hey guys, I plugged in a scan tool today and noticed while the engine was running the timing advance was between -22 and -33 degrees timing durring mid rpm revs. I use premium fuel so whats the deal, isn't this alot even at idle it's -22 degree?

Also you guys should check your tps voltage as mine was very low at about 2.5 volts closed, funny it never showed a code on the dash but it did pop up on the scnner. would this cause my timing to be retarded so much?

 

That's the normal reading for these cars. Tuned cars are around the -15 to -20 mark.

 

Do the srt6's run timing similar to that as well?

 

I hope not. That seems REALLY retarted. My data logger usually shows between -15 and -9 under WOT.

 

Exactly, that seems to be really conservative.

 

It is counterintuitive, but most scanners will report a negative reading when the timing is actually BTDC, and a positive when it’s ATDC.

From Carchip:

Trip3TIMING.jpg

data courtesy c32AMG-DTM

Trip12TIMING-1.jpg

 

so what are the real numbers?

 

Out of all the N/A cars I've scanned I have yet to see a positive number. Tuned, untuned, wutever. I'll scan an SRT next week to let you know. At least we know they are good for some nitrous.

 

Your numbers should rightly be interpreted as advanced, i.e., BTDC. During light load and idle conditions, it’s perfectly permissible to have high readings such as yours. They serve to sharpen throttle response, increase part-throttle torque, and reduce fuel consumption.

It’s the WOT data that is most important to some, as those are what the DME is signaling while you’re having a go against the bloke beside you. Granted, supercharged engines are altogether different, as their 9:1 compression ratio combined with ~15 PSI+ and 91 octane are indeed a fickle combination. Because you are local, perhaps we can catch up to compare relevant/pertinent data and respective performance.

Your actual ignition spark advance can be easily verified by simply reading when it occurs with a suitable timing light against the harmonic balancer:

M112-113timingmark.jpg

 

I'm curious now as to how acurate the scan tool is versus a timing light.

I went out for another run and filled up the tank with scan tool in hand. After warming up I did a couple downshifts from a cruising 4th gear to a quick shift to 3rd, and what I got was; at cruise I run -34 degrees with a steady throttle, then as soon as I downshift and go WOT the scanner jumps up to -12 or sometimes -18 degrees.

Now I know the obd2 port is slow at feeding information packets to the scanner, but there is no way I'm getting zero degrees or anything close to it.

I will also be doing the whole front grill mod as my IAT is pretty high for 75mph.
I get 100-105 F intake temp, while outside air is 72 F. I'm definatly gonna have to buy a Cold intake after those readings, as that is quite the change in Temp.

 

Just did another timing test with the same scan tool in my chevy silverado, it has a 5.3L v8.
this engine idles at 17-18 degrees positive timing. And under WOT it advances to about 32 to 38 degrees positive timing.
and when I get off the gas it will advbance up to 50 degrees positive timing then slowly come down to 17 degrees again at no load.

any thoughts on this? I'm thouroughly confused. is there anychance the scan tool is reading the crossfires' timing out of phase? which is why I get negative numbers?

I'm using the INNOVA ScanTool CANOBD2 1303