Knock at part throttle?

[JDSfastGN]

Alright, I just got my motor back in and everything is running great. Well tonight I was on the beltway cruising at 60 or so and decided to slowly get into the throttle. Only about 1/4 throttle, and 7 psi. Well I saw 1-7 degrees of knock. I've never had knock before and I know it isn't false because, if it was something loose, I'm sure it would read knock when it shifts into 2nd or 3rd since they hit very hard. The only things that I can think of were that I had my heads ported and polished with the bigger valves and I installed a powerplate. I did drill the EGR hole. But from what I understood the EGR passage in the heads is now smaller after I got my heads done (does this sound right?) My coolant temp was 165 at the time and my fuel pressure is at 45 with the line off. I am going to change my fuel filter on friday. Since I had the motor out and the fuel lines were open could, the open fuel lines cause the fuel that was in there to somehow clog the filter? Or is my boost just coming too soon and the chip isn't putting in enough fuel. This is my 87 below so if anybody has any ideas, that would be great.

 

[Ormand]

NOT EGR

EGR does not function when the engine is under boost, so you can rule that out. What scan tool do you have? What were O2s? More info needed, but sounds like a low fuel issue.

 

[Chuck Leeper]

KNOK KNOK??

How about some scan tool readings when this is happening??
That will help in narrowing it down..

 

[JDSfastGN]

Ok I'm still using my ancient OTC 2000, so I was not able to get the O2s on those runs, but on separtate runs, I was in the .860 range at the same amount of part throttle. TPS is .042 at idle and 4.64 at WOT, thats about all I got, sorry its so vague guys , but thanks.

 

[JDSfastGN]

anybody else got any ideas? I'm going to change the fuel filter first, but will I need my chip reburnt? It was burnt for my old combo that did not have the ported and polished heads and the 204/214 cam. Could the fuel jsut not be proportional to my tps reading (it thinks that since the TPS is reading a low number that it doesn't need as much fuel) Does this sound right. It does not knock at part throttle unless you are in third gear on the freeway mostly. It mostly hangs around 2 or so, but at one point it saw 7. Thanks

 

[Matt Weiser]

I'm having a similar problem so I'll be curious to hear how you chase down yours and any advice from others. Mine may be false knock from my 3" downpipe rubbing the frame -- gotta fix that soon. But it happens under the same conditions as yours. My setup is fairly mild in comparison: 30-lb. green stripes, stock turbo and fpr, Walbro 307 hotwired, new timing chain and valve springs. If it's not the downpipe I may swap in a 237 fpr I have just to see if the original fpr has gotten lazy. Any other ideas?

 

[gnturbo]

my car does absolutely the same exact thing but are you getting 29 degrees of knock on a knock gauge or retard degrees on a scanmaster?If I ease into the throttle at highway speeds,I will get a progressive knock on the gauge that will go clear to the red but I only see about 5-6 degrees of retard on the SM.it still pisses me off cuz I can't make it stop.I have checked the converter,exhaust,crossover and the motor has a strap on it.When the knock happens I have blms right at 130 and my o2's are around 790 -800.Everything looks great and the car runsgreat with no audible knock.I don't know what could be causeing it.I have tried three different gas stations also thinking it may be octane related.Maybe somebody knows but you are not the only one with the same problem.I feel your pain everytime I get on the highway and try to ease into it.Usually if I stomp it and let her rip it will not knock only if I try to creep into the boost.I was kinda thinking that there is so much of a load on the motor and the tps is not showing that an increase of fuel is needed so as boost creeps tha fuel is not increased and it gets lean.I am just taking a stab here.Does load have anything to do with fuel delivery?

 

[blackbuick87]

JD get another chip burned since your new heads changed the way your engine breathes completely. Part throttle O2's are hard to judge since they dont display exactly as it happens and the stock O2 sensor sux.

Is your new cam the same size as the old one? If its bigger that just exacerbates the situation.

Get a proper chip for your setup and at least a scanmaster or TL for good readings. Hopefully that will cure it

 

[ES1]

I will share what I have found out been told.
I used to not have part throttle knock but it showed up one day and I have not been able to get rid of it.
1st - I added octane (100) and it went away.
I added alky with a 93 chip and a Power Plate and it deceased but did not go completely away
I tried 100 octane chip and the part throttle knock came back strong.
WOT knock is ok it's just the part throttle (before the alky kicks in)
I asked about this in the alky section and Chad said he got rid of his by pulling timing from the chip before the alky kicks in.
So it seems like the cure is more octane or less timing in the part throttle area.
Add the octane first to make sure it is not false knock.

 

[JDSfastGN]

Ok well I loosened and retorqued my knock sensor and firmed up all my connections to my ESC module, and now I don't get any crazy readings of 29* of knock. I get 1-3* now and just like what blackbuick87 said I need to get my chip reburned. I finally got a good reading on my O2s and they are fine at 10 psi but when it hits 13 psi or above the O2s dropped to 640 or so. I'm just leaning it out putting that much more air through the motor with out having my chip compensate for it. Thanks a lot guys, yall have been great.

 

[ijames]

Several chips I've seen have a problem with midrange, partthrottle leaness causing knock. It soungs crazy but the safest way to drive these cars is either very light throttle, less than 2 psi boost, or foot-to-the-floor where most every chip gets the fueling right. No in between.

 

[Matt Weiser]

gnturbo: sounds like you and me are having the exact same problem. I also get worried when I merge onto the highway and start to see the knock count climb on my Scanmaster. It also happens real bad when I'm on a long continuous grade on the highway. Normally the knock counts in such cases are small (<10) but sometimes it gets up around 20. But then it seems like if I give it a bit more gas it goes away completely, even though I'm still climbing the same hill! Makes me think it's not false knock at all, but maybe the TPS isn't showing enough throttle opening at the right time. (I know my TPS is adjusted within spec 'cause I just did it.)

I'll start off by trying more octane, though the best we can get here in CA is 91! ... :-( ... Maybe I'll do some before/after runs with Tlink to get a better handle on the problem.

BTW, I'm running a stock chip.