Check Engine Light Flashing

[ElPurtre6886]

I just got a set of hooker long tube headers put on my 96 z28, as well as a qtp exhaust cut out. i drove it and as i was leaving ips a check engine light came on. i drove it for a few days thinking the sensors would get used to the work done and the light would maybe go out. a few days later the check engine light started to flash. i ran the codes and had 2 o2 sensor codes, an egr flow malfunction code and a random multiple cylinder misfire code. the egr was removed so i ignored that. ips says that the plugs are fine and that the o2 sensors might be going bad and to replace them. that is the reason the cylinders are misfiring because the o2 sensors has it running to rich. ips said that if i changed the o2 sensors the only code that should be left is the egr code. do you think this is the problem and should i spend the money to replace the o2 sensors? please let me know what you think.

[Mojoe]

Why are you second guessing the shop you had work on your car? What if I take the time to tell you what I think the problem is? Are you going to ask everyone else what they think? Seems to me like a waste of my time if you aren't going to believe what I have told you.

 

For what it's worth, unless you have some sort of piggy back ECU or something else to manage the motor, I'd say they pointed you in the right direction. But, What do I know, I'm a Mortgage Broker. Maybe you want to ask a gun smith says.

[AJ]

maybe you should have taken it back when the light came on and let them look at it since they did the work. if it ran find before and then you had the problem after the work was done then maybe they messed something up, it happens. they'll prolly stand behind it if they messed up.

[ElPurtre6886]

whoa im not second guessing anyone. i was just told multiple things from ips. first it was the check engine light flashing was only a warning, then it was the light should always flash until the car is shut off, then it was the light will only flash when a cylinder is misfiring. alls im saying is i just spent 1500 bucks and i dont want o go blow another 120 for a few o2 sensors. i was just asking for an opinion.

[ElPurtre6886]

thats the thing i just took it back to them to check out after the light came on. they said it was maybe the o2 sensors because they looked old. so idk what they are going to do. all i know is i have to replace the sensors and if that doesnt work then idk. never would have expected headers and a cut out would give me such a problem

[Mojoe]

you are getting several codes. That is why it may be several things. I know my first post labeled me a dick. The point I'm making is they know your car best right now. They can't say it's "this", when you have several codes for stock equipment. You modded the car and now the stock, non self learning ECU is throwing codes. Trouble shooting sucks. I know this more than most on here. If it's something you can not do yourself, you have to pay someone to do it who knows how to.

 

EDIT:

 

Also, is the car running fine?

 

Have you check on forums specific to your car and seen if other people have run into this when doing the same mods?

[Martin]

well thats what happens when you mod cars. things start to break. maybe they didnt screw in your O2sensors or a wires pinched or maybe it realy is just going bad since the cars 11years old. i dont know how ips is since ive never delt with them but i have heard good things but you can never know for yourself if you dont get under a car and do the hard work, you just have to take there word. if your fine with that then keep doing what works for you.

[Buck531]

The flashing SES light normally means the misfires. I'm going to go out on a limb and say that possibly a plug wire hit the header and fried it. That's happened to me before. Same with the o2 sensors. Possibly a wire was hitting the header and fried it.

 

Just my .02.

[V8 Beast]

IPS is right. My car had bad 02 sensors + bad plug wires and it did the exact same thing. Granted I have an LS1, but the symptoms are the same. If I were you I would replace the 02 sensors, check the voltage on the wires, inspect the spark plugs, and find someone that can tune LT1's (not sure if IPS can or not).

[ElPurtre6886]

the car has been running shitty. sometimes it seems like the car is running fine but other times it shakes real bad and seems to be lacking power so im guessing its the misfireing thats causing that. now it seems the check engine light is flashing constantly. all the plugs and wires are fine so i guess ill just replace the o2 sensors and go from there. it just sucks because i never had a problem with them and now that i put 1500 into the headers and cut out, now im having problems. in my opinion i thought they would be responisble for this. not the o2 sensors being bad but if that doesnt work i think they should fix it. i mean do i have to get it tuned? they acted like if i replace the sensors the codes should go away.

[V8 Beast]

the car has been running shitty. sometimes it seems like the car is running fine but other times it shakes real bad and seems to be lacking power so im guessing its the misfireing thats causing that. now it seems the check engine light is flashing constantly. all the plugs and wires are fine so i guess ill just replace the o2 sensors and go from there. it just sucks because i never had a problem with them and now that i put 1500 into the headers and cut out, now im having problems. in my opinion i thought they would be responisble for this. not the o2 sensors being bad but if that doesnt work i think they should fix it. i mean do i have to get it tuned? they acted like if i replace the sensors the codes should go away.

 

What part of town do you live?

[craig71188]

As stated before - the flashing MIL is for a type "A" misfire - the type that is bad enough to damage the cats.

 

Codes for other stuff are just that - at 11 years old, depending on the miles and how driven, the front O2's probably need replaced for maintenance reasons (they do wear out). That's not to say it will make the O2 codes go away.

 

The fact you don't have an EGR on the car and on a '96 (OBDII) it is monitored by the PCM isn't going to help matters.

 

The problem is, on an OBDII car, the PCM looks at a lot of stuff - and cross checks it to other sensors - when you start modifying stuff without the knowlege of how it all interacts - you get these types of problems.

 

Is the shop responsible? Depends on what you paid them for - if it was to install headers and cut outs - well that's what they did. The fact is may cause other issues is not necessarily their responsibility.

 

You need someone with a good scan tool and an understanding of how all these systems interact - particularly when modded to sort this out. It could be the car is too lean with the headers/cutouts, the injectors can't keep up (lean misfire) and this can set an O2 code because their not in the range the PCM wants to see.

 

But hey, I'm just pissing in the wind because I haven't seen the car - I'm just a Master Tech guessing on very limited information.....

[V8 Beast]

As stated before - the flashing MIL is for a type "A" misfire - the type that is bad enough to damage the cats.

 

Codes for other stuff are just that - at 11 years old, depending on the miles and how driven, the front O2's probably need replaced for maintenance reasons (they do wear out). That's not to say it will make the O2 codes go away.

 

The fact you don't have an EGR on the car and on a '96 (OBDII) it is monitored by the PCM isn't going to help matters.

 

The problem is, on an OBDII car, the PCM looks at a lot of stuff - and cross checks it to other sensors - when you start modifying stuff without the knowlege of how it all interacts - you get these types of problems.

 

Is the shop responsible? Depends on what you paid them for - if it was to install headers and cut outs - well that's what they did. The fact is may cause other issues is not necessarily their responsibility.

 

You need someone with a good scan tool and an understanding of how all these systems interact - particularly when modded to sort this out. It could be the car is too lean with the headers/cutouts, the injectors can't keep up (lean misfire) and this can set an O2 code because their not in the range the PCM wants to see.

 

But hey, I'm just pissing in the wind because I haven't seen the car - I'm just a Master Tech guessing on very limited information.....

 

 

You hit the nail right on the freaking head. The sputtering and shaking that the car is doing is becasue the bad sensors/misfires are causing the car to try and stall out. And its almost like a vacuum leak in the way it acts. The car will surge, buck, and sputter, but will not do it consistently. Then when it does happen you will get the flashin ses light. The exhaust probably smells rich, and the car feels like its only running on 6 cylinders. Just make sure you swap out the o2's before the spark plugs go bad... hopefully its not too late.

[ElPurtre6886]

i live up off of schrock road and cleveland ave. yeah i figure the big thing is replace the sensors and go from there. i mean for the first few days it was running great up until the light started flashing. so maybe the sensors did go bad, who knows.

[MrMeanGreen]

The flashing SES light on your OBDII GM is an active misfire being counted in one or more cylinders.

 

I will tell you from experience after doing headers in my LT1, you're probably rubbing a plug wire on a primary and burned through it, causing your misfire.

[V8 Beast]

i live up off of schrock road and cleveland ave. yeah i figure the big thing is replace the sensors and go from there. i mean for the first few days it was running great up until the light started flashing. so maybe the sensors did go bad, who knows.

 

Check the voltage on the wires, and pull a few plugs to make sure they are ok. Then go from there.

 

Edit: Yeah, what Ant said.

[ElPurtre6886]

ok well i changed the o2 sensors then disconnected and reconnected the battery. the ses light was gone (of course) then came back on flashing. i scanned it and the only code i got was the random multiple cylinder misfire. all the other codes were gone. so i have no idea why my cylinders are misfiring if all the plugs and wires are ok.

[Dave1647545494]

yep if your hedders didn't come with fire sleeve for the plug wires I'm sure one or more of them are all burned up..... fix the burnt wires first and clear the codes then see if the light comes back on.... if it comes on for egr only you can have it removed from the pcm by a tuner...

[Dave1647545494]

if you need the light cleared after you fix the wires pm me and I can do it or most autoparts stores have a janky little scan tool that will turn off the light

[Buck531]

Damn.. didn't I say the above.. above?

[MrMeanGreen]

I think I was his age when I dicked with my first flashing SES light

 

It's a wire or more than one. Go find it and replace it. LT1s with headers are notorious for it.

[SlowZ06]

I think I was his age when I dicked with my first flashing SES light

 

It's a wire or more than one. Go find it and replace it. LT1s with headers are notorious for it.

 

This man speaks the truth. I think you spoke with one of the guys I work with (Advance auto in Powell) and when he asked me, I told him the same thing. We did Arizona Speed & Marine headers on my friend's 95 Z28, and aside from the fact they were a PITA to install... we burnt a few plug wires afterwards.

[Guest Hal]

As stated before - the flashing MIL is for a type "A" misfire - the type that is bad enough to damage the cats.

 

Codes for other stuff are just that - at 11 years old, depending on the miles and how driven, the front O2's probably need replaced for maintenance reasons (they do wear out). That's not to say it will make the O2 codes go away.

 

The fact you don't have an EGR on the car and on a '96 (OBDII) it is monitored by the PCM isn't going to help matters.

 

The problem is, on an OBDII car, the PCM looks at a lot of stuff - and cross checks it to other sensors - when you start modifying stuff without the knowlege of how it all interacts - you get these types of problems.

 

Is the shop responsible? Depends on what you paid them for - if it was to install headers and cut outs - well that's what they did. The fact is may cause other issues is not necessarily their responsibility.

 

You need someone with a good scan tool and an understanding of how all these systems interact - particularly when modded to sort this out. It could be the car is too lean with the headers/cutouts, the injectors can't keep up (lean misfire) and this can set an O2 code because their not in the range the PCM wants to see.

 

But hey, I'm just pissing in the wind because I haven't seen the car - I'm just a Master Tech guessing on very limited information.....

I've seen a master tech take 2 hours per oil change lol. However, you sir are dead on.

[ElPurtre6886]

haha yeah that was me. corey sold me the o2 sensors and ran the code. but yeah idk i checked all the wires and the plug on cylinder one, which runs the leanest, was fine so i think im just gonna take it back to ips and see what they can do.

[Guest nasty57]

IPS is right. My car had bad 02 sensors + bad plug wires and it did the exact same thing. Granted I have an LS1, but the symptoms are the same. If I were you I would replace the 02 sensors, check the voltage on the wires, inspect the spark plugs, and find someone that can tune LT1's (not sure if IPS can or not).

 

Check with Randy, i know he has some LT1 software because we did my car and i gave it to him.