RonD.

I posted a question about this once before and got some recommendations. I've tried different brand 93(prefer Sunoco) lowered my boost from 18 down to 16 and added 5 gallons of unleaded 105 to 1/4 tank of 93. Still get a slight ping when rolling into full boost, really only noticeable if I'm pulling a slight grade or on WOT 2nd-4th. I'm running old school with custom Max chip to my mods (Super 48, Dual-port, stock AFM, Headers, full 3" catless) for running at 18 psi. Good AFR's although slightly rich low 11's on full boost. Runs great. I don't beat it I just don't want to hurt it. Any other suggestions?

Black51

Sounds like there might be something else going on internally. I would consider an engine rebuild if you're getting knock at 16psi.

GPA951s

Unless that max chip is setup for all your other bolt ons you seriously need to take the car to a tuner who knows what he’s doing.. the af ratio might be good but seems to me there is too much timing. You might get away with it on the street but it’s not long for this world on the track.. rpr tuning in md is my go to guy and he custom burns the chips for your setup..

Perry 951

I agree with the above comments about overly aggressive timing given your setup, pressure, A/F, and choice of fuel. I ran 91 octane in mine for 70k miles at 18psi and 11.5 A/F and had next to no knock counts logged. Call John @ Vitesse and have him make a new chip for you.

Tom M'Guinn

Why do you say you are getting a ping? Do you hear it? I've blown more head gaskets on a 951 that I should admit and never heard it ping? Not saying you can't hear it, but I never could. You might want to get a knock counter or VKnock to confirm. In contrast to the 951, I drove a Euro 911SC for a while that hated CA gasoline, and the pinging in that car was very audible... Does it continue to pull hard or does it stumble a bit? If stumbling, then consider the ignition (cap, rotor, plugs and wires).

RonD.

Tom,

My basis for hearing what I'm calling "Ping" goes way back to driving many makes of mostly everyday grocery getters from the 70's on up. Back then it was always called "pinging" usually due to poor fuel quality. Car pulls hard no stumble or idle issues. All ignition parts are near new with the exception of the coil, which could possibly be original. My gas mileage on road trips is very good. It's really not too bad even when I drive for fun. Ping is only audible under WOT and slight at best. My concern is obviously not to hurt anything. As far as the chip goes I worked directly with Russ on all my mods. The only factor, which could be of significance, is I assumed I had a cat as it turns out PO had hollowed it, Russ felt a different chip would address my rich issue FQS is at -3% which helped slightly but a new chip would provide better performance. Unfortunately, Russ passed away before new chip was burned.

Thanks for info on RPR and Vitesse

Tom M'Guinn

Yeah, I'd get a knock counter or VKnock just to confirm what you are hearing is really knock. Not saying it isn't, but would be good to know for sure. Most people blow head gaskets (in these cars) before ever hearing it ping. Have you checked your knock sensor and its wiring to make sure it's working? Does it go away when you lower the boost even more? Maybe try the FQS to pull some timing? If it's really pinging at 16psi with a blend of 105 and 93 octane, then either the tune is way (way) off, or something it going on with the motor. I once saw a car with so much carbon on the piston it was acting like a glow plug...

Cam timing marks all aligned? Compression ok? Good old fashion copper plugs like BPR7ES?

V2Rocket

fun experiment - get a knock sensor connector and splice the wires to one end of a a long 1/8" auxiliary radio cable.
plug the cable into your AUX input in your car radio (if you have one), switch to AUX input and turn up the volume...you will be able to hear the pinging as you drive.

did that years ago before i got a logger, lol.

Tom M'Guinn

Very cool idea. Have you tried it and confirmed it works on the 951?

V2Rocket

Worked on my NA when I was tuning a one-off MAF kit.
Bolted the knock sensor to the stock location.

RonD.

Pulled the plugs BPR6ES NGK R .026 gap #1 cyl. lean I suspect failing injector? they are original to my knowledge. Could be cause of ping???

Black51

That's definitely suspect. You need bigger injectors than stock to be running 16-18psi, especially with an old school chip that is probably running aggressive timing.

RonD.

Black51, I put up another post to try and get 1 known good injector to test with. FQS at 0 was to rich so I've been running position 2 -3%. Leaned it a little AFR's full boost low to mid 11's. Other 3 cylinders are burning good.
thoughts on the plugs I'm running NGK BPR6ES .026 gap. Cars been running great aside from the ping.

Black51

I run BPR7ES plugs. As long as you aren't fouling plugs you'll be fine with those.

RonD.

Lightbulb! Pulled suspect injector, bench test working, OHM 5.6, thoroughly cleaned and flushed. Bingo, no ping, replacement plug no longer lean burning. Runs great. Sending all 4 for service and flow matching over the winter.