Injector Cleaning

My mpg has dropped off. When brand new, car got 32-33 commuting. Then it went to 30. Now I am getting 25-27. If I set the cruise at 56 I can eek out 29. Car has 153K miles on it. New plugs. I usually run WaWa gas. Do any of the over the counter "dump it in the tank" cleaners actually work? How about the auto shop cleaners? Any other ideas on what I can do to up my mpg (other than slowing down)?
 
My mpg has dropped off. When brand new, car got 32-33 commuting. Then it went to 30. Now I am getting 25-27. If I set the cruise at 56 I can eek out 29. Car has 153K miles on it. New plugs. I usually run WaWa gas. Do any of the over the counter "dump it in the tank" cleaners actually work? How about the auto shop cleaners? Any other ideas on what I can do to up my mpg (other than slowing down)?

20" chrome wheels?:lol:

Aircleaner, all anti pollution stuff, higher tire pressure.
 
If you're going to try any of the off the shelf products, use Sea Foam. You WILL notice an improvement right away, but that's just due to the product itself. If the performance gain doesn't last after that tankfull, you probably need more serious cleaning. I would suspect tho, that the loss of fuel mileage is less the injectors and more other factors, like engine age.

There are some self-help videos on youtube for removing and cleaning injectors. Not as efficient as a $3000-5000 shop machine can do it.

I wanted to replace the injectors in my GMC truck. $100 a pop x 8. I run a can of Sea Foam every couple of tanks instead.
 
If you're going to try any of the off the shelf products, use Sea Foam. You WILL notice an improvement right away, but that's just due to the product itself. If the performance gain doesn't last after that tankfull, you probably need more serious cleaning. I would suspect tho, that the loss of fuel mileage is less the injectors and more other factors, like engine age.

There are some self-help videos on youtube for removing and cleaning injectors. Not as efficient as a $3000-5000 shop machine can do it.

I wanted to replace the injectors in my GMC truck. $100 a pop x 8. I run a can of Sea Foam every couple of tanks instead.
I figure some of it is the ethanol in the fuel (I've heard a claim of 10% cut in mpg due to it), engine age and dirty injectors. Will try the sea foam. It's still better than the Suburban gets...
 

Gilligan

#*! boat!
PREMO Member
Another thing to do is jhave a qualified shop check the calibration/output of the sensors that are critical to the injector firing pulse width in the first place; they can be out of calibration enough to affect your gas mileage but still within the limits that preclude setting a code that will turn on your CEL.

O2 sensor(s), Mass-Air sensor, BAP sensor, IAT and coolant temp..those are the ones that the ECM uses to determine where you are on the fuel map and how that value needs to be modiifed to achieve target AF ratio. The O2 is arguably the most critical of all of them as far as affecting your mileage.
 

glhs837

Power with Control
Gilligan, those should pop a CEL, though, if they are far enough out. Gives some timeframes that the drops have happened. If tyhis latest drop is since fall, then I might pin it on winter gas. The addiitve package changes, and the winter package lessens MPG. My car drops 1.5-2mpg in the winter over the summer.

Also, and this might sound silly, but you have kept up on your tire pressures, correct? If they were filled to 32 psi after driving 4-5 miles back in August, they are pretty low when the temp is in the 40-50s. Figure roughly 1psi per 10 degrees, and tires that were at 100F when filled to 32psi are sitting at 26psi when cold at 40F, and only get back up to at best 30 when driving.
 
I check my tires regularly. I usually run 42-44 PSI. Sticker on door calls for 32, but the tires are rated for 44, so that's where I try to keep them.
 

glhs837

Power with Control
If you are running 42 set hot, then your are really running them over max pressure. You are still not really dangerous, given engineering margins of safety, but I think that might be pushing them more than you need.

In any case, that's not your issue with MPG. Overinflation can have negative effects on handling and tire wear, but it shouldnt affect MPG in a bad way.
 
I figure some of it is the ethanol in the fuel (I've heard a claim of 10% cut in mpg due to it), engine age and dirty injectors. Will try the sea foam. It's still better than the Suburban gets...

I had a '64 Jeep Wagonneer. 350ci (or thereabouts) with a 4 bbl carb and beach tires. 8mpg on the highway. But that was also back when gas was under 50 cents a gallon.
 

Gilligan

#*! boat!
PREMO Member
Gilligan, those should pop a CEL, though, if they are far enough out. .

No indeed..the valid range of the O2 sensor is quite wide, yet it only needs to be out of calibration a few percent to make a noticeable difference in fuel consumption.

The error testing and thresholds that throw a CEL are pretty crude; something has to be really wrong to create a signal that far out of range.

I build custom EFI setups...including the customization tuning of the ECMs that go with. Current project is multi-port EFI setup on a supercharged....1949 Ford flathead V-8.
 

itsbob

I bowl overhand
I figure some of it is the ethanol in the fuel (I've heard a claim of 10% cut in mpg due to it), engine age and dirty injectors. Will try the sea foam. It's still better than the Suburban gets...

And winter gas has additives that drop your MPG even more (from what I understand).

Also if you gas up in Calvert they get hit with the Metro fuel mix additives that produce less smog.
 

willie

Well-Known Member
I figure some of it is the ethanol in the fuel (I've heard a claim of 10% cut in mpg due to it), engine age and dirty injectors. Will try the sea foam. It's still better than the Suburban gets...
Everything I own that burns gas has lost mpg in the last couple of months. Both Shell and Wawa went down in mpg at the same time???? I think we're being hoodwinked about the ethanol. Besides hurting fuel usage, ethanol can really screw up an engine not designed for it.
 

bcp

In My Opinion
I wanted to replace the injectors in my GMC truck. $100 a pop x 8. I run a can of Sea Foam every couple of tanks instead.

100.00 is pretty cheap for an injector. Where did you get the price from?
 

itsbob

I bowl overhand
Everything I own that burns gas has lost mpg in the last couple of months. Both Shell and Wawa went down in mpg at the same time???? I think we're being hoodwinked about the ethanol. Besides hurting fuel usage, ethanol can really screw up an engine not designed for it.

I wonder if anyone has even done a calculation if you could decrease everyone's MPG by say 10% how mucn more tax revenue the state will take in increased gas sales..

Add a little addtiive that makes the gas less efficient (probabaly on a fraction of a cent per gallon) and increas revenue by millions..
 

Gilligan

#*! boat!
PREMO Member
I wonder if anyone has even done a calculation if you could decrease everyone's MPG by say 10% how mucn more tax revenue the state will take in increased gas sales..

Add a little addtiive that makes the gas less efficient (probabaly on a fraction of a cent per gallon) and increas revenue by millions..

I've seen a couple different tech articles that analyzed and discussed the (detrimental) effects of ethanol and other additives on engine efficiency or fuel consumption. I'd have to google search to find them again..but they are out there.
 
100.00 is pretty cheap for an injector. Where did you get the price from?

Advance Auto. $97 each. I just could not see spending over $800 for injectors that *might* improve the performance.

Part # 67166
 
Last edited:
I've seen a couple different tech articles that analyzed and discussed the (detrimental) effects of ethanol and other additives on engine efficiency or fuel consumption. I'd have to google search to find them again..but they are out there.

I find it interesting that NASCAR is now advertising that they use an alcohol blend. Also interesting that more motors have blown up recently than I remember seeing previously, but haven't heard one word or complaint from any team owner or driver. It's like they are being paid to shut up about it.
 
Top