detonation on shift to third

[John B]

I'm getting close to sorting out the tuning, but I get detonation (check engine light) just after the shift into top gear. Boost is 15PSI, wide band is reading 10, the plugs are Autolite A64s, cam and ignition timing stock. Should I retard cam timing 2 degrees? Or should I retard the igniton timing first?

[cordes]

Have you tried running a higher octane to ensure that it's knock and not noise?

Have you tried pulling a degree or two of timing at that point in the map?

You're probably dropping down to an area where you could be more prone to detonation and also the duration is getting pretty high by the time you get up into third.

[Tbird232ci]

I'd assume that he is already running at least the highest octane pump gas in his area. We get 93 around here, but many places get 91.

I'd try pulling out some ignition timing as it's easy to and easy to reverse if it doesn't help. Low RPM's, boost and high load seem to be a recipe for detonation. My 2.3T Thunderbirds were bad for it, my SC, not so much.

[John B]

So a couple degrees of ignition timing is the consensus? I'm using the highest octane available.

[John B]

Have you tried pulling a degree or two of timing at that point in the map?

I don't have the knowledge or equipment to do that. I'm using a Shelgame cal.

[cordes]

I don't have the knowledge or equipment to do that. I'm using a Shelgame cal.

Try retarding the distributor timing a couple of degrees then. You'll lose timing across the whole map, but that's pretty much your only option.

[jackerman]

Install new plugs do a hard pass shut it down pull the plugs and that will tell you if the timing is to far advanced. You want the marks on the strap to be in the the bend of the strap. If its to close to the base of the strap its to far advanced. Can alo try a colder plug if its on. At low 10 air fuel it could be to rich also.

[shackwrrr]

Pull a couple degrees with the distributor for diag reasons. If it goes away then its in the tune but if it stays then its something loose under the hood. check for anything in close proximity to the intake or head. I had a bad issue at one point that I thought something serious happened, I popped the hood to find my boost controller resting on the intake and you could see where it rattled against the aluminium.

[tryingbe]

Buy scanner so you can monitor knock and degree pulled at real time.

[John B]

. At low 10 air fuel it could be to rich also.

At WOT in top gear, what AFR should I be aiming for?

[jackerman]

i have been learning on the tune myself but i try to keep it between 11.1 and 11.5. if the problem still exists then i would pull 2 degrees off the base timing. I was having the same problem checked my plugs and saw i was getting pre ignition from being to advanced

[PunKid]

Install new plugs do a hard pass shut it down pull the plugs and that will tell you if the timing is to far advanced. You want the marks on the strap to be in the the bend of the strap. If its to close to the base of the strap its to far advanced. Can alo try a colder plug if its on. At low 10 air fuel it could be to rich also.

exactly!

[Force Fed Mopar]

Go 2 steps colder on the plugs.

[cdavis]

Go 2 steps colder on the plugs.

I just crossed referenced the ap64 autolite. It crosses to a champion rn12yc. That is too hot of a plug. I agree with Force Fed Mopar, 2 steps colder on the plugs.

[jackerman]

I like to run ngk gr4 but the next colder plug is gr5. I feel the car runs the best on gr4 but im sure its a personal preference

[zin]

4s and 5s are kind of hot to me, but then I'm usually dealing with 3-400HP nitrous kits, not too many of those running warmer than a 9-10!

I haven't crossed the plugs, but a Champion actually crosses to a 4 NGK?.. Most "stock" plugs I've dealt with seem to cross to a 5-6, seems like I may have to experiment a bit!

Mike

[jackerman]

[QUOTE=zin;1019705]4s and 5s are kind of hot to me, but then I'm usually dealing with 3-400HP nitrous kits, not too many of those running warmer than a 9-10!

I haven't crossed the plugs, but a Champion actually crosses to a 4 NGK?.. Most "stock" plugs I've dealt with seem to cross to a 5-6, seems like I may have to experiment a bit!

Mike

Hey what plugs do you run. Im just curious for future.

[zin]

I'm partial to the NGKs, mostly because the are easier to read than a darker colored plug (Autolites,etc) and an easily decoded heat range, backwards though it may be to my eye (1=smoking hot, not in the good way, and 10-11 ice) .

Mike

- - - Updated - - -

I'm partial to the NGKs, mostly because the are easier to read than a darker colored plug (Autolites,etc) and an easily decoded heat range, backwards though it may be to my eye (1=smoking hot, not in the good way, and 10-11 ice) .

Mike