Jump to content



Photo

Misfire when engine cold & fully warmed


  • Please log in to reply
7 replies to this topic

#1 seagull369

 
seagull369

    Advanced Member

  • Members
  • 104 posts
 

Posted 25 January 2015 - 12:48 AM

Have a bit of a mystery on my hands with an '88 Chevy Nova, which really is a rebadged Corolla using the carbed 1.6 liter SOHC 4A-C Toyota engine.

 

With engine cold, there is a miss on the leftmost cylinder. When it warms up slightly, the miss goes away and engine runs fine. When the engine reaches full operating temp, the miss returns and continues from then on out. This sequence happens like clockwork every time and the miss is present regardless of engine RPM. I checked compression and spark strength under both conditions (when stone cold and fully warmed) and found both to be good. The spark plug in the offending cylinder was changed (along with the others + spark plug wires) but problem continues. I checked the plug after the engine idled for a while and found it to be a bit carboned (that could be cuz the car wasn't driven), but nonethess I changed it again, but problem remained. Oil level is good and was just changed. A distributor cap and rotor are on order, but I don't think that will change much. Anybody have a clue on what might be going on? Not sure if I have a lean/rich ratio or if something is up with the valves/lifter for that cylinder. Next time I visit the car I planned on grounding out the plug wire on that cylinder, running the engine for a bit, then checking to see if the plug is wet or not just to make sure it's getting fuel.  

 


#2 meme

 
meme

    Advanced Member

  • Members
  • 159 posts
  • Gender:Male
  • Location:PA
  • Interests:sure as hell isnt cars.....thats my job
 

Posted 10 February 2015 - 07:35 AM

the accelerator pump diaphragm, leaks and dumps fuel into that cyl, rebuild carb. 



#3 Karrpilot

 
Karrpilot

    STAFF

  • Staff
  • 6,188 posts
  • Gender:Male
  • Location:Chicago Zone
  • Interests:Ex Ford Tech 22 years.
 

Posted 10 February 2015 - 08:12 PM

Meme, when is the last time you saw a vehicle with a carburetor in the Wall-Mart quick lube? If a accelerator pump diaphragm leaks on a carburetor, it usually effects ALL the cylinders, not just one.

 

But you knew that, right? :rolleyes:


No longer working at dealerships. Government employee. Now i get paid to fix Fords.
ASE master tech
Private Pilot High Performance / Complex Rating.


#4 meme

 
meme

    Advanced Member

  • Members
  • 159 posts
  • Gender:Male
  • Location:PA
  • Interests:sure as hell isnt cars.....thats my job
 

Posted 12 February 2015 - 07:32 AM

its not a Ford,  its a Toyota, worked for Toyota dealer 4 years,  back in the day,   but u knew that!  correct?   back to your dump trucks



#5 Karrpilot

 
Karrpilot

    STAFF

  • Staff
  • 6,188 posts
  • Gender:Male
  • Location:Chicago Zone
  • Interests:Ex Ford Tech 22 years.
 

Posted 12 February 2015 - 04:17 PM

Meme, being a porter car jockey for a Toyota dealership, did you ever open up the hoods on one of the cars, and visibly see a carburetor? Those items probably disappeared around the same time your mother was changing your diapers. Well, at least one would hope she changed your diapers.)

 

As far as my dump trucks go, that's where the employment fun begins. You won't see any of them in your Wall-Mart quick lube. Your boss is too cheap to install the necessary lifts needed to repair them, and I doubt your tire machine and oil drainers have the capacities required in their services.

 

But then again, you do get the employee discount.


No longer working at dealerships. Government employee. Now i get paid to fix Fords.
ASE master tech
Private Pilot High Performance / Complex Rating.


#6 VW Techguy

 
VW Techguy

    Advanced Member

  • Members
  • 321 posts
 

Posted 22 February 2015 - 09:46 PM

Walmart lol. Had a customer tow his Touareg in after Walmart put 2 sizes smaller tires on the front of a full time all wheel drive vehicle said it's not why his transfer case is making popping noises. I told the customer the tire guy was most likely stocking butt wipe 6 months ago.

#7 seagull369

 
seagull369

    Advanced Member

  • Members
  • 104 posts
 

Posted 05 June 2015 - 10:45 AM

Just thought I'd provide an update on this..

 

I decided to replace the intake manifold gasket to see if that would help. Although that didn't end up helping any, when I had the intake manifold off, I happened to notice a little 'do-dad' with 2 vac ports on it screwed into the runner going to the cylinder that was having the misfire. After replacing the gasket, I decided to plug up both ports on this part (which I found out later is referred to as a 'fuel filter' by toyota) and the vac hoses going to it. Car runs fine now

 

Toyota wants $60 for the part and online I found it for $40, but for now I think I'm just going to leave it as is.

 

Here's a picture of  similar one I found online circled in red, in case anyone's curious as to what it looks like: http://s233.photobuc...68042c.jpg.html



#8 Karrpilot

 
Karrpilot

    STAFF

  • Staff
  • 6,188 posts
  • Gender:Male
  • Location:Chicago Zone
  • Interests:Ex Ford Tech 22 years.
 

Posted 05 June 2015 - 06:07 PM

Good thing you didn't listen to Meme. Sometimes a little surgery and inspection goes a long way. Not to say that at some point, a carb overhaul might be in the cards, but I have yet to see one cause a single cylinder misfire.

 

Meme has not been posting for a while. Me thinks his manager has him stocking and busting tires. Little hard to screw that up. Well, for most of us.)


No longer working at dealerships. Government employee. Now i get paid to fix Fords.
ASE master tech
Private Pilot High Performance / Complex Rating.



1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users