M20 Oil Contamination / Consumption

[SilverShadow]

This is following on from a old post that I cant find no more...

Story goes as follows:
Ӣ Hartge M20 H27 engine with Hartge ECU.
Ӣ Engine originally came with an adjustable fuel pressure regulator (which has been removed and replaced with a 3.0 bar oem fpr).
Ӣ Engine was stripped as it was burning oil - following was done:
o Head complete reworked, pressure tested, new guides, stem seals, valves lapped, skim etc.
o Block inspected, bores honed, new rings, crank polished, new bearings etc
Ӣ Injectors rebuild by injector tune.
Ӣ Break in method I used 15/40 mineral oil and first 50miles miles I drove it purposefully to bed rings and then normal driving. After 10/40 semi synthetic was used.
Ӣ After 4k miles engine continued to burn oil approx. 1ltr for every 600miles and blue smoke was visible.
Ӣ Compression test was carried out and readings were around 180psi.
Ӣ Leak down carried out with less than 10% leakages on all cylinders.
Ӣ Decided to rip the head off with the help of a BMW specialist to inspect the rings and seals.
o Head was stripped once again and inspected. No anomalies found however we replaced the stem seals for good measure.
o Pistons out of the block, rings were gapped correctly (120degrees), bores checked with a bore gauge and all in tolerance. Again no anomalies found.
o Used OEM piston rings were used this time around.
Ӣ Break in method this time around was the same mineral 15/40 and have done around 500miles and its still smoking and consuming oil like a biatch!!!

I know its early days but no ways it supposed to smoke like this. Day by day its getting difficult to start and today there was a massive back fire.

I havv’t had the chance to look at the spark plugs yet however I have been analysing the oil and I have a feeling the oil is being contaminated by fuel ”“reasons are below:
o Less than 500miles and the oil is total black.
o Oil smells of petrol.
o Oil viscosity seems much thinner compared to normal.

I have carried out the checks on the blue temp sensor from the ecu port and sensor hot / cold and readings are correct.

Its running the correct 2.5 injectors alongside afm.

Had the car on a gas analyser and the mot chap said it’s letting a lot of un burnt fuel out.

I keep wondering into why there was that adjustable fpr on the engine when I first purchased it ”“ could it be that now its over fueling to an extent where its thinning the oil causing it to flow by the rings and burn?

From what I have described above what’s people thoughts on the oil consumption and smoking?

Any help on this nightmare would be much appreciated

[motormanmick]

Hello silvershadow,

rising rate fuel pressure regulars are used on low boost turbo applications and in your case a stroked motor, the 2.7 will use more fuel than a 2.5 and 2.5 injectors have a certain duty cycle, if they exceed that then the 2.7 may suffer starvation, 3 ways of achieving that adjustment, larger injectors or a rising rate regulator and or a remap.

Your best indication of what is going on is the gas analyzer by the mot guy, too much fuel. Check your plugs, they will show signs of excessive fuel, injectors will only put out what they are told to do, so that may be your problem, so look at afm, throttle position switch and along those lines, something is telling your ecu to over fuel, hopefully the ecu is ok, mind you, I'm no expert on fuel injection, just some thoughts, Cheers.

[SilverShadow]

Thanks for the feedback MotorManMick!

This brings me back to thing why there was a adjustable FPR on the engine when I first bought it...

As I have checked the blue temp sensor, AFM, TPS I'm more inclined to start looking at the ECU and the map..

Is there anything else that I should look at interms of over fueling?

Hoping to get some recent readings of the gas analyzer this weekend.

[HairyScreech]

Sounds like it is overfueling, how much do you trust the ECU?
I have the kit here to check what the ECU is set up for but obviously your pretty far away unless you regularly make your way down to the west country.

[SilverShadow]

Mr Screech! I remember you helped quite a bit on my original post....

What can I say about the ECU apart from that it was supplied as part of the engine and that it's stamped with Hartge logos. I've opened the ECU and saw that the chip is heavily glued into place - apparently this was a trade mark by Hartge/birds to stop their maps being read.

Upon the rebuilding on the engine and investigating what Hartge used to build the 2.7 it was always a different build depending on what engineer worked on them and what they were able to get their hands on.

I've concluded that what I have is a eta block with crank and a standard 885 head (original head may have been damaged in some sort of way). Since then I have added a schrick cam and other tuning bits but have always kept the ECU which was supplied with the engine....

[motormanmick]

Reason for the adj frp is that the fuel injection system is designed around fueling a 2.5 and lets say the std regulator works at 42psi.The 2.7 needs wore fuel, so lets say the adj fpr is set at 46psi (10% increase) this gets the air/fuel ratio back on track, so no ecu tuning required, if it's cammed and chipped, them more fuel is required and the adj frp can handle that up to nearly max fuel pump pressure.

[HairyScreech]

^^ agreed, they should only ever really be used to reduce the pressure at low speed to extend the range of big injectors downwards, not to use them to make small injectors act bigger.
And even then it can only be mapped properly if the car is using a MAP based ECU tune. For it to work you absolutely have to map the car based on RPM Vs Manifold Pressure (speed density) so its application is tiny.
Anyway that's another topic entirely.

To me it sounds like there is too much fuel going in, it will thin the oil, it will make it chuck out high HC (burnt oil and fuel), it will foul the plugs and make it run rough.

What kind of piston is in the thing? B25 style ones or flat tops?

The 885 head may be original but if it is a replacement then my concern would be it is not breathing as well as it used to when new and now is over fuelling.

3. bar regulator is good, that's stock and rules that out. Did we ever check the part number of the fuel injectors?

It might be worth doing an oil change and investing in a cheap WBO2 to check out how it's fuelling when driving.
These are now so cheap that it's almost a easy diagnostic tool.
http://www.14point7.com/products/slc-free

Otherwise find somewhere willing to give it a dyno run and check the AFR on the dyno.

I'm suspicious everything is working as intended but normal fuelling is well off for the car now.

[SilverShadow]

^^

What kind of piston is in the thing? B25 style ones or flat tops?

The 885 head may be original but if it is a replacement then my concern would be it is not breathing as well as it used to when new and now is over fuelling.

3. bar regulator is good, that's stock and rules that out. Did we ever check the part number of the fuel injectors?

It might be worth doing an oil change and investing in a cheap WBO2 to check out how it's fuelling when driving.
These are now so cheap that it's almost a easy diagnostic tool.
http://www.14point7.com/products/slc-free

Otherwise find somewhere willing to give it a dyno run and check the AFR on the dyno.

I'm suspicious everything is working as intended but normal fuelling is well off for the car now.

Thanks for the response.

It has the flat type piston tops (eta type) and below is a pic of one of the injectors which I believe is the m20b25 version.

How does the WBO2 connect to pull off the readings (via the ecu or diagnostic port etc)

[reggid]

When you pulled the head what did the bores look like? Over fueling can wash the bore of oil and glaze them or long term they will go smooth with little cross hatch remaining. The cross hatch which are tiny valleys holds some oil so that’s why honing process is important.

[SilverShadow]

When i done the initial build i had the bores honed.

When i done the recent strip/build the cross hatches were still good. I was told there was no need to hone again.

[reggid]

When i done the initial build i had the bores honed.

When i done the recent strip/build the cross hatches were still good. I was told there was no need to hone again.

Assuming whoever made the assessment was correct it doesnt sound like oil consumption is caused by over fueling washing the bores otherwise there would have been evidence of so.

if the assessment was incorrect that would explain why you still have an issue.

nevertheless the fueling is a issue and should be fixed ASAP then oil changed and continue to run in, you dont need a adjustable FPR it actually creates issues. it is totally the wrong way to tune.

what have you done with the valve cover vent hose if anything?

[SilverShadow]

When i done the initial build i had the bores honed.

When i done the recent strip/build the cross hatches were still good. I was told there was no need to hone again.

Assuming whoever made the assessment was correct it doesnt sound like oil consumption is caused by over fueling washing the bores otherwise there would have been evidence of so.

if the assessment was incorrect that would explain why you still have an issue.

nevertheless the fueling is a issue and should be fixed ASAP then oil changed and continue to run in, you dont need a adjustable FPR it actually creates issues. it is totally the wrong way to tune.

what have you done with the valve cover vent hose if anything?

Agreed - adjustable FPR has been removed as per my previous post.

I have done no alterations to the vent hose from the rocker. It’s being fed through to the TB as standard.

Now that we have confirmed that the AFM, injectors, FPR, blue sensor, throttle body are all standard b25 parts should I be concentrating my efforts towards the ECU in regards to over fueling.

As i dont have access to a fuel pressure gauge at the moment I had some oil contamination test strips, below are the results:

As you can see there is a large light outer circle which confirms that there is too much fuel in the oil as per the chart:

Oil test showing a larger light outer circle.


Chart indicating there is too much fuel in the oil.

[HairyScreech]

Mega halo on that spot.
Injectors look like standard b25 bits.

I think the only thing left is to confirm when this thing is over fueling.

A wbo2 gauge has its own display and you would have to keep an eye on it to see when it goes rich.
A dyno run would give the WOT afr but no transient fueling.
Suspicious this is over fueling at a very light load. Hence no bore damage.(also e30 blocks are double hard bastards. I ran one with a hole in the sump for 8 miles with no bore damage)

Worth swapping another ecu and chip in for a trial? I have a 173 ecu here that you could borrow and pop a 2.7 chip in. Not using it on mine.

[motormanmick]

[quote="SilverShadow"]This is following on from a old post that I cant find no more...

Story goes as follows:
Ӣ Hartge M20 H27 engine with Hartge ECU.
Ӣ Engine originally came with an adjustable fuel pressure regulator (which has been removed and replaced with a 3.0 bar oem fpr).

Just a thought, it would probably be a good idea to ask Harge about the original state of tune, I mean, did Harge do the original tune being chip in the ecu in conjunction with the adj fpr and then redo the fuel mapping based on that combination.

Adj fpr's are not the way to go standalone as previously mention by fellow zoners, but when done in conjunction with a remap on the ecu done on a dyno will produce good results.
Question is, did Harge fit the adj fpr, if they did, going back to std may cause you problems when you sought out the over fuelling.

Just did some googling and found this.

See article below, Birds Auto, according to the article did extensive tuning/moderfying to these engines, they would be a good source for info, especially anyone working at that time when they did all the tuning work, by the way, your cam is 280 degree as stated in article

http://www.birdsauto.com/editorial/edit ... april-1989

[HairyScreech]

The fpr is a working oem bmw one.
The injectors have beem off to injector tune to be tested and cleaned.

Both are working as intended.

There was a thread a while back and I am pretty sure every normal mechanical reason has been explored.

[SilverShadow]

OK quick update on this...

Got a friend coming over next weekend who has a fuel pressure test kit to test the fuel system.

Out of curiosity how do you go about testing the fuel pressure and what should the readings be?

What should the conclusion be after carrying out the test?

[reggid]

should be 3b (43.5psi) on m20b25 FPR but if its idling it will be a bit lower 38psi as the reference is the vacuum unless you unplug the vacuum hose where it will be 43psi. with your spec engine it might idle at 40psi as there will be less vacuum on a cam with more overlap

[SilverShadow]

Ok guys some further movement on this issue.

Today i had the fuel pressure tester conncted up and had just over 3bar of pressure when the engine was idling and with rpms:



When the engine had stopped running the pressure remained just under 3bar after 10mins being switched off.

http://i336.photobucket.com/albums/n335/jags320i/Mobile%20Uploads/20160220_143956.jpg[/img]

So i assume the mechanicals of the fueling system is fine as the above tests eliminates faulty fps and leaky injectors...?

Should i be looking towards electrical now e.g. ECU map etc?




.

[Brianmoooore]

That pressure looks a bit high for an engine on idle. Is the reference vac. pipe to the inlet plenum all good?

[reggid]

yeah youd normally expect to see 37-38psi (2.6-2.7b), even with a cammed engine id still expect 40psi

[SilverShadow]

That pressure looks a bit high for an engine on idle. Is the reference vac. pipe to the inlet plenum all good?

Hi Brian is this the pipe that comes from the rocker cover to the inlet?

[maggspower]

That pressure looks a bit high for an engine on idle. Is the reference vac. pipe to the inlet plenum all good?

Hi Brian is this the pipe that comes from the rocker cover to the inlet?

I would imagine he means the one from the FPR to the inlet. It controls the FPR.

[SilverShadow]

That pressure looks a bit high for an engine on idle. Is the reference vac. pipe to the inlet plenum all good?

Hi Brian is this the pipe that comes from the rocker cover to the inlet?

I would imagine he means the one from the FPR to the inlet. It controls the FPR.

Sorry my bad. Yes that vacuum pipe is fine.

Would that much of a buffer make a difference in contaminating the oil?

Im leaning more towards at tackling the ecu now... whats peoples thoughts on the next steps?

[Brianmoooore]

Sorry my bad. Yes that vacuum pipe is fine.

So why is the fuel pressure high?
This won't be all the reason for your problems, but as is often the case with E30s, several minor faults add up to make a big one, so it makes sense to sort things as you go.
What happens to the gauge if you snap the throttle wide open?
How reliable is the accuracy of the gauge?

[SilverShadow]

Sorry my bad. Yes that vacuum pipe is fine.

So why is the fuel pressure high?
This won't be all the reason for your problems, but as is often the case with E30s, several minor faults add up to make a big one, so it makes sense to sort things as you go.
What happens to the gauge if you snap the throttle wide open?
How reliable is the accuracy of the gauge?

Agreed I want to sort all the minor faults while I'm trying to sort the current major issue.

I will revisit the vac pipe and connection and report back.

The gauge dipped down approx to 2.5bar (35psi) when the throttle was opened.

As a side not I took the car out yesterday for a drive as my daily run out of MOT. Once warmed up and under load while changing gears, I am getting the occasional back fire from the exhaust (loud pop) and smoke dispersing.

Signs of over fueling??

[Brianmoooore]

The gauge dipped down approx to 2.5bar (35psi) when the throttle was opened.

Pressure should INCREASE when throttle is opened.

[SilverShadow]

OK I'm stumped with this now.

I spent all evening yesterday trying to find out on the net how the fuel pressure works on a M20 and having not that much of luck.

I went out during lunch to re check the vac pipe from the FPR to inlet and it seems fine; no cracks, not brittle etc.

I started her up and took the vac pipe off from the FPR and the engine continued to run. There was suction from the pipe which is a good thing and gave her some revs and she didn't seem hesitant or anything like that?

I need help on this, how does the fuel pressure work and what should the pressure be during idle, with revs and shut down? Also why is the engine still running when i removed the vac pipe that controls the FPR?


Confused dot com!

[Brianmoooore]

Fuel pressure should be whatever is written on the FPR above the pressure in the inlet plenum.
When the throttle is wide open, the pressure in the plenum is close to atmospheric, so the gauge should read what is written on the FPR.
With the throttle nearly closed, as on idle, there is a partial vacuum in the inlet plenum, so the pressure on the gauge is reduced by this amount.
If your pressure drops on WOT, then it suggests that your fuel supply can't keep up for some reason. Filter? Pump? Restriction in pipe?

[SilverShadow]

Fuel pressure should be whatever is written on the FPR above the pressure in the inlet plenum.
When the throttle is wide open, the pressure in the plenum is close to atmospheric, so the gauge should read what is written on the FPR.
With the throttle nearly closed, as on idle, there is a partial vacuum in the inlet plenum, so the pressure on the gauge is reduced by this amount.
If your pressure drops on WOT, then it suggests that your fuel supply can't keep up for some reason. Filter? Pump? Restriction in pipe?

Thanks for this info Brian!

last couple of questions that I can't get my head around is that the FPR is a OEM 3bar unit. So at idle what could it be causing the higher pressure (3.1)? Also when I remove the vac pipe I would of presumed that the engine would stalled due to the FPR not creating pressure from the removed vac pipe.

[HairyScreech]

Would be worth combining a fuel pressure check with a vacuum gauge check, they should move inversely, the vac gauge up and the pressure gauge down.

I know we have been through this before and the motor has been rebuilt since but are you 100% sure there are no air leaks from the manifold?

Did we do the fuel filter last time round? I have seen E30s running about with low fuel pressure and the original 1980s filter still fitted! Just a little bit blocked up!

Edit to add - Could this just be a read herring? It should go up with WOT and load.
But we are talking about snapping the throttle on an engine with no load, resulting in a very high rate of acceleration of the engine, will this give the same expected result even with the short duration the throttle can be opened before hitting the rev limiter.

Also just looked back for the other thread and found you have tried another ECU since I last looked at it, with no real change to the amount of smoking even though it was a stock 325 ECU.
So we can forget that at least for now.

General question to all in this thread - If a jack had found its way onto the fuel lines and pinched/partially blocked the feed and return could this explain the high pressure at idle and restricted/low pressure when revved?

[Brianmoooore]

General question to all in this thread - If a jack had found its way onto the fuel lines and pinched/partially blocked the feed and return could this explain the high pressure at idle and restricted/low pressure when revved?

Interesting theory! Would explain both gauge readings.
Any back pressure in the return line would be added to the gauge reading at idle, and restricted flow in the supply line would cut the pressure at WOT.

[HairyScreech]

And the fuel lines are only a slipped jack away from the chassis leg....