Darren Darling the founder of The DPF Doctor network and the global brand ambassador for JLM Lubricants
Darren is a respected and well known columnist for several automotive trade magazines and his Facebook page is a hit with thousands of visitors worldwide. Darren speaks at conferences in the UK and overseas too whilst running a thriving workshop, managing the JLM Academy and building his DPF Doctor Network! For this issue of JLM Drive we share one of Darren’s latest columns in Aftermarket Magazine and ask him why he swears by JLM Products.
Mazda CX-7 2.2 D DPF blocked due to low boost pressure. This vehicle was presented to us with fault codes P2463 - DPF Soot Accumulation and P2459 - DPF Regeneration Frequency. No other fault codes were present. After discussing the history of the problem with the customer, we were informed the DPF had been cleaned 2 weeks previously but was now causing problems again. This appears to be a classic case of treating the symptom not the cause. It’s something we see often and it’s why we undertake an assessment of the vehicle to identify the root cause of any DPF problems. Moving on to the DPF assessment.
We did have a blocked DPF with pressures in excess of 150mb at idle! This DPF had been cleaned elsewhere just 2 weeks ago so we were dealing with an issue that was causing the DPF to block quickly rather than the DPF being unable to regenerate (we had already ascertained driving conditions were good due to the customer’s commute to work).
We quickly established that boost pressure and mass air flow was low. A high restriction in the DPF would affect these. We smoke tested the boost system to rule out any leaks. This passed the test. We then cleaned the DPF to get a closer look at boost pressure and air flow without any excessive restriction in the exhaust.
We successfully cleaned the DPF using the JLM DPF Clean & Flush kit. We now had a healthy 4mb of pressure at idle; no fault codes or limp mode. Rid of the exhaust restriction we could find the problem. We worked in reverse order on this vehicle because we’d usually look for the fault first before cleaning the DPF but in this case it was the right approach.
We could see when monitoring MAF/EGR there was an issue with the EGR valve not fully closing. We addressed this by stripping and cleaning the EGR. We then moved to the boost issue and started testing the control side of things. As you can see by the picture, we had no vacuum at the turbo so we worked backwards. This is also the case supplying the boost control solenoid.
The Mazda uses a vacuum pump driven by the timing chain. This has two outputs; one feeding the brake servo, the other supplying the boost solenoid. We had healthy vacuum feeding the brake servo but very weak vacuum feeding the boost solenoid. On closer inspection we could see the pump outlet was partially blocked with carbon. We attached a pipe and used some JLM Air Intake & EGR Cleaner leaving it to soak for a few minutes.
Why do you recommend and use JLM products?
JLM Lubricants design and manufacture a range of high quality products. And this enables us to offer a premium service to our customers. As a brand ambassador I work closely with JLM, evaluating products and suggesting new ones. For example I played a key part in the launch of the JLM Diesel Intake Extreme Clean Toolkit Pro. I tested it on problem vehicles in our workshops with a 100% success rate. JLM’s focus never strays from the trade. The team understands that as professional motor mechanics we have to rely on products that are best of breed and that always get to the root of the problem fast. I like it that the JLM team regularly launches new products too. They listen to their distributors and to mechanics and they spot gaps in the market where there’s a need for a product way ahead of what’s on offer or where what’s on offer is not good enough for the trade. And they’re really nice people to work with.”