Question about timing and detonation

jbpt1970 · Post by **jbpt1970** » Wed May 23, 2007 11:02 pm

This may be a dumb question but, how would I know if my car is detonating? I have an '05 mustang gt with c&L cai and diablo street tune modified for 93 octane. The car seems to run great, but I checked under the hood with the engine running today and could hear some "noise" from the valve covers that could be described as "knocking". I also hear similar sound upon initial acceleration with the windows down. I have no engine light or anything. Any advice.

Post by **mikel** » Thu May 24, 2007 1:18 pm

Monitor total timing in the live data to see if the PCM is pulling timing at any point when under load.
If so, it may be pulling timing because of knock.

Thanks

jbpt1970 · Post by **jbpt1970** » Thu May 24, 2007 5:11 pm

What do I look at. I did a data log and looked at spark advance which goes from 16 to 22 deg while at idle? Is this what I should be looking at?

jbpt1970 · Post by **jbpt1970** » Thu May 24, 2007 5:28 pm

One additional question, When I modified the tune for 93 octane, I added 2* to the global spark advance but did nothing to the others based on RPM. Should I have?

Post by **mikel** » Fri May 25, 2007 9:00 am

OK, lets see here, you took the tune that we spent weeks developing on the dyno and added timing to it, and now you want to know why the car is detonating? Hmmm....
I would suggest setting the timing back to stock before going any further.

Detonation will rarely ever occur at idle or with no load on the car.
Make sure you are using high quality gasoline as well.

Thanks

jbpt1970 · Post by **jbpt1970** » Fri May 25, 2007 10:12 am

mikel
I only added timing suggested by you guys to bring the 91 octane c&l street tune to 93 octane. I did this by adding 2* on the global timing parameters. Nothing else in tune was changed. I'm not sure if what I'm hearing is normal or not. It could very well be normal (at idle). I just want to be sure I didn't do something wrong. Your reply suggests maybe I did. So if you could clarify the procedure to make the c&l 91 octane street tune in the u7140 93 octane it would make me feel better. Sorry if my previous posts were confusing. Thanks

jbpt1970 · Post by **jbpt1970** » Fri May 25, 2007 1:45 pm

Just thought of something, I updated the software the other day. I restored the stock tune first, then did the update. When I re-tuned the car, I did as I did before choosing the C&L street 91 octane tune, then addidng 2 to the global timing(for 93 octane). Did I need to do that again, or was it already increased from the first time I tuned the car? (before software update).

Post by **mikel** » Fri May 25, 2007 3:35 pm

Ahhah!
OK, sorry I missed the part about modifying the 91 C&L tune for use with 93.
I do think there may be an issue with the fact that you applied the same change twice.
Go back into the spark adder parameter and see where it is set.
It should only be at +2.

Thanks
Mike

jbpt1970 · Post by **jbpt1970** » Fri May 25, 2007 10:22 pm

Mikel
I didn't know how to view the parameters so I just restored the stock tune, then reloaded the c&l street tune. I hit modify and went to global spark advance. It was set at 0 so I went to the right (added) 2. Once I did this the tool place an * next to this parameter. I then loaded the tune. Does that sound correct, and in the future how do you view the parameters without have to restore the stock tune like I did? The car seems to run fine. Thanks for your help.

Question about timing and detonation

Question about timing and detonation

RE: Question about timing and detonation