#*#% Knock

[captflash]

I've been chasing a knock situation for a while now at I'm at a loss. New walbro fuel pump, new fuel filter, new ac delco O2 sensor, new maf. Knock doesn't come in until 3000+ rpms but it shows up without fail. I've checked the fuel pressure, it gives 1:1. Set at 38lbs with the line off, 43-44 with the line on. I tried adding fuel on the chip , ramping up the alky as per julios instructions from his tuning the alky kit and still KNOCK!!!! Sometimes it comes on slowly, 1.1-4.+ at about 95 mph, at other times it will be 0.0 then the next reading is 7.8. I welcome any help or suggestions and I thank you kindly in advance.

 

[whitehot1]

I've been chasing a knock situation for a while now at I'm at a loss. New walbro fuel pump, new fuel filter, new ac delco O2 sensor, new maf. Knock doesn't come in until 3000+ rpms but it shows up without fail. I've checked the fuel pressure, it gives 1:1. Set at 38lbs with the line off, 43-44 with the line on. I tried adding fuel on the chip , ramping up the alky as per julios instructions from his tuning the alky kit and still KNOCK!!!! Sometimes it comes on slowly, 1.1-4.+ at about 95 mph, at other times it will be 0.0 then the next reading is 7.8. I welcome any help or suggestions and I thank you kindly in advance.

I have never ran a Turbotweak chip and don't know how they are setup as far as the fuel pressure goes but are you sure the Fuel pressure if supposed to be at 38lbs with the vac.line off?

Also you might want to get the car running right without the alky turned on first then stepup to the alky.

I'm able to run 20psi boost without the alky turned on and have no knock on 92 octane.

Something seems wrong there with it somewhere.

 

[1fast6]

At what boost is this happening? Does it change if you change the boost?

 

[aminga]

Most TT chips are setup for 43 lbs line OFF

at IDLE it should DROP when you put the line on.

 

[Squid4life]

1. Is this using an alky chip from Eric?
2. Was the car tuned to NO knock prior to swapping to the alky chip and adding the alky?
3. Downpipe hitting?
4. HR motor mount?
5. Are you tuning in 3rd, like is suggested?

 

[Buix893]

Yeaaa try 43lbs line off...

 

[86GN-862+2]

Either running lean or Not getting enough time retard. Fuel filter? Injectors? Fuel pressure low? Loose timing chain? Cambearimgs worn ? Low oil pressure? Springs not appropriate ? Dang don't wanna keep going here. Too many factors.

 

[gs462]

most tt chips are setup for 43 lbs line off

at idle it should drop when you put the line on.

100 % correct, Get that fuel pressure up.

 

[that national]

I think he has his numbers mixed up, he says its 38 with the line off and 42-43 with the line on

 

[captflash]

Thanks for the info/responses. The motor was completely rebuilt about 6000k miles ago, top to bottom. The comp 212/212 cam was new at the rebuild, all new bearings ect. My fuel pressure is set low according to what you say so I'll begin there. It is a Turbotweak Chip from Eric, HR motor mounts and I'm taking the readings in 3rd. Downpipe hitting, I don't know but all around there is a fair amount of clearance but I'll look closer for marks on the downpipe. Good oil pressure, new timing chain at the rebuild, came with the cam, new valve springs all in the cam kit, fuel pressure is rising 1:1 but if I'm starting low it ect. I'll set the fuel pressure at 43lbs. line off as has been suggested. Thanks to all for the input, I greatly appreciate it and I'll let you know the outcome.

 

[whitehot1]

I've been chasing a knock situation for a while now at I'm at a loss. New walbro fuel pump, new fuel filter, new ac delco O2 sensor, new maf. Knock doesn't come in until 3000+ rpms but it shows up without fail. I've checked the fuel pressure, it gives 1:1. Set at 38lbs with the line off, 43-44 with the line on. I tried adding fuel on the chip , ramping up the alky as per julios instructions from his tuning the alky kit and still KNOCK!!!! Sometimes it comes on slowly, 1.1-4.+ at about 95 mph, at other times it will be 0.0 then the next reading is 7.8. I welcome any help or suggestions and I thank you kindly in advance.

Have you ever, since getting this new engine installed and running been able to get it to boost without any knock?

If so when did it start to show knock,after a hard run or changing out a sensor or other parts?

The more info you can provide will help with finding the source of this problem over the internet.

 

[captflash]

I've fought the problem intermittantly since the rebuild and had it conquered until about 6 weeks ago when the maf started going. It has always been lurking. But I'm going to take things easy and slow until I find the source.

The TT chip is set for 25lbs boost and I'm currently running 18-19lbs but before my next run I'm going to turn ther boost down to 15-16 and start from there.

 

[Squid4life]

The TT chip is set for 25lbs boost and I'm currently running 18-19lbs but before my next run I'm going to turn ther boost down to 15-16 and start from there.

If I was in your shoes (and I am... same KR issues) I would go back to the regular chip, not the alky chip. Tune it that way for NO knock whatsoever. Then, change to the alky chip. This may be what you have done, not sure.

 

[gs462]

Any updates on this issue?

 

[captflash]

several things. I set the fuel pressure at 43lbs line off, it was at 54lbs, and I turned the boost way back, 14lbs. No knock. As suggested I checked the clearance on the downpipe/upper control arm and it's CLOSE. Real close. When I lean on the passanger side fender the upper control arm hits the downpipe with very little effort. I don't have a torque strap on the motor, I took it off when we put in the H & R motor mounts but I will be reinstalling the strap soon. Thanks for all the suggestions and help and I'll post as I tune.

 

[huntsg]

i chased a similar issue for 6 months. It turned out to be a bad MAF (I had a "new" rebuilt OEM). I suggest starting there with either a known good MAF or move on to a LT1 or LS1 set up.

 

[captflash]

I'm normally away in a remote area with no access to parts ect. Drove back to Florida 2 days ago, got a known and proven MAF and changed it out. No *%^#@ knock! I gave it the acid test yesterday coming back from the shop on I 95 and zero knock. I'll be at PBIR tonight for the ultimate test and tune. Thanks all for your feedback and help.

 

[Squid4life]

Congrats on getting her fixed! Now, enjoy the heck out of it!!!!