YOUNGGUN96

ok guys I really need yalls help on this one. I've got a 96 z and this is what it is doing: when you first crank it then it is fine until you let it run for awhile and then it runs like a big ole turd!It seems to have something to do with wot because you can just barely ease into the gas and its ok but if you try to get on it hard then it want to pop back through the exhaust mainly but the tb also. Its like a lean pop but when it is really warmed up then you can go from a idle and hold it to the floor and the rpms will go to about 2200 and stop and it will pop and bang and just run like crap but the rpms will not go any higher. Now if you ease into the throttle then the rpms will go on up there and it wont start actin up till farther into the rpms. Also when you hold it at wot it smoke horribly,it seems to be white and mostly black. I hooked it up to the scanner and it is showing NO misfire codes!! How this is I do not know because it sure as hell feels like a major misfire to me. The only 2 codes that it is showing are catalyst effiency low bank 1 and also secondary air injection. I have checked the fire and it is awesome,and the fuel pressore is about 41-43 at an idle. Could this be a tps or ks? It really seems to me like the coil is braking down. Does this happen often? My dad is a certified mechanic along with my boss (we all work at the same shop) and none of us could figure out anything and we messed with it all day long. like I say before it gets warmed up it will smoke tha tires off like usual but after its watmed up then it takes 5mins ta get to 80mph. Any of you guys input would greatly be appreciated,this is my daily driver and I really hate having to ease it around. PLEASE HELP ME!!!!!!!!!!!!!!!

ledfootz28

did u get it freescanned or run datamaster?im assuming if u messed with it all day u ruled out a blown head gasket,i dont really know could be somethin internal??

97Z-M6

check your coil wire but your o2 must be bad. rreplace it. that happen to abuddy about 3 weeks ago and that is what it was. but check the coil first.


the reason it runs good before while cold is becuse the pcm has to do 3 things before it uses the o2s for fueling.

1 the o2s have to reach at temp of 450 (i think)

2 the car temp has to reach 140 F

3 and pcm has to time out. 3 minutes.

once all these are met the o2s begin making correction and the bank 1 on your car is bad so it goes to a fuel rich and dumps fuel to keep from running lean.

just change it and youll be ok.

YOUNGGUN96

ok 97 if what you say is true about the 3 step then um im about 99% sure your right. sounds good to me anywhay.(if your wondering im refering to the o2). Thanks for yalls input...anyone else

YOUNGGUN96

BUT, hold on one second....On the scan tool my 02's (all of them) show to be working right.

ny_z28man

If you have an actual scan tool check your O2 sensor reading and make sure it's in the range of 900 to 100 or even lower. It should fluctuate (looks like a sine wave) If it doesnt fluctuate very much it's probably bad.

GreenDemon

I take it you are having detonation?

I would spend the $50 to take it in to a trusted and knowledgable shop- they've got some cool diagnostic equipment most people can't afford.

When my car started running like crap I took it in and they hooked it up to this automotive oscilliscope thingy (don't know technical name) and it basically showed how well the ignition system was working.

It turned out to be opti.

Every time I would reset my ecm it would run bada$$, 5 minutes later I couldn't dip into the throttle or I would start chugging along...

Anyway, most of the ignition is heat sensitive, so I'd look to that. Or a sensor somewhere, it sounds like one might be bad and as soon as you go closed loop the ecm can't figure it out.

YOUNGGUN96

my o2's are within that range. And forget tha 50 bucks im gonna fix this myself. (hopefully) Is there any possible way that this could be the cat like the code is reading? The code that its showing is a 420 which is 99% of the time a bad cat but also a bad or lazy 02. I dont know everything you guys say just about makes sense but there all alot different! anymore suggestions?

97Z-M6

you have 4 o2 sensors the one behind the car is bad. thats why the ctaalyst effincency code is up that o2s is saying your cat is bad or the o2 is bad.

97Z-M6

just gut the cat buy you some o2 simulators and be done with it.

YOUNGGUN96

What are 02 simulators? I have heard that name mentioned on this site several times but dont know what they are. Also if you gut the cats does it effect anything beside turning on the ses light? I have heard that it can mess up the fuel mixture and stuff like that <------------- clueless on lt1's....

GreenDemon

O2 simms trick the ecm into thinking the cat is working properly and combusting any left over fuel- even if there's no longer a cat at all...

YOUNGGUN96

Awesome.....how many do I need and where do I find em? Also if anybody knows how much they are then that would be great to..thinks so much for your help

YOUNGGUN96

Does anyone know where the cheapest place is to get the sims? Also do I need all four or just 2? thanks

97Z-M6

you just need the rear 2 dont mess witht he front 2

try www.thunderracing.com

www.ls1speed.com