knock problem

[gn84guy]

Hey all, I need a little help figureing out what to do to remedy this little problem im having with knock. I just got my car back from the shop where i had my crank sen, cam sen, ign mod, plugs, and coil replaced and it runs like a dream! They also did a fuel injector cleaning, and throttle body cleaning as well. But i took the car home afterwords, and i was getting one green light on my knock guage just crusin at 55mph not on the gas at all! The shop told me that they filled the car up with about 3/4 of a tank regular gas (89-90 octane) and 1/4 premium (91-92) so i went and got some octane booster thinking that it may need more octane. Dumped that in thinking that may solve the problem, but it didn't...Took the car out and stomped it, and the boost only went up to 4.8#. Yet, i was getting one yellow light on the knock gauge so i let off cause i dont feel like learning head gasket 101. Do you have any ideas what this is? Do i have a fuel delivery issue, or could it be something else?
Oh yeah! the shop also did a compression test and checked the fp at idel, and everything is where its supposed to be.
Thanks again for all the help,
Robert

 

[Jerryl]

....... i had my crank sen, cam sen, ign mod, plugs, and coil replaced and it runs like a dream! ...Took the car out and stomped it, and the boost only went up to 4.8#.

Robert,

No offense, but I can't correlate the dream if it only goes up to 4.8 lbs boost after stomping it. Was it running THAT bad before? 4.8 Pound boost reading is also a pretty accurate reading. What are you using to read your boost?

Did you have any knock or boost problems before?

Do you have any vacuum leaks and access to a scan tool?

 

[gn84guy]

none taken..i was just saying it is running like a dream compaired to the way it was running before which was really crappy. but anyways, it is an aftermarket boost guage i can't remember what kind it is, but actually i think i hooked it up wrong because of what i read on another thread so i took it off. im going to reinstall it using the little brass fitting behind the fpr method. It was knocking a little before i brought it into the shop and had all the work done. i dont have a scantool yet, and i haven't replaced the vac lines yet. Its on my to-do list though. Could that cause it to lean out at higher rpms? I'm just trying to get my thoughts to where im going to start first. thanks again

 

[buickpower]

Often the culprit of leaning out on the high end is the fuel pump. Is yours stock and is it hotwired? If you have a gauge going to the rail, you can watch during boost to see if fuel pressure is increasing as it should. Definitely replace those lines when you get a chance.

 

[boosted84]

which ignition mod and coil did you use that can be the cause of the knock if its the wrong ones or they could be deffective so it could be that and the bad gas also the octane boost most times does more harm than good in my opinion the low boost can be caused by the knock from these problems good luck let us know what happens also does the car have an adjustable fp reg they could have just turned it down when they did the injector service

good luck Anthony

 

[gn84guy]

thanks agian for the feedback. Im going to replace my vac lines tomorrow, and if that doesn't help im going to look into buying a fuel pump/hotwire kit for this thing. It still has the stock pump and everything on it, and it doesn't have an adjust. fpr yet. Thats also on the to-buy list for later in the future. I also have a temp guage and a oil presure guage that i still need to hook up, but im starting to think i might need to get a fp guage as well. thanks again for all the help.