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Guess I have a "knock monster"

mkyota1

mkyota1

New member
Hi guys. I have picked up a 1999 gtx around a month ago and have been reading and reading on this site and others to try to build it up a little. After much research I decided on a 3.4 setup. First, I started with a set of speed daddys with no cat and a cherry bomb to go with the existing slp catback. Second, I did the LIM and did a mild port job on the s/c, nothing crazy. At this point I got a Aeroforce guage. I was not thrilled with the ~5* of kr even after the headers. I have no idea what it was before? I tried some al 605s that didnt help.

At this point I thought that I would try a tuned pcm. I went with Will at Overkill. I went ahead and ordered it for the 3.4 with the mods that I already had with the hope that it would help with the kr. I was informed that it would be "OK" to run for a while on the stock pulley it would just be a little rich at higher rpms or under load. It almost got rid of all of it. I would sometimes get little blips under .5*. I noticed the LTFT was reading clost to 0 at idle and very light load, but it is around -10 to -12 on the highway. Seems to be pulling a little fuel. I thought it might be like he said about running the stock pulley.

So I went on and ordered the 3.4 pulley and some al104's. I installed them and reset the pcm and went for a drive. After about 45 min of normal driving to let the computer learn I started to get on it. Now I was getting up to ~6*kr. I know not good. The LTFT was still about the same. So not wanting to hurt the motor I put back on the stock pulley and the 605s. The o2 sensor was locking in good about .930.

I would like to know what you guys think about my problem. I am pretty confident that it is not false knock because it goes away with the new pcm and stock pulley. I have tried some seafoam to try to clean the injectors and remove some carbon from the combustion chamber but no help. I have read about possible hot spots due to headgasket overhang. Does this sound like a tune problem to you guys? How much do you think rockers would help? Enough to be worth it?

Sorry about the novel. Hehe. Any thoughts would be appreciated. Thanks in advance.
 


some cars need more than others to run smaller pulleys. the best thing for you would be to find someone local to scan/tune your car. if it needs it, throw some more mods at it before dropping pulleys. all you can do is experiment to see what your car can do.

rockers would help, but i bet this is a tune problem.
 
Alright thanks. Yea im thinking of just going with a 3.6 and try to get it as close to knock free as I can. Trying to get into the 13s. Ran a 14.3 the only time i had it at the track. These heavy 18s are not helping hehe.
 
I bet some of it might be false.

Check your lower motor/trans mounts...they might needing replacing...along with that header DP hitting your sway bar...check that as well.
 
I have checked the usual causes of false knock. The mounts look good. I can't feel any clunking. I know nothing is hitting the swaybar because it isn't there. It must have broken because the previous owner removed it. Im actually going today to get a replacement. Trans dipstick tube is clear.

Im thinking it is not false knock because with the stock pulley and the tuned pcm i have virtually no knock. If it was false knock wouldnt it still be there?
 
i find it weird. with intake, exhaust, colder tstat, colder plugs etc im running a 3.4 pulley, tuned, with no knock retard on my scan gauge.
and the car runs and performs like a champ.
 


Knock Only tells 1/2 the story of how your car is performing. GrandprixGTP1. I bet your drowning in fuel and have crap for Timing. I could run a 2.7 on my car with a 9 afr and 15 timing. Doesnt mean I should


OP: Id have to say you need to work on your tune. Going off of narrow band values for WOT readings is shooting in the dark
 
Alright thanks guys for the replies. Looks like i will need to look into a more detailed tune for my car.
 
01gpgt01 said:
Knock Only tells 1/2 the story of how your car is performing. GrandprixGTP1. I bet your drowning in fuel and have crap for Timing. I could run a 2.7 on my car with a 9 afr and 15 timing. Doesnt mean I should


OP: Id have to say you need to work on your tune. Going off of narrow band values for WOT readings is shooting in the dark
Click to expand...


"drowning in fuel?" and how would my timing be crap.
like could u explain, sorry:P
i wanna learn more about it.
 




Wait in your post did you say you added headers and STILL had 5* of KR? That doesn't seem right even there.....
 
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