HELP Changed thermostat now runs horrible! flashing SES PO300

[tgivs]

Started a few weeks ago wife got a ticket for inspection sticker so i had to get the SES light off!

First light was for an o2 sensor, changed that an turned light off
Second light was for Camshaft position sensor, changed an turned light off
Third light was for the air injection check valve, changed an turned light off!!
Fourth light was for the thermostat, Changed an turned light off

After the thermostat i went to drive it an when i came to a stop it would die! an now throwing a PO300 code. Havent changed the Spark plugs since my wife bought the damn thing so could that be it? Crazy thing is that it was running beautifully before this thermostat swap! Maybe a coil???? i dunno, my friend is a mechanic he has been doing all the work on it but even he was confused at this!

car has 1509XX miles on it.

If anyone has an idea or solution please let me know!! Thanks so much!!

 

[The_Roadie]

Welcome! What's your vehicle profile?

Definitely get Delco 41-103 plugs if you're an I6. Then clean the throttle body if it's never been done.

 

[tgivs]

i6? and yea we gonna change the plug tomorrow for sure. you think there is a coil that bad?

 

[The_Roadie]

Bad coils typically throw a P030X code where "x" is the cylinder number with the problem. But it could be.

 

[djthumper]

Since you are posting in the GMT360/370 platform with an I6 we can only guess that is what your vehicle is since you have not completed your vehicle profile. With that said roadie is the man to listen to at this point.

 

[tgivs]

aha, i gotcha. thanks!

 

[triz]

Did you change the plugs before?

Did you properly burp the cooling system?

 

[Chickenhawk]

Disconnect the battery to change the thermostat? If so, follow The Roadie's advice: clean the throttle body.

And you are way overdue for a plug change. Use 41-103 plugs and be sure to seat the coils properly. If not, you can roast a coil very easily. It is very common to go years with no coil problems and then as soon as you pull a plug, you get coil misfires and need a new coil.

 

[tgivs]

No never changed the plugs, But the funny thing is that it was running great before we changed the thermostat and right after we changed it it is running like crap!!! lol

Chicken: Yes we took the battery out when we changed it.

 

[triz]

No never changed the plugs, But the funny thing is that it was running great before we changed the therstat and right after we changed it it is running like crap!!! lol

Did you burp it? And how is the level?

 

[tgivs]

Triz: I was not here when he changed it, i will ask him though. Would it run like crap if he did not?

 

[Ryda55555]

Could it possibly be a clogged cat? I know after i changed my thermostat i noticed my cat was starting to rattle and im going to need to change mine soon to restore some power plus it sounds pretty muffled and sluggish sometimes
But yea i would definitely change the plugs and do a throttle body clean before anything and slowly go through the process of elimination

 

[tgivs]

Yea, its not just running sluggish, it dies if the a/c is on when i come to a stop and its running like total ass! Last night the engine light started blinking for a min. From stuff i have read if the light is blinking, do not drive it! so right now i'm at the stage of changing the plugs tonight and i'm gonna buy a coil just in case it throws a PO30X code!

Ever since i paid this thing off its been light after light after light, and now barley running! i'm about to sink it haahah no i wouldn't do that!!

 

[tgivs]

what i'm really asking is if any of you have heard of that? the car running great, changing a part and then right after barley even running!! I just cant figure it out! to me it makes no sense!

would taking the battery out for a while then putting it back in, would that cause a coil or a plug to just go bad? Or is it possible that new camshaft sensor is bad? i am just throwing ideas out their now lol!

All you guys that have replied, THANK YOU so much! this is a great forum an i will utilize it more!

 

[Black_tb]

I would def clean throttle body. Clean it good by taken it off and scrubbing it

 

[Sparky]

what i'm really asking is if any of you have heard of that? the car running great, changing a part and then right after barley even running!! I just cant figure it out! to me it makes no sense!

would taking the battery out for a while then putting it back in, would that cause a coil or a plug to just go bad? Or is it possible that new camshaft sensor is bad? i am just throwing ideas out their now lol!

All you guys that have replied, THANK YOU so much! this is a great forum an i will utilize it more!

If the throttle body has never been cleaned the computer has compensated for a really grimy throttle body. When disconnecting the battery the computer resets to default and expects a clean throttle body. But, if yours is still filthy, it'll run bad (mostly at idle), could misfire, whatever, because of a lack of air. Stalling with the AC running when at a stop is also a common symptom.

Things I would do first:

1) Disconnect battery again, and clean the throttle body. Cheap and surely needs done.
2) Change the plugs, with the AC Delco 41-103.
3) Reconnect battery.

Good chance that will take care of it.

I wouldn't bother with replacing coils until you've done those steps.

 

[djthumper]

If the throttle body has never been cleaned the computer has compensated for a really grimy throttle body. When disconnecting the battery the computer resets to default and expects a clean throttle body. But, if yours is still filthy, it'll run bad (mostly at idle), could misfire, whatever, because of a lack of air. Stalling with the AC running when at a stop is also a common symptom.

Things I would do first:

1) Disconnect battery again, and clean the throttle body. Cheap and surely needs done.
2) Change the plugs, with the AC Delco 41-103.
3) Reconnect battery.

Good chance that will take care of it.

I wouldn't bother with replacing coils until you've done those steps.

Beat me to it!

 

[tgivs]

Well my dad owns a mechanic shop an i just had it towed to him, they are gonna clean the throttle body, change the plugs and see if that works. I dont have time to do it. Gotta go back to work!!


Thanks so much for your help! hopefully thats all it is :o) I'll post the solution after its fixed for others to read! maybe it will help someone else!

Thanks again!!!

 

[tbyoda]

Check out MAY03LT youtube site he's got a great amount of how to videos. He is also on GMT same user id.

Cleaning a Chevy Trailblazer throttle body I6 4.2

http://m.youtube.com/watch?v=VdvgsaDmkac#/user/MAY03LT

Spark plug replacement
http://m.youtube.com/watch?v=hB95ERNaUUk&feature=plpp#/user/MAY03LT

 

[triz]

what i'm really asking is if any of you have heard of that? the car running great, changing a part and then right after barley even running!! I just cant figure it out! to me it makes no sense!

would taking the battery out for a while then putting it back in, would that cause a coil or a plug to just go bad? Or is it possible that new camshaft sensor is bad? i am just throwing ideas out their now lol!

All you guys that have replied, THANK YOU so much! this is a great forum an i will utilize it more!

It happens sometimes. Sometimes when you hook the battery up you might blow something usually a fuse. I would go with a plug change and make the coil packs are sitting correctly. Go over the work and make sure you didn't accidentally disconnect anything by accident. Cleaning the TB and MAF at the same time as the plugs...you cant go wrong there.

I only ask about the coolant because yes if its not properly burped or topped off you can have some idling, run on problems. I don't think that your case and Im 90% sure that new plugs and cleaning of the MAF, TB and making sure nothing is unplugged will solve your problem.

 

[DDonnie]

My money is on the throttle body. Sparky is right about the computer expecting a clean one after the battery disconnect. Just so you know, cleaning a throttle body is ridiculously easy.

 

[Ryda55555]

For my voy if i turn on the A/C or idle and give it gas the idle will drop and then return back to normal
It might be the plugs cause i didnt replace them with the Delco ones but i know they're platinum plugs i changed 8 months ago and i cleaned the throttle body last month
Only thing it could be is the plugs or cat for me

 

[tgivs]

It threw a PO301 code at the shop. Gonna change that coil by

 

[djthumper]

It threw a PO301 code at the shop. Gonna change that coil by

Was everything else done? TB cleaning and plugs replaced?

 

[MAY03LT]

would taking the battery out for a while then putting it back in, would that cause a coil or a plug to just go bad?

There have been a fair amount threads where a perfectly good running truck would run like crap and set misfire codes after the battery was disconnected. I've never seen any definitive explanation as to what causes this. The only variable is the pcm running the misfire readiness monitor after the battery is hooked back up.

 

[tgivs]

Ok, we replaced the #1 coil, changed all 6 plugs an cleaned the hell out of the throttle body! She runs beautiful now! Hope this will help someone else!

The code that brought that on was PO300 an the next day a PO301

Thanks again guys! Very good info and help here!