Hooked up new battery , now flashing check engine light

[Tipsey Hussle]

 

• apologies if this isn’t the right thread on forum 

Was having problem with my truck starting. So got a new battery and it fired right up.  Like 30 mins later check engine started flashing.   And seem to misfire   , then when I stopped in my drive way. It went from Blinking to steady Light.   To off.   Then back on to steady ,    Drove down the street. It started flashing again.    

now this truck has 220k miles.  So it could be a number of things.   

many advice ( on a budget , cus I wouldn’t be riding this if I had $$ for a new one 1). Lol 

 

many where I put new battery it just reset everything and chances are it could work itself out after driving a while ?   I’ve read that ,

Or disconnect battery and a while and try again ??  
 

  But other then trying that.   Any advice ?   Or anyone else had this issue ? 

 

 

thanks a lot.   Any replies would be greatly appreciated 

[Jsdirt]

Check and make sure every cable is TIGHT and its connections clean. If there was a bad connection inside, it may have got worse by handling it during the battery swap. Voltage drop test both cables while it's cranking -  you'll need a helper. Anything more than 250mV and I'd replace the cable. But, make sure the terminals are tight FIRST.

 

If that all checks out, look around for any wiring that might have got tugged on and damaged, or any connections that are unplugged or not together tight.  If after all that you're still having misfires, you've got nothing to lose by disconnecting the battery for a half hour or more, and reconnecting it later. And if that doesn't work, start from the beginning diagnosing a misfire - check for good spark, fuel pressure, intake leaks, etc..

[Tipsey Hussle]

3 hours ago, Jsdirt said:

Check and make sure every cable is TIGHT and its connections clean. If there was a bad connection inside, it may have got worse by handling it during the battery swap. Voltage drop test both cables while it's cranking -  you'll need a helper. Anything more than 250mV and I'd replace the cable. But, make sure the terminals are tight FIRST.

 

If that all checks out, look around for any wiring that might have got tugged on and damaged, or any connections that are unplugged or not together tight.  If after all that you're still having misfires, you've got nothing to lose by disconnecting the battery for a half hour or more, and reconnecting it later. And if that doesn't work, start from the beginning diagnosing a misfire - check for good spark, fuel pressure, intake leaks, etc..

Thanks so much.  I did take battery off again. But not for 30 min.   I jus see it blinks when driving sometimes.  Not all.    Then will be a regular engine light when stopped 

[Jsdirt]

Blinking light means it's a catalytic-converter-melting misfire. I wouldn't drive it if at all possible until you get this figured out, unless you live where they don't do emission testing - in that case it won't matter. If the cat melts, just punch it out and move on.

 

The way you describe this sounds like an intake manifold leak. Under part-throttle cruise when vacuum is highest is when they'll leak the most. Common cause for a P0300 random misfire code. You can check for that by using a soda or water bottle, punch a small hole in the cap, and squirt water onto the gasket mating surfaces between the head and intake manifold. Any changes in running, or to fuel trims while watching live data on a scan tool, and you found the issue.

 

EDIT to say, also check to make sure a vacuum line didn't somehow get knocked out of place or torn in half.

Edited September 16, 2021 by Jsdirt

[Tipsey Hussle]

No they don’t check emissions around here.    But I’m lost on tine bottle water trick.    Po 301 I got codes P0449  and P0455. On the check at auto zone.  That says cylinder 1 misfire. 

Edited September 17, 2021 by Tipsey Hussle

[Jsdirt]

So you have a P0301? Yes, that's a cylinder 1 misfire. The other 2 are EVAP codes.  Not a problem unless that vent is sucking air in and leaning out the mixture when the purge valve opens.

 

Find and fix that misfire, and you'll be good. Doesn't have to be a water bottle - just get water onto the gasket surface. But skip that for now since you've got a specific cylinder with a miss. Troubleshoot that first.