I want this knock GONE

[BlackMetal]

Yeah...I know...another thread where someone wants help with a knock issue. Sorry. It's getting on my nerves though, tonight I had an Eclipse pull away from me on the highway because my ScanMaster started registering knock. I can't ignore this problem when 4 bangers start pullin' on me.

Stock 87 GN purchased last August with 26k miles on it. Currently at 35k. Big mouth cold air kit, cat removed/test pipe with dump installed, Kirban 3" DP still running unported stock elbow, adjustable FPR, Racetronix pump and hotwire kit. Changed the spark plugs myself back at the 32k oil change, didn't see any fouling or signs of running lean. Fuel filter was also changed...

Here's the ScanMaster data I took in the garage tonight when I got home after losing to an Eclipse...

AF 05
L8 34
INT 122-132
BL 136
AtS 79
TPS .40
IAC 41
cc 15 up to 254

I currently have my fuel pressure bumped up to 44-45psi. Still getting a high block learn reading. Haven't found any obvious vacuum leaks yet...so I don't know what's up with the BL.

Now, onto the knock. From a stand-still, I can punch it 3/4 throttle and get away with a nice launch. If I floor it and get above 12 or so pounds of boost (still judging off the stock boost gauge, sorry), then I get knock. That doesn't bother me too much, I don't find myself doing full throttle launches very often. It's only problematic in the situation I already described, trying to accelerate when I'm already at highway cruising speed. Are these cars really just quarter-mile monsters and I'm asking too much of it on the highway, or should a GN not be sluggish pulling away from any speed? I couldn't have caught the Eclipse if I wanted to, but I certainly didn't want to when I saw 9.4 on the knock display.

I'm fully prepared to try an RJC powerplate, a turbo tweak cheap, a better intercooler, whatever, but I know throwing parts at the problem is not the right way to go about this. Should I be looking for a serious problem, or is this just typical GN behavior on today's pump gas? (Well...even if this knock is still expected running the stock chip with todays gas, I still have to get my fuel trim down)

Point being, summer is coming up, I just dumped $1400 on wheels, but if my car is going to be all show and no go, I'm no better than the ricers. I have no intention of taking this car to the track, but during the cruise night season, I want to be able to get on the throttle a few times and not feel like I'm torturing the car. Speaking of summer, I know I've had a few Chicago guys in past threads already offer to meet me and try to help me out. Since the cruise nights are starting up, if I can't get this taken care of myself, we certainly could meet up at a show or something and try to figure this out.

Thaaaaanks again for reading, hopefully this will be the last thread of this kind that I have to post.

 

[TurboBuRick]

Need to check out fuel preasure under load.

 

[denn454]

there are a few things i'm not seeing here. whats your boost and what kind of gas are you running? how about timing on the chip?

i am limited to 91 octane at the pump, anything more than 12# of boost and i'd see knock (20* timing i believe, pretty mild whatever it was) there was not a thing i could do to get rid of it, fuel pressure was on the rich side for me (o2's around 490-500) i tried litterly every thing everyone could suggest. the only thing that worked was lower boost. about 10# and the car ran significantly better. or about 5 gallons of 110 in the tank and 15-17# and no knock. the only thing i could come up with is it was simply too much boost for the poor quality of fuel from the pump.

a power plate will help out some, i never tried it personaly but i've seen other people use them with good results (and other people not see a bit of improvement) a bigger ic will help but i don't think the cost is going to justify your goal of simply lowering knock, unless your wanting to go faster also. if the car is rarely driven (which 10k miles since august tells me it isnt) race fuel would be a wise choice. or alcohol is always a great option also. lots of info on that, do a search.

for the time being lower boost is the quick easy answer.

 

[TurboBuRick]

I could help you out. I got a fp gauge we could prop up by the winshield and also have direct scan. Let me know.
Rick

 

[BlackMetal]

there are a few things i'm not seeing here. whats your boost and what kind of gas are you running? how about timing on the chip?

Well like I said, anything above 12lbs boost and I start seeing knock, but if I floor it I can peg out the factory boost gauage. So I guess my car hits 15-16lbs of boost. I always use 93 octane gas. Timing on the chip is whatever it was from the factory.

As far as saying I need to check FP under boost, ok, so let's say we hook up a gauge that we can watch while I drive and find out that it isn't good. What would there be left to fix? I've already replaced the FPR and put in a better fuel pump, so if I was getting bad fuel pressure, what would there be left to do?

 

[TurboBuRick]

Well like I said, anything above 12lbs boost and I start seeing knock, but if I floor it I can peg out the factory boost gauage. So I guess my car hits 15-16lbs of boost. I always use 93 octane gas. Timing on the chip is whatever it was from the factory.

As far as saying I need to check FP under boost, ok, so let's say we hook up a gauge that we can watch while I drive and find out that it isn't good. What would there be left to fix? I've already replaced the FPR and put in a better fuel pump, so if I was getting bad fuel pressure, what would there be left to do?

You know as well as I do it could be a number of things but you gotta start somewhere. Sounds like fuel system is taken care of but will not hurt to check. Could be MAF going bad. Direct Scan would tell us alot. Also you really need a real boost gauge. No?
Rick

 

[fatride]

Should of bought Alky instead of the Bling Bling......................

 

[MiamiHenri]

buy alky

Should of bought Alky instead of the Bling Bling......................

I drive in 100 degree temps with high humidity almost all year, when I finally put on razors kit I fell in love with the car. I run 24 lbs of boost all the time on pump gas. Why I didnt do it sooner is my only regret. The car is so fun to drive now. Call Razor he will hook up.

 

[Alaskabuick]

boost guage

You need to get a Good boost guage, with a factory guage how do you know your not running 25 pounds?

Is you wast gate working ok? Your boost may be really high, hence why it ran better with the race fuel?

Check all your waste gate hoses and operaton.

Just a my 02

Dennis

 

[JoelGN]

I drive in 100 degree temps with high humidity almost all year, when I finally put on razors kit I fell in love with the car. I run 24 lbs of boost all the time on pump gas. Why I didnt do it sooner is my only regret. The car is so fun to drive now. Call Razor he will hook up.

Amen brother! Alky is definitely the best bang for the buck. You'll have to get a boost controller to go with it. Tune it right and get another 100 hp.

 

[BlackMetal]

Yeah I have a vacuum/boost gauge sitting here in the box, haven't gotten the time to install it yet. I know I can't keep going off the factory one.

Alky would of course help but I thought that was a tad overboard for a car that I don't plan to run at the track or run much more HP than what came from the factory. I guess if nothing else fixes the problem I could try it, but again, didn't think I had to go that far when I'm just trying to have a near-stock street car.

 

[DavzGN]

Get a different chip. The factory chip's timing is too high for today's gas. Many of today's chips are a lot better than the old factory one.

HTH
David

 

[Kevin87TurboT]

Turbo6, your O2 readings are in the dangerous level. You typically shoot for 780 mV at WOT with the factory O2 sensor. You're at only 490-500mV! It sounds as if you're not getting enough fuel. You can turn up the fuel pressure or install an alky injection system and then start tuning...preferably with a wideband O2 sensor. It's difficult to turn with a one-wire sensor...they're very inaccurate. Good Luck.
Kevin



"i am limited to 91 octane at the pump, anything more than 12# of boost and i'd see knock (20* timing i believe, pretty mild whatever it was) there was not a thing i could do to get rid of it, fuel pressure was on the rich side for me (o2's around 490-500) i tried litterly every thing everyone could suggest. the only thing that worked was lower boost. about 10# and the car ran significantly better. or about 5 gallons of 110 in the tank and 15-17# and no knock. the only thing i could come up with is it was simply too much boost for the poor quality of fuel from the pump.

a power plate will help out some, i never tried it personaly but i've seen other people use them with good results (and other people not see a bit of improvement) a bigger ic will help but i don't think the cost is going to justify your goal of simply lowering knock, unless your wanting to go faster also. if the car is rarely driven (which 10k miles since august tells me it isnt) race fuel would be a wise choice. or alcohol is always a great option also. lots of info on that, do a search.

for the time being lower boost is the quick easy answer.[/QUOTE]

 

[BlackMetal]

Get a different chip. The factory chip's timing is too high for today's gas. Many of today's chips are a lot better than the old factory one.

HTH
David

Yeah, I've heard that before, I think I'm going to start simple and try something like a TurboTweak chip before I go installing alky on a street car.

Alright well now I have a few options for getting rid of the knock, now I just have to figure out why my block learn won't go below 135.

 

[carrddine]

just curious what is your bl# at wot,does it peg out and if so whats the #....mine seems to stay at 128 until I hit wot then it goes to about 130 or so..

 

[BlackMetal]

just curious what is your bl# at wot,does it peg out and if so whats the #....mine seems to stay at 128 until I hit wot then it goes to about 130 or so..

Not sure, I don't spend very much time at WOT with my car behaving the way it does. If it doesn't rain too much this weekend maybe I'll take the car out and try to take some readings while I'm driving.

 

[GNVYUS 1]

I had the same problem when I got both my GN's, factory boost gauge was red at 15lbs and then the car felt like it had a 1000lb weight on the back end.

Installed a PSI gauge and it was almost 19psi, months later, rod knock.

I would bet your over boosting, and no amount of fuel is going to help that especially if your already running super lean.

Take it easy on her till you get the gauge on, then consider getting 60lb injectors if you plan on getting on the car. There is no need for anything smaller on these cars anymore. Eric can set up a chip for those in a heartbeat that will feel like the stocker.

Good luck.

 

[Squid4life]

X2. Take it easy until you get the boost gauge installed, have Eric @ turbotweak.com hook up a chip (he friggen rocks!!!), then verify fuel @ WOT.

 

[BlackMetal]

I had the same problem when I got both my GN's, factory boost gauge was red at 15lbs and then the car felt like it had a 1000lb weight on the back end.

Yeap, sounds very similar to how my car felt last night, except I never peg out the boost gauge any more since I know my car knocks.

Where's a good place to T into the vacuum lines? Last weekend I tried to hook the gauge into the line that runs to the passenger side valve cover but I couldn't get a reading off of it?

Well...after buying the wheels I wanted, I have about $2100 left that I could use towards my car. So I guess I'll get this boost gauge installed, see what my car is really running, and either get a street chip or get an alky kit and the akly chip.

EDIT: Do most auto parts stores carry vacuum hose, or where can you get it? I want to have enough so I don't have to worry about screwing up.

 

[Gary Wells]

I teed in on passenger side just aft of where the hard line is going up to the doghouse. Used 1 of those plastic "t's" sold in the auto stores, 1 end goes to the metal hard line via a short hose connector, 1 end goes to the hard black plastic line that goes ofer to the passenger side, and the "T" goes to about 10 feet of about 3/16" or so which is just jury rigged to go under the hood on dirver side at the rear and goes into the door jamb area, and then goes into thru the window to a vacuum-boost gage that just lays in the tray just ahead of the shifter handle. just temporary for right now.