Diagnostic Scan Tool

**mani** · December 13th, 2010 12:28 PM

Hi. Just want to know if anyone here has tried the product Auto Tap Express DIY OBDII Diagnostic Tool which I found in the net worth around $150. I am really interested to buy the product but want to know if it's worth the buck. Thx a lot.

**oj88** · December 13th, 2010 12:46 PM

Add another USD100 for the license to use the software. It seems to be a nice tool to have around in the shop. It's more for troubleshooting and viewing different parameters about the engine. It's not the same as the ones used to tweak an aftermarket piggy-back or plug-in replacement ECU.

I use a ScanGaugeII, btw. It has none of the snazzy graphics. But it serves its purpose without the need for a laptop.

**14myXUV** · August 31st, 2012 02:56 PM

can these scan devices/tools be used for regular tune-ups? i was told, by local dealers's service, that scan is to be used only if there is a problem (or error codes) appearing on the console. i'm planning to have scan service for my car for tune-up purposes until I heard of this advice.

other thoughts?

**jick.cejoco** · August 31st, 2012 07:38 PM

Originally Posted by 14myXUV

can these scan devices/tools be used for regular tune-ups? i was told, by local dealers's service, that scan is to be used only if there is a problem (or error codes) appearing on the console. i'm planning to have scan service for my car for tune-up purposes until I heard of this advice.

other thoughts?

a scan tool is just a tool, period. if you don't have the training about how the engine's computer systems work nor have the information to the diagnostic trouble codes and their repair procedure, read up. get trained. otherwise, like most shops that have a scan tool is a mere dog and pony show that they have it and only use it as a code reader. maybe if you have the factory manual and the scan tool, this will be a safe start. there is still no substitute for a trained, experienced and equipped technician.

**14myXUV** · September 5th, 2012 07:53 AM

*jick.cejoco: so, the scan tool can be used for performance tuning of modern cars contrary to casa's claim that it's only for diagnotics (trouble codes reading)?

**jick.cejoco** · September 5th, 2012 08:24 AM

Originally Posted by 14myXUV

*jick.cejoco: so, the scan tool can be used for performance tuning of modern cars contrary to casa's claim that it's only for diagnotics (trouble codes reading)?

not an expert on aftermarket tuning but you can buy software to load to your laptop to tune your desired performance. this is usually included when you purchase an aftermarket pcm.

**14myXUV** · September 6th, 2012 08:14 AM

Originally Posted by jick.cejoco

not an expert on aftermarket tuning but you can buy software to load to your laptop to tune your desired performance. this is usually included when you purchase an aftermarket pcm.

thanks. i don't plan to do it myself. i just want to get confirmation that engine scanning CAN be used for tuning coz I hear differently from others (pang troubleshoot lang daw). hanap na lang ako nang shop na meron nito at capable.

**jick.cejoco** · September 6th, 2012 08:53 AM

Originally Posted by 14myXUV

thanks. i don't plan to do it myself. i just want to get confirmation that engine scanning CAN be used for tuning coz I hear differently from others (pang troubleshoot lang daw). hanap na lang ako nang shop na meron nito at capable.

check this website:
MegaSquirt | Engine Management System | Electronic Fuel Injection - DIYAutoTune.com.

**oj88** · September 6th, 2012 09:45 AM

As mentioned, diagnostic scan tools are just that, scan tools. They basically allows you to see and clear DTCs whenever the CEL is lit up. Some can provide real-time engine runtime information like AFR, MAF/MAP, timing advance, ECT, O2 sensor readings, and a bunch of other stuff. More advanced scan tools also includes a data logger to allow you to view historical data. But suffice to say, a scan tool, per se, is generally used to get information OUT of the ECU. Think of it as an interrogation device for cars.

Although, some scan tools may also incorporate the ability to change certain parameters, these are usually limited to resetting the ECU, throttle position or assigning keys to the immobilizer and such. Example of these would be the Honda Diagnostic System (HDS) that's used in dealerships.

ECU tuning is whole new animal and can be done in various ways. But three methods are most common:

1. Replace the factory ECU with an aftermarket one that can be tuned or have has been pre-configured for performance
2. Re-flash the factory ECU to mimic an aftermarket ECU
3. Attach a piggyback (via DLC or physically spliced through the ECU connection). Some ECUs may need to be re-flashed or "cracked", if you will, in order to make this work

ECU tuning gives you the ability to remap and recalibrate engine parameters to maximize any performance parts you may have installed (ie. aftermarket injectors, intake, exhaust, turbos, etc.) and it requires a very deep understanding what each setting can do and how it affects the overall balance. You can actually destroy your engine if you dialed in the wrong values.

So, if a scan tool is to interrogation, tuning is to brainwashing.

**14myXUV** · September 7th, 2012 08:55 AM

thanks for the exhaustive explanation. i guess my confusion is on my understanding of tune-up by which i was only referring to optimum, out-of-casa performance and not aftermarket enhancing gadgets.