94 Jimmy running rich, rough, and not easy on the wallet, opinions anyone?

[brambo]

95 Jimmy running rich, rough, and not easy on the wallet, opinions anyone?

Sorry for the mistake, It's a 1995 !!!
First off we only had this GMC Jimmy for a short time, and I am not very mechanically knowledgeable but I do know some things.
Ever since we owned it once in a while while pulling a hill it will act as though it's running out of fuel, even with plenty of gasoline in it, (almost as though it is firing on 3 cylinders) yet around town it's fine.

Also it runs and idles a bit rough, I heard from several people it can do this for a long time but I am just curious as a new owner of this vehicle..It goes through gas like water, and the exhaust is how do you say, very potent, I'll put it that way...

The spark plugs have just been done, but I was told the rear one is a little difficult to get at and "may" have not been properly inserted and if so, what kind of issues can that lead to? All in all, I can honestly say it's a good vehicle, it hasn't yet let us down, but it does run quite rough...

Also, I don't know if anyone could answer this one but, the transmission was replaced before we got it (I'm told it's a Allison transmission if that sounds right), and it seems to like to shift when increasing in speed at high RPMs, almost like it isn't gonna shift, then suddenly it goes to the next gear..It hasn't had a problem yet where it doesn't shift through the gears but it does hesitate a bit first...

Also, at low RPMs in Reverse, it will sometimes die out unless you keep one foot slightly on the brake and one on the gas...But it seems to only do this in Reverse... I was told by a dealership that works on these, that the transmission when replaced actually sorta learns from the way you drive? I don't know if there is any truth behind this, but they think that is why it shifts as higher RPMs...

If anyone reads through my post and thinks they may know what's going on, any details at all are very helpful.
It's a 1995 jimmy auto, and 4x4 with a bit over 150k on it, the rest of the details I don't remember off the top of my head, I'll add on here later.

Thanks

 

[ferretx9]

Unless you've been around this vehicle for the last 5 years , and have the receipts
in hand , then it sounds like a complete tune-up is needed to start :

plugs &
plug wires
air filter
gas filter
distributor cap / rotor
PVC valve
inspect and replace any worn / cracked vacuum lines
oil / filter change

Without these basic parts being in good running order , no vehicle
is going to run right , get the best mileage it can , or be properly
diagnosed for any other issues it may have. -

you have new plugs , but if the wires are shot then new plugs do
no good ,
you have new plugs and wires , but if cap and rotor are shot ....

While you're at it , might as well inspect belts , hoses ,( consider having
radiator coolant changed if needed ) and check the oil levels in the
differentials .

Good luck and C U on the road !

 

[kbold]

im running into the power issue to. mine seems to do it more once its been driving longer distances but doesnt overheat and holds 10psi away from factory specs on each cylinder. also the stalling in reverse is due to Ignition coil pack, when you go between gears it changes the resistance in your ignition and if your coils going bad itll be either to much resistance or to little.

 

[cferry7]

OP -
What type of Fuel Injection System does your 95 Jimmy have ?
IF you have MPFI , then remove the Top Upper Intake Manifold - Inspect the area for residue fuel, next Inspect / Diagnose the Spider.

 

[kbold]

any difference with stuff you have tryed? im still running into issues.. i changed fuel filter and plugs and it snapped out of it performed great now the idles acting weird and it has almost no power when fully warm but idles great when it wants. has 30-35lbs of oil pressure at idle and around 60 on highway.. pretty sure gauge is off a bit. no oil useage or coolant..

 

[Molson02536]

any difference with stuff you have tryed? im still running into issues.. i changed fuel filter and plugs and it snapped out of it performed great now the idles acting weird and it has almost no power when fully warm but idles great when it wants. has 30-35lbs of oil pressure at idle and around 60 on highway.. pretty sure gauge is off a bit. no oil useage or coolant..

Try cleaning your MAF sensor and replace your MAP sensor if the MAF cleaning didn't help. Also giving your engine a http://seafoamsales.com/sea-foam-motor-treatment/. Note there will be smoke for a few min so don't try this inside a garage.

Start with these simple things and recheck your vacuum lines and replace any that are damaged with cracks.

Good luck and stay safe

Molson02536

 

[kbold]

Try cleaning your MAF sensor and replace your MAP sensor if the MAF cleaning didn't help. Also giving your engine a http://seafoamsales.com/sea-foam-motor-treatment/. Note there will be smoke for a few min so don't try this inside a garage.

Start with these simple things and recheck your vacuum lines and replace any that are damaged with cracks.

Good luck and stay safe

Molson02536

turned out to be a plugged catalytic converter, and the muffler had a hole in bottom of it size of a coffee can, also the check valve on the brake booster hose was bad so it wasnt working correctly and was getting either to much vacuum(air), or not enough making the system run super rich or super lean.