R500 K Emissions. HC 1,000ppm Solved again - several years later.

[anthonym]

ok so we failed again, miserably, still 10 x too much HC Hydrocarbons. Reading 1,000 where we need under 100 (as previously successful)

This is after lengthy sessions with Steve G on the maps (remote access). Dave at Powerspeed says it cannot be the cat even if the cat were faulty because the error is so large. 

Replaced

injectors plug leads (except centre), dizzy cap (not rotor), alternator pulley back to standard size so it works at tickover, engine loom replaced last Winter (Thanks Revilla), two coolant temp guages (ECU and Stack) give same readings, Cam belt replaced with great care (thanks SM25), maps tweaked extensively (thanks Steve Greenald). She does not use oil or coolant. Power is as massive as ever.

Tweaking the maps in "live adjustments" up or down only made matters far worse.

Compression test two years ago:  (hot engine wide open throttle.)

on 26/6/17 (1) 206 (2) 210 (3) 220 (4) 215 (thanks SM25)

and today (hot engine wide open throttle.)

on 09/7/19 (1) 170 (2) 180 (3) 190 (4) 185 BUT may be depressed because I was limited in strength to push down while also pressing the starter button inside the car.  I will redo it with assistance, but these at least look consistent as between each other. 

Latest suspects:

A Spotted a massive short from centre dizzy plug to dry sump tower, but when the plugs were reinstalled this stopped.

B No 3 reads 3 (cfs?) on the airflow whereas 1,2 and 4 read 5. There is no facility to adjust except in tandem with no 4.

Static gap is currently 1mm per Minister guide. Today CC say it should be "5 and 5" meaning airflow 5 and static gap 5mm. 

In the above the static gap is 4mm too little meaning less airflow, except the airflow is perfect at 5 as recommended by CC, except No 3.

Dave at Powerspeed observed that it may be less air being demanded rather than the airflow being restricted, which indicates a "mechanical" problem: burnt valve, worn cam or other fault - and that's not fixable here as far as I know.

It seems to me that this leaves a (my first) leak down test, so that will be fun.

 This No 3 issue (including its sooty plug) has been around for a very long time.

My questions:

Could it be as simple as the static gap is too small at 1mm?

Is there any way to adjust TB No 3 alone? Will at least averaging 3 & 4 make any difference?

Anthony

[anthonym]

This is what 5mm looks like compared to my existing gap, these are both 3 & 4

That’s a 5mm drill bit.

[anthonym]

So it strikes me that with such a small gap, any % difference between the two could be massively empasised.

the difference between 3 and 5 is 40% of five. (Or 66% of three)

At a 1mm gap that equates to 0.4 of a mm of tolerance, 

whereas

at 5mm gap that 40% equates to 2mm 

so 2 divided by 0.4 = 5 meaning to achieve the same percentage constriction at 5 mm as at 1mm requires an increased margin of error of 500%. 

Conversely to achieve what at 5mm is a 500% error at only 1mm requires a difference  so small i.e. 0.4mm is to be practically impossible to measure and certainly to see. 

This will of course blow the TPS position out of the water.

ok, so told NOT to do that.

http://www.turbosport.co.uk/showthread.php?t=154681&p=1676676&viewfull=1#post1676676

cleaning no 3 TB is a possibility

[oilyhands]

You say that altering the fuelling in live adjustments made it much worse, that doesnt make any sense. If you reduce the fuelling sufficiently the engine will run lean and eventually stop running. During this adjustment there will come a point where the hydrocarbons drop through the floor and the NOx goes up. It’s unlikely that the point you are at now is the lowest the HC can go. Balance the TBs and set them so you have approximately 5.5kg /hr. This is the correct airflow for idle on your engine, Then adjust the fuelling with idle control switched off, as you lean off you will feel the engine start to stumble, at this point the fulling will be on the cusp of Stoi/lean and HC will be lower.

Oily

[anthonym]

That’s what I thought. However

the airflow is at CFS 5535 for cyls 1234.

That is a 40% error induced at cyl 3, being delivered fuel intended for an airflow of 5 cfs. 

So whatever we dowith the maps that imbalance doesn’t change. 

The barrels can be adjusted only in pairs. I gather today that one pair should derive a total of 10kg/hr , though the Workshop Notice 18/12/2002 expects this to be say 4.5/5.5 not down to 3. So this proposes I reset that pair to say 6/4 . However, that’s still 20% less airflow so that cyl will be still rich. 

I gather as above that just one rich cylinder can create excessive HC. The limit here is 100ppm. Thelast successful test we were at 75ppm.  (I now know). So this IS something that has changed. 

Given this engine is intended come to you for “refresh” in a few months I am loath to engage in doing it now. Titan and CC are both due to comeback to me shortly. Something called Silverstone currently has their attention. 

All the rehab work so far is in any case efficacious and exposed all sorts of other issues, but .... Currently I am working on Dave@Powerspeed’s view that this richness in cyl 3 is indeed capable ofcausing the 10 x HC. The sooty plug adds to this. 

Also seems to me that as everyone has said, first balance the airflow, which I did, but methinks the degree of difference should not be (ie is not acceptable) what I am seeing. A matter of degree. Which renders the mapping helpless because it can’t map per cylinder and is therefore given bad data for cyl 3.

Elephant in the room  may be the case. 

anthony

[anthonym]

Or should I rebalance regardless?

[anthonym]

It may be. There is nothing wrong with the Titans and valve or timing troubles are causing insufficient air draw, I gather. However, there is no loss of power or poor running , far from it. 

[CageyH]

Can you confirm what units you have used to balance the throttle body air flow?

You have mentioned both CFS and Kg/H. They are not the same.

[anthonym]

The Kg/H are from the CC document.

The CFS is me assuming that's what the numbers on the airflow meter are.

[anthonym]

so. if I remove the throttle bodies, attach a hoover to each one to suck through, test each one with airflow meter. If it is the same or close even for no 3 as the others, then the problem is in the engine not the TBs.

[oilyhands]

I doubt that would work as the juxtaposition of each TB against the other will vary as will the opening, they need to be bolted to the head in the correct alignment. 5,5KG/hr is the correct airflow at idle.

[anthonym]

Can’t admit to really understand that, which is fine. These are adjustable only in pairs, so I was thinking that whatever they may be set at, the offending pair will show the same hoover flow or they won’t, and if they are the same it’s an engine internals problem Only you can fix.

[aerobod - near CYYC]

I would say it is worth a try, would indicate if your #3 roller barrel is leaking around the barrel itself. Perhaps collect datapoints for different openings on each barrel and plot them, should give a line or curve that has an offset if there is leakage around the barrel. Assuming you can get a consistent vacuum from the vacuum cleaner. You may also find that #4 is the culprit for leakage if #3 is running rich relative to #4

[anthonym]

Thanks James.

I've ordered some new ones from Titan. I 'll have these old ones refurbished by Titan and decide what to do with them after that. If they are goosed then keep or sell for parts. I usually never sell anything, just not in my skillset.

I've posted an "interest?" in Marketplace.

Anthony

 

p.s. why? I think it's because one of the most consistent comments I am hearing is the word "wear". 20 years is a long time. Time enough I feel.

 

p.p.s. then I'll do the Hoover test, just to see  :-)

[anthonym]

 

 

Not sure where you are going with the dial gauge. Let me explain. You're looking for something that is reducing airflow from 5 units (whatever they were) to 3 units. That's a lot.

The things that affect air flow will be

1) Cylinder volume (all the cylinders will be the same).

2) How fast the engine is turning (again, all cylinders will be the same).

3) How well each cylinder can fill with air.

Point (3) is a function of how much resistance the air meets on the way in, and can be down to things like the valve lift, valve timing, shape of the ports, air filter etc. etc.

But the point is most of these only make much difference on the limit when the engine is at high RPM and struggling to get air into the cylinders fast enough.

At idle, the cylinders had loads of time to fill and so it would take a major obstruction to make a big difference. There's one massive obstruction in there that makes most of the difference - the throttle valve (or roller).

Unless your valves really weren't opening much at all it wouldn't kill the airflow at idle. And if that was the case

1) It would drive like a bag of spanner (and you say it drives fine).

2) It would sound like a bag of spanners (you know what old engines sounded like when the clearances were too slack, loads of cam rattle, well it would take many times that much extra clearance to kill the breathing, it would sound like it was knocking itself to death).

So if I were you I would whip the cam cover off (takes 10 minutes!) and have a look for anything really obvious. If you're really still suspicious, check them with a feeler gauge as you suggested.

I don't know what the clearances should be cold but you're really only looking for a big difference on cylinder 3 relative to the others. If it all looks in on piece and there are no silly clearances then it won't be valves.

The only other things I can think of that would give you a massive imbalance in air flow would be pretty major compression failure, but you would know about this in other ways (i.e. your compression tests were fairly even, it's not drinking oil or blowing a gale out of the breathers).

 

[anthonym]

these throttle bodies act in pairs and have no adjustment between them. At idle the static gap is very small, starting at a standard static gap of 1 mm before balancing.

So if no 3 is a mere 0.4 of a mm less open than no 4, that’s a 40% difference, at idle, but as engine speed increases that 0.4 of a mm difference remains the same and becomes insignificant.

I am going to replace them this week anyway, and the above is the only explanation I can dream up given those parameters etc. In other words in my theory the issue gets worse pretty much only at idle.

edit: so I should check the airflows at higher revs.

 

 

[anthonym]

[CageyH]

I found your problem.

You have throttle bodies for 4 cylinders, and valves for 5.

 

[revilla]

Haha! They look fairly clean though in those pics.

[CageyH]

The picture tells you there is still a valve.

The other side would be more interesting.

[anthonym]

those are all No 3. others short;ly ish

[anthonym]

note to self from regin

 

Is it the M8's fixing the TBs to the head?

If so I'd do them up at around 20Nm (Same as sump pan M8's) and start from the centre and work out. If the bolts are A - B - C - D - E counted from the pulleys at the fron of the engine I'd do them up in the order C-D-B-E-A.

Hope that helps.

[anthonym]

Need CO under 0.5

[anthonym]

However the above isa celebration of HC down from over 2000ppm to mostly under 100ppm, with new Titans

[aerobod - near CYYC]

So, it sounds as though your main problem may have been leakage around the throttle barrel on #3?

Perhaps still needs a bit of nudging on the trims or Lambda targets? CO2 looks not too far off at 14%, but slightly high (indicating too much carbon to air, or a bit rich mixture) assume CO next at 0.89% (also high due to a lack of oxygen), O2 at 0.41%, HC at 65PPM, NOx at 46 PPM and Lambda at 0.99? May just need to get the Lambda up at 1.00 to 1.05 at low revs and low throttle openings to get the CO down, but too high will drive the NOx up.