Need help diagnosing misfire and reading plugs

[monteperformanc]

Since I changed out my radiator in October I have had some random misfiring that is sometimes noticeable at idle and more apparent when getting on it. But I have been taking it easy until I can figure this out. But it doesn't always happen.

I took out the plugs and to me they look okay except the #3 ground strap is a different color than the others.

I run e85 on this car.

I checked compression and they were all between 140 and 150.

# 3 is the middle, #1 is on the right.

This is the other side of the engine

I checked the ohms on the plug wires and they are all good.

 

[Pronto]

First thing I'd do is replace them with NGK gapped at 28 tight and see what happens.

 

[Dhos1]

What he said^^^^

 

[monteperformanc]

I was going to get new plugs anyway so I can do that. These were also gapped at 28.

 

[Chuck Leeper]

Can't "read" them w/o seeing the straps.
What are you using on the threads?

 

[monteperformanc]

Are these any better? There was nothing on the threads I put them in dry.

 

[turbo89]

Are these any better? There was nothing on the threads I put them in dry.

I'd check the injector while you were there ..

 

[Chuck Leeper]

A better pic of from the ends, so we can see the timing on the strap. From what I can see it looks like the heat is too far toward the base of the strap, indicating a bit too much timing.
Cutting the thread off will provide a look at the fuel ring at the base of the porcelan...
As mentioned, a look at the injs might be in order, too.
Lean??? Data log{s}??

 

[monteperformanc]

A better pic of from the ends, so we can see the timing on the strap. From what I can see it looks like the heat is too far toward the base of the strap, indicating a bit too much timing.
Cutting the thread off will provide a look at the fuel ring at the base of the porcelan...
As mentioned, a look at the injs might be in order, too.
Lean??? Data log{s}??

Are you saying all the plugs show too much timing, or just #3? Is there a special tool to cut the thread off? Thanks.

I don't have any recent data logs. The afr seems to be in the 10's when getting on it.

 

[monteperformanc]

These are Autolite 23's. Would that be the correct heat range for 25+psi, 24/22 timing?

 

[SCOOBY DOO]

A friend I race with uses a 12 volt zip wheel to cut the plug on his nitrous Camaro after each run.

 

[monteperformanc]

I put new plugs in and went out to record some logs. The first time i got on it, it did it again. It's really more of a cutting-out rather than a misfire. If you look at that part of the log you can see the tps signal is dropping while I am accelerating. This happened once when I was at the track. Could this be a bad tps sensor or something else? .dat file attached.

 

[Thumper]

i am not a professional plug reader, but my opinion is it's to lean. I would like to see your 02 numbers in a pic like you gave us above. What my concern is....... I have never seen a car / chip with enough fuel for 25 psi at half throttle, when those conditions happen it almost always lean, could be a faulty tps but it looks fairly steady reading, either way let's see the 02 numbers in place of vehicle speed please.

 

[monteperformanc]

I agree it is too lean. I was also surprised to see that much boost at part throttle. Here are screenshots of O2 and WBO2 which do not look right at all. However during all this fuel pressure looks okay which does not make sense to me?

 

[monteperformanc]

This is also an intermittent problem. It doesn't always happen. Most of the time it seems to run fine.

 

[TurboDave]

Is that supposed to be a WOT pull? TPS is way low if it is. And if if isn't, why are you running so much boost with so little TPS??

 

[monteperformanc]

Is that supposed to be a WOT pull? TPS is way low if it is. And if if isn't, why are you running so much boost with so little TPS??

Maybe not full throttle, but close to it. At least 3/4. Looking at the log I see injector PW really drop right before it starts cutting out. Could that be a result of the cut-out or the cause of it? It drops from 21 to 3 in that frame!

 

[dynoman]

These are the plugs I use , non-projected tip , resistor , readily available & cheap ! NGK 4323 http://shop.advanceautoparts.com/p/ngk-nickel-spark-plug-br6fs-4323/12031657-P
Also like Pronto said , close up the gap . I run .028" with a TR6 ignition .

 

[Thumper]

e85 with single walbro and 60s may not be enough fuel volume, I don't run e85 so i'm not very versed with a good setup. lmho that's not enough fuel system/volume for that boost level on e85.

Something is not just right, its not a plug issue, its deeper than that.

what is your wot tps voltage?

 

[monteperformanc]

I agree it's very lean and it wasn't always like that so something has changed. I am going to turn the boost way down and try to figure out what is going on.