Fuel System Cleaner..??

[Arnold]

I put this GM Fuel System Cleaner in.. the mileage INSTANTLY went up about 16%. I don't really believe in stuff like this..I put it in because I just bought this car..and after driving it several thousand k..I figured it would not hurt. I have done this with my other vehicles.It has never made any difference in fuel economy..but has fixed 2 gas gauges,rough idle,smoothed out engine performance.Sure..I guess it fixed a few problems.
This vehicle had NO problems and ran like new BEFORE I did this.
 The GM stuff IS aggressive! And not cheap either.MINOR over treatment is ok. This stuff I would not fool around with. The directions are to put it in at an empty tank..THEN add a tank of gas. This way it gets sucked in quick and strong at first.
 NOW I am scratching my  head (LOTS! of hair left ) as to what/where the "problem"? was. Clearly something has been improved/fixed.I am definitely NOT going to looking myself..but I will probably mention it when someone else services it. This is a d/d.

  The vehicle is a 2007 Uplander Extended 4wd ex Police vehicle with a 3.5.
  I bought it online at a very good deal..and was too far away for me to check out. I very reluctantly had to drive the 3 hrs to see it..at night..and literally drove it around the block at about 25mph.Seemed ok. Part of the deal was that the dealer I bought it from would allow ANYONE I wanted to check it out..and they would just do whatever they said it needed. The dealer certainly had confidence in it.
  Anyway..I get the vehicle..didn't need any work really..and I was very pleased with it.
Runs like new.
  My fuel economy improvement over my other 4wd truck was an instant 40%!

  I figured it would not hurt..to put some of this stuff in..so I did.

  I literally put the stuff in,tanked it up,drove it and the little mpg computer showed the mileage had improved 16%. My first thought was that that gizmo..which WAS accurate was now toast. Maybe because of this stuff I put in.

  No..the mileage improved and has stayed that way.
  It was already getting an average of 23-25mpg checked every tank..in horrible winter driving conditions..the mileage went to about 28..maybe a hair less..and has stayed there.Ya..the horrible winter driving conditons are the same :evil:

  I dunno..it appeared it fixed something..I dunno what??
 Any ideas?

 Thanks :!:  

[jaybee]

My guess would be fuel injectors that weren't bad enough to throw a code or cause drivability problems but weren't atomizing properly.

[1800guy]

I wonder how close GM's formula is to Sea-Foam?   I never believed in "miracle-in-a-can" either, but seeing is believing.  I'd agree that modifier deposits on the injector tips were most likely affecting fuel atomization.

[Arnold]

My guess would be fuel injectors that weren't bad enough to throw a code or cause drivability problems but weren't atomizing properly.

 Thanks very much guys
 
  I did sort of think it was plugged injector that had been loosened up..maybe it was..but I dunno..it ran so well..not only to me but to a buddy who has had I think 6 0r 7 of these things and his buddy is a GM Tech here.It probably was just that Thanks Partially plugged injector.Wow! The parameters/limits are that far apart that they can obviouslly tolerate a leaning out this much.Maybe a cel was just about to go off.Or a richening up. I wish now that just for fun I had at some point
gave this  thing a good scanning.I won't know now.
 I had thought maybe some restriction in the filter?(I hear the filter is in the tank. That makes me so happy )
 It did pass 2 emmissions tests here..but I do not really trust them here
  It also passed an inspection by a very reputable garage in Toronto.
   I don't know what the tolerance is in their tests.Public tolerance is zero so they stopped doing tail pipe tests  and do a computer test. You need so many drive cycles to pass..since the cel was fixed or it failed emmission.
Drive cycles have been in cars for like ever now..I am pretty sure my 93 Escort had one.

  It just seemed to throw me off..that this many people..the vehicles computer.. did not see/feel this thing as rich..which of course it was.
  It is a Police vehicle..who knows what is different..who cares.I think the Police V6's have 300h/p. I just always baby the thing and it is great on gas..like a little 4wd tank in the snow haha.Some mini van it weighs 5000lbs.

  It started saving me 40% in fuel costs   got just great mileage..then I poured this stuff in and now it is better on fuel

  lol..now it will quit because this stuff was too aggressive and ate away something or some gizmo  

   Thanks again Guys

[Arnold]

I wonder how close GM's formula is to Sea-Foam?   I never believed in "miracle-in-a-can" either, but seeing is believing.  I'd agree that modifier deposits on the injector tips were most likely affecting fuel atomization.

 Ah No..not related. You cannot put too much Seafoam in really. Depends on how aggressive and smokey you want it to be. I think it is pretty cat safe. I have found that Seafoam only goes so far. And if you really want to foul something up it is next to impossible to do with Seafoam. Pretty hard to glaze plugs with deposits by using Seafoam.
 
   This GM stuff I think..and according to people in the industry is by far the most aggressive fuel system stuff around.
   Other manufactuers QUIETLY use it..on their own..and oh yeah ..buy it from GM.It can be too aggressive.
I would make sure I had an engine in really good shape before I put this stuff in.I go with Seafoam first..and if there is a big change..then I know that there is something plugged up and stay far away from the GM stuff for now.
   I actually ran Seafoam through my Suburban no change..good. Then the gas gauge quit..and I used that stuff for the gas gauge and it fixed that.
Not long after that I took it in for service and told them the above.They were pretty sharp and pulled the fuel filter off with lots of fresh crap in it. This thing was now plugging up.
  I had a lot of confidence and knowledge about the service of this vehicle and drove it several thousand miles before I did this.
   I am about 99.99% sure that if you took some very poorly taken care of car running very poorly that this stuff would loosen crap up and just plug it up real quick almost assureadly destroying the cat. I can't imagine any cat going through that. "Cat safe" often means that it is not that strong.
 
  Ya GM says "Minor overtreatment not harmful".No kidding.They don't try and sell you multiple treatments.

   I use a few Seafoams in the gas and if it does not make any difference it is a pretty cheap test to see that all is pretty good...then I do the aggressive GM stuff.

   I got too aggressive in dealing with my backyard egr repair in my work van that I plugged up stupid bad :oops:
   SOooo I poured in the GM stuff..and then tried to beat the carbon out.

    When it warms up I will change the plugs I plugged up :oops: