Hi Folks,
I have a problem with my na fc.
Its basically stock with an aftermarket "sparkdog" ecu and bigger exhaust.

It used to run fine.

about a week ago I degreased the engine bay using degreaser and my karcha pressure cleaner.
As a precaution the battery was not connected when I did this or for the following week.
I let it sit for a week to allow everything to dry (connectors etc) its been fairly warm here so I figured that was long enough.

I then connected the battery and tried to start it but when it does start it only runs for about 3 seconds then dies.

It does the usual 3000 rpm cold start ( I think thats what its called) and then it just dies.
It doesnt matter if you try to keep the revs up with the throttle it just dies after about 3 seconds, when the cold start disengages.

I have gone through and checked every connector I can find, I unplugged them and they were all dry but to make sure I sprayed contact cleaner in them and then some crc (kind of like wd40,displaces moisture) let it sit for a day and tried again today, still the same.

It had half a tank of fuel in it but to make sure I put another 16 litres in it and still the same problem.

The only thing I cant reach are the primary injectors to check if they came loose or something as they are buried under the top half of the inlet manifold.

I have checked every vacuum hose and connector I can see, I also checked the ignition leads, i even took the top plate off the distributor/crank angle sensor and sprayed some contact cleaner in there, it was all dry.

I even took off the tps and connected the multimeter,fully closed it reads about 0.5 and open about 5.4k ohms.

Im lost and could use some help trying to diagnose the problem.

Any help would be greatly appreciated,
Thanks.

 

The two things I have seen that cause that symptom:
*BIG vacuum leak [like the hose to the BAC, where it connects to the intake flex tubing]
*No connection to the AFM

It is not your primary injectors [AFAIK those are the only ones used for startup].

 

Thanks for the reply Derekcat,
my car doesnt have a afm, it has an old sparkdog ecu in it and thats connected to a t piece thats connected to the top of the fuel pressure regulator by a small vacuum tube that I think tells the ecu the manifold vacuum etc.
I guess that the ecu probably runs off the tps and the other sensors that its connected to in the harness, fuel injected cars are not my strong point so I am not really sure how the whole thing works, I left the mechanic trade when fuel injected cars became popular.

regarding the BAC, its still connected to the flexible intake tube but the car doesnt have an afm, it just had a k&n pod filter on the end of the flexible intake tube.
I took the pod filter off a while ago and it didnt affect the cars ability to run,idle etc.
all I did was clean the engine and now it has this problem.
I just checked the BAC resistance with a multimeter and its within range to the fsm,11.6 ohms.
Just to check, I blocked the big hose that comes off the BAC to the intake tube and no difference, still does the same thing.
I just checked the whole engine that I can see and I cant see any hoses or connectors that have come loose or split.

 

Try getting a hold of BumpStart (pm him) He is in Oz and knows his cars.

 

Thanks misterstyx69,
I will pm him and see what he thinks.

 

You dislodged the grease that was holding it together all these years!

I'd check the throttle linkage and thermowax. They could have been shifted or something while you were cleaning it; it seems to me that when the cold start drops then there is too much slack or so in the cable and that slams the throttle body shut? Just a guess. I've never heard of a sparkdog ECU before, otherwise I would have suggested the AFM as well.

 

texFCturboII
I think you are right about the grease

the problem is that it does it even when I try and keep the throttle open at the pedal., its like something is just shutting down either the spark or fuel, it just dies no matter if you hold the throttle open or not.
the throttle seems to be working fine.

I can smell a little fuel when the engine stops like usual, I dont know, Im lost.

I will do a search on the thermowax.

sparkdog ecu's are an old australian ecu, I did contact the guy that made them but he doesnt have any software etc for them anymore, but it ran fine before this.

just a questions for the folks out there, does the engine run on the primary injectors during the cold start ?

because thats the only thing I cant get to as they are buried under the manifold, everything else seems to be where it should be.

I have double and triple checked the entire engine bay that I have access to and cant see anything that has come off or has water in it, the only thing I can think of is that there is something around the primary injectors that has come off and Im not taking off the entire top half of the manifold to check as Im not sure I would remember where to put everything back.

If anyone can confirm for me that the problem is under there than I guess I would have to try but If there isnt anything wrong after I pull off all that crap I wont be too happy, especially if its something simple I am missing thats easily accessible.

I am hoping there are some rotary guru's out there that can diagnose the problem,
any help would be greatly appreciated,
Thanks.

 

The engine doesn't use the secondary for starting or idling or driving below 3800 rpm.

 

puddle could have formed and not dried. when you went to start it could have shorted out the ECU's injector drivers. open it up and take a look.

 

Thanks Walken, I'll have a look.

 

Hi Folks,
I just tried checking if the coil packs are getting voltage,they sit at around 12.4v with the ignition on, while cranking they drop down to about 8v then when the engine fires it comes back up to around 12.4v.
I then kept an eye on the meter while the engine dies and there is no change so at least the coils are getting power, no problem there.
I did this with all the coils.
"edit" I just tried with the timing light and its getting spark during cranking, for the few seconds it runs the light lights up like normal and as the engine dies and is still spinning it has spark, so it looks like a fuel problem.
what do you guys think ?
what do you think I should do to check the fuel delivery ?
Thanks.

 

You can always spray a second of starter fluid into the intake duct and see if it fires up for a few moments.

 

satch, it does start and run for a few seconds then dies.

 

S4 or S5? And have you tried jumpering the Fuel Check Connector?

 

12/85 s4, and no I havent tried that.

I looked in the fsm and the pic isnt very helpful.
after doing some searching on here I think I know which plug but just want to make sure.
is it that black plug with the 2 female terminals with one black and one brown wire that comes out of the harness that is connected to the harness that leads to the afm ?

I will post some pics in a few minutes, have to get on the other pc.
if so, what happens, does this switch the fuel pump on ?
what im asking is what is the purpose of jumping that connector ?
Thanks.

 

here are those pics of the plug I think is the fuel check connector, is this it ?

any help would be great.
Thanks.

 

It bypasses a switch inside the AFM to turn the fuel on in case the AFM is problematic. And yes you have the right plug.

 

that was my first thought.


have you the stock parts around to replace to start trouble shooting the ecu and other sensors?

 

sounds like a fuel pump voltage issue.

check the fuel pump voltage at the connector mounted to the LR strut tower underneath the plastic backed carpet cover. the wire you need to backprobe is the black/white wire between the strut tower connector and the tank.

bet it drops to zero after the prime cycle is done.

beyond that i have no clue how your ECU controls the pump. it may have 2 different circuits, one for priming function and one for running function. you will need to give specifics on how the pump is wired and works from the ECU.

 

I do have a standard ecu and a afm but I dont know how they wired in the aftermarket ecu, if they cut wires etc.

to satch and RotaryEvolution,

I did the jumper and it does start now and run but it idles at around 2,500 rpm and runs pretty rich, there is black smoke out the exhaust when giving it a bit of throttle.

I have to manually push the throttle linkages back and it settles at around 1200 rpm.

I back probed that black and white wire with no fuel check jumper and there is no voltage and when the ignition is turned on it blips up to 0.02 volts for half a second then goes back to zero.

I did the same with the fuel check connector jumped and with no ignition its zero but when ignition is on it sits at around 11-12 volts.

so what do you think is causing the problem now that I have done the fuel check jumper and it runs ?

regarding how the fuel pump is wired to the ecu, I dont have a schematic or wiring diagram for the ecu but I will look around and see if I can trace the wires back from that connector where the black/white wire connect (it connects to a blue wire in the 4 pin plug that goes to the harness) and continue back to the ecu.

also, when I switched the engine off after about 2 minutes of running I noticed some smoke coming up from under the front of the manifold where the front rotor housing is, so I looked around and noticed that the oil injector housing on the front rotor housing has no hose connected to it, I have attached some pics.

there is also some engine oil pooled on top of the rotor housing.
after looking at the fsm it looks like the hose connecting the nozzle to the manifold oil nozzle must have come off.

so looks like I will have to take the top half of the manifold off to fix it.

I will try and take off the thermostat housing and the alternator to see if I can get in there that way but if that doesnt work I will have to take off the manifold.

but regarding the fuel issue, what do you guys think is causing the problem ?
if it was up to me I would just leave the jumper in but I noticed a hissing sort of sound coming from the primary injector area so I dont know if thats normal but I dont remember that before when the car was running fine.

I sniffed around the area to see if I could smell fuel but didnt smell anything.

any help would be great,
Thanks.

 

The jumper helps alleviate a problem w/the AFM so you might want to focus on that item.

 

im convinced its the airflow meter. take it out, and let it sit in the sun upside down to try it out.



ps, never pressure wash anything in the engine bay. always use a light spray.

 

He doesn't have an AFM. I'd ditch that Sparkdog and find a stock ECU.

 

I guess the 'dog' ate it.

 

If you don't have an AFM then your ECU must send a ground to the Circuit Opening Relay, which governs the voltage to the fuel pump. The relay is Yellow and Black and it's located under the dash just to the right of the steering column. Bottome row has two wires w/the righ most wire being Brown. W/the engine running this wire needs to have a ground signal. W/the engine off, but key to on this wire would have battery voltage to it. So chances are the device which supplies the proper ground to this Brown wire w/the engine running is faulty. Jumpering the Fuel Check Connector places a ground on this Brown wire.