writing on silver cam covers. the one i have now is a blue top head with 7 rib block supposingly running 4agze internals. there is no proof of this and im not pulling the head to find out lol. the engine came complete bar the dizzy. i just pulled everything off it and chucked my ancillaries on it.

i should add my car was sat for 3-4 months outside im wondering if damp or cold has killed something? i put fresh petrol in even tho the tank was empty

[allencr]

basically when i hold a steady cruising speed i.e. 30mph in 5th gear at very slight throttle the car will start chugging and shakes me backwards and forwards in my seat until i either give more throttle or push the clutch in.

30 in 5th is a driver education problem, not an engine problem.

[ae92dude]

30 in 5th is a driver education problem, not an engine problem.

why's that? i like to save fuel sometimes. i dont see the point in wasting fuel if there is nothing on the road worth racing. fuel costs £1.35 per litre over here so for £20 it barely takes my fuel gauge above quarter from empty. and its 30mph speed limits round here with a few speed camera's.

[dnegative]

Lugging the shit out of the engine won't save you fuel and is bad for your bottom end

[maj]

why's that? i like to save fuel sometimes. i dont see the point in wasting fuel if there is nothing on the road worth racing. fuel costs £1.35 per litre over here so for £20 it barely takes my fuel gauge above quarter from empty. and its 30mph speed limits round here with a few speed camera's.

WTF. You drive it at full throttle in an incredibly underdriven gear because you think it saves fuel?

It does not matter what RPM your engine is running; modern engines can run at moderate RPM and use 3/5th's of SFA fuel.

Every time you touch the throttle, think of it as using fuel. You press your foot down, throttle body opens up and lets more air in, the air requires a level of fuel to mix in, so your injectors compensate. The longer this happens the more fuel you are burning.

Some cars are torquey little things and don't mind being driven around in their torque band at low RPM, the 4AG is not one of these engines though. They love to rev and should be allowed to, also the overrun sounds sweet and guess what? Overrun barely uses any fuel in factory trim.
I'd imagine at 30mph for "cruising", you'd have it in 4th and sitting around 2,500rpm

[jondee86]

Sounds like you could have a couple of problems. You need to check that the water temp sensor (for the ECU) at the back of the head (?) is connected and working. If you have an open circuit in the wiring or in the sensor itself, the ECU will think the engine is cold all the time, and run rich. Typically, the engine will run like crap at low rpm, but work OK at wide open throttle.

Yes, you need to verify that zero deg on the timing marks, really is TDC. Then double check that the cam timing is correct, and then check the ignition timing = 10 BTDC with the diagnostic plug jumped, otherwise 15-17 BTDC. Idle speed should be 850-900 rpm when checking the timing.

Cheers... jondee86

[ae92dude]

checked water temp sensor its fine within specs. i stripped the dizzy out today and cleaned it put it back together and still the same. so i left it ticking over to warm up and i noticed something i didn't notice earlier there is a loud ticking/clicking sound coming from the injectors. if my hearing is correct its the 2 injectors closest to the gearbox side of the engine. its ticking that loud i can hear it over the engine idling. its like a fast ticking and it definately sounds electric related.

[wiso]

Well if it is something electrical the only thing left to assume is the ECU is shagged. according to your posts you have already checked every other electrical component that runs your engine. You have checked all the mechanical settings on your engine. 9 times out of 10 the 4age will run rough for the reasons here people have mentioned. but since your 100% sure you have eliminated it.

The ECU controls the injectors, so if your injectors are acting weird....

Maybe open the ECU casing make sure nothing is burnt out or has leaked its guts on the board