Alrite so for the past couple of months my 2001 GMC Jimmy(my dad has the F150 ) has been idling rough, has occastional weak starts, and fails to idle sometimes, it will die sitting in traffic if the gas isn't applied. so i took it in for service today as well as a routine service(Carmax). Well, they called my dad around noon(I was in school) and told him that they were going to clean the injectors, clean the throttle body spacer, and put a new fuel filter in. They also told us to start using Medium grade, 89 here, from Texaco. One of the service managers said that cheaper gas companies use chemicals to boost the octane. Now heres the thing, we bought the 4 year 50k warranty with the car, so they have to pay for anything major. I really don't understand why I'm being asked to put 89 gas in a car that has a engine(4.3 Vortec) that was designed for 87 octane. Are they trying to dodge a larger problem?

Thanks in advance for your responses,

Alex

p.s. sorry its not about an F150 :o , this is just the best all around forum i've ever come across on the internet haha

 

sounds like just a common vacume leak. nothing more nothing less

 

Its a GMC.. Get rid of it and buy a ford that will solve all your problems.

 

I have an 89 GMC truck with a 4.3,that I have been beating since new.
I have always used 87 octane with no problems. ( old TBI )
I tend to agree that it could be a vacuum leak, but if you can't remember when the fuel filter was changed, it's overdue for a new one.
By the way, when you buy cheap no name gas...... you get what you pay for.

 

thats the thing, i dont buy cheap no name gas, well atleast i don't think so :P i always buy my gas from the same place, Wiegels, its a convenience store chain around knoxville. The price isn't cheap compared to everyone else, its really about the same, personally i just like the gas stations around here, their nice, and are in convenient locations. But since its not a gas station chain, im sure they take bids from the companies, so it could end up being cheap gas. We'll see, i drove it home and really didn't notice anything different.

and as for the "sell that gmc comment" to tell you the truth my dads 04 F-150 has had a lot more problems then my car has, the brakes are going bad again after a supposed "we fixed it for good" the power window in the back has screwed up twice, the black leather on the driver's seat is starting to come off after only 38k miles, and its got the damn cruise control recall. But i do agree i would rather be driving a ford, but the Jimmy was my first car, and its pretty damn nice at that(SLT Trim, got with with only 24k miles) Im currently trying to get the old man to give me his 150 and have hm buy a new 07 denali haha.

anyways thanks for your posts guys, its comforting to know whenever i have a question i can get some positive input.

Alex

 

your problem is most likely the EGR valve is stuck open with a piece of carbon. Should set a check engine light, but not always. Remove the EGR valve and install a gasket with a sceen in the inlet port, about 8 bucks, to stop the carbon problem. Make sure the valve is not still stuck open when you reinstall it. It only going to be open a little. most vacuum leaks with this motor give a high idle. spray bottle with water can safely and easly find a leak if it has one. if possible check the fuel pressure. Vortec motors down two pounds of fuel pressure will not start easly. They will not hold residule fuel pressure if it is the fuel pressure regulator. All this will cause this problem

 

alrite thanks for the info, ive only drove it home from the dealer, we'll see how it performs in the coming weeks.

 

I heard that a Turbonator would fix any GMC engine problem.

 

Alex, not a Ford or GMC but I had a Nissan that was doing what you described. The Nissan mechanic checked things over and suggested that I run 89 octane in it. I really doubted that that had anything to do with the problem. But what the heck, next fillup I put in 89.

You know what? Hesitation problem solved. I can't explain it, but it worked.

Ran 89 in her for the next 250K+ miles. Never had another hesitation problem.

Joey

 

Once again, I think this guy has it figured out.

It's not a vacuum leak, and it's not octane related. Virtually all gas stations get their gas from the same refineries, the only difference is the additives. I would suggest going to a different gas station from now on, but you don't need to switch to 89.

 

Almost all gasoline comes from the same pipelines. From there out it's the additives (such as detergents) that certain companies use.