Stuttering?

**LgndKller20073** · 01-14-2009, 10:37 PM

My engine seems to stutter when I'm between 1,500 RPM and 2,000 RPM but only when I'm at cruising speed doing about 40-50 MPH, but it also seems to do it on hills no matter the speed I'm going. If I go over 2,000 it goes away, and if I'm under 1,500 it's not there either. When it stutters, it will go to about 1,900 RPM, then drop to 1,700 then go back to 1,900 and so forth until i let off the gas and hit drops below 1,500 or i hit the gas and it goes above 2,000. Any ideas what it could be? By the way its an auto V6.

Also, it seems to happen only when I'm in 4th. It seems like it can't decide if it wants to downshift to 3rd or stay in 4th.

**suede** · 01-14-2009, 11:48 PM

How are your plugs and wires?

**BowTied** · 01-15-2009, 03:43 AM

Sounds like it could be the fuel pump. Being aggravated by an alternator low voltage area. Check your voltage gauge note the voltage just before, through, and after the problematic rpm range.

And suede suggested the other more likely problem. Plug wires are easy to check for routing and damaged wires. It is better if you can make sure they don't have too much room to move. Sometimes these problems don't show on the insulation and only the internal conductor is breaking down.

**BowTied** · 01-15-2009, 03:47 AM

One way to help isolate the fuel pump is to charge the battery to 100% full and then fill the tank up. If the problem greatly reduces or goes away it is the pump. (And could be foreshadowing a failing alternator.)

**One_Bad_TA** · 01-15-2009, 06:22 AM

My car did this under part throttle at 2500 RPMs. The problem was my MAF sensor. Dont know if its the same for you cause it happened at all speeds

**LgndKller20073** · 01-15-2009, 09:07 AM

So it basically comes down to:

1.Plugs and wires
2.MAF Sensor
3.Fuel Pump
4.Possibly Alternator?

Would any of these cause my gas gauge not to work? It will show I have a full tank until about 250 miles and then begin to drop suddenly and end up at empty at about 275....and any of these would cause my gas mileage to drop?

Also, as far the voltage, it stays the same throughout. the only time my voltage ever drops is when i have the lights on and my bass hits really hard.

**BowTied** · 01-15-2009, 08:01 PM

The 1st 3 possibilities can all effect gas mileage.

Have you had this car very long?

I don't know about the 6-packer tank mileage. But the Gas Gauges are notorious for being imbalanced to the high side. The upper half is much closer to 2/3 of true capacity they all trail off around 1/2 to 3/8 of a tank.

Start ruling things out. Plugs then Pump. (Visually inspect and check signals at the MAF when you give the plugs and wires a once over.) But that won't rule it out. You need a program to monitor MAF signals for a full diagnosis.

I take it you aren't getting a code?

**LgndKller20073** · 01-15-2009, 08:22 PM

Its been in the family since around 500 miles. The only code I was getting was for the EGR valve, which I replaced, but that was nearly 6 months ago. My gas gauge used to be pretty well off, until recently. As far as replacing goes, whats the easiest after the plugs and wires?

**BowTied** · 01-16-2009, 05:12 AM

Well the MAF is surely easier than a fuel pump.

How many miles on the car?

The increased consumption is making the gas gauge seem even worse.

But that might be indicating regurgitation (gas coming back out of the inflow side) with and over-heating of the pump. These acting to vaporize the gas (this would be worse with less gas in the tank.)

The pump could be eliminated if the car does not drive better (including on hills) with a full tank of gas!

**LgndKller20073** · 01-16-2009, 10:33 AM

there's just under 58K on the car and it doesn't get any better regardless of a full tank of gas or not.

**BowTied** · 01-16-2009, 11:15 AM

Then check those plugs and wires. If they are anywhere near needing changed then just go ahead and replace them.

**BowTied** · 01-16-2009, 11:18 AM

Oh and I wouldn't drive the car if it is performing that bad. No more than enough to test.

**LgndKller20073** · 01-16-2009, 11:35 AM

yeah, i'm pretty well screwed on not driving it cause it's my DD. I'll probably go and buy some plugs and wires and just replace them anyway since it's supposed to be nice this weekend.

**SAGGIN** · 01-16-2009, 11:38 AM

I thought u were going to tell us about a speech problem you have...

....na, but the tips above are a good place to start.

**0rion** · 01-17-2009, 07:55 AM

check for vacuum leaks also. The pcv hose on the passenger side that goes into the intake likes to crack on the backside. Pull that hose off and inspect it carefully right in the bend and see if it's cracked. I also wouldn't replace the MAF until you get some MAF cleaner and clean it. You can get a can of cleaner at any parts store.

**LgndKller20073** · 02-11-2009, 07:21 AM

so, as it turns out, it was my transmission being low on fluid. when i had it changed a few months ago, the asshats didn't top it up right so I was running about a quart and a half low.

**BowTied** · 02-12-2009, 02:53 AM

This is the problem with troubleshooting (especially in a message board forum)when you don't get info on what has been worked on lately.

A RPM and gear related problem and shifting symptoms, I couldn't have been the only one thinking Transmission...but that almost always rolls in gently and steadily.

If you had said the tranny was worked on you probably would have got the answer in 20 minutes.

**UC Warrior 1** · 11-07-2009, 12:37 PM

So this past summer i replaced my fuel pump in my car. Everything was fine afterwards until my muffler fell off. I had it off for quite some time because i didnt have much time to deal with the different sized pipes. After a while the engine light came on with some issues. The car started stuttering and sometimes would auto shut off. I brought it in and they ran the tester, there was like 9 things that came up and could have been either on of those. Most dealt with fuel/ sensor stuff.

Well i replaced the muffler thinking that was the problem but soon afterwards it started doing it again. It ran fine until i went to pass someone on the highway and when i blew past them with hard acceleration and brought it back down to speed (15MPR) Thats when the car started acting up again, the rest of the drive would sit around 2000 RPM but in order to accelerate at any rate id have to floor it. It takes about 3 seconds before it kicks in and jumps up to like 6000 RPM accelerating slowly. It sounds like it is backfiring in the back as well as the front...Not sure what could be the problem. If i let the car sit for a week it kinda fixes itself and is fine again

If i break the lights also dim...Alternator?
I really hope it is not the fuel pump because ive gone through 2 of them and their expensive as shit.

**suede** · 11-08-2009, 07:01 AM

Originally Posted by UC Warrior 1

So this past summer i replaced my fuel pump in my car. Everything was fine afterwards until my muffler fell off. I had it off for quite some time because i didnt have much time to deal with the different sized pipes. After a while the engine light came on with some issues. The car started stuttering and sometimes would auto shut off. I brought it in and they ran the tester, there was like 9 things that came up and could have been either on of those. Most dealt with fuel/ sensor stuff.

Well i replaced the muffler thinking that was the problem but soon afterwards it started doing it again. It ran fine until i went to pass someone on the highway and when i blew past them with hard acceleration and brought it back down to speed (15MPR) Thats when the car started acting up again, the rest of the drive would sit around 2000 RPM but in order to accelerate at any rate id have to floor it. It takes about 3 seconds before it kicks in and jumps up to like 6000 RPM accelerating slowly. It sounds like it is backfiring in the back as well as the front...Not sure what could be the problem. If i let the car sit for a week it kinda fixes itself and is fine again

If i break the lights also dim...Alternator?
I really hope it is not the fuel pump because ive gone through 2 of them and their expensive as shit.

check for a loose plug wire