05 northstar crank sensor codes runs like *shoot* PO 336 386

[jsnyder49090]

bought a gxp for a song but runs like crap.Codes are as follows 108 manifold absolute pressure circuit high,300 random misfire,336 and 386 crank sensor range/perf A & B.I googled and said to clean the sensors but wanted some input from others who have been down this road.I havent had any luck throwing parts at these codes trying to resolve in the past.Thanks a head of time for any help.

[CMNTMXR57]

P0108 - Means that the MAP sensor is probably faulty seeing something more than the maximum 5 volts.

P0336 - The "A" circuit of the sensor isn't functioning properly. The drivers of this could be a misfire (which you seem to have with a P0300 (there should also be a P030x which the "x" is the cylinder(s) affected), a bad CKP sensor, relector wheel damaged (teeth broken or just worn), metal shavings have built up on the reluctor wheel or the magnet on the CKP sensor, bad harness or shorted out wires in the harness.

P0386 - means that the CKP sensor has seen a signal voltage in excess of the normal 5 volts. The drivers of this could be a misfire (which you seem to have with a P0300 (there should also be a P030x which the "x" is the cylinder(s) affected), a bad CKP sensor, relector wheel damaged (teeth broken or just worn), metal shavings have built up on the reluctor wheel or the magnet on the CKP sensor, bad harness or shorted out wires in the harness.

So I would fix you misfire issue first.

[jsnyder49090]

There is no specific cyl misfire I will do plugs and wires as maintenance but I would of thought it would say which cyl it is. The car sat so it has bad gas it's been running a little better the more I run it but no where near 100%.The previous owner seemed to think the cat was bad but idk how he came to that conclusion.I will probably cut that off just to eliminate that factor as well.

[CMNTMXR57]

If the car has sat for awhile, I won't say that doing plugs won't hurt but there are no wires on this engine. It is a C-O-P (Coil Over Plug) setup with those coil modules bolted to an aluminum bracket GM likes to call a "Cartridge". The coil simply mounts over the top of the plug (it has a spring loaded tip to accomodate) all as one unit. These aren't common failures, but occasionally... White64Goat just had that with his...

I'd look at fuel lines, filter, clogged cats, etc, in addition to old/bad fuel. If it is an erratic misfire, it most likely isn't ignition. Ignition would be a constant, timed event type of misfire.

[jsnyder49090]

Ordered a fuel filter and will cut cat off and pipe it. I was just hoping it was simple as cleaning the sensors. I think I will add some E 85 to help clean but the inside of the TB didn't look bad at all.Will do that then update.

[J Wikoff]

A can of seafoam will clean better than e85 will.

[CMNTMXR57]

Cutting the cat off won't fix it, and you'll end up generating several more codes to go with the three you have now. Post-cat HO2S codes, catalyst below threshold codes, etc... Not an advisable route if you ask me.

TB has nothing to do with this. It's merely an air inlet. It should be clean.

[jsnyder49090]

please tell me you dont believe sea foam does anything. and i have used E 85 in numerous cars with good results .If i cut the cat off i would get the CEL turned off of course. i dont see a need for it not when i am trying to eliminate problems.Its one good thing about our *shoot* state no sniffer tests.

[CMNTMXR57]

Seafoam is actually pretty potent. I would use it in a non-E85 setup car before E85.

Running E85 on cars not intended for E85 isn't the best idea, especially if doing it repeatedly. One tank or two won't kill anything. It's not that the engine won't consume it, it's that fuel lines, pumps, etc, aren't really set up for that much of a blend of corn in them and can quicken their deterioration due to corrosion and may add to HO2S issues causing more DTC's to command the MIL on.

You can't just "turn the light off" after removing the converter. You can no longer buy O2 Simms on the open market (might find some on Fleabay though). Otherwise you option is to find someone with tuning software such as HPTuners, LS1Edit, or other, and have them convert those codes from a Type A, commanding the the MIL on, to a non-MIL commanding, non-emissions flagging, Type D code. This may or may not be worth it cost wise, in addition to removing a pollution control device, to try to fix something that isn't the source of your problems. I'm not being a fuddy-duddy, as I run cat-less on my GTO even here in a emissions testing are, but I have taken the correct avenues to "tune" it properly so as not to set off the emissions flags when tested.

[J Wikoff]

I see cutting the cat off as an attempt to fix these issues as wasted effort.

[jsnyder49090]

Sea foam doesn't have one active ingredient that does anything maybe the little bit of alcohol but the naptha or pale oil does nothing whatsoever it's like a Lucas product all marketing and pure garbage.I used to use sea foam before I knew better.I have used E 85 in several vehicles long term and not one thing happened at all even pre OBD II vehicles.And yes I meant use hp tuners to shut the light off.If the cat is restricted why wouldn't I cut it off you think I would buy a POS supposed OBD II or III compliant aftermarket that is going to set off the CEL for PO420 anyway.I appreciate the opinions but a lot of these responses are nonsense and do not help with not just buying parts and throwing at it.

[J Wikoff]

We're trying to help. But it seems like the things you are determined to do are not going to help your apparent electrical problems. No one has suggested to do anything with the cat other than not cut it out.

[CMNTMXR57]

1) Sea foam is 100% fine. I would use it before putting E85 into a non-E85 prepped vehicle. Plain and simple

2) You keep INSISTING on cutting off your catalytic converter WHEN YOU DON'T EVEN KNOW IF THAT'S THE CAUSE. The two of us have repeatedly said that it is highly unlikely to be your problem, yet you still insist it is. If it WERE your converter, you most likely would have other catalyst codes or post-cat HO2S codes in conjunction with the other three you have. Especially if you're funneling E85 through the system.

3) There is no OBDIII

4) Again, you don't just turn the code off. You are simply changing the type class that the code is. Type A, is an emissions code, that will set a current DTC, commanding the MIL on and generally won't clear until 40 consecutive, successful operating cycles happen without another failure. At which time, it will put it in a history DTC file. A class Type D, is a non-emissions, non-MIL commanding code. It's along the lines of your CD changer not communicating with the vehicle, or your satellite antenna not communicating. But at the end of the day, the code is still there.

We're trying to help you, but you are being obstinate. Cut your converter off. I really don't care. But I'm going to bet that after cutting it off, your problem will still be there, so you've accomplished nothing, other than adding to your problems.

I wish you the best, but I am done here.