Octane Question

[kma697]

I've been chasing a knock problem so I went to the track and mixed some 104 octane with 93 octane( probably 50-50 at best 60-40) I had 1 run with 0 kr, 1 with .7kr and 1 with 2.8kr.  Would the race gas cover up the detonation from a bad MAF???  After reading threads on other boards an example was stated that gradually laying into the boost and getting detonation is probably an MAF, which is exactly where I'm at.  Any help is appreciated guys and girls.

[Recklessrob]

I've been chasing a knock problem so I went to the track and mixed some 104 octane with 93 octane( probably 50-50 at best 60-40) I had 1 run with 0 kr, 1 with .7kr and 1 with 2.8kr.

[87natty]

Your MAF should hit 255 grams on your Scanmaster at WOT. That'll tell you if it's spot on or not, I think.

And Rob's right about the screens. Keep them on. Straightens the airflow.

[Be4u]

imho, keep the screens...both of them.

[kma697]

I havent messed with the screens so they both should be in, and as far as original MAF it probably is it still has AC Delco engraved on it even though reman's would I guess.  My scanmaster has read different numbers for the AF....like 1 time its 168 then next time I had a test pipe put on and it read 228 then that nite it read 255!!!  So  I guess I'll be ordering an MAF.  :idea;  Thanks guys :prayer:

[Recklessrob]

let us know how it works out.

[1turbo6]

This sounds exactly like the problem that I am having (low boost knock) but I also have a pretty shitty idle. this is before and after a new engine. Rob tried to help me figure this out. I was told by a buick guy (Russ Merritt) it was most likely the MAF. so I borrowed a spare from rob(after his computer, coilpack and module ) and wouldnt you know his reman maf was bad. the car ran wicked bad so I pretty much put it up for the year. I will convert to a ls1 MAF and translator in the spring and also try to put a set of roller rockers on. I am now waiting for the snow so I can pull out the sledz.

[kma697]

Yes if this reman I just ordered doesn't work then I will more than likely convert, just depends on if i want to spend anyMORE money on this car.  Putting some money aside for an 04 Cobra then I will retire the TTA for awhile

[SuperSix]

Since the KR increased with eah run - Maybe heat has something to do with it?

[kma697]

Since the KR increased with eah run - Maybe heat has something to do with it?

It didn't....1st run was 3/4 throttle or so to see if the detonation showed on the Scanmaster and I got 0 on that run, 2nd. run flashed 2.8 max, 3rd run was .7.  Last two were to the floor,  1st 14.17, 2nd 13.95, 3rd was 13.925 all @98mph remember this is in a TTA.  I may go back since I replaced the wires and coil pack but I can still here the miss at idle, even worse when COLD.

[Recklessrob]

Whats your fuel pressure set at ?

[kma697]

Don't know gauges are in the works....well at least next.

[kma697]

Update....rema n MAF was good and the car feels stronger and smoother BUT it still detonates when I roll into it in 2nd gear.  Guess I'll keep digging!!! :smt071

[sun dog]

Update....reman MAF was good and the car feels stronger and smoother BUT it still detonates when I roll into it in 2nd gear.  Guess I'll keep digging!!! :smt071

 
Get some Gm Top engine cleaner (or equivalent) and clean out all that built up carbon around the heads.  That might be creating a hot spot and pre-ignition.
 
Just a cheap thing to try.  I have noticeable results in every vehicle I do it to.

[sun dog]

I wonder if the knock sensor (which is very low tech) is picking up a vibration from the engine or tranny shift that would simulate an actual spark knock.  Since you mentioned an engine miss and the reading while shifting to 2nd.

BTW, I just like guessing at this shit I have no idea.