I unplugged the advancer while the engine was running on CNG. Nothing happened. That confirmed it, the advancer wasn’t connected at all!
BHPIAN MOTO_RREVVER recently shared this with other enthusiasts:
A Little Background
I fitted my Maruti SX4 VXi 2008 with a CNG kit sometime in October or November 2021. Since it’s an older car, it doesn’t have the kind of sophisticated variable ignition mapping that can automatically adjust spark timing for the slower ignition characteristics of CNG fuel. So, I asked the installer to include a CNG timing advancer kit in the installation.
Since then, I’ve driven the car for over 50,000 km, and I always felt a power lag, especially while driving through the ghats. On many occasions, I had to shift down to 1st gear, even though I felt the car should easily manage in 2nd gear, given its beefy 1.6 litre engine. I had made peace with this, thinking, “This is the best CNG can do.”
A few days ago, while I was under the hood checking fluids and cleaning the engine bay, I noticed a loose connection on the timing advancer-the plug was almost unplugged. I fixed it properly and, out of curiosity, tried changing the settings of the advancer. It’s a simple process: there are two switches, numbered 1 and 2. If 1 is ON, the timing is advanced by 6 degrees of crankshaft position; 2 ON gives 9 degrees; if both are ON, you get a 15-degree advance.
Image of advancer, emergency plug and connector that goes into the advancer or emergency plug.
To my surprise, both switches were OFF, which meant the advancer was completely inactive.
Image of the switches in the advancer.
How I Found About The Missing Advancer?
I had driven the car for over three years without the advancer ever functioning. I switched on the 6 degree setting and tested the system. However, the advancer still wasn’t working while in CNG mode, revving the engine didn’t light up the advancer’s indicator.
Initially, I thought the advancer was faulty and needed replacement. But then it struck me, How has the car even been running all this time? Technically, if a car is fitted with a faulty timing advancer, it shouldn’t start, because the crank position sensor (CKP) data goes through the advancer to the ECU. If the advancer fails, that data doesn’t reach the ECU, and the car refuses to start.
Then I remembered the emergency bypass plug that comes with these systems. In case the advancer fails, the plug bypasses it and sends the CKP signal directly to the ECU.
Out of curiosity, though I knew I shouldn’t do this, I unplugged the advancer while the engine was running on CNG. Nothing happened. That confirmed it, the advancer wasn’t connected at all!
And that, my friends, this is why I strongly recommend being physically present when your car is in the hands of a mechanic.
This is a textbook example of work ethic violations-sadly, very common in India. And mind you, I had chosen one of the top-rated CNG retrofitters in Pune.
I was angry, of course. I’d been driving a sluggish car unnecessarily for more than three years even after paying for the advancer kit. But I was also curious. Will my car feel peppier once the advancer is connected and functioning properly?
So, I went to a different CNG installer, I’ll never return to the old one. I explained the situation. The new mechanic inspected everything and found that all connections were in place except for one: the crank position sensor wire (pink wire) leading to the petrol ECU wasn’t connected. It took him just 10 minutes to fix.
Connections which were already good, power, ground and advancer return signal to the CNG ECU.
Image of crank position sensor wire, cut by the new mechanic where the advancer wires was connected in series to fetch the CKP data.
And yes, now the advancer is working. I noticed an immediate improvement on my drive from Pune to Mumbai and back. I was waiting for a proper ghat drive before posting this, so I could observe whether the difference was truly significant. And yes it definitely is. I climbed almost all the ghat sections in 2nd gear with AC on, fully loaded with 4 people and luggage. Earlier, the car would jerk in 2nd gear in the same sections. Now, the difference is night and day.
After the fix
Looking back, I feel like a fool. I drove a sluggish car for over three years, even though I didn’t have to, and I paid for a part that wasn’t even connected. If something like this can happen to an informed Team-BHP member, I can only imagine the situation of an average, non-technical car owner. That thought truly disturbs me.
Check out BHPian comments for more insights and information.
