What to DO Now???

[zackp]

Ok guys well I got the lower intake manifold gaskets installed along with all others etc. Car runs better but still is by far not right. Still has a miss and seems like it don't have no power I guess I'm going to try a new coil pack and finish putting the 6th plug store only had 5 for some dumb reason yesterday. To be honest I think I just want a new motor so I know what I have any one you all know of that builds a decent motor? Or what parts is good to get I wouldn't care if to throw some nice parts together for one or whatever just want a dang good running car without worries so please help point me in the right direction bc this thing is really making me mad.

[Fivefingerdeathpunch]

year and model of car please.

also any SES lights?

[zackp]

00 pontiac gtp and yes says it keeps saying missfire cyl 4 but done changed everything on it basically going swap coils around and see if it changes to another cylinder tomorrow but I'm worried she may done something bad to it by using 89 for gas, and the lim leaking as bad as they were. Any ways any help be great bc I really like this car but ready run it off in the ditch right now.

[BillBoost37]

You put swamp water into your gas tank, had known issues and cylinder 4 is maybe having an issue. I'm glad you realize it and aren't looking to blame the car for the issues.

[Rico]

If you swap coils around and still have a misfire on #4 then do a compression test on that cylinder.
With a misfire on a particular cylinder you have to think differently...worst case then go backwards.

If the piston or valves are damaged and you're unaware of it you'll be chasing your tail with replacing ignition stuff and waste a lot of money.

[zackp]

Well knowing my luck with this thing it will have a hole in the piston or some crap. But where should I look for a new engine or can you point me in the right direction for parts to get to take it to a machine shop around here. So what parts can I get to make it even quicker than before and run better but still be reliable??? Cam, Pistons, etc.... let me know and thanks guys and gals..

[Rico]

I think you're jumping the gun. Diagnose this first with a compression test on cylinder #4 and go from there.
These engines are tough as nails...although a little finicky. There might be another 100k left in this one.

[Anthony Smith]

These engines are tough as nails.

I verrry much disagree, in MY experiences these engines take very little true abuse without catastrophic failure. I've never understood why people always say thier so tough. I do agree that a compression test and leakdown test should be your #1 concern in this situation though

[EJOUIE]

I see where this is going. Out of the ashes arises a racekar.


My advice? Buy headers now.

[BillBoost37]

I verrry much disagree, in MY experiences these engines take very little true abuse without catastrophic failure. I've never understood why people always say thier so tough. I do agree that a compression test and leakdown test should be your #1 concern in this situation though

I'll disagree with your disagreement. Overall these motors are tough. Right up until you do one or two things. Like running piss water for fuel and drop pulley sizes. That's a pretty sure way to toss a piece or two of piston into your catalytic converter.

[Anthony Smith]

On another note Ive dealt with more damaged sII 3800s that were N/A than boosted, then again I work on peoples DD rides more than "racekars" so its rare to even get a call for something on a L67 powered car.

OP - Single cylinder misfires are usually super easy to diag. if you have a scan device where you can see the misfire counts. After verifying compression, just start swapping every component one at a time with one of the holes that isnt misfiring, plug wire, coil pack, injector, and plug.

[zackp]

Ok guys as some you know car was running ruff and loosing coolant. So I changed lim gaskets, supercharger gaskets, etc, spark plugs, and plug wires. And car runs alot better but still not right. So I done a compression check like suggested and they are all between like and 110-118lbs. But I am still getting a mis fire on cylinder 4 I pulled wire off this evening and had wife crank car and it shows plug is getting fire? I have seen hotter by far but that's with my msd on some other motors i've had. Any how what should I check and can't be much left but possibly maybe a fuel injector or the coil, but like I said that it is throwing spark. Any Ways let me know what you all think and thanks.

[matt5112]

#1: avoid MSD coils for these things, they fail prematurely.

were the plugs gapped?

And that comp is VERY low.

was it cold?

What are your LTFT's like?

[zackp]

the msd ignition i was talking about was on a couple 350 small block chevy's I had and yes plugs were gapped and motor was cold yes. kind hard check hot to me at least. and LTFT's like??? don't know what your talking about there

[Fivefingerdeathpunch]

long term fuel trims.

If you have a vac leak, it'll be pegged at +16.4

[txslow6]

Miss on cylinder 4 could be an injector not sealed properly. Check to see if there is a vacuum leak there. While the engine is running spray carb cleaner around that injector. If the car hiccups then you have found one of the possible multiple issues you have with the car. I would go ahead and spray anywhere a vac leak could develop.

Food for thought- the head could be cracked. It could be so small that you don't notice it with the naked eye. As a last resort you could pull the head and have a machine shop take a look at it.

[rynoman03]

^^ I was thinking the same thing. It could even be a clogged injector. When was the last time you ran some seafoam through the car ?

[Mjcanton]

Are you still losing coolant? if so I'd be worried about the head.

Also, how bad is the misfire? Is it just sometimes or absolutely nothing on 2? Last week 5's injector went out on my car. I changed coils, plugs, wires and then finally injectors before the miss jumped cylinders. My injector was stuck open so there was a lot of fuel in the cylinder.

I would try swapping injectors if you tried everything else. if that's not it you should probably start thinking about heads.

[BillBoost37]

First thing to do is please don't make more threads with nearly the same name. This makes it confusing to those helping you out. Second is having the second thread means people have to go back and find out what you've already done/tested for and maybe left out of the second thread. No biggie..helps us out though.

[Rico]

And that comp is VERY low.

Since all cylinders are low it's probably just the gauge's accuracy.