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Old 04-02-2012, 08:13 PM   #1
mojomello
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Default pinging issue

I have a 94 940t that pings just as I start to roll into boost, then runs fine. I use 93 octane+an octane booster, my coolant is new, air filter is a k&n, freshly cleaned. I modded the airbox a little by running a tube out to the front of the car to help with intake air temp.
If I drive like an old lady, it runs great. It also runs great if I beat the hell out of it, it's just that split second when I first start to spool that it goes "knock knock" and I say "who's there?" and then it takes off like a raped ape. I've been searching the older threads here and I believe I've managed to convince myself that I need a new knock sensor, but I wanted to see what yall thought before I go get one.
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Old 04-02-2012, 08:18 PM   #2
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Stock injectors? Boost psi? any other mods?

Typically it's lean, in my experience, until the computer starts it's accel. enrichment. A typical bandaid fix is larger injectors.
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Old 04-02-2012, 08:39 PM   #3
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Yeah, stock greentops. psi is 16, only other mod is 3 inch cat deleted exhaust. I didn't mention psi because it pings before it boosts. I should also mention that I live in Fl. and ambient air temps are hardly ever optimum, although it didn't always do this.
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Old 04-02-2012, 08:51 PM   #4
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What are you're AF/R's under boost, and AF/R's when you tip in?
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Old 04-02-2012, 08:55 PM   #5
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I was having the same issue even with the browntops before the chip, cooler plugs stopped it.
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Old 04-02-2012, 09:06 PM   #6
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Quote:
Originally Posted by Satsukeshi View Post
What are you're AF/R's under boost, and AF/R's when you tip in?
Actually, The first thing on my stage 2 mod list is a wideband, so I don't know what the afr's are yet. It's been stage 1 for a year now, and I'd say the pinging started 2 months ago.
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Old 04-02-2012, 09:37 PM   #7
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My suggestion is a set of 4 NGK Copper BPR7ES.

I don't know a whole lot about LH2.4 (still learning) but it seems there's a timing issue on tip-in somewhere around 0 vacuum/boost that can cause pinging. Have you run some injector cleaner/done a Seafoam treatment?
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Old 04-03-2012, 10:18 AM   #8
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Yeah, you really need a wideband for these sorts of things. That way you can really find out what's going on, in correlation with your boost gauge.

What 944Turbo said is essentially correct. Bigger injectors (forcing it rich), and also making sure to let the ECU learn about 200 miles after any reset (#1 fuse pulled, battery disconnect...), can help.

Ditto on the plugs.
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Old 04-03-2012, 05:14 PM   #9
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Awesome. Thanks for everything, guys. @944 Yes, I've done the seafoam treatment both in the tank and pulled into the mani through a vac line. I'll definitely get some of those NGK's asap. @Satsukeshi I've been looking at a PLX Device wideband for awhile now, I guess this is as good a reason as any, to cough up the $200. I wasn't going to progress any farther with this car till I got it, so maybe this will motivate me. lol
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