I recently purchased a 2004 Malibu with the V6 engine. It has over 104,000 miles. It was well maintained, oil change every 3,000 miles, etc. Engine seemed to run smoothly when I first drove the car. A handheld scanner detected a cylinder 6 misfire.I recently installed new spark plugs and wires. The compression in cylinder 6 is good, and the mechanic didn't mention a misfire. The gas mileage is still very bad. 15 MPG average for city and highway.Yesterday I added BG 44K fuel treatment incase the injectors are clogged. Any ideas?

 

i have an 07 malibu 4 cyl. and i expected better gas milage outta a 4 cyl....how do u drive ur car? u liek to speed? or take it nice and slow

 

I accelerate gradually, and don't drive fast. I am being especially careful because I am trying to get better mileage.

 

What kind of spark plug & plug wires did you install? That can make a difference if you went with an aftermarket plug wire that is too long & a plug that is not the right one.

For the plugs you are better off installing AC Delco plugs in the car. They might cost around $7 per plug if I remember correctly, but the car will run at its best with the best fuel ecomony. As for plug wires AC Delco is also your best bet, but those can be more costly than the plugs.

 

How many fill-up did you do before checking MPG? Did you go to the same pump / nozzle?

 

I have a 04 with same engine. I agree with the poster that says use the plugs it came from the factory with, regardless of cost. There is a resistance issue from not using them, electronics are picky. The right plug is 41-101, I get 20 mpg around town even in cold weather.

 

"Around town" is very relative...with the same engine, I get about 16MPG every winter. However, I drive in NYC...I've come to accept the terrible mileage this time of year. I get 19-20MPG city in the Spring-Autumn, and 31 highway.

Seems that's just how the 3500 is.

 

actually its a 3.5 the 3500 is a different engine.

GM 3500 engine may refer to:
* DOHC LX5, Oldsmobile V6
* Vortec 3500, Straight-5

 

If that is the case why would there be engine covers on Malibus that say 3500 V6 on them? On some 04 & 05 Malibus I have seen the covers that say that while newer Malibus have a cover that say 3.5 V6 on them.

 

I don't know, you must look more Malibu covers than I do. My 04 has no cover, I just know my 3.5 is not a DOHC engine.