66331 Tru-Spark Ignition Firing LED Indicator, Adjustable Sensitivity, Green,Red

This is the second one of these that I've had. I should have never let a co-worker borrow the first one. He quit and I never got it back. It's a nice little unit for testing to see if you have a plug that's firing like it should. It has a a clip so can stick it in your pocket. A thumb wheel that you can turn the sensitivity setting up or down with. The pocket clip acts as an on switch. Just hold it down and the green light comes on. Put it next to a plug wire or a coil tower or a spark plug boot. And if getting spark. The green light will pulse red every time it fires. The top part of the pocket clip hold in the three coin batteries that makes it work. The first one I had the batteries lasted for a long time. (several years) Fairly rugged. Had mine fall out of my pocket onto a concrete floor many times and it never effected the way it worked. Handy device that I feel is well worth the money.

Had a dead coil on #1 cylinder 2014 silverado. This tool did exactly what it was designed to do and showed me which coil was dead. I only used it thisnkne time so far, but I'd buy it again!Pro tip, take the button cell batteries out when not in use that way when they go bad they won't destroy the internal electrical terminals.

Saved me a very high priced remote service call for problems with my boat engines. I was haveing problems on one of my engines, it was running rough and would not go above 3000 RPMs, With the help of my boat yard mechanic (B&E in Michigan City Indian AWESOME team) on the phone I checked the plug wires with the above tool to find out that one engine was not firing on 2 of the 8 cylinders, through additional trouble shooting we replaced the plugs and all 8 are firing. This $19 dollar tools and $12 for 2 spark plugs and i am running smooth again. A remote service call would have cost at least $300. This tester is easy to use and calibrate even if I only use it ounce, which I wont, it was more then worth it.

bought it in hopes it would work for coil on plugs. tried it on a 05 gmc envoy, 00 mustang gt and a 17 ram. didn't read them at any angle. worked rather well on the spark plug WIRES on a 00 mustang v6 and a 73 challenger. even showed on a 51 Ford 8n surprisingly.

The product and this seller is BS from start to finish. First, I ordered this item on May 10, 2022. It did not get delivered until May 31, 2022 and that was after I had to follow up with the company. They did not bother to ship the item until I made an inquiry with Amazon. Next, the product was DOA upon arrival. So, I went out and bought fresh batteries. The device still did not work. I am in the process of returning the item now. The seller will deduct $3.97 from my refund to ship this non-functioning device back. Between having to buy batteries (which, of course, are not common and I will never use) and return shipping costs, this transaction was a waste of time and money. BS.

The sensitivity dial works great. It allowed me to get it set at a correct level for what I was testing. With the tester I was able to diagnose the cylinder with no spark easily. The only thing I wish was different with the tool is that it used normal batteries instead of the watch style batteries. Minor issue since it comes with batteries. I am very pleased with the purchase.

I'm here to buy a second one of these. I love the tool but it is just too delicate. On my first one the body separated and it got a loose connection on the circuit board. I'm going to super glue my next one at the seams. Also be careful not to lay it down on the clip or you'll drain the batteries. It really should include a protective case as it is more delicate than calipers. I haven't found any comparable tool. It's an awesome tool, just be sure to handle with CARE and have extra backup batteries. Works good in full sun, led is still visible.

This thing is rather flimsy, but it does what it is suppose to very well. I tried it on a 1998 Honda Civic at the shop I work at and it picked up the impulses perfectly fine. The car has a distributor plug type ignition that's exactly what this tool is suppose to test.The bad thing is that this thing doesn't seem to work on the COP (Coil Over Plug) types as I tried to see if it'll detect the impulses off a plug on a 2002 L4 Honda Accord. I put the tool all around the plug and nothing made the tester blink no matter what sensitivity put it on. I believe the COP types have too much shielding so the tester can't sense anything. Darn!