cjj
Part of things
Posts: 275
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Aug 13, 2020 20:52:42 GMT
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Thought I'd pop over a thread for ideas, as old cars seems to be the right choice. My CityCoupe (just qualifying as Retro, perhaps) was bravely shoved in for its MOT today. I've rebuilt almost the entire car and was thinking, driving it over there, 'this thing is tight as a drum'. It arguably drives better than new (has various improvements over standard spec). Anyway, these were my emissions results: Some background: - Recently serviced with genuine Merc oil & Filter - New NGK plugs x 6 - Recent Bosch Upstream (manifold) Lambda - K&N Element filter - Aftermarket exhaust that is a little old, but has a good downstream sensor and still very much has a cat - Full coolant change in the last 1000 miles with new thermostat. Gets up to temp and stays there nicely. The old plugs didn't suggest any wild over-fuelling and looked about par. The set on the left are the bottom three, which I believe are always a bit sootier (think they're wasted spark). The exhaust is a little old and I had a bit of bother with it blowing a little from the manifold connection (it's obviously just the one box job), but the results to me don't just read "air leak". I've ordered some Cataclean as I have read that they do wonders (especially on these, with similar results), but thought I'd mention it to see if anyone else had any other ideas? I used to be bang on for diagnosing emissions stuff when I was into shedding years ago, but I have to admit that I'm back to basics now as I've forgotten most of it. From what I can recall, high on all counts suggests perhaps that the cat is a bit weak, hence cataclean, as opposed to just high lambda (air leak), or high CO (cold/needing a service), or high HC (rich). It's probably the first time I've had a full house. Any experience on Cataclean, or alternative ideas? I'm not even sure how quickly it gets to work.
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Last Edit: Aug 13, 2020 20:53:01 GMT by cjj
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stealthstylz
Club Retro Rides Member
Posts: 14,829
Club RR Member Number: 174
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Aug 13, 2020 21:51:16 GMT
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Does it use oil? Most of the Smart engine rebuilds I do is because they won't go through emissions as they're burning as much oil as fuel/air.
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cjj
Part of things
Posts: 275
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Aug 13, 2020 21:59:36 GMT
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Does it use oil? Most of the Smart engine rebuilds I do is because they won't go through emissions as they're burning as much oil as fuel/air. Nope, fully rebuilt (also: you'd see it on the plugs). There's not a lot of it that hasn't been rebuilt, though, which is the curio.
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Last Edit: Aug 13, 2020 22:00:03 GMT by cjj
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stealthstylz
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Club RR Member Number: 174
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Aug 13, 2020 22:04:07 GMT
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It's not just all the collected curse word from before rebuild burning out of the exhaust is it?
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cjj
Part of things
Posts: 275
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Aug 13, 2020 22:12:50 GMT
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It's not just all the collected curse word from before rebuild burning out of the exhaust is it? No idea. The exhaust actually came off another I was breaking, so it's possible. I am tempted to clean it out, although I'm not sure what with. I have some premium thinners that I was thinking might be useful to swill it out with?
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stealthstylz
Club Retro Rides Member
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Club RR Member Number: 174
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Aug 13, 2020 23:23:39 GMT
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We cap the end off at work then brim them with neat traffic film remover then leave overnight and rinse out. It could be the cat that's knackered though if it's been burning oil beforehand.
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Aug 14, 2020 20:47:59 GMT
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Before you worry about the cat you need to get the lambda correct, it could be out because of the sensor but you have changed that, lamda being out means it can't trim the fuel because it has run out of tuning range or the cylinders are not all behaving the same. It could be an injector or something displacing air such as piston or valve leakage or crankcase fumes coming through the breather.
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Last Edit: Aug 14, 2020 20:55:47 GMT by kevins
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Evilution suggests you’d get the engine check light on if it was a lambda sensor issue... www.evilution.co.uk/421I wonder if the exhaust lambda is located properly- I guess you’d have spotted a problem during rebuild if it wasn’t seated or was moved elsewhere since the exhaust was fitted. I remember back in the day I had an emissions test on my city coupe with a brabus exhaust fitted to compare results against an aftermarket smart exhaust that had been produced in the UK that was giving questionable emissions results. Let me see if it’s in my emails nearly 20 years on...
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mk2cossie
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As there is quite an exhaustive list of new parts fitted, are they all guaranteed genuine parts? Are the spark plug gaps correct, and is the upstream lambda sensor a genuine Bosch one or possibly a universal one?
It may just be the second catalyst, but getting live data and checking the readings would be my first port of call
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cjj
Part of things
Posts: 275
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Aug 15, 2020 18:09:58 GMT
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Evilution suggests you’d get the engine check light on if it was a lambda sensor issue... www.evilution.co.uk/421I wonder if the exhaust lambda is located properly- I guess you’d have spotted a problem during rebuild if it wasn’t seated or was moved elsewhere since the exhaust was fitted. I remember back in the day I had an emissions test on my city coupe with a brabus exhaust fitted to compare results against an aftermarket smart exhaust that had been produced in the UK that was giving questionable emissions results. Let me see if it’s in my emails nearly 20 years on... There isn't any scope for the oxygen sensors to move anywhere. One goes in the manifold, one after the cat. With regards to an EML, it depends on the failure mode of the sensor. I have a few spare post-cat ones that look different to the one that was in the downstream location, so I may give one of them a go. As there is quite an exhaustive list of new parts fitted, are they all guaranteed genuine parts? Are the spark plug gaps correct, and is the upstream lambda sensor a genuine Bosch one or possibly a universal one? It may just be the second catalyst, but getting live data and checking the readings would be my first port of call Yes, all parts are genuine in such that the plugs were NGK, the sensor is a genuine Bosch and also the correct part number. There is only one catalyst. Did some live readings earlier on the warm up, with nothing untoward going on. It's going into closed loop Upstream is switching okay (it's the newish Bosch one, < 500 miles on it) As the Delphi system seemed to be a right PITA to find the downstream, I used torque: Nothing's jumping out at me so far. I put a borescope into the exhaust to look at the cat, which seemed fine (no obvious signs of damage/blocking) and filled it up with some thinners for most of the day. It came out like this, this afternoon, so it's done something at least. The thing that makes me believe it's not just the cat being weak is that there is potentially signs of rich fuelling. It's turbocharged, so any air/boost leaks are going to be obvious really. The top PCV valve seems fine but I've ordered a new (genuine) one as it has 2013 on it. I've dumped a bottle of Cataclean in there too, so will need to give it a drive once I've swapped out the downstream sensor and put it all back together
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Last Edit: Aug 15, 2020 18:10:49 GMT by cjj
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Rich
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Aug 15, 2020 19:19:41 GMT
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That bank 2 sensor looks very flat-line. Like, not actually sensing flat line. I’d expect a small variation on a graph of a downstream. Shouldn’t be huge but I’d expect to see something.
In regards to I believe freshnmintys comment about engine RPM most emissions systems require a tach sense Based off alternator pulsing for the test to commence, ie, a battery connection, and even at a slightly incorrect RPM it should still fall within the emissions Expected results to a point.
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cjj
Part of things
Posts: 275
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Aug 15, 2020 20:29:48 GMT
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That bank 2 sensor looks very flat-line. Like, not actually sensing flat line. I’d expect a small variation on a graph of a downstream. Shouldn’t be huge but I’d expect to see something. In regards to I believe freshnmintys comment about engine RPM most emissions systems require a tach sense Based off alternator pulsing for the test to commence, ie, a battery connection, and even at a slightly incorrect RPM it should still fall within the emissions Expected results to a point. It was done manually according to the sheet (engine is a PITA to get to, and alternator isn't accessible) but I do have a taco pod anyway.
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Rich
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Posts: 6,234
Club RR Member Number: 160
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Aug 15, 2020 22:02:14 GMT
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That bank 2 sensor looks very flat-line. Like, not actually sensing flat line. I’d expect a small variation on a graph of a downstream. Shouldn’t be huge but I’d expect to see something. In regards to I believe freshnmintys comment about engine RPM most emissions systems require a tach sense Based off alternator pulsing for the test to commence, ie, a battery connection, and even at a slightly incorrect RPM it should still fall within the emissions Expected results to a point. It was done manually according to the sheet (engine is a PITA to get to, and alternator isn't accessible) but I do have a taco pod anyway. Basic battery connection is all that’s required but not all test stations are using the kit yet and there are some cars that they just can’t use them on but that’s by the by really. I’d be questioning that flatline on the downstream, see what swapping it for a different one does.
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mk2cossie
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Aug 15, 2020 22:32:11 GMT
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The downstream is supposed to be flat, its to tell the ECU the catalyst is functioning properly I'd be more concerned with why the upstream isn't switching quickly enough and consistently if that reading was taken on a fully warmed up engine
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cjj
Part of things
Posts: 275
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Aug 15, 2020 22:39:47 GMT
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It was done manually according to the sheet (engine is a PITA to get to, and alternator isn't accessible) but I do have a taco pod anyway. Basic battery connection is all that’s required but not all test stations are using the kit yet and there are some cars that they just can’t use them on but that’s by the by really. I’d be questioning that flatline on the downstream, see what swapping it for a different one does. The battery is also a bit of a pain to get to. I doubt many people would know where to find it As mentioned above, the post-cat sensor shouldn't switch. 0.45v is, generally, spot on. Hence confusion.
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Last Edit: Aug 15, 2020 22:43:15 GMT by cjj
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Aug 15, 2020 23:17:22 GMT
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So the engine is showing as running very lean on the calculated lambda - your cat is not doing anything at that point, limit is about 4% out of stoichiometry.
However your plugs do not look lean so I am thinking exhaust leak before first sensor. This would richen the engine hence high CO and HC but then throws off the calculated lambda. Can we see Short and Long fuel trims at idle and 2500 please.
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Last Edit: Aug 15, 2020 23:22:37 GMT by wightfug
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There isn't any scope for the oxygen sensors to move anywhere. One goes in the manifold, one after the cat. The second sensor plugs into the exhaust as standard so I meant does the aftermarket exhaust have the hole for the sensor to plug into or has the sensor been moved out of the way and not functioning but as you’ve done a full rebuild I think you’d already know if that might be the problem any way. Was the turbo manifold replaced as part of the rebuild? I’m sure you know they’re prone to cracking so potentially has a non visible hair line crack that is letting gases escape. Just thinking along lines of above suggestion about leak before first sensor. Edited to add: It is a common fault on the old 600 turbo for cracks to appear in the manifold. This leads to loss of pressure and escaping waste gas, if this occurs the lambda sensors get confused by the readings and the engine will pulse under normal driving. The cracks aren't very easy to spot but some can be very obvious as seen below.
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ChasR
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Where did you buy the pre-cat 02 sensor from?
I bought my NTK sensor for a French company known as MA for short. Like the oil cooler on my M3, it was defective, but natuerally, everyone loves that company as it's branded names for cheap, albeit with potential quality issues (I wonder if they sell rejects TBH!).
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cjj
Part of things
Posts: 275
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So the engine is showing as running very lean on the calculated lambda - your cat is not doing anything at that point, limit is about 4% out of stoichiometry.
However your plugs do not look lean so I am thinking exhaust leak before first sensor. This would richen the engine hence high CO and HC but then throws off the calculated lambda. Can we see Short and Long fuel trims at idle and 2500 please. I've got little to no chance of getting away with fast idle revs unfortunately - I have bad neighbours. I might catch a chance whilst they are out, but it's not a viable option. Note: It isn't because the car is loud - they are just sociopathic. I get practically harassed if I drop a spanner.
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