I have just purchased and installed a scanmaster 2.1 on my 86 GN. come to find out its showing knock under boost only , but not always at same amount of boost.. knock has reached extremly high to 16.0 without catostrophic failure at one time.. i really need help with this issue before i ruin my engine..my current mods are adj. fuel regulator with gauge , hot wire , walbaro 255, injector harness, 009 inj, 5557 precision turbo with 3 downpipe and rjc boost controller and power plate ,9 cold air intake and im running 91 octane and fuel pressure is set to 43 line off ..car also backfires at times of knock but not always .I would really appreciate any suggestions due to this matter so i can get this fixed so i can enjoy my ride without a worry of poppin a head gasket or even worse.. THANKS
Need help with knock issues
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What chip? What is your fuel pressure at WOT? If that knock is real you're lucky you haven't had a headgasket failure already.
What are your 02's on the scanmaster on the recall? I would have to say you're running lean with too high boost numbers. What is your boost set too?
What are your 02's on the scanmaster on the recall? I would have to say you're running lean with too high boost numbers. What is your boost set too?boost
Before anyone can help you they will need to know the amount of boost you are running. have you verified with a fuel pressure gage 1 to 1 increase with your boost gage. Is your tps voltage set correctly maybe post your reading from your scan master.Normally that amount of boost you are running in relation to your octane in your fuel equals knock if every thing else is working properly.I've only been able to run 15 lb. of boost safely on 91 without alk.others have run more
Before anyone can help you they will need to know the amount of boost you are running. have you verified with a fuel pressure gage 1 to 1 increase with your boost gage. Is your tps voltage set correctly maybe post your reading from your scan master.Normally that amount of boost you are running in relation to your octane in your fuel equals knock if every thing else is working properly.I've only been able to run 15 lb. of boost safely on 91 without alk.others have run more
i jus installed the turbo last week and set boost low for the break in i havent went over 10 lbs .knock seems to be happening around 6 to 10 lbs..not sure to exactly which chip i have .previous owner installed.. and as to fuel pressure at wot not sure due to my gauge is rail mounted.. and tps is set to .44 at idle engine off and .46 idle engine on. at some time of knock o2 counts where over 800
87granny
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If it's a bigger turbo than what the chip was burned for you will need to add fuel through the chip to compinsate for it (if it's a TT chip) when i went with the 49 i had to add 10% more fuel than stock or it would knock. Or the pump is going south as described above are you sure your getting 1 to 1 while in boost for fueling
Your not confusing o2 readings with K amounts are you?
I just installed the 255 fuel pump and regulator only a couple months ago..Could the pump not be flowing enough fuel for my combo?? For starters i'll purchase a new chip which I now know I should of done that regardless with my upgrade. And also empty out the 91 from my tank and try a higher octane..Am I looking in the right direction with these changes or is there something i may be overlooking?? Thanks for your responses I am taking every reply to thought for i am somewhat new to this car so please forgive me if I may ask a dumb question or two
knock
I would look at the ecm see what chip is there also call eric get a turbo tweak chip.Then I would change your gage on your fuel rail (add a hose) so you can view from your windshield while driving,some just tape to windshield verifiy you are getting a increase of 1lb of pressure increase to 1 lb of boost.That is alot of knock at so low of a boost level!! something is not right whether it is false boost or not I would change chips and verifiy fuel pressure with boost first I would also do this first before changing fuels and stuff first.there is no reason why this will not run on 91 oct get your car set up right first then make adjustments then only change one thing at a time.if you have correct voltage of tps at wide open throttle maf 255, 02's 750-800 (safe) 13+ volts to your hot wire setup for your fuel pump. 1to1 on fuel pressure and boost your knock should be very low if any.
I would look at the ecm see what chip is there also call eric get a turbo tweak chip.Then I would change your gage on your fuel rail (add a hose) so you can view from your windshield while driving,some just tape to windshield verifiy you are getting a increase of 1lb of pressure increase to 1 lb of boost.That is alot of knock at so low of a boost level!! something is not right whether it is false boost or not I would change chips and verifiy fuel pressure with boost first I would also do this first before changing fuels and stuff first.there is no reason why this will not run on 91 oct get your car set up right first then make adjustments then only change one thing at a time.if you have correct voltage of tps at wide open throttle maf 255, 02's 750-800 (safe) 13+ volts to your hot wire setup for your fuel pump. 1to1 on fuel pressure and boost your knock should be very low if any.
Ok with that said now I have a place to start. Replace chip, check 1 to 1, tps at wot maf signal and o2's, I feel im headed in the right direction now as at first I wasnt sure where to start.. "I see said the blind man" thanks for the help and ill be placing my order for a chip and fuel line some time this week ..Thanks again and ill post the result after i make my changes....
Rafs-T-Type
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Sounds like you have a nice list there to start, but what's the fuel line you speak of? If you need the line to make it your your windshield I'm sure someone will lone you one. Another item for your list....How about your fuel filter....Have you checked that out lately. Best of luck! Hope you get her running good soon 
I replaced the fuel filter about 5 months ago when I replaced the fuel tank due to rust and a leak...I guess it wouldnt hurt to put in a new one since there pretty cheap to buy..I just mainly want to verify the problem before i start throwing parts in a desperate attempt.. Also does timing have anything to deal with knock what i mean is if my timing may be to advanced or retarded current chip says 19 degrees also this chip was put in before my mods..but now with all my mods and changes plus a engine rebuild could my car sweet spot meaning correct timing have changed????
the chip in your ecm must match your mods the tt come with the timing set for the turbo you are running and the amount of boost you specified when you get you chip made
.I'm afraid you are playing Russian roulette if you do not get your basic correct before you start making adjustment you are truly headed for disaster 19 degree timing would be someone running about 21-23 lbs. boost with 91 oct.+ alky
.I'm afraid you are playing Russian roulette if you do not get your basic correct before you start making adjustment you are truly headed for disaster 19 degree timing would be someone running about 21-23 lbs. boost with 91 oct.+ alky
WOW.. the settings on the chip were what the previous owner had set ....I honestly didnt know how important the chip was to change..This is my first project with this car so im still getting to know what the basics are and what to change with what mods...I now know a bolt on isnt just a bolt on...Will the chip maker direct me as to what timing should be set at for which turbo i have??
the chip maker will program the chip for the amount of boost you are going to run (per your instructions) the chip has adjustment that can be made depending on the chip you choose (timing and fuel plus several other). the more you read on this site the more you will know what not to do.You have a scan master that is good but if you don't get your tune correct it will not save your head gaskets the chips I have bought have been very close and have not required any adjustment
Ok..Thanks for this site ..Ive been going to school to become a tech and most my instructers know very little about this car so i get little help there but there tools come in handy.So thanks for your input. Im definitly going to stay out the drivers seat untill i get the chip. and ill check my fuel to boost ratio at school with there fuel guage and hose after i get it .
