[RandalJ]

jc, I have been wrestling with this issue all summer long. Living in Phoenix, with daytime temps that have reached as high as 117 this summer, I think that I've probably put the Autothority MAF to its limits.

(one of the previous owners had installed mine too)

I have not only an engine knock problem, but also an intermittent off-throttle stalling problem in the hotter weather. The knocking does not occur until the engine is hot - above the first hash mark on the temp gauge - but the stalling would happen during warm-up more often than when hot.

I have had the car about a year now, and I remember experiencing this for a short time before it cooled off last October. Both problems disappeared from October to late May (The car ran superbly, and I even did a DE in November with no knocking), and I had put them out of my mind, but by June both issues were back.

I have pretty much tamed the off-throttle stalling problem this summer with some advice from Steve Wong on adjusting the trim pot to a leaner idle mixture. I think it was at 5.2k, and now is at around 3k (I'd have to double check). Now, my understanding at the time was that this control was for idle air/fuel mix - and maybe indirectly it is - but I did not realize that this was the ambient air temp sensor circuit, which would have relevance under all throttle conditions.

In any case, the "plunging tach" stalling problem was tamed a bit, but the detonation remained. I would get the detonation when the engine was hot (above the first hash mark), A/C on, and when accelerating wide open beginning at about 2700-3000 RPMs. The A/C is a big factor because the condensor on the lid is pre-heating the air into intake. I can get knock even with milder temps (80's) inder hard throttle if the AC is on.

I ran a 50/50 101/91 octane mix (approx 96 octane), and even higher, and still had the knocking at the higher RPMs on really hot days (above 107 or so), so I knew the problem was pretty severe.

I tried a chip from Steve, with the timing retarded a bit from the Autothority map, but still above stock. It helped quite a bit, and now I have the knocking above about 4000 on the hottest days. He and I are corresponing to try to fine tune, but he mentioned your posting to me.

I am curious as to what you used as a temp sensor to replace the trim pot. Do you have the specs on it? I'd like to set my pot to what your sensor would read at, say, 100 or 105F, just to see if I can duplicate your good results, with the current chip from Steve, and with the Autothority chip back in. I'd be content to just to seasonally adjust the pot with summer setting, and a fall/winter/spring setting.

Thanks