Lots of Clicks - Mixture Still Rich

[Pawel66]

I continue struggle with my idle. Spent a couple of hours clicking the idle screw left (10-15), then the main rack screw right (5). Next day I drove to a technical inspection to get the readings of the exhaust. Below on the pictures is what I got (zbyt duzo means too much, bogata means rich).

I guess I have to continue clicking or remove the shims from the barometric compensator... but it is getting to be a lot of clicks. Feels strange.

I have new injectors, I have non-leaking CSV, I do not hear any air from the WRD. Anything else "central" or "major" I should check that is driving the mixture rich?

[jameshoward]

These are old cars. If your engine is worn i.e. hasn't been rebuilt you shouldn't expect miracles. Your readings aren't horrible. What MPG do you get? Fill to the brim, drive a lot, re-fill to the brim.

Also do the linkage tour on the member site. It may take a few times to get it to sit perfectly. Check the timing. Do the valves. And so on.

All the info you need is on the site and it's excellent. None of the jobs are difficult.

Oce you've done that (and forgive me if you have done so already) go back to your gauge and check again. It would be interesting to see what the new readings are.

I'd certainly do all of this before going anywhere near the barometric compensator.

[Pawel66]

James, thank you!

I have been through all this  . Going to the meters is one of the last steps. Engine is rebuilt and runs great at higher speeds. Idle is an issue. My worry is: I kept leaning it quite a lot - you see where I am.

I guess time for a couple of checks and perhaps time for radical shims removal... if there are shims under BC to remove...

[Pawel66]

Ok, done some tests...

On picture "idle only" you see 6 plugs after 10 minutes engine run on idle only.
On picture "after drive" you see cylinder 3 and 5 and 6 for comparison.

Plug 3 was dry in both cases. No smell of gas.

When I pull the lead from cylinder 3 while engine is running at idle, no difference in the way engine is running. So no. 3 does not work on idle. It works while driving - the colour of the plug changed, but is much much leaner than the other cylinders.

Apparently when the idle mixture was richer, and the no. 3 plug was as sooty as the rest (we looked at them at that time), the cylinder was getting some fuel. When we leaned mixture - it stopped. It is also getting less fuel on higher revs than other cylinders, but it is getting something.

I edited the post to add: engine is running much smoother when it is warming up. I think it is because the WRD is increasing fuel supply and it is enough for cylinder 3 to work. Then after, say, half a minute or a bit more, the engine revs slow down. And they start being uneven. This is when less fuel is supplied as WRD is off. There are no other start aids - just the CSV that works for 12 seconds maximum, and WRD. I have no solenoid on FIP.

What I figure, we have FIP, fuel line and injector that can be responsible. We have recently had FIP on the bench as we had to re-install it (we figured it was reversed 180 degrees before). We checked for plungers movements etc. and everything seemed to be fine.

Line - we were aware that after applying zinc during restoration the line may get clogged. So it was checked for that.

Injector - I thought I had all of them new (I lost my records from that time  ). But I can see 5 injectors are bronze colour, the injector no. 3 is aluminum colour, which makes it automatically a suspect (just because it is different). I will start with the injector replacement.

Please write what you think - any advise is helpful.

[stickandrudderman]

You should be paying attention to the "HC" reading from the pictures. They are WAY too high.
"HC" stands for "Hydrocarbon" is basically unburned fuel.
Your readings are telling you that you have a combustion problem; not all of the fuel that is being injected is getting burned. Ideally they should be around 500, not 3000!
You need to start with the basics:
Check cam timing.
Check condition of cam.
Check valve clearances.
Check compressions.
FIT NEW SPARK PLUGS.
Check & adjust points using a dwell meter.
Check ignition timing.
Once you have done all that you can start to look for failed leads either with an ohmmeter or better still, an engine analyser, or what I do, pull off the plug leads one at a time (yes, engine running and you might get a shock but once you're used to it it's actually pretty harmless) to see if you get any change in RPM or engine note.
You can also see the HC reading rise when you disconnect the plug lead (because the fuel is definitely not getting burned now!) and you can use this reading to help you identify any cylinder that doesn't raise the HC when the lead is disconnected.
If you notice a lack of change in RPM or engine note then that cylinder is not firing. Swap that lead to a different cylinder, eg: swap lead 4 & 5 AT BOTH ENDS! and see if you can move the fault to a different cylinder. If you can then you know that the lead (or most probably just the cap) is faulty.
You can do the same with injectors; swap them over and see if you can move the fault to a different cylinder.

[Pawel66]

Stick, thank you. This is a good lead.

I think I need to sort out cylinder no. 3 issue. The plug was just dry when I took it out.  I think with this one there is a fuel delivery problem.

And you are right - I should follow up on the HC reading if this is the case, as you described, thank you. Most of the checks you listed I did. But what you wrote makes me think that maybe the inlet valve on cylinder 3 is not opening as it should... We set the valve clearances very thoroughly recently. We checked compression. I have now 123 ignition with settings as recommended on this forum and the car is driving very well with them. All the leads and plugs are new, we were looking at sparks onall cylinders - blue and solid. Plugs have maybe 1000km.

I think I need to sort out the cylinder 3, try to get the engine work even at idle with mixture close to what it should be - then have the reading again and see CO and hydrocarbon.

Thank you for bringing this!

[stickandrudderman]

You'll probably find that if you get your HC to come down your CO will go up because CO is a product of combustion.

[Pawel66]

Sounds like a threat 

Thanks, I tend to think if I decrease amount of fuel supplied, I will probably get both down. I just need to have the No. 3 kick in. Then we will see what will happen.

[Pawel66]

Ok, did next step. I removed the Barometric Compensator to check it and look at the shims I have there. No shims  . Just one thin, more a seal than a real shim. Nothing to take out and make the mixture leaner if need be.

But...

My BC was stuck, of course. But not the way they are usually stuck (I was not looking into it because the usual fault of BC makes the mixture leaner, which was opposite to what I had). It was stuck in some regular position. Maybe because of plating... I made it move. It reacts to pressure changes (took a vacuum food box from my wife). Perhaps it will stick a little bit more out now.

Checked WRD again - quite a noise, dies out as engine warms up, revs go down, noise stops, normal idle. So it seems ok.

Waiting for injector to replace for cylinder 3. If it is not the cause, then line, valve and cam, FIP.

[Flyair]

Paweł
Be brave

[Pawel66]

I was. I took that vacuum box from my wife.

[Pawel66]

Ok, here is where I am:
1. I replaced the injector on cylinder 3 - no change, cylinder 3 leaner than others.
2. I swapped injetors - cylinder 3 still leaner than others, so injectors are ok.
3. I removed and cleaned the fuel line to cylinder 3. It was ok, I think - clear air blow goes through it, when you inject some gas on one end (with injection needle, as the holes are just 1mm on both ends), it immediately flows from another end.

So injectors are ok and line 3 clear.

I measured how much fuel is coming out of the lines, before injectors at starter speed. I disconnected the lines, placed a file under and measured during 15 seconds engine crancking (one ofter the other, not simultaneously during one crancking). I received 0.4ml from line no. 3 and 1ml on line no. 6. So more than double the amount of fuel.

Now the important question is: shall I conclude my trouble is in less fuel delivered to cylinder 3?

If it is so, the next step is FIP and the next part in FIP is the check valve. and the next step could be swapping the check valves (I abviously do not have one). Would you agree? What else can I check?

[Cees Klumper]

I agree that the issue seems to be with the amount of fuel delivered by the pump. I don't think the check valve would influence that, only stops the fuel from leaking back out of the line into the pump when the engine is off if I am not mistaken. So during operation, the check valve should not influence the amount of fuel going to the injector. Perhaps the little piston for cylinder no 3 is stuck it its bore inside the FI pump? Just a wild guess. Best I suppose would be to take the pump to a specialist to have it checked.

[Pawel66]

Cees, thank you for your voice there.
Last time we had IP on the bench the rack was moving freely and the pistons were moving up and down and rotating, the cylinders pins were in place. Yes, I have to check the rack movement now as well as see if the piston in line 3 is moving after disconnecting the line and removing the fitting and check valve - I will do it in one session probably next Friday.

Sending IP for check and repair is something I would like to avoid - the only place here to do it is the Bosch service with very bad reputation. That is where my IP was rebuild and I seem to have issues with it...

Section 3 in the pump gives fuel, just less than other sections. Could be the piston gets stuck from time to time or its cylinder rotates with it from time to time. But I thought if the check valve is there to hold fuel up in the line and it is not holding, each time the piston goes down, some fuel goes down as well. I know there is fuel pressure in the IP, but there is also pressure in the line. Could be too simplistic thinking or not being aware of other facts of course

[stickandrudderman]

At this point I would be sending the pump to a specialist for o/haul/calibration.
There's one here in the UK that everyone uses and is excellent.

[Pawel66]

Yes, it may end up this way, thank you. I will be kindly asking for e-mail/webpage most likely.

I will just check the valve and look at the piston travel - it is a relatively easy check. If that does not bring results, I guess I will have to send the pump for repair.

[Pawel66]

I am after the next round of activities, it feels like I did not progress much...

So let me provide an update for the next generations and to ask for your kind advise.

First of all: I made a mistake last week measuring the amount of fuel I got from fuel lines. Yestarday I had my mechanic help me in the garage and he said that for the measurement of amount of fuel I should have waited until I have fuel dripping from the lines and then put the syringe under to measure the amount. My mistake.

To cut the long story short, after swapping the check valves in the pump and cleaning/blowing them, then measuring the fuel delivered I have:
1. Spark plug on cylinder 3 is dry (when running on idle for 5-10min) and it has very bright, very lean color; the rest of the plugs are sooty, like too rich. It is same as on the picture posted above).
2. When I pull the leads off the plugs when engine is running - I have very visible effect on cylinders 1,2,4 and 6, a bit weaker effect on cylinder 5 and a very faint effect on cylinder 3. The engine changes note when you pull the lead on cylinder 3, but it is a change that is hard to notice.
3. The amount of fuel delivered from lines (before the injector) either at the IP or at the end of the line is 0.8-0.9ml for line 3 and 1.1-1.2 on line e.g. 6. This is 15 seconds crancking (separate for both measurements, linkage at idle). So the difference is there, but not as substantial as I thought.
4. While we had the IP with check valves removed, I verified that the pistons are moving up and down and the cylinders are not rotating. The IP rack moves freely and it comes back to where you pushed it from.
5. I swapped the ignition leads of cyl 3 with cyl 2, but the effect stayed with cylinder 3 (to follow an advise of one of you).
6. I did a lot of other check ups as per your advise and as per what i managed to find in the forum (e.g. compression, engine timing, CSV, WRD etc). I have 123 ignition.
7. I have no other symptoms of the misperformance of the car than vibration on idle, overall going rich with cylinder 3 semi-working. It starts and runs great.

My questions would be:
1. Overall - what do you think? 
2. Given the smaller difference in fuel delivery (say 0.85 vs. 1.15ml) - is fuel delivery the likely reason for weak work of cyl 3 or I shall look elsewhere (additional air coming through the manifold gasket, valve not opening fully, cam wear etc.)?
3. Shall I check the fuel delivery after injectors? I have eliminated injector as a cause before. What I am after is that some diffferences in fuel delivery may be off set anyway by opening pressure of the injector. There are also some tolerances there...

It is an important point as I think for fuel delivery I did what I could in the garage. I would have to send the IP for repair - long time, lots of money etc. without being sure if the fuel delivery difference can be the cause of trouble.

Please kindly let me know your thoughts.

Pawel

[450sl]

if you remove your return valve you should feel the IP nr3  piston move up and down.. ( do this with an toothpick)

[Pawel66]

Thank you!

Did that. It does move up and down. As I wrote: the piston moves up and down, the cylinder is not turning with it, the rack moves freely and comes back to where it was when pushed.

[450sl]

If you where a bit closer to me i could lend you my spare IP

[Pawel66]

Thank you! This is the idea I would not dare to ask... but it would be very useful indeed! The distance is not that big and I would pay for courier and insurance certainly.

Look, I do not have the specs for the IP and tolerances of variance for fuel delivery between cylinders. All I know is what was mentioned on the forum on injector opening pressure tolerance, which is quite substantial.

What I think I would do, if there is no other advise on the forum, is a couple of simple checks of the other possible causes:

1. I would check the fuel delivery after injectors on line 3 and other line (I am just not sure here if to cranck the engine or just run it). See what the diffrence is there.
2. Check the current clearance for inlet valve on cyl. 3. When we set it some months ago it was on the spec, let's see what is it now.
3. Check the cam height (I think I can do it when I have the cam in level position) vs. other cams heights.
4. Look at the valve if it looks or moves different than the other inlet valves.
5. Check for "unauthorised" air caught from the side - I guess spraying some starter near the intake manifold gasket would tell if this is a problem.

There must be a bloody reason for this cylinder to be so lean...

These are relatively simple and inexpensive tests. Even if I have to remove cylinder head to do something with the vlave or if I have to have new camshaft manufactured - this is no problem and not too high cost.

The biggest worry is that I cannot fix the IP in Poland. The shops here are perfect with diesel. A pump like ours - no spares, no specs and overall - a mystery. I had my pump done at Bosch - well, it works in essence, but you see we are struggling with it. When I pulled out check valves, they had old gaskets... It takes months to have them look at it. So I have to send it abroad. It is costly, so I will have beans for dinner for a month, but it may be a lot of time - and the season is just starting...

Thank you again for your kind attention!

Pawel

[450sl]

 Pm me

 Mark

[Pawel66]

Let me please provide further update on the topic. I am doing as for me the biggest value lays in those threads that were describing activites and ended with positive results.

I did the checks I was describing in the previous posts:
1. We sprayed quite an amount of flammables around the places that could be suspected of letting the unauthorised air into the cylinder 3 (manifold, injector, CSV, etc.). Nothing.

2. Checked the clearances of valves, shapes and condition of rockers and other elements, particularly the ball pins, compared conditions of valves in cylinder 3 to others. We found nothing that would be out of norm or diffferent.

3. Checked the cam hights - differences between cams heights for inlet valves were 0.1mm. So cams are ok. Not worn, visibly ok.

4. Then we did another measurement of fuel delivery - from injectors: all cylinders, one after the other, 30seconds, engine running on idle. Here the amounts were 6 to 6.5ml, but cylinder 3 had 5ml. Now: the tolerances in Bosch specs on fuel delivery are small, around 5% for higher speeds and around 15% for idle if I read it right. My difference is 25-30%.

So I guess this is it. I have to fix the pump. Since I did the exercise with the check valves (and this is the only thing I could do myself), what I think I will do - my mechanic will take the pump to the place where it was fixed - Bosch. And will stay there so that they fix it when he is there. We will see what will come out of that. I think they are able to regulate the flow if you make sure they really do it. I will not have to pay for rebuild as I did that before.

I have made the mixture richer again so that the cylinder 3 runs for now untli we are scheduled at the service.

[stickandrudderman]

Please be sure to come back with the results for the sake of future readers. Unfinished threads are very irritating.

[Pawel66]

Certainly, will do.
I find it very tempting - it must be fairly easy to adjust volume of fuel per section in the FIP. I see there are these screws there under every plunger - maybe they are there for this purpose... Curious what will happen when you turn them a bit...