Flashing Check Engine Light

[the99hoe]

Hey everyone,
I'm new here and i have a question. I have a 99 tahoe 350 and have been experiencing a flashing check engine light. I don't have any cats on it right now because they started breaking apart and clogging up the pipes. I have been losing coolant somewhere but cannot trace it. I only notice the coolant on my garage floor, it seems that is the only place it leaks. I have 140k on her now, I'm hoping that this isnt a head gasket but am looking for others who may have experienced this same thing. I live in OK and it has been snowing and sleeting and cold as you know what, don't know if this would affect it. please help me trouble shoot this.

 

[peterey2]

well no cats would throw your O2 sensors off and make them send a false signal. have the code read and go from there.
as far as the coolant leak, have the system pressurized via the cap, and look for leaks. usually with a head gasket leak you can smell coolant in the oil, or you'd be loosing coolant without seeing anything on the ground.

 

[2000 limited]

same problem here with the colant i could not find the leak no where you need a new intake gasket..

 

[peterey2]

intake gasket? how so?

 

[2000 limited]

these vortec's are common on this trust me. when there is something wrong with my rides that i can't figure out i search the comp like a mofo. lucky i have a friend of mine that works at the dealership and i watched him do this and he also said that these vortec's leak from there intake gaskets and when pulled that sucker of and i had 2 small crackes one on each side

 

[peterey2]

ya i know they go all the time, cause ruff idle, yada yada. but that shouldnt cause a coolant leak.

 

[Sepiroth]

The flashing check engine light means that the truck is having a or more misfires. Go to any auto parts chain stores and have then put a code reader on it to determine which cylinder/cylinders have the misfire.

 

[DefEddie]

When the check engine light flashes,that means the engine is experiencing type "A" misfires.
Type A misfires are misfires bad enough to cause internal physical damage to the engine or destroy the catlytic convertor.
The most common misfire is a type B misfire,and will simply cause the misfire monitor to flag the check engine light on.
Light on=Bad
Light flashing=more Badder

 

[DefEddie]

The coolant leak is probably at the rear of the intake.
I'm betting it doesn't leak out while running either.
It leaks into the engine causing misfires,and when you shut it off and the motor cools-metal contracts and it leaks out onto the ground without the engine vacuum helping suck it in.
Shine your flashlight down the backside of the engine and see if it's wet after you shut it off.
Of course that's a wild guess over the internet with only 2 generic symptoms to go by.
It just so happens i'm also in Oklahoma,I pm'ed you for your location.
It's doubtful you are,but if your near me then you can swing by my shop sometime and I can verify it.
I've got everything we would need to diagnose.

 

[treepete]

Light on=Bad
Light flashing=more Badder

hahaha awesome.

I agree here, cats could be the trouble, and the mysterious leak sounds like intake gasket. If your gasket IS giving way, consider yourself luck that ou got 140K out of it.
Your problems are fixable however. its just gonna cost you parts and some time to replace it. not a bad weekend project if your mechanically inclined.

 

[1998hoe]

I have a 1998 2-Door and i have a Blinking service engine light that goes solid .. Is there a difference ? I am going to autozone today to have codes ran. Just wondering if anyone else has had this problem?

 

[lesterl]

Flashing means you have an engine damaging misfire and solid means you have an emissions issue, the first is a critical issue don't drive it, the second is not so critical could mean poor fuel economy or reduced power.