Suddenly hard to start

[baz]

My engine has developed a case of not wanting to start, hit or cold. Lots of banging, the odd pop out the exhaust. When it does catch it runs fine but it's getting harder and harder to get it to start.

Checked valves, pulled plugs and they were dry and looked fine. Tried adding more fuel to start up map, tried reducing fuel and makes no difference. Tried different advance settings it's currently at 13° for 500 and 800rpm 14 at 1000rpm.

Anyone got any ideas what I should look at next?

It used to start first turn hot and second turn if really cold.

I switched back to a vw starter motor recently and it doesn't spin up as fast as the old skoda starter, could it be something to do with injector pulse time on cranking?

[spoolin70]

First thoughts while I drink my morning coffee :

How old is the fuel ?
What's the battery voltage ? (Fully charged)
Any outside air temp compensation or enrichment ?
Any idle air control valve/solenoid ?

Just thinking out loud

Stay safe
Darren

[baz]

Fuel is fresh and from same garage. Battery fully charged. Does have air and water temp compensations but these settings haven't been changed. It's seeing around 10% advance compensation at current temps. No idle control.

[spoolin70]

Hmmmm coffee finished now

Did the starting problem only appear when you changed to a VW starter motor ?

I might be totally wrong so don't quote me and please do your own research but isn't static timing 7.5 deg btdc and ignition at TDC at 900rpm.

[baz]

Well it did and didn't, the starting issue happened first I think as I think it's what broke the skoda starter. Possibly kick back which I believe could be caused by over lean or too much advance. So I enriched the start map and reduced the advance. It made no difference just gets harder to start each day.

[richie]

I haven't got dta on this laptop so can't check but thought it had a cranking timing pre set, and until engine see's X rpm[usually about 800 then it stays at cranking timing so any changes you do won't make a difference anyway

Logically it worked before you swapped starters, so most likely that   is it new or old vw starter? Skoda starter spins it slightly faster , ecu needs to see certain rpm from trigger to start and vw starter is borderline on that and if its older stater then.

You can check sensors are all good via diagnostics on ecu just to confirm but if its all good when it does actually start then unlikely to be that.

Simple test to see if its fuel or spark related, get a cap of petrol and pour a little down each stack, or if you got brake/carb cleaner a decent squirt down each stack then quickly try to start it, if it makes no difference then its spark related, if it fires up then its fuel related

[richie]

Also seen something similar when trigger wheel came lose on pulley

[richie]

And   is it popping through throttle bodies? or banging in exhaust, popping through intake is usually lean, banging in exhaust is unburnt fuel

[spoolin70]

Do you have a diagnostic display page ?

Some DTA models do.

If there is a box marked - STARTING INFORMATION
Quote from a manual :

When the engine is stopped the message “Engine Not Turning” is displayed at the bottom of this box in RED. If the engine reads as turning it is likely thier is a fault with the crank sensor or the wiring.
If the map is opened in offline mode this box is not coloured.
When the engine starts to crank the message “Turning – Attempting to Synchronise” appears in RED. The ECU is attempting to reconcile the information you have given it in General Engine Settings about the crank wheel to measure both the speed and position of the engine.
If this message is displayed the engine will not start and there will be NO injection or spark.

[baz]

Thanks for the help fellas.

Go back to the start for a minute. The skoda starter was working fine and car was starting perfectly up until February. In January I pulled the engine apart and replaced the cylinders and rings and had the valve seats re cut.

When I put it back together it started reasonably OK but not as good as previously. I played around with ign and fuel to try fix that but never got it right.

Then the skoda starter broke, bought a new skoda starter it broke like the first one straight away. Realised the problem wasn't the starter motor at this point and investigated causes fir the broken starter and learned about kick back.

Reduced the ign down to 7 and it started reasonably well with th vw starter but not spinning as fast. Lived with it for last month or so but it started getting harder and harder to get it to catch. Played with ign and fuel but neither seemed to make any difference. Put settings back to map I had from dyno tune where everything was working fine before engine was rebuilt.

Yesterday it kept jamming the starter so I'd rock it in gear and it'd work again. Then it just refused to start yesterday evening and this morning and kept jamming so I pulled the motor and found a mashed flywheel with 10 teeth in a row missing!

Need a new flywheel and need to know what's causing it?

We all love pics

[richie]

That sucks, maybe piece of broken starter inside bellhousing still?

[baz]

I separated the engine from the box expecting a few teeth to fall out but nothing yet. Haven't pulled the motor completely free yet, but will do tomorrow so I'll see what I find.

[leec]

Hi Baz,

Sorry to see the damage. I still have the flywheel I bought from you, do you need it back?

[baz]

Hi Lee thanks for the offer but that wheel has the bigger dowel pin holes so won't suit. Hopefully there's no more damage I'll know when I strip it down today.

[leec]

Yes, I remember now. 11/32 dowels.

Sure Richie had DPR flywheels in stock.
Lee

[baz]

Yes, I remember now. 11/32 dowels.

Sure Richie had DPR flywheels in stock.
Lee

Yep just gotta see that nothing else needed and place an order

[baz]

That sucks, maybe piece of broken starter inside bellhousing still?

No broken starter pieces but 3 separate missing teeth along with the damage above, found 2 teeth in Bell housing the third one is from the centre of the pic above and must be the one that mashed up the flywheel.
The skoda starters didn't do the damage as they broke clean off being self supported.

[Rocket Ron]

As I understand it the Skoda starters don’t throw out far enough for long term use. I’ve not had first hand experience but I understand that the face of the starter has to be machined to get it to engage with enough metal to metal not to cause damage to the flywheel after relatively short term use.

[baz]

As I understand it the Skoda starters don’t throw out far enough for long term use. I’ve not had first hand experience but I understand that the face of the starter has to be machined to get it to engage with enough metal to metal not to cause damage to the flywheel after relatively short term use.

I know a guy running one unmodified longer than me with no issues. The engagement wasn't ideal but it wasn't damaging anything. The chinesium starters broke clean off. The vw starter having the support bushing didn't break, instead the flywheel did.

[andy198712]

it is EFI right?

are all your sensors reading normal, correct values? IAT, CLT (if you have one for warm up), RPM while cranking ect?

what ecu?

[baz]

Dta s40. Sensors all reading OK and works fine once started.


Pic of skoda starter engagement, another 5mm would make it almost full. No damage to ring gear showing.

[Martin S.]

Generally having too much advance while starting an engine is bad because as your starter is pushing the piston to tdc, the spark happens in advance pushing back at the piston, fighting the starter motor.
What’s the advance when cranking?
Model Ts had adjustable advance from the drivers seat. https://youtu.be/WaHq9ivaEok

[baz]

It was kicking back at 13, but only after I rebuilt the top end, new rings and cylinders. Never did it before in 3500 miles.
I'm running slightly more deck now too so if anything the compression should be slightly less than I was before.

[baz]

Well I'm back up and running a couple of weeks now, ignition is 7.5 below 1000rpm. Modified skoda starter with vw gear welded on and it starts perfectly again hot or cold, and I've had some help and advice on getting some other issues ironed out. My pedal speed measuring time was way too slow and correcting that has helped drive ability hugely. Couple of rich spots in the higher revs to sort out and I'll be happy with it.