Yes reading went higher with oil squirted in, just about equal gain for all cylinders, but not a massive amount - in the 0.6 to 0.8 bar range  - so under 10% rise. I see 14 to 15 bar on my re-ringed 11:1 compression engine when warm, dry test. 

righto...if mines piston trouble i guess it would be a broken ring as maybe you recall i honed and re ringed it , but ran fine on the carb with great emiisions

With 22inHg steady reading at idle I'll be very surprised if anything mechanical is up. 

 

You can test all rings at once with vac gauge too. Open throttle to 2000rpm and let it snap closed. Vacuum should head towards below 3inHg  but not quite reach 0 then hit nearly 25 inHg when close and settle back to 22 idle.  The deceleration phase is pulling air by engine spinning inertia against closed throttle. If a ring is bad it wont seal on the downwards stroke.  

 

https://dannysengineportal.com/checking-your-engine-with-a-vacuum-guage/

Edited 19 September, 20187 yr by dvderlm

pretty sure it does that 

 

got one of these new for a tenner at a steam rally

 

https://www.ebay.co.uk/p/Mityvac-Model-04050-Silverline-Plus-Automotive-Kit/1328511223

Mityvac are ace. You can neasure and override the vacuum for something.

 

New theory. The Fuel Pressure Regulator is giving correct pressure at output port but leaking fuel down the vacuum control tube into the manifold?

It'd be rich, but uncontrolled rich and with no vacuum loss. High CO, high HC and you had what looked like clean oil that could not be from a breather?

 

I think the FPR is on end of fuel rail on MPI. 

  

yeah not a bad idea ...maybe i should look at it more

 

i applied some vac to the fpr and it holds steady , fuel pressure reads as it should with and without vac , i do have another i can swap over 

 

yeah the tool sounds pretty cool if you know how to use it

I doubt that the rings are causing your problem, but when you say that you honed the bores before fitting new rings, did you also scrape off the wear ridge near the top of the cylinders? What can happen (I am not saying that it has happened in your case) is that a new ring CAN strike the bottom of the wear ridge and brake the ring.

 

Regards

wasnt a noticable ridge ...just gave it a light hone so the rings would bed in

 

assume a broken ring would make a noise /smoke which theres  none

See what the compression tester reads? 

just opened up a spare ecu (runs same)   and noticed these look like theyve been hot

 

think its a voltage reg , theres one each side of the board 

 

should i be replacing them or what lol

If they are regulators, not IGBT transistor ignition drivers.

Oh, plenty of spares I see. That's one benefit of living in Silicon Fen.

Integrated circuits grow on trees around here: Acorn, Raspberry, Apricot, Apple, Bush, Thorn, Blackberry.

theyre not my spares 

 

will look into it further  see if i can get some part numbers

Arw you getting excessive hydro carbons

cold compresion results

 

1*  150

2* 170

3*170

4*140 ?

 

i did *4 first and fear i might have not cranked it enough....ive dropped the adaptor down near the starter so will try it another day when i retrieve it

 

all plugs same colour and fairly normal looking  , while its not text book readings i think its probably near enough that it should run acceptably?

If you can see gauge while cranking keep going until it stops rising.

 

I chucked some figures in a cranking calculator and reached 174psi for 10.5:1 of ABD. (Not sure about rod length or ABDC inlet valve  closing)

http://not2fast.com/turbo/compression/cranking_pressure.shtml

.

 

I can get the 220psi of my best cylinder with the same calculator and values I'm reasonably sure about.

 

Edited 25 September, 20187 yr by dvderlm
acdc atdc abdc abcd

9.5-1 according to this

 

regardless...do you agree while not ideal its not so hideous to cause major issues ?

 

will try again with a warmed engine some time

I found 10.5 on Wikipedia, lol

https://en.wikipedia.org/wiki/List_of_discontinued_Volkswagen_Group_petrol_engines

 

Yes, it's not awful. I'd prefer to see over 140psi and #4 is more than 10% below best cylinder, but for cold reading nothing there shouts bust.

You could try it from #1 to #4 next time cold.

 

okay your cam seat to seat duration is not as wild as 290. (fudging that, using 78.7mm stroke as inches, but rod length still a guess).

Edited 25 September, 20187 yr by dvderlm

7 hours ago, steveo3002 said:

..ive dropped the adaptor down near the starter so will try it another day when i retrieve it

magnet on piece of string?

its brass lol...think i can poke at it with a coat hanger hopefully it will fall out the bottom

Disconnect the battery if you doing that with a metal coat hanger near starter motor terminal!.

 

I branded my thumb poking below my carbs with some wire.

vw specs 10-15 bar

max 3 bar differance ...so a pass , i will consider it good enough

10bar is 145psi and you got 140 psi = 9.65bar for cylinder#4.  But cold measurement with oil very viscous, so I agree, probably okay.

 

Still a mystery.

right still no progress , tried yet another ecu i borrowed just the same

 

ive swapped every component that makes the engine run , most of them more than once , tried timing all over the place

 

do you think id be mad to pull the head and have a better look ...try some liquid behind the valves see if they leak ?   ive got most of the stuff  already just need a h/g and bolts 

 

 

or honestly what would you do

Get a bore scope and have alook first?

borescope wont tell me about the valves...think i will just pull it unless anyone has any other ideas

 

will cost me like £40 which ive been throwing at it weekly in parts and tools to try and fix it