Pinging with ZZ4 -- I now have data!
Thread Starter
Pro
Joined: Jun 2001
Posts: 509
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From: Edmonds WA
Pinging with ZZ4 -- I now have data!
OK, I got a cable and I got software and I've captured some data. I'm new to this... so, I'm not up on just what these values should be and I don't yet know enough to easily spot something that doesn't look right.
I'm seeing knock counts in the 50's when accelerating uphill. The Air/Fuel Ratio is in the 14-15 range most of the time, but will drop to the 11's with the throttle above 50%, including WOT. 02 is the 800-900 range. MAF in the 130-200 range. Knock retard seems to be a max of about 6 degrees.
Any help diagnosing this will be most appreciated! :)
I'll be happy to send data files if anyone is willing to look at them :yesnod:
I'm seeing knock counts in the 50's when accelerating uphill. The Air/Fuel Ratio is in the 14-15 range most of the time, but will drop to the 11's with the throttle above 50%, including WOT. 02 is the 800-900 range. MAF in the 130-200 range. Knock retard seems to be a max of about 6 degrees.
Any help diagnosing this will be most appreciated! :)
I'll be happy to send data files if anyone is willing to look at them :yesnod:
Pro
Joined: Jan 2001
Posts: 681
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From: Newton (Wichita Area) Kansas
Re: Pinging with ZZ4 -- I now have data! (K87ZZ4)
What is the spark advance at WOT? It should be 38 degrees max when WOT. It may go as high as 50 if you rev it while parked. Maybe your base timing is too high. Do you know what it is?
Can you hear the engine pinging when you're accelerating uphill? Perhaps your knock sensor is giving false readings.
Can you hear the engine pinging when you're accelerating uphill? Perhaps your knock sensor is giving false readings.
Thread Starter
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Joined: Jun 2001
Posts: 509
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From: Edmonds WA
Re: Pinging with ZZ4 -- I now have data! (jmr302)
Spark advance at WOT is showing about 30-35 degrees. The base timing is set to the factory mark, which is 10 degrees BTDC, according to factory spec for the ZZ4. According to others that are running ZZ4's... they are not having pinging problems with factory set base timing of 10 degrees.
Yes, I can hear pinging when I'm accelerating... and it's especially bad going uphill; at times, I will hear what I consider to be knocking... which makes me nervous.
I replaced the knock sensor a few weeks ago... on the chance that would make a difference... but it didn't.
Mike, I'm using an AKM cable and Craig Moates' software, for the moment. As I understand it, that same setup will work for your 86, but not your 96. I may use some more sophisticated software in the future, especially if I start programming.
Yes, I can hear pinging when I'm accelerating... and it's especially bad going uphill; at times, I will hear what I consider to be knocking... which makes me nervous.
I replaced the knock sensor a few weeks ago... on the chance that would make a difference... but it didn't.
Mike, I'm using an AKM cable and Craig Moates' software, for the moment. As I understand it, that same setup will work for your 86, but not your 96. I may use some more sophisticated software in the future, especially if I start programming.
Burning Brakes
Joined: Nov 2000
Posts: 1,012
Likes: 1
From: Bowie MD
Re: Pinging with ZZ4 -- I now have data! (K87ZZ4)
With my custom chip, I was told to run 6 degrees. The low 11 figure in fuel air mixture means, (I think) that you are running lean at higher quicker demand for fuel. A fuel pressure gauge with hose, duct taped to wind shield is what some use to verify that it is a fuel issue rather than a timing distributor issue. I am guessing you did like I did and reused your old distributor, because the new ZZ4 distributor with it mechanical advance set up for the zz4 would not adapt to your car. Hope you get it worked out.
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Joined: Jun 2001
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From: Edmonds WA
Re: Pinging with ZZ4 -- I now have data! (corvette1990)
I've been suspecting it is a fuel issue, because playing around with base timing has not really resolved the problem... when I backed it off to somewhere in the neighborhood of 4-6 degrees, there was less audible pinging and knocking, but then I had noticeable hesitation on hard acceleration. I haven't measured fuel pressure on the car... do I just buy a guage with a long hose and tap into the fuel rail? If I recall from reading some about fuel pressure... it should be in the 40's, right?
Would higher fuel pressure likely solve that problem? (that is, a new fuel pump?) Or, does this point to injectors and fuel delivery at that point?
Yes, I reused the distributor out of the L98 for that reason.
Would higher fuel pressure likely solve that problem? (that is, a new fuel pump?) Or, does this point to injectors and fuel delivery at that point?
Yes, I reused the distributor out of the L98 for that reason.
Race Director
Joined: Aug 2000
Posts: 11,506
Likes: 4
From: Vancouver,Wa.
Re: Pinging with ZZ4 -- I now have data! (K87ZZ4)
If you have a zz4 long block and the zz4 cam you will need to give the thing more fuel bottom line............. You are running the thing way to lean. My answer is SVO #24 and get you a chip. Marcho polo should be a able to help you out. He is a mod here in the forum..
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Thread Starter
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Joined: Jun 2001
Posts: 509
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From: Edmonds WA
Re: Pinging with ZZ4 -- I now have data! (corvette0096)
A mechanic I talked to briefly today said that he thought that an air/fuel ratio in the 11's was running rich. Does that jive with anyone else's experience?
I'll be happy to get better injectors and a chip if that will solve the problem; I just want to make sure I don't have different problem. It seems others have run the ZZ4 with a stock setup and not had timing problems.
I'll be happy to get better injectors and a chip if that will solve the problem; I just want to make sure I don't have different problem. It seems others have run the ZZ4 with a stock setup and not had timing problems.
Melting Slicks
Joined: Apr 2002
Posts: 3,019
Likes: 0
From: down that one road next to that big tree
Re: Pinging with ZZ4 -- I now have data! (h rocks)
sounds like you need some prom re mapping. should solve the problem right there. good luck with a chip, i emailed & posted twice & got no help. offered $$ & the whole 9 yards. wound up going with ed wright, at least he seems interested in doing good work for $
