Spark plugs causing bad MPG? - 2005 Lancer, OZ, 53k miles

Is this possible?

I cleaned my engine a week or two ago and got the service engine light.

My brother plugged in a computer to read what the issue was and something with the sparks or piston, it was misfiring. (sorry its so vague)

But we checked under the hood and found out spark plug #1 was not 100% sealed, and pushed down. Barely noticeable the gap, but it was.

We took it out, looked at it, pushed it back in properly. Cleared the cars memory (for start up light) and it never came back on.

But last night i went out into the car to program an address into my GPS since i was leaving at 445 AM, and i had the car on, it was IDLING. but every so often, the RPM would sort of... DROP???

as in, a misfire?...

i just purchased the car on the 5th, i took it to my mechanic before purchasing it, he did say the car had the "wrong" spark plugs so, that and this... hmmm. Cant be too off here can I?

anyways, will this also lead to bad MPG? I got 22.90 MPG... so i decided to drive it easy to and from work, work is 24 miles away, one way, 19 of which are highway. so i decided to cruise and take is easy, used alot of cruise control and kept it under 75 MPH a few days later I fuel up. Do the math, and get 23.71 MPG!!! I only gained .81 MPH, and the other thing was, i was driving fast prior! and revving it hard at the lights and wasting gas. so i was in shock! even upset!...

THANK you all for your time and advice.

 

i once noticed having the wrong plugs and gap lead to poor mileage.

 

hmm thanks. oh, the only "mod" on the car is an SRI intake, and ill ask another question, doesnt that if anything help out the MPG, even if its small difference?

the 4 days that i drive home from work its after midnight, normally 130AM, so the weather is a lot cooler and not as hot as the day (live in miami), so i figured hey, the car should be breathing cooler air. considering i have an SRI i figured that it would help a tad bit.

My best friend (whom i purchased the car from) most likely didnt notice this, and wasnt really big into cars or doing anything but fueling and driving. So i have no doubt he didnt even notice he was getting bad MPG. but my 94 corolla was getting 27 MPG, consistently and i drove that car hard!!!!

 

what plugs are they? what did you set the gap to?

replace the plugs with NGK v-power plugs and gap them correctly and you should be all set.

 

Don't know! I'll check, but yes I will replace them with those you mentioned! But when I pull them out I'll post back.

Thanks.

 

atilla hit the nail right on the head. Get those V-power copper core plugs for $1.50 a pop and be set to go.

 

What gap you running on those current plugs?

 

Sorry, but what are you reffering to when you speak of the gap?

The gap at the tip of the plugs??? Give me 5 minutes and ill post high resolution the pictures of my old plugs and the new ones i just put today.

 

ive noticed alot of the ngk plugs are pre gapped already

 

it's always good to double-check them before putting them in your car. i can't remember the gap off the top of my head but i have my little emissions sticker on my old hood in the basement that has the gap range. i usually go right about in the middle of what recommends on the low side and on the high side. i THINK it may have been .036 but i haven't done my plugs for awhile.

 

double post... check below!

 

old and new spark plugs...

NGK V-Power... $2.50 a pop...

How bad would you guys rate the old plugs?

If anyone is wondering I used a Nikon D40, Digital SLR camera for these pictures, with an external flash; SB-600.

 

si no maybe so? bump....

 

well I noticed one thing short ram intakes suck hot air from the engine compartment when the factory set up is more of a ram air set up pulling in fresh cool air from the front of the vehicle. that is probably your fuel milage issue also using cruise is not going to save you mpg's because it will try and keep the mph no matter what the road grade is hill or flat so it will floor it if needed to maintain set speed try not using cruise and being easy on it also this time of year fuel mileage sucks because it cooler out and the fuel blend is crappy although this may not pertain to you being in a warmer climent
hope this helps

 

i got the cylinder misfire error code. i was running the denso iridiums and 8mm wires. i replaced the plugs with the ngk v-power and got oem replacement wires, and boots for the coils.

the stock plug gap is .039 but i set it to .035 instead and its never run better!

now the error code is gone!

if this doesnt fix the problem then start looking at your injectors.