Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Knock sensor Qs

General Tuning Discussion

Forum Posts



Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads


Hi Andre/everyone,

First and foremost Im new'ish to ECUs and tuning but I enrolled myself with HP academy to learn and improve my knowledge/skills.

I own a 99 audi A4 1.8T quattro and the engine will be pulled apart soon for a complete rebuild with stronger parts. I was looking at the knock sensors yesterday and a question popped up. FYI, the bosch ME3.8 ECU has 2 knock sensors located between cyl 1-2 and 3-4.

Whilst logging the ECU using a VCDS(vag com), I noticed it knows which cylinder is experiencing knock ie timing pull. Having 2 knock sensors and 4 cylinders, how does the sensor know which side is actually knocking?

Another question is, it appears that I need to run a standalone ECU as the functions I have with my current reflashable ECU is limited. I would really like to retain knock control feature. What sort of feature I need to look at in an ECU(iirc vipec i88, Haltech Elite2500 and motec M130 has that capability) to have a good knock control similar to the factory if not better?

Thank you.


The Vi-PEC would be my own choice, just from having lots of experience with them. The knock co Tyrol knows which cylinder is knocking because it knows which cylinder is getting fuelled and getting ready to fire and puts the knock cylinder ID on that one

As Chris mentions, the ECU knows at any point in time which cylinder is firing, hence it can then look at the signal from the relevant knock sensor during a small window of crankshaft degrees where it expects knock to occur. Using two knock sensors on a 4 cylinder engine helps improve the sensitivity of the system to knock and hence makes it easier for the ECU to accurately detect knock.

At this point I haven't had the opportunity to try out the knock control (or anything else for that matter) on the new Haltech Elite so I can't comment about the system from first hand experience. Knowing how hard Haltech worked on the Elite though I doubt you would be disappointed. The Vipec and M1 both do an exceptional job of knock control - In fact given the age of your Audi I would place money on it that these ECUs would do a better job of knock control than your stock ECU.

The M1 is quite restricted currently on the trigger patterns it can recognise and hence if you plan to go this way you would want to make sure the Audi trigger pattern is supported. Your easiest option may actually be the Vipec as they offer a plug-in ECU for the Audi A4 1.8T. This saves the wiring hassle and makes installation quick and easy.

Thanks Chris and Andre,

Appreciate your reply. I have looked at Vipec's software and have been playing around with it(offline of course) and find it very user friendly. The help function certainly helps a lot. I'm now hunting for a VW Passat loom and associated in UK as it's hard to get one here in Australia at the right price. Once that's hooked up I'll get th vipec plug in.

Thank you


We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?