Engine Cutout Problem - HELP!

[RIOT1]

Before anyone says anything.. i have searched and found nothing identicle.

Car: 1989 R32 GTST

Problem: After an hour or so of driving, engine will tend to CUT OUT briefly for a split second. It doesnt even attempt to fire. Can be driving in gear and nothing.. just dies. Ignition remains on and you can stab the throttle on and off and wont do shit till it decides to start firing and go back to normal engine cycle.

Happens at almost any rev range in any gear with any boost pressure.

Tried solving it by.... :

- Checked fuel pump - OK

- replaced fuel filter

- replaced air filter

- replaced air flow sensor

- replaced spark plugs

- replaced coil packs

- replaced crank angle sensor.

- Checked lines for vaccume leaks (checked BOV too, slightest leak when vented to atmo)

The only things left i can think of is injection and ECU..

but the question is WHY only after an hour or so of driving.. it runs like a dream for the first part.. doesnt miss a beat.

I'm lost

Any suggestions would be great

cheers

[Sumo]

Hrmm, thats quite a list you have there.... You dont have an immobiliser at all? I have seen a 97 mitsubishi pajero not fire due to a faulty immobiliser.

Other then that, maybe its worth sending it to a specialist mob that repair ECU's or just buy a second hand one from a wrecker and try to plug it in when your other one refuses to fire. If your game you could check for dry solder joints, and resolder on the PCB.

Your charging system is fine is it? Maybe its not regulating and overcharging? Im not sure how advanced the computers are but they would have some method of spike protection.

Its really hard to say without seeing the rig

Cheers

Sumo

[strutto]

Have you tried the ignitor / PTU up the back of the cam cover?

[RIOT1]

  Quote

Have you tried the ignitor / PTU up the back of the cam cover?

Yes replaced this and all the leads going to and from it..

dry solder joints is a good suggestion. could explain somewhat why it ****s up after running for a while.. when it heats up could oxydize some more.. or something? :|

[Sumo]

well mate, im no expert

but a dry solder joint will work until the conection heats up, heat = resistance, and once the resistance is substantial enough it looses the signal?

Its just something else to try

Cheers

Sumo

[RIOT1]

yeh i think thats a no go-er... replaced the entire ECU and still same problem.

spoke to the old man nad he said there should be an Injector temperature sensor. Which is either ****ed or activating too early shutting fuel off.. which makes sense coz thats the exact feeling i get... lack of fuel and no combustion

its next on the list.

after that i think ill cut the car in half and import another ;0

[Sumo]

yeah, electrical problems suck

next on the list check the resistance of each sensor and make sure they are within spec....

get a pin out map of the ECU and start checking signals - this is very time consuming I know but you'll have to find it one day

[Sumo]

another sensor would be an oil pressure switch..... You will have a sensor to power your gauge, but their should be an on/off switch for the ECU and light on the dash.

Im only generalising as I dont work on skylines that often and do not know them inside and out.

Cheers

Sumo

[=premo=]

ive only just imported my r32 four door gts-t 89. i seem to be having a very simular problem. i havnt got it registerd yet so i havnt be able to play with it much but some drives it will be fine then others it has the same problem, doesnt seem to be a length of time and has happend mostly when axcelerating hard.

it just dies and doesnt come back for 5-10 seconds no matter what i do which is a pain when ur in the middle of overtaking. i have also found that when coming to a stop the revs fall below 500rpm then slowly come back. so if you do find the cause of your problem would you be able to pm me so i can try it with mine.

cheers

[B0oStEr]

I have an '89 4door that I bought in December that seems to have a similar problem.

It runs fine, then suddenly cuts out.

Length of running time doesn't seem to make a difference. It was doing it at idle or on the overrun but now it's missing and then cutting out as it starts to comes on boost but runs perfectly 99% of the time.

[TRY032]

I had the exact same problem.......

i had to replace the battery, tighten battery terminals, and tighten the earthing strap!!

it toook me almost a month to work it out and several auto elects!!!

[Sumo]

Seems funny, your battery is generally most stressed when cranking and if their is a crook connection she will be real doughy to start.

Sumo

[B0oStEr]

There are a couple of smaller wires running off the positive terminal that feed ignition etc.

If these were dodgy but the main terminal was ok it could still start.

[The Dan]

Primo and Booster....it sounds like you both have a problem with your fuel pump.

This does not always mean the pump itself is at fault either.

The earth wire goes through an earth switch to lower pump noise at idle. Try checking all earth points...the main ones anyway. Battery and so forth. Check earth to fuel pump and check pump relay also.

You all need to hook up an oscilliscope to your car while driving with it connected to your ignition, AFM and fuel pump. When it happens you'll know where to start looking.

[=premo=]

finaly sounds like sumone knows what going on. thank you, but ummm whats a oscilliscope? i take it its some type of multi meter device??

im going to spend a good day on it 2morrow (changing all mods back to standard to get it complied), any left over time befor work will go into fixing this problem, ill let you know how i go.

thanks again

[The Dan]

An oscilliscope is like a multimeter but it measures in waveform so you can see injector pulse, voltage rise and fall and most other things which will determine where the problem is located.

All you gotta do is set it up on different sensors or devices and drive while someone watches the scope. When your engine cuts out you'll see what device stopped working first or which sensor gave a faulty waveform or voltage.

To buy they are a few hundred dollars (for a good one anyway)

We have a ScanPro at work worth $15,000 and it can do almost everything for diagnosis of these problems. The only thig you need is patience. It would be hard to get your hands on a decent one but you can still achieve the same sort of results with a multimeter. You just have to make up some extra long cables for it and test every sensor one by one. The main ones you'll be checking will be ECU power and earth, Ignitor power, earth and signal, AFM voltage and fuel pump voltage.

With the AFM you can remove it, make up some wires to give 12v to pins 5 and 3 and test the voltage on pin 2 while blowing through the AFM with a hair dryer. This should give you a fair idea on the accuracy of the AFM.

[Sarkis]

My car was doing the exact same thing a few days ago.

I am running 12PSI on stock internals, I dropped the psi down to stock and it seemed fine.

I think it may have been overheating

[=premo=]

Hmmm boost could be the problem, im running 13psi (0.9bar on the HKS gauge). However the only mods i can see on my car are the exhaust and pod filter, no boost controller or anything similar. so how the **** do i get it back down, keeping in mind this car (import) is yet to go for the roadworthy test to get it registered.

Is it possible to be running 13psi with only a N1 cat back (3inch) and pod filter????

cheers