Vs v8 fail to start

[scoop1]

For two years I have battled with failure-to-start when slightly warm to warm.

Now I have beaten it for $94.99 and I want to share this because i have not seen the full story on this site or others.

Ok. I could always get the car started from dead cold first pop.

But if I muffed that start, or switched off at the first milk bar (IE try to re-start 10 seconds later or 10 minutes later) I hadno hope! The engine would roll over but be dead. Absolutely dead. You would think the immobiliser had got it by the throat.

I have read so many posts and they suggest: fuel pump, fuel filter, fuel pressure, water temperature, Ignition Control Module (ICM), plug leads, distributor cap, hall sensor (which acts as the crankcase Angle sensor on V8 and is an absolute bastard to get at right at the back of the engine).

You have to pull the bonnet off, and people have put pillows on the manifold and knelt on them, or layed down on an old mattress!

What were Holden thinking when they designed this nightmare?

So I did nothing on distributor, or leads, it was just too horrific. Please god let there be something else wrong.

Just Commodores contributors, scores of contributors, gave advice and it helped so much, thank you all!

You can bet all that stuff you talked about will go wrong too, in time, because the old girl is 200,000km old, twice round the clock.

But I found the answer in the Holden VS S Service Manual Supplement 3, page 6C2-2C-15.

After a tow-home I had replaced the fuel pump and filter. (Website contributions were invaluable.) The filter was blocked (that probably burned out the pump). When it was running again it accelerated like a new car. So it seemed the fuel was then ok.

But not still would not start when just slightly warm.

So I got the ICM repaired by a great bloke (neil_prosser16@hotmail.com) who has done them for years.

That improved things. I would get the ICM done if I were you. They are infamous for failure. Just do it.

But the car soon fell back heavily into its bad habits.

Ok, here's the method that worked for me just in case you have not seen it.

Ask yourself: Is it fuel or spark?

I got the engine into a no-start condition, lukewarm, and I got my son to crank the engine while I sprayed Aerostart into the intake. Absolutely dead. So it was not running lean.

Could it be running rich?

I pulled out the fuel pump relay (easy to find under the bonnet) and I cranked the engine.

After a few turns (no throttle) probably about 6-10 windovers it roared into life!

So it WAS FUEL! And it was TOO RICH.

WTF.

Spark was fine! Forget the new dizzy bits.

This thing roared into life.

So why too rich?

I looked up "symptoms" in my Holden VS Series Service Manual Supplement Volume 3, Powertrain Management -- V8 Engine.

Page 6C2-2C-15 discusses TOO RICH.

I found the oxygen sensor can be TRICKED (yes they said TRICKED!) into thinking the engine is running too lean. So it over-richens it.

How does this happen? Well, the sensor can believe the exhaust is too lean when it gets "DIRTY"

It can then tell engine management the exhaust is too LEAN and to widen the injector pulse to richen things up a bit more.

You would think it would smell the overwhelming eye-watering stink of half-burned fuel and tell engine management to lean things up.

But if the sensor is DIRTY it is dysfunctional. It can't get to the exhaust air to smell it. So it can richen things up big time.

It's a vicious circle. More misfiring results. More soot copies down. The sensor gets dirtier.

So I pulled my sensor out (easy) and it was covered in black soot.

I could have cleaned it but there was a fair chance it was just too old at 200k. I think it was failing and that was what started the soot building up in the fist place.

Repco give me a new "two wire" (goes on the left manifold, and it is two wire for the standard 165kW V8.)

Installation was relatively easy. You plug-disconnect behind the engine. Screw the new one in from underneath the car.

(Be careful to put stands in to back up the jack. I even shoved a ramp under the passenger side wheel after a stand moved about it bit with a BANG. Scary because you are well and truly under there to get to the oxygen sensor. Some people say turn the left wheel away to get room but I didn't have to, and I would put the car on ramps if I had to do it again. Much safer.

Screwed the newy in (don't clean the tread it is specially coated with glass beads (!) and graphite. The graphite burns away but the glass beads stay intact and stop the thing welding itself to the pipe.

Connected the leads. Turn the key. This car is brand new!

There are many reasons why your V8 can get hard to start and you will see them all on the websites like this.

All the stories are true. One of them might be for you. But I urge you to try this experiment.

- look at your exhaust tip. Is it jet black inside with powder? The sensor has short term response to engine management in a few seconds! A few firing strokes and it is dialling up mixture that is rich you can'r sustain flame and the plugs probably get wet too.

- if the exhaust is black, then get the car to fail to start.

- then pull out the fuel pump relay.

- roll the engine over for quite a long time. Say 10-20 seconds if you have to. If it starts it then it was simply too rich.

Such an easy diagnosis to do before you go looking for spark and spark timing.

I will probably do everything over time. Fit new fuel pressure regulator. Check the pressure with a gauge. Fit the dizzy cap, and expensive leads, rotor and hall sensor. Get all the weak links out of the system.

[dave94calais]

Hi I have a vr v8 having problems starting and running new fuel pump and filter new igniton modual and coil had an auto elec look at it fixed the wire on the battery + big red wire and put a new conection on the purple wire on the starter motor ran for 2 days then nothing just turns over starts some times but will go 100km trip fine but on the way back will stall. Did as you said pulled the pump relay nothing put it back in and it started

[dave94calais]

Any one know what to do next. Forgot to add only had problem after the I had one of the interlock device taken out. Central locking playing up to press lock car locks and then unlocks on its own but factory alarm is still set. Can lock all doors from drivers door with the key help if you can

[scoop1]

dave94calais


On the fuel mixture...you could drive my car to Darwin, and it would never fail on the cruise part of the drive.

The spark plug tips showed me the mixture is ok on the road. Nice grey colour.

The rest of the plug was black, black, black.

Mine V8 is cranky just at startup.

If it failed driving on the road (as you might be talking about, I can't tell) then maybe just maybe it is so rich (on the road) it is starting to stumble.

Generally, have a look at your exhaust tip.

If it is all black, rather than grey, rich mixture has got to be part of the problem.

I had ignored this basic.

I was so convinced it was ignition.

Then (having finally realised it could actually be fuel) I pulled out an easy-to-reach spark plug (up the front, passenger side.)

By pulling the fuel relay then starting successfully out you have proved to me that that the mixture at that time was too rich.

I changed the oxygen sensor and the car is better but I think the fuel is still running too rich.

So I might have had an externaly clogged oxygen sensor rather than a permanently, internal, failure

Putting a new one is gives certainty though that the sensor is no longer a problem, and the car also runs better.

After changing the sensor (not expensive) there are two things to do at this stage.

1. Drive the car about a few days. That's what I am doing for now.

Let the computer re-adjust mixture from new driving history.

I am an amateur and don't know how long that history will be. Also the pugs could be replaced. I will do that.

But on a VP V6 I have, I got the Crank Angle Sensor replaced and it took a couple of days to getting running properly.

Traumatic for the computer.

Computer says WTF.

I think the PCM needed time to re-adjust. what else could it be? Ran like a train after a days ro so and still does after a year.

2 Wahtever you do, if you still have to pull the fuel relay out to get it running it is still too rich and (it would clog up my new oxygen sensor in time.)

My next step will be to replace the fuel regulator (easy to access). If that doesn't fix it ( I have had a couple of events where I had to turn the key again and give it a little throttle) I will get a fuel pressure gauge, learn how to break into the fuel line (easy to access) and have a look at the pressure against the Holden guide figure.

I think buying a gauge will be a good investment because I will be able to diagnose the fuel delivery anytime. If there is a problem, say clogged filter, I can test the fuel first.

Then, only if that delivery and pressure is ok, do I go forward to fuel injector failure, and finally to ignition system problems.

Good luck Dave don't give up!

The way I see it is we not paying finance on a new car, that that leaves us thousands (well let's make it hundreds) to spend on replacing whole groups of components to clear up an area of failure. I see others on website do this.

For example I had a radiator failure and got that replaced. While they were there, I got them to replace EVERY water hose.

There are about 12.

So I hope I have got a "new car" as far as the cooling system is concerned.

I should have replace the temperature sensor (hiding under the throttle) while it was all opened up.

I didn't because this is a new culture for me, replacing EVERYTHING related to a problem, on the basis that the rest of ti is probably worn out or at least becoming likely to fail.