I know that there isn't oil vapor in the egr, lol. I was thinking of the pcv for some reason. Since that's come up, is there a tube in the pcv system, or is it just the valve under the map sensor? Hoping to install a catch can.
QUOTE=bumpin96monte;716493]Do you have a scan tool? I'd start by learning to read the common sensor values - MAF, MAP, O2, IPW, etc. You can also see what the individual cylinder misfires are showing. The goal is to see what the inputs are vs the outputs to see if there is anything that helps point to something there.[/QUOTE]
This is the scan tool I have. https://www.amazon.com/gp/aw/d/B00UJV3E12?psc=1&ref=ppx_pop_mob_b_pd_title
I know how to get to the sensor data, I just don't know the normal values in order to compare them to the current.

 

The 3800 is a pain for doing catch can(s) because pretty much the entire system is done through internal passages. You certainly can add a catch can, but then you end up having to run some external lines and other mods to make it work.

On my monte, I ended up doing a fully external system so I could run larger hose and install catch cans on each side of the circuit. It's not pretty though but I didn't have a lot of choice as some of my mods completely blocked portions of the stock PCV.

Probably worthwhile to hop on YouTube and see if there are any good videos for how to scan / what to look for. It's a powerful tool, so its worthwhile to learn how to use it.

I'd think the key things you'd look at for something like this would be fuel trims, MAF, MAP, front O2, and specific cylinder misfire counts.

 

If there's a guide to doing that I'd love to see it.

I stated earlier in the thread that I tried replacing the spark plugs as an early diagnosing step. I just pulled those new plugs, and I believe I know what cylinders are the issue. It appears to be down 4/6 cylinders. The plugs were soaked in gas/black. But the two that are good look brand new. The two good cylinders are 2 and 5. This does line up with the coil pack theory, as the two good cylinders are off one coil, and the other four run off the other two. But I already tried replacing the coil packs from aftermarket to original and back. So idk. Here are a lot of pictures.

 

Not trying to promote another forum, so mods feel free to delete if this breaks the rules, but here is a pretty in depth thread:

​http://www.grandprixforums.com/how-to-write-ups-tech-tips/107289-the-pcv-thread.html

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In terms of the plugs, I honestly dont think it would even run on only 2/6 cylinders. If it did manage to run at all, it should be absurdly rough.

A good way to confirm if those cylinders are truly dead is to disconnect that plug wire and see if it changes how the engine idles. If there is no change, that confirms a dead cylinder. An IR temp gun on those runners should do the same.

If you're really leaning towards ignition and you're pretty sure it isnt the coil packs themselves, you could look deeper into the ICM. Maybe that has a bad connection or two? Also, since you've got a known good coil, you should be able to swap coils and see if the problem moves with the coils.

 

I'm fine redirecting to another forum.

I was going to suggest testing the ICM, it seems odd that only 2 of 6 cylinders are fine. I was leaning towards checking injectors, but now I'm not.

As for the PCV and a catch-can... I wouldn't bother unless you modify a ton. I am a huge advocate for a catch-can on direct injection, but if you use high-quality fuels, and do regular oil changes, I don't see a point in these engines.

 

Here's another thought - you say you've got 2 clean plugs and 4 plugs soaked in gas / soot. Maybe the 2 clean ones are the ones not firing and/or rarely firing?

Here's what I'm thinking- those plugs may be nearly spotless because the cylinder isnt firing. It's just passing the gas and air mix right out the exhaust. The O2 sensor sees a ton of excess oxygen, thinks it's way lean and starts dumping fuel to get to14.7:1 up to the point where the fuel trims are maxed. Now the cylinders that are firing are running silly rich causing the carbon buildup and trapping the raw fuel smell.

On the scan tool with the engine running, what are the STFT and LTFT? If they're both hugely positive, the above case could be right.

 

I agree that it's not really worth it for the NA 3800 setup. I can see some merit on a boosted setup where you're octane limited that you dont want excess oil going in the cylinders to maximize how much boost / timing you can run.

To be honest, I do run one on my NA LS2 GTO also, but it has much higher compression than a L36 and is octane limited via timing due to our crumby 91 premium. It's also a 5 minute install on the LS engines - pop a tiny hose loop off, run fresh hose from each barb to each side of the can, and bolt the can up.

 

I believe bumpin's theory may be the correct one. Like I said, I don't know how to interpret the numbers the scan tool puts out, but I know how to relay them to you guys. Right at start up, the short fuel trim was 0, and long was about 6. As I let the engine idle, the short jumped up to a max I recall seeing of 21, and the long trim moved up to about 13. I'll include pictures of the rest of the data in case it's of any importance.

 

Obviously the first thing that pops out are the fuel trims. STFT is where the computer makes instant adjustments based on the O2 sensor (once in closed loop / CL mode). If it keeps seeing the same need for that STFT, itll slowly transition that over to LTFT.

What I'm seeing in your case is that you've got a lot of LTFT (nearly maxed if your estimates are right), plus the O2 sensor is still showing lean and you've got a ton of STFT too to try and pull that value up. So it's clearly dumping too much fuel and based on the big variety in plugs, it's likely not a single global issue (like a post MAF vac leak or something).

Does your scanner have a misfire counter by cylinder? If not, it's not a huge deal as you've already got a clear indicator on the plugs. Would just be nice to see if those cylinders were missing 100% of the time or if theyre intermittent.

I guess for the next step, you'll have to diagnose the injector or ignition for those cylinders. If I dont have known good spares, I like to swap existing components around to see if the problem follows. Personally, I'd unplug the pcm after each round of changes to zero those fuel trims out.

 

I picked up a multimeter, and 12v testing light, and tested the ICM this moring. The two posts that connect to the middle coil pack (cylinders 2 and 5) were completely unresponsive while the car was being cranked over. The top and bottom were functioning as expected. For whatever reason, whether it was just age, or possibly my fault over tightening the coil packs, the ICM failed. I went to a local junkyard, and picked up a replacment for 19$. I tested it when I got home, and all three pairs of posts passed. After puting the coils and wires back on, I cranked over the car, and it runs just fine now. I want to thank everyone who helped diagnose this problem with me, especially bumpin. I always wondered if the people who regularly reply to my many posts remembered me.