I did several 1/4 mile runs after I installed my Edelbrock headers and brand new o2 sensor. First and second gear are nice smooth 900mV range ramps. Once it hits third gear is starts descending rapidly to about 400mV and stays down until I let off the throtle. I wish I was at home so I can show you the exact Diacom graph. I tried giving it more fuel (almost 95 in the VE tables) between 90-100 KPA but it still does this. The engine runs fairly well at WOT, but I cant really tune it w/out gettting some accurate info from the sensor. My old 80K mile o2 sensor in the exhaust manifolds didnt do this at all. Could this indicate a bad sensor ? I should mention at idle it goes from 40-50 to 800-900 almost every 1/2 second. It does this at light cruise too. Maybe it's time for a heated sensor ? Still downt explain the WOT weirdness though since it should be nice and hot.

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

Tune by O2 voltage long enough and you'll have problems.
My O2 drops to 0 at over 3/4 throttle (turbo application), and the WB O2 sensor is readin 12:1.
If the car is actually going lean try monitoring the fuel pressure, and see if it's a delivery problem first

 

Could be... I'll tape the gauge to the windshield tonite and do a 1/4 mile run and see if the pressure is steady. Thanx for the tip... but else is there to tune by without an o2 sensor ? hehe (I'm a newbie in case you haven't noticed).

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

You need to look at the plugs and measure the performance.
The best of tuning AIDS, are just aids.
Mix EGT WB O2 Knock sensing and with out looking at the plugs you can still kill the motor.
Like I keep saying
notes, look at trends, measure performance
detonation slows you down. It's not like it's a good thing.
Measure measure measure the only way to do it.

 

Hmmm.. I guess I'll need to learn how to read plugs!

 

Well I went out.. took #3 out and took a couple of pics. They look fine to me! These are Bosch Platinum plugs. Here's a couple of pics...



and



What do u think ?

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires.

Best ET 13.5@105 mph

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

http://www.truspeed.dhs.org/Members/...dmondIndre.htm

 

blade
look pretty good to me the second looks a little dark. But over all clean. somtimes if you idle they can richen up quick.
I guess I take a pic of one of my plugs. mine are pretty lite with scrapes on them. I was using the bosch platys with nitrous. I guess the nitrous tears up the plantium.
Dennis

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85 vette,383,miniram,ZF6,4.10's..best ET 11.66@1187.00 60' 1.62
w/100HP nirous 11.05@127
http://geocities.com/bowtie8

 

Yeah I know you can't really see what color the plug is. But it does have that light brownish color that Chilton's says it should be a good running condition, going by their color chart on the back of the back cover. Today I finally got around the cutting my new Accell wires and puttting them on. I took it and it was almost like a night and day difference in throtle response. If I'm lucky maybe I'll gain a tenth of 1 mph on the G-Tech.

------------------
92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires.

Best ET 13.5@105 mph

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

http://www.truspeed.dhs.org/Members/...dmondIndre.htm

 

Those plugs are way way rich

but you cannot go on what the plugs look like now to tell you what its doing at WOT, by reading the plugs now you are only telling us what your fuel mixture is like when you shut the car down .. provided the plugs are relatively new and arent "stained"

you want to start off with some new plugs with just a couple miles on them and they should be just a tiny shade darker than white, and if you look deep down in the insulator should not have any black on it at other than PE mode

IN pe mode, (wot) you want just a whisp of black ring down deep where the insulator meets the metal
the rest of it should be just a beige color, far lighter than those plugs you have pictures of

the only way to look at the wot plugs is to pull them in wot runs

wanna know how you are doing at 5000 rpm? well get in a higher gear like 2nd with a 700r4 or 3rd with a t5, and just hammer it, when you get to 5000 cut off the ignition and throw it in neutral.. be sure to do this on an empty road with a shoulder
then jsut coast to the side, and pull a plug and inspect it for the features i told you about.

Knocking will show up on the plug too, like little specks like fly turds


lemme find you a real good link on plug reading

and btw i wouldnt run bosch platinums for this

 

http://www.nightrider.com/biketech/spkplghnbook.htm http://www.nightrider.com/biketech/readplugs.htm


these two guides are by far the best plug reading articles ive found on the net, its a motorcycle page but the same info applies
the first link is like a general information beginners guide to plugs

once you get the hang of that read the second one and that tells you the stuff you need to know to tune with the plugs

 

The resolution isn't that great but:
If that is a pinkish hue to them that's magense, change brands of gas, it forms a conductive ash deposit after a while
Some sort of $$ plug, just use the right autolite. They have a harder set of electrodes, and don't erode as fast.
Need a better lite close up, but too rich again the actual hue of the photo looks off or bleached some.

The M/C site and the plugs there are absolute worst case, and extended use at worst case.

You need to get a few sets of plugs and start measurung performance per fuel change.

Depending on which ecm your using and how you have things set, if DFCO is enabled coasting down and putt puttting to look at them is fine.

On a carbie you go dead rich on onver run, and make the plug readings no where near as bad on ecm stuff. Again varies,
Cheers

BTW there are some better plug photos at the GN Ttype site

 

agreed, on the first article, however, the second article goes into far greater detail (not neccessarily pictures allthough their cutaway pic was very enlightening for me when i saw it) on what to look for