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Discussion Starter #1
More interesting was what happened when I turned the water injection off- last itme the power went up, basically because water doesn't burn
. This time however, the power dropped slightly and we could just hear the onset of pinking (knocking).

The overall lambda was OK but I still felt it had to be a fuelling problem as the DI cartridge was only a couple of weks old.

Anyway, today I pulled the plugs out and this is what I found... 1 & 4 black, indicating too rich, 2 & 3 (2 especially) brown/white indicating too lean. So, clearly the lambda had been correcting overall running 1 & 4 rich and 2 & 3 lean.

I've swapped injectors 1-2 and 3-4 and will have another look at the plugs in a day or so.

The injectors all have the same resistance, and are relatively new, so I'm a bit confused to say the least as to what might be causing the problem.

Any ideas?

[edit] for those that don't know, car is a 93 Trionic B234
 

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The intake manifold can't feed all 4 cylinders exactly the same way, and it's reasonable that inner ciylinders can get air more easly than the external cylinders.

I hope this is not your problem, I would have no clue to solve this , seems like a limit that a non-racing engine can't pass.

Just a thought.
 

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Has anyone had a problem burning their plugs? This is the second time the plug on cylinder #2 looks burnt, but it is only that cylinder. The rest of my plugs look fine and the deposits at the tip all look like the one pictured. The top spark plug is brand new and unused.

 

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Discussion Starter #6
Originally posted by BillJ:
[qb]Mark, nothing to do with that baffle you removed from the intake, I suppose? I know it's only supposed to be useful at idle, but...

Then again, I think you've had it running properly since you took it out? [/qb][/b]
That's a good thought, Bill, but as you say it has been running happily since I took it out- and it was only over #4 cylinder, and apparently it's function is to stop too much air rushing straight in to #4 at lower revs/load- and as the state of #4 plug indiicates the opposite effect I think I can rule it out.

My own thoughts are leaning towards an injector problem- 'll take a look at my plugs again tonight and see what the state of play is. Maybe I'll have some more clues then.
 

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One thing you should remember when examining spark plugs is they only give an overall indication to the running conditions at the time the engine is stopped. To get a clear indication you need to do a 'plug chop' which means at the running conditions you want to check you have to switch the engine off and coast to a stop and then pull the plugs...letting the engine tickover before stopping will invalidate the test and the colour of the plugs.
i.e to check correct mixture at full throttle you need a long straight road and need to be WFO in say 3rd until max revs then kill the engine, coast to a stop and check then.
 

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Discussion Starter #9
Having swapped them for a week or so (1-2 and 3-4), I took a look again today...





Not happy . It's never blown a head gasket before, even during the extremes of overheating that led to the last head cracking!
 

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Discussion Starter #12
It gets worse... or more confusing depending on your point of view... yesterday, fearful of damage, I pulled the APC solenoid fuse so I could only run base boost.

Tonight, I went to my local garage to have a block test- basically a device to determine whether there's any combustion vapour working it's way through the coolant.

Result?

Negative.

Scratching head, I decide to grab Tech II to pull fault codes. Result? P0605 indicating a fault with the ECU. Reset it. Reset boost. Put APC fuse back in. Go out for drive with Tech II still attached. OMG!!! Flying machine- in this weather??? All the
fully restored, but still overboosting (I actually heard pinking at 1.9 bar in 3rd gear
). Don't have a prob with overboosting, known issue, have got a cure up my sleeve . Lethal acceleration in 2nd (managed to unstick the Bridgestones round a corner in the dry!!!!)

Now all this might make sense if I hadn't previously disconnected the battery for a while, which would have cleared the fault codes and reset the base boost, yet still had no improvement.

So maybe I have a problem with the ECU, but I wouldn't expect that to cause the apparent rust on #2. I'll try it for a day or so and see how it looks. It's always (remotely) possible that I do still have a gasket problem but it's only leaking into the cylinder.

I'll keep an eye on it for a while and see what happens... grr grrr grrrr
 

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Mark, you might have moved on a bit now, but here are the plugs from my Aero for comparison with a car in a not-greatly-dissimilar state of tune (similar peak boost pressure, etc.)

If it helps to know, the engine was idling for a minute or so before I let it cool, then pulled the plugs. They all look the same to me.



[Edit: the order, left to right, is 1-2-3-4]
 

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Discussion Starter #14
Thanks, Bill - they're what I would expect to see, based on previous experience. As I said, I think the next thing to do is take a look at mine again tomorrow...
 

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Sorry to hear about this Mark. I do just wonder whether the cylinder head polishing and porting might have anything to do with your problem... I'm sure that the work you had done was to a very high standard but if too much meat is taken from the chamber, different comp. ratios can result. Have you checked the compression ratios? The other issue is how consistently the ports were ported and chambers polished.

ERP,

Watch out! I burned two sets of plugs before I melted no. 2 cylinder


Alanb
 

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Discussion Starter #17
Alan, AFAIK the process does not touch the combustion chamber other than to install the larger valves, so compression ratios should not be affected. I am tempted to undertake a compression test though (hot and cold).
 

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Discussion Starter #18
Originally posted by Mark in Ireland:
[qb][How come you have a Tech II lying around!  
     :eek:     I've been after one of them for ages now.    [/qb][/b]
I don't, I just have a good relationship with my local indy specialist who has one
 
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