No bucking....but pinging!

[hquick]

Finally got the bucking sorted out. Jezza decided he thought it was IAT spark related (due mostly to heatsoak) so we decided to try altering the Spark IAT table (B5911) to stop it pulling so much spark due to high intake temps.
This worked great. Bucking disappeared completely.
I still get strange KR readings..sometimes for no reason at all...cruising along at around 100kph and BAM...KR appears out of nowhere.
I get audible pinging at around 95-110 Kpa and 2000 or so rpm.
I just can't seem to keep the timing up to it.
Any idea's?
Usually if I stab the throttle I get a large KR spike but I can ease into it reasonably hard and no KR???

http://img.photobucket.com/albums/v35/hquick/80KR.jpg

Thanks

[Delco]

Audible pinging is definately too much timing , given that your car is blown I would expect to use a lot of burst knock to eleviate the knock by anticipating the timing retard needed.

looks liek it has way to much timing on the transition into boost.

[hquick]

Thanks Delco.
Currently burst knock is disabled. I'll re-enable it and see what difference it makes.
Problem with the timing is, more timing and I don't get bucking but I get ping and KR. Less timing and I get less KR and bucking but no pinging.

[JezzaB]

Basically after about 6 months of trialing and test its come down to this. It just cant seem to take timing down low around 40km/h

It can only hold about 7-10 tops in the 40km/h area when coming from a slowdown and then start moving again. If you set it to 10deg it is fine when the IATs are cold (cold start) but as soon and you drive for a while or boost up it will drop to 6deg of timing (from pulling with IAt vs Spark) and "buck" (just not enough timing to move the truck)

We've tried more fuel to try and quench the pinging, leaning out to see if its too much fuel,etc. We worked out the IAT was getting some heatsoak and fudged the IAT vs Spark a bit.

We've come to the point that basically when its cold it will ping (too much timing [12deg-ish] and when its hot it is fine [10deg-ish with some KR spikes]
Pull it out and it will buck, leave it and it will ping. The truck just wont take any timing in that area.

Only other thing i can think of is to try and apply no IAT vs Spark in that exact bucking area (not easy) and command 10deg-ish

Jez

[oztracktuning]

Have you looked at how quick it richens up under load and set the AFRs and timing lower on the transition into the problem situation. Also look to faulty IAT reading excessively high leaning out the fuel mixture.

Maybe try some other plugs as well.

[JezzaB]

Have you looked at how quick it richens up under load and set the AFRs and timing lower on the transition into the problem situation. Also look to faulty IAT reading excessively high leaning out the fuel mixture.

Maybe try some other plugs as well.

Steve we havent focused on the lean out on the throttle tip in. Purely because its pretty easy to fix. Thats not the problem.

High IATs leaning out the fuel mixure. Well we had the A0014 at 1 and dialed in everything. then tweaked it for high IAT and low IAT. one hard thing is Howard doesnt have an intercooler to it makes massaging the IATs even more creative. Just like my old non-intercooler or water injected Powerdyne

The hard bit is making the truck take timing. Its ok in most situation. Sure there is some KR here and there but it wasnt removed or played with purely to discern the ping vs buck in the 40km/h area. and I mean there is a very small window for timing between the 2.

It wont take timing its come to that.

Plugs, I believe they are NGK TR6s (Colder plug). Should be perferct for the application.

Jez

PS Thanks for advice though! Appreciate it.