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compression / misfiring

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savingzildjian5

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Discussion starter · #1 ·
My car was misfiring really badly after being tuned, so I took the car to my local dsm shop. They told me that they think the tuner fried my piston rings when since my BPR7ES were burnt out hard like it was really "pig lean." So I took the car back started ripping apart my engine to swap a junk yard motor in. After I got the head off I noticed my pistons are covered in a carbon build up "extremely rich." So I called the dsm shop and told them what I found. They told me to put even cooler plugs in the car and bigger wires, however made no suggestions on what to use. The only thing I cannot really figure out is why the compression in the one cylinder was like 80 and all the rest were in the 130s.

My questions
Should I just put the engine back together and then do a compression test both wet and dry to find out if my rings are shot?
If i switch the plugs to BPR8ES and larger wires, will that really fix my problem with the ignition/misfiring?

My Setup
Head
Ported and polished 6 bolt, SI 1mm over sized valves, SI dual valve springs, Manely titanium retainers
Block
7 bolt block, .020 topline pistons, balance shaft eliminator kit,
Supporting mods
fic 750cc injectors, walbro 255, aeromotive afpr, ets pro-race fmic, precision t3/t4 60trim, dsmlink
 
#2 ·
Do not just "slap" it back together. If you have it all apart, just check it.

Could have did the test with the head on and found out if it was the rings before you took it off ;)

Carbon automatically makes you think you're running rich?
 
Discussion starter · #3 ·
With the amount of carbon there, yes I think it was running extremely rich. After all running lean shouldn't produce a huge carbon build up. As I said I already had compression tests done cylinder #3 was in the 80s and the #1,2,4 were in the 130s. However, I am not sure if the amount of carbon could have cause the compression to go down. I know that typically a carbon build up makes compression higher not lower. Hense why I am so confused.
 
Discussion starter · #4 ·
Sorry I forgot to mention I check the walls of the piston and there are no impressions anywhere. I can run my finger nail against it and there are no notches. However, I can see a swirling pattern on the walls, but it kind of looks close to the swirling pattern when I got the engine back from the machine shop.
 
#5 ·
130 is low. 80 is deadly.

I'd check your head first since it is off of the car, if that comes clean, then check your pistons/rings.

I did a compression test on my car and came up with 175-175-163ish-175. That's remotely where you should be. Hell, I probably could have kept cranking on the 2nd cylinder and got a 175 :p
 
Discussion starter · #6 ·
i know i should be 160+ but the engine isn't doing it for some reason. I am going to check the head tonight/tomorrow. I was thinking about it and I came up with the idea of bad valve guides. Since the piston/rings look good to me, and my buddy thats a mechanic said the look fine.
 
Discussion starter · #7 ·
However, I still cannot figure out what was going on with my ignition. That my plugs are that burnt from running lean, but the head/pistons are coated in carbon like it was running extremely lean. Could the 7mm wires have caused it?
 
#8 ·
Wires are going to cause you to misfire if they are shit, or not fire at all.

If you think it is ignition related, check your coils, wires, and transistor pack.

If you think it is fuel related, look at your injectors, fuel pump, and fuel filter.

Good timing also helps.
 
Discussion starter · #9 ·
I check the coil. The coil read out like it should. The wires are brand new but oe ngks. I didn't check the transistor pack yet because I don't think that the transistor pack would kill spark plugs like that.
I know that the timing for the belt was dead on however, I am not sure if the dsmlink timing was good or not. It was on its default setting for the timing.
 
Discussion starter · #11 ·
I have show it to 2 mechanics and they both agreed that they are burnt from being run super lean. When I first took the plugs out they were caked in a white substance that was a result of being run lean.

However the ironic part is if it was running lean why is there so much of a carbon build up on my valves and pistons? Hense I think there is a problem is somewhere in the ignition. Mainly I was thinking that the wires were too small. My mechanic buddy told me he think the plugs are to hot and need to go back another step and I need thicker wires.

So when the two things are put together it is extremely frustrating and hard for me to actually determine anything. One thing I can think of is the carbon is related to the valves and the bad plugs are because of the ignition.
 
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savingzildjian5
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