Son of a Shogun
A misfiring Mitsubishi Shogun provided Ryan with his latest challenge
Published: 17 January, 2023
By Ryan Colley, Elite Automotive Diagnostics
Did you know you can fix a misfire with a simple oil change? If you want to know how then please read on. I was recently tasked with looking at a mischievous Mitsubishi Shogun with a 3.5L V6 GDI engine. This engine a rare sight in the UK, which causes issues when trying to research the engine's configurations. The issue is a lack of available service information, as you will see.
I was contacted by a local garage who asked me to investigate a misfire this vehicle exhibited when running at idle. They informed me the misfire was permanent and that they had already serviced both the ignition system and the fuel injection system. They also informed me that they had carried out a compression test and that the results were equal for all cylinders so, they were a little stumped as to what the cause could be. In their eyes, they had covered all the possibilities.
I started by scanning the vehicle using our diagnostic equipment. A misfire for cylinder #5 was stored. I then used Mode $06 data in the EOBD menu, which records misfire data per cylinder. I could see there were 27 misfire counts for this cylinder, confirming the fault code to be correct. More importantly, no other cylinders were reporting misfires. This was a cylinder-specific issue. Next, I verified that both the ignition system and fuel injection system were operating correctly, as advised by the customer. This was done quickly using an oscilloscope, measuring coil and injector current. I could clearly see both ignition coil and fuel injector current events for the misfiring cylinder. I then carried out a relative compression test using the oscilloscope, and sure enough, all cylinders were equal and consistent. With this data, there was one other option; To connect a pressure transducer to the oscilloscope, remove the spark plug and install this pressure transducer into the cylinder to measure real-time pressure, plotted over time. If there were any valve train issues, we would likely see them using these pieces of equipment.
Pinpointing the cause
As you can see if you refer to Fig.1, there were certain anomalies occurring within this cylinder. We can clearly see that the exhaust pocket is rounded, which indicates a slow change in pressure, over time, as opposed to a quick snap-open of the exhaust valve, which is what is desired. You will also notice the exhaust plateau is shifted to the right, indicating that the fault is related to a valve duration issue. Because the exhaust valve is slow to open, it is also slow to close, causing it to affect the intake valve event. The intake valve opening event appears delayed. Logic should make it impossible for the cylinder to draw into a vacuum if the exhaust valve is connecting the intake manifold to the exhaust via the still-open exhaust valve
Knowing there are anomalies occurring in this cylinder I wanted to check a known-good, non-misfiring cylinder. So, I moved the test equipment from cylinder #5 to Cylinder #2, which was also on the opposite bank. As you can see from the idle, in-cylinder capture of cylinder #2 as seen in Fig.2, there is an obvious difference in the valve train events. The exhaust plateau is not shifted to the right, and we can clearly see that the exhaust valve event displayed a quick opening, which is desirable.
Accurate analyses yield confidence
Armed with this information we could then confidently inform the customer that there was an obvious valve train issue for cylinder #5. Before dismantling the engine, I connected a pressure pulse sensor to the intake manifold, and using a current clamp, synced to cylinder #2’s ignition coil event. I compared the intake pulls for each cylinder on this engine. This was simply to back up my diagnosis of a valvetrain-related issue for cylinder #5.
If the exhaust valve is opening late and closing late, then this will affect the intake pull and valve overlap for that cylinder. As you can see in Fig.3 and Fig.4, there is a 7-degree difference in the intake pulls between a good cylinder and the misfiring cylinder #5. Please note that the valve overlap event is different on cylinder #5 compared with the other cylinders. This now confirms more so that there is a definitive exhaust valve train problem on this cylinder which is affecting the intake valve event.
I then wanted to research this engine configuration to ascertain which type of valve train system Mitsubishi implemented. It was very difficult to find anything conclusive. Therefore, knowing the vehicle had a valve train issue, I advised the garage to remove the rocker cover and inspect the camshaft and lobes for any abnormalities. They reported back that the camshaft and lobes looked in good serviceable condition, with no excessive wear. At that point, it was very difficult to determine whether the valve spring or possibly the hydraulic tappet was causing the problem. I recommended that an oil flush should be carried out. If that rectified the issue, then we would know the problem was within the hydraulic tappet. However, if the fault remained then the issue would clearly lay with the valve spring or valve seat area.
Committed to a correction
After the oil flush and change was carried out, the customer stated that there was an audible ticking noise. However, this noise vanished shortly thereafter. With that, the misfire vanished as well, thus confirming that the issue was within the hydraulic tappet on this engine. The vehicle has run many miles since the flush was carried out and is no longer misfiring. I also took the liberty to check the Mode $06 misfire counters in EOBD data after the vehicle returned for its inspection. This also confirmed no misfires present.
Sometimes we are limited in the information we have available to us, as technicians. Although this is an inconvenience, employing logic and understanding can lead to a hypothesis of the likely fault, paving the way for intelligent tests that can flush the fault to the surface for us. This proves, once again, that the most valuable tool a technician possesses is the one between his or her ears.
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- It ain’t over ‘til it’s over
At the RingMechanika day run at the Ring/OSRAM H.Q in Leeds in May, one of the highlights was the workshop solutions van. The two companies use this to keep garages up to date with their latest products. In partnership with sales staff from factor partners like Motor Serv, Ring and OSRAM’s Ehsan Ali traverses the nation in what is effectively a mobile shop window and live action catalogue all rolled into one.
During the summer, Aftermarket took the opportunity to hop on board as Ehsan and the van made their way around Cambridgeshire, starting at the Motor Serv branch in Cambridge itself, and ending up at the nearby village Over.
Successful
Working with Ehsan on the day was Frazer Dunn, Motor Serv Business Development Manager. “I look after Cambridge Motor Serv branch,” he said. “We make appointments with the customers so we can visit them and make them aware of what we’ve got.” According to Frazer, this kind of live experience works really well: “It's been very successful. When they've seen it in here, they order it and it goes through to our branch.”
Eshan has been the man in the van for about a year now: “It has been really good. Mechanics prefer to touch, feel and use the products.” With only one van for the whole of the UK at present, Ehsan is a busy man: “We cover everywhere, we have one van and one of me.” With that, we were off.
Awareness
Our first stop took us a few miles up the road to Bottisham and local garage EC Autocare. Frazer’s contact at the garage was Tony who came out to view what was available on board. When asked how useful having a visit like this was, particularly on a busy Monday, Tony observed: “It's a good thing, because we haven't got time to go and have a look. We might be able to look through a catalogue, but you don't actually see what it's like, what the quality of it is. If you can see it, then you get a good insight into what you're buying and what you're actually getting. For me, it's a win all round. You have a look. They’ve got something there that you want, you buy it. If you don't get it on the day, you keep it in mind.” Tony was only buying a few small items, but took interest in a OSRAM work light, and then bought some headlight bulbs for his own car.
This was still a good result for Frazer though: “He's getting a few things today, but then now he's got the brochure, so he could bring into the branch and order.”
Ehsan interjected: “Sometimes it is difficult because the mechanics don't have a lot of time when they come on, so you've got to try to engage him straight away. I don't like to be too pushy though either because it's about awareness. I don’t want them to think I am just trying to sell them something.”
Collaborating with a BDM from the factor also means the full Ring/OSRAM range gets the attention: “Teaming up with the factor, the reps will know what we do as well. Garages often just think we just sell bulbs. They don't realise what other big-ticket items we have.”
Extent
The fuller extent of the offering came into play at our next stop, a few more miles in the other direction. Box Hill Motors serves the eponymous Cambridge suburb of Box Hill, and conveniently sits next door to local used car dealership Urban Car Company, who use Box Hill Motors for MOTs etc. First out was Stuart Saunders from Urban Car Company, who was interested in buying a battery charger. “We see the guys from Motor Serv about once a quarter. This is the first time I've seen the Workshop Solutions van. It's a nice set up. Sometimes you just need to see things in the metal before you can really decide.
“It's always better, especially if it's something that's a few quid. If you ring up and say what you got, what are the options? They can only answer your question, oh, you've got this. If you ask how heavy something is, they can’t really tell you how heavy I or the mechanics here will find it.”
He added: “I'm looking at a battery jump pack for our cars. It's got to be light enough to be able to move around. I also need to know how big the clamps are, because the clamps have been an issue before.”
Insight
At this point, Phil Reynolds from Box Hill Motors emerged from the workshop, for what turned out to be a stream of short visits, each one resulting in a purchase. Commenting on the van, Phil said: “Everybody does something different and it's good to get to know what each manufacturer brings to you. Then if it comes in a van, you can remember what it was. It's as handy as browsing through the catalogues, as or even Aftermarket magazine. You might see something and think ‘oh that’s a good idea’. It gives you an insight of what's going on.” Phil and his wife Sharon took on the garage originally in 2002. While it looked like a typical edge-of-town industrial estate setting, they are actually sat behind a Tesco superstore. With the car dealership next door, they have a steady stream of customers.
As Frazer pointed out, when it comes to this kind of enterprise, it is the owner of the garage or the workshop manager that they are looking to engage with: “We want the person who can make decisions to come aboard.”
Explaining how the customers pay for the items they acquire via the van, as Phil returned for four dash cams, before coming back a third time to look at some of the lighting products, Eshan said: “They pick something they want, but they don't pay on the van. They pay on account after 30 days. If they buy quite a bit of stuff, the sales rep might say you could pay over 60 days.”
Brilliant
Aftermarket’s last stop with the van took us to Over Garage, where we spoke to technician Sean Tipple. While the guys were not buying anything that day, they did appreciate the visit:
“It's nice to see what's new and what's out there. Today we are having a quick look to see what we might need in future.”
With that, Aftermarket opted to get off for the day. Summing up, Eshan said: “Sometimes, people come on board, not looking to get anything but an item they did not know we did will catch their eye. In the end it’s about letting everyone know what we do and showing them the special offers.” Frazer concluded: “The visits we have done today have been very successful. It’s been brilliant.”
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With a view to offering garages a taste of la dolce vita, the latest product release from Klarius Products includes a full exhaust system for the Fiat 500 (2007-2010). The rest of the latest additions to the company’ range of exhausts, CATs, DPFs and mountings cover a veritable who’s-who of major automotive names, from Ford to Mercedes-Benz taking in Hyundai, KIA, Volvo, Volkswagen, Mitsubishi and more. This includes an exhaust for the Ford Focus from 2018 onwards, a DPF that covers both the Nissan Qashqai and Renault Koleos, and DPF covering Fiat’s other little giant, the Panda, along with the Alfa Romeo Grande.
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