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What have you done to your Elgrand today?

Not on my own Elgrand but on a customer Elgrand... It was brought to me on a trailer a few days ago running terrible, the owner (who is on here but I won't say who it is, they can identify themselves if they wish) thought the problem might be plugs/coil packs. I did some diagnostics... The LPG ECU had logged that petrol injector pulse duration was very short compared to normal for any given manifold pressure. I did my usual electronic cat test which revealed bank2 was flowing more air than bank1, meaning it was possible there was a front cat blockage on bank1 (the owner said rear cats had already been decored). I removed the drivers side (bank1) rear cat section, no cat debris in there, I stuck a bit of pipe through it, yes it was decored, stuck a camera through it to confirm no bits of cat in it, it was clear. Managed to stick the camera up the exhaust to see the rear end of the front cat on the drivers side, it looked normal. Still it seemed to me (due to the other evidence) that the front drivers side (B1) cat was blocked, so I removed it, drilled the spot welds and corner seam welds holding the heat shield around it, cut it open, decored it, welded the cuts in the cat, put the heat shield back on re-welded the spot welds and seem welds. During the decore I could see that indeed the cat material was damaged, melted in places, even though this wasn't evident when I checked with the camera, so it was already seeming I'd done the right thing. The owner had supplied new plugs and coil packs, the plenum has to come off anyway to remove the front cat(s) the way I do it (which is more or less the same way that I did the write up about years ago). While I had the plugs out I did a compression test, all good at around 200psi and all well within 10% of each other. I did notice that the coil lead to number 3 cylinder could have maybe been loose but I was fitting the new coil packs and plugs anyway. Put it back together with the drivers side front cat now decored, new plugs and coil packs, she ran sweet. Took it for a test drive, all good! The owner will be able to collect and drive it home now instead of having it collected on a trailer and then scrapping it. Good result, the owner is very happy :-)
 
Lpgc said:
Not on my own Elgrand but on a customer Elgrand... It was brought to me on a trailer a few days ago running terrible, the owner (who is on here but I won't say who it is, they can identify themselves if they wish) thought the problem might be plugs/coil packs. I did some diagnostics... The LPG ECU had logged that petrol injector pulse duration was very short compared to normal for any given manifold pressure. I did my usual electronic cat test which revealed bank2 was flowing more air than bank1, meaning it was possible there was a front cat blockage on bank1 (the owner said rear cats had already been decored). I removed the drivers side (bank1) rear cat section, no cat debris in there, I stuck a bit of pipe through it, yes it was decored, stuck a camera through it to confirm no bits of cat in it, it was clear. Managed to stick the camera up the exhaust to see the rear end of the front cat on the drivers side, it looked normal. Still it seemed to me (due to the other evidence) that the front drivers side (B1) cat was blocked, so I removed it, drilled the spot welds and corner seam welds holding the heat shield around it, cut it open, decored it, welded the cuts in the cat, put the heat shield back on re-welded the spot welds and seem welds. During the decore I could see that indeed the cat material was damaged, melted in places, even though this wasn't evident when I checked with the camera, so it was already seeming I'd done the right thing. The owner had supplied new plugs and coil packs, the plenum has to come off anyway to remove the front cat(s) the way I do it (which is more or less the same way that I did the write up about years ago). While I had the plugs out I did a compression test, all good at around 200psi and all well within 10% of each other. I did notice that the coil lead to number 3 cylinder could have maybe been loose but I was fitting the new coil packs and plugs anyway. Put it back together with the drivers side front cat now decored, new plugs and coil packs, she ran sweet. Took it for a test drive, all good! The owner will be able to collect and drive it home now instead of having it collected on a trailer and then scrapping it. Good result, the owner is very happy
Click to expand...
Caught it just in time then simon.
What makes a cat clogg or melt rather than crumble, oil, rich mixture ??
I’ve known garages put cleaners in when they suspect clogging or blockage often making things worse.
Nice to know this one has possibly been saved
 
Highway Dave said:
Caught it just in time then simon.
What makes a cat clogg or melt rather than crumble, oil, rich mixture ??
I’ve known garages put cleaners in when they suspect clogging or blockage often making things worse.
Nice to know this one has possibly been saved
Click to expand...

Obviously they melt due to high temperature. In this case I reckon the high temperature was caused by one or more of 1. some pre-existing partial blockage inside the cat, 2 if the coil on cylinder 3 wasn't properly connected (or if there was a misfire on any of cylinders 1/3/5 on bank 1 due to an ignition problem) it would cause that cylinder to pump air and fuel into the cat on bank1. 3. If the mixture differed on cylinders on bank1 (1,3,5) the lean cylinders would pump excess air into the exhaust while the rich cylinders would pump excess fuel into the exhaust, the fuel and air can then burn in the cat/exhaust.

Yes mate like you I doubt a cleaning potion would have helped at any stage.

Caught it in time but then again it would hardly run as it was, so it probably wasn't like the owner would've been driving it around while the problem got much worse. I do reckon we caught it in time though, it doesn't seem to smoke etc. The owner made the right decision having it trailered to me for sure.
 
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I forgot to mention in my post #37481 above that I also checked to make sure an injector wasn't stuck open by physically looking into the ports while there was fuel pressure and by waiting 10 minutes after stopping the fuel pump then opening the petrol feed to the injector rail to make sure fuel pressure hadn't been lost, I found injectors didn't seem to be leaking and there was a squirt of petrol when I disconnected the feed to the rail, so both tests pointed to injectors at least not leaking or stuck open. After I put it all back together and it was running OK I watched the trace of the lambda voltage flicking to make sure it is smooth, it is. By watching the voltage flick at low enough rpm with fast enough sample speed you can detect if some cylinders are running a much different mixture than others because instead of a smoothish voltage change there's a sudden jump as the gasses from an offending cylinder pass the precat lambda probe then an equally sudden jump when the 'normal' burned mixture from one of the two other cylinders flows past the lambda sensor. Or in other words if you imagine watching the voltage gauge move 'around the clock', if each cylinder on the bank has close to equal mixture the dial on the gauge moves quite smoothly in one direction and then back again but if a cylinder has different mixture the dial will start to move around the clock but suddenly backtrack before continuing around the clock so the movement around the clock isn't smooth. You need a fast sample speed to be able to determine whether or not this is happening because at slow sample speeds the dial on the clock will seem to move in jumps anyway and you can't tell whether the voltage change is smooth. The rpms and engine load need to be low otherwise the exhaust gasses in the manifold can get mixed up too much before they reach the lambda sensor and/or the lambda sensor shield can trap some of the gasses so the voltage doesn't fluctuate as quickly as mixture changes flowing past it and/or the faster the rpm the faster the sample speed (and/or your eyes and brain lol) need to be to pick up on the unsmooth jumps in readings, in the case of eyes/brain you could set up data logging so you could review flick response in slowed down time but there soon comes a point where rpms mean sample speed is too slow to detect unsmooth voltage jumps in sampled data.
 
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It is my van that Simon @Lpgc has been working on I am more that happy that his hard work has paid off and I will be going by train tomorrow morning to collect it, I tried to change the coil pack and plugs myself but ended up with a multi cylinder misfire P0300 after doing so and it was at this point that I had a chat with Simon via this forum as I don't have a laptop and I would not know how to read the live data .As Simon has advised I will now need to look at the the other cat or replacing both with new that I already have just not got round to it
Thanks again Simon for your hard work and knowledge
Michael
 
When up to Yorkshire today to see Simon @Lpgc to collect my van Simon was busy with another client working on 🇺🇸 car so did not get to chat but he did give me a a little bit of my exhaust I will mount it and place in van as a reminder of what can happen when your front cats fail, I had no issues on the way home but did run out off LPG but this only worked to my advantage as it showed me the van worked OK on both types of fuel I just need to sort out the exhaust for one last time I do have replacement but with gravel driveway I will need to sort out a mat I can work on
 
Mot pass a few weeks ago, new rear pads fitted as they were an advisory item. Renewed some slider pins that I managed to begin to round last time. I got a mobile mechanic to help me, before i ended up needing to replace calipers due to poor DIY skills. Learnt a lot. The mobile dude said i was putting too much grease on the sliders, he said do a thin film all over. A touch extra to help the new top slider in with its rubber tip being new and tight to get in. Opinions welcome.

2 sofas taken to the council tip.

Still loving owning this machine. So far only discs, pads, wheel bearings and tyres have needed attention. Plus a secondhand rear matrix for a rare leak. Oh, there is sliding door cable job that is possibly permanently on hold.

Basically money well spent!
 
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