stangkiller2005

iTrader: (15)

so i recently got a 96 lt1 m6.

when i first got it it had a blown head gasket, but still fired up idled fine with no knocks. got head gasket replaced. due to budget wasn't able to replace wires just plugs. I noticed 3 of the msd wires were burned. car came with jba shorties and they are not much help for installing spark plugs and wires. i got SES light not to shortly after getting car back.

problem:
so over the powerband theres major hesitation gets worse under any heavy throttle and even more after 2700rpms. i cleaned maf, thottle body. been running 91. did the pressure test and there dosnt appear to be any vacuum leaks.

the codes were checked and appeard with 3 missfires. maf functioning at 5-6g's "before being cleaned", i beleive something about the fuel trim being at 27 or something like that. 02s could use a swap. and it also came up with the two codes "P0171, P0174"

to me it feels like a waterpump. no power at all up top. hard to accerlerate on the freeway at times. car also has an inline NOS fuel pump. im in the process of trying to get new wires, but i know that will not solve complete problem.

any insight is greatly appreciated.

Paul Bell

iTrader: (9)

It very well may be all from the ignition wires. You do say three are burned. Look at the engine running in the dark. Arcing anywhere? Replace them and see how it runs.

Make sure you get them right, it's easy to get them mixed up on the passenger side.

Then cap, rotor and coil. Space the coil off the head-it'll stay cooler.

The water pump will not affect power or driveability. Are you overheating? How many miles on this car?

stangkiller2005

iTrader: (15)

no overheating. car just had head gaskets replaced along with thermostat, and runs cool. the only thing that comes on is the coolant level light. the stupid sensor has the tendency to pop off the radiator. it happened once to me. and i guess a few times on the previous owner.

o and i almost forgot. when my mechanic typed in on the computer to check codes i noticed on the printout he accidently entered 98 z28. idk if that make a difference or not?

Gojira94

iTrader: (4)

Your codes in OBD II will mean essentially the same thing as it would on an LS1-equipped 98, since you mentioned it. They refer to MAF sensor (which happens to be interchangeable from LT1/ LS1) and the front O2 sensors. P0171 and P0174 "Bank too lean" 0171 is the odd bank (1,3,5,7) and 0174 is the even bank (2,4,6,8). If you've cleaned the MAF, go ahead and try the front O2s. Nook & Tranny (LS1Tech sponsor) sells a pair for $100.00, which is a pretty good price. Don't go for Bosch or other brands. Adding new wires (which is probably adding to the stumbling) will be a good step. If you'd like to try some wires under $100.00, Taylor Thundervolt 8.2s are 50Ω per foot, like the popular and more expensive MSDs. I'm trying a set in a build I'm working on now.

AChotrod

iTrader: (17)

My car was a turd with a burned wire and also a turd when the MAF went bad. Get the wires fixed first then if the problem isnt fixed swap out the MAF with a known good one. BTW I had the same JBAs when I burt my wires.

96azz28

make sure that the sensor is all the way in mine popped out once and it was a mess after and for wires Taylor 8mm for a low budget, I have them on my car with ngk plugs and I have had no problems witht them.

Paul Bell

iTrader: (9)

Lostsa guys have had issues with Taylor wires-including me. Plenty posted about this. Arcing for no reason. Mine were pretty new, never burned or yanked on yet they loved to arc randomly. Pony up for a set of MSD's.

Good advice from everybody but do start with new wires before proceding on anything more in-depth.

Apply a little grease to the O-Ring seal of the coolant level sensor to make getting it all the way in easier.

stangkiller2005

iTrader: (15)

Awesome thanks guys! I'll defenatly start with the wires and o2 sensors. I hope it's not the Mac because this one is ported. Witch may also b the problem? I had the car running and unplugged it, and didn't really notice a change in the idle or anything. Dont know of that's a good sign or not. My car has msd wires. Sucks some are burned :/

z28cam1970

wires probably arent helping performance but bad wires cannot lead to a lean code go after the o2's and or check for any vacuum leaks make sure the vacuum lines are all on and not broke or cracked

z28cam1970

also check for a vacuum leak at manifold since that was just off seen this many times take some throttle body cleaner and spray around intake while engine is running (keep away from exh and dont soak engine to avoid fire better off if done with engine cold)listen for rpm changes when spraying

stangkiller2005

iTrader: (15)

yea we did the vacuum leak test were it pushes air into the motor and it will smoke wherever the leak is. i had two but it was just because CAI was not on all the way. but we bolted it all up and problem persist.

stangkiller2005

iTrader: (15)

would the bad o2s cause my car to buck and not have any power under heavy/WOT?

Paul Bell

iTrader: (9)

Pretty much, uh no.

RamAir95TA

iTrader: (2)

Ported MAF isn't helping anything either, in fact it's doing more harm than good. MAFs are calibrated to flow an X amount, not X + whatever material has been removed. Not to mention stock MAFs can support massive HP. Get rid of it - it's basically trash now.

Ditto with the Taylors - they were the worst set of wires I ever had. Switched to 8.5mm MSDs and running like a champ - no arcing, no cracking.

Since you only have a problem under load/WOT, that leads me to believe it's ignition-related. The plugs have to work much harder under extreme pressures and any weakness will exacerbate itself. Start with the wires before you do any more speculating.

z28cam1970

with a lean condition at wot throttle you have a fuel starvation problem and ignition problem would give you a rich condition at wot could possibly be o2s but chances of both o2s failing at same time is slim could also be a maf problem telling pcm less air is entering than actually is

Paul Bell

iTrader: (9)

Troubleshooting any car: KISS (Keep It Simple, Stupid).
　
After doing all the obvious things such as spark plug cable firing order, vacuum leak, confirmed fuel injectors and all sensors are plugged in, then move onto testing:
　
Start with the easiest item first, the ignition (in the case of the LT1, the ignition is more often the problem than in other engines).
　
You don’t need fancy tools or scanners to test the ignition. Often, a spare spark plug and a spark plug cable are all the tools you need. The engine starts and runs so there’s no blown fuses.
　
How are the spark plugs in this engine? Recently new? Correctly gapped? How many miles on this cap & rotor? It the cap correctly vented?
　
As you’ve already said there’s three burned cables, fix them before you assume anything else amiss. Poor ignition can cause misfire codes.
　
Fix the ignition. Runs good? Great! Still runs bad? THEN move onto other things.
　
When you say MAC, you mean MAF?

stangkiller2005

iTrader: (15)

yes maf sorry. i will try to find an ls1 maf and get rid of the ported one. it also has msd 6aL box. plugs are new. only a couple hundred miles on them. swapped them when i swapped head gaskets. they are ngk iridium. they were gapped, but i was under the impression that iridium plugs do not need to be gapped? although they were not at correct gap when they were purchased so mechanic gapped them. the problem is more noticeable at WOT, but you can feel the lack of power when driving. i know that could be because of the wires though.

ill swap wires, look for maf and see if problem goes away. if it does not ill swap 02s, but ill probably swap anyways because i dont think they are new, and scanner said they were not doing their best.

im not sure how many miles are on opti im 4th owner. the car has 91,3xx miles.

RamAir95TA

iTrader: (2)

Eliminate another variable - the 6AL. They are one of the most overused and unnecessary parts for an LT1. Again, sometimes a fault with the aftermarket ignition system can cause poor running conditions, so unplugging it/removing it/selling it should be tried. My N/A 383s ignition system has an MSD Blaster coil, NGK plugs, and MSD wires - everything else is STOCK.

What reasoning do you have behind the O2s "not doing there best?"

A ported MAF lets more air into the motor than what the PCM thinks, so this could also be the cause of the lean condition.

Sounds like you have some de-modding to do from the previous owner's dumb-assery.

stangkiller2005

iTrader: (15)

is it hard to uninstall the msd box? what do i have to unwire it from? the car has a dry kit hooked up on it. i just havnt used it.

my mechanic has a scan tool that tells you live whats happening with car. shows how much maf is flowing at, idle, what cylinders misfiring. things like that. and i remember him saying the 02s were not working properly or something that the scanner told him. i could have just misunderstood him.. the maf problem makes sense, ill try to find one.

z28cam1970

lean condition will make o2s look like they are lazy but they are just responding to lean condition that pcm cannot adjust out being the adapts are at full rich already (which sets p0171 & p0174 code )