1998 Pontiac Transport Drives Sluggish

[98Pontranport]

Hi All, 1st post here......
I have a '98 Transport, 163,000 miles on it, all seems fine when driving until you get to where you're crusing at 45 mph or so, than there's like a sluggish performance when pressing the gas pedal, kind of like a back and forth jerking motion. Could this be a bad fuel filter, bad spark wires, or worst a tranny problem? I bought new Bosch platinum plugs today, I'll put them in tomorrow.
Anyone had/have a similar problem with theirs?


Thanks

Mick Scream

[98Pontranport]

Well, scratch the attempt to change the plugs being that 3 are in front and the other 3 are hiding back by the firewall I believe....I'll let the boys do it when I bring it in for servicing.
Still acting bad. Tranny was flushed 2k miles ago.

[ibarra_design]

Originally Posted by 98Pontranport

Well, scratch the attempt to change the plugs being that 3 are in front and the other 3 are hiding back by the firewall I believe....I'll let the boys do it when I bring it in for servicing.
Still acting bad. Tranny was flushed 2k miles ago.

Hi there Mick 98Pontranport,

I was checking the forum today, I do have the same problem with a '94 I just got last week. It was running great when I purchased it, then all of a suden started "acting" the same way you describe it. "Playing" with the gas pedal helps, it seems that if I stop giving gas and then accelerating just a bit makes it go; however it runs rough such as if a plug wire was loose. Did you fix yours? I certainly appreciate if you and anybody from the forum can answer tp this email.

Thanx!!

[LMP]

I had these symptoms (would not want to accelerate past 45 mph, but playing with the throttle would help a little but if I kept the throttle to the floor, then it would, after 4 or 5 seconds, accelerate which was not ideal if one wants to overtake).
It proved to be the Mass Air FLow sensor. In my case, it was simply dirty because I had used the car for a little while without an air filter.
Cleaned the MAF sensor with artist paintbrush and alcohol and all returned to normal.

[ibarra_design]

Originally Posted by LMP

I had these symptoms (would not want to accelerate past 45 mph, but playing with the throttle would help a little but if I kept the throttle to the floor, then it would, after 4 or 5 seconds, accelerate which was not ideal if one wants to overtake).
It proved to be the Mass Air FLow sensor. In my case, it was simply dirty because I had used the car for a little while without an air filter.
Cleaned the MAF sensor with artist paintbrush and alcohol and all returned to normal.

Thak you LMP for responding this quick!!

Now, would you indicate me where is this thingy please???? How do I get to it?

Thank you again!!!

–Mig

[LMP]

YOu did not state what engine you have. Here what that looks like on a 3.8... this is just at the intake manifold, where it joins the flexible tubing from the air filter....
www.avigex.ca/xport/maf.jpg
www.avigex.ca/xport/maflocation.jpg

There may be other causes to what you describe, but in my case, that was it, and this is after everyone at GM service and other places were ready to go for fuel pump, fuel filter, computer, .........It cost me just a little patience and 2 drops of alcohol....If built like mine, the active part is just a tiny shiny string in the path of the airflow. It was covered with a coat of clay like material that did not belong there......

THe 3.1 does not have a MAF sensor: it uses a MAP (manifold pressure) sensor.......
EGR valve is also an easy culprit to investigate, very very often the cause of serious engine irregularities.

[ibarra_design]

Originally Posted by LMP

YOu did not state what engine you have. Here what that looks like on a 3.8... this is just at the intake manifold, where it joins the flexible tubing from the air filter....
www.avigex.ca/xport/maf.jpg
www.avigex.ca/xport/maflocation.jpg

There may be other causes to what you describe, but in my case, that was it, and this is after everyone at GM service and other places were ready to go for fuel pump, fuel filter, computer, .........It cost me just a little patience and 2 drops of alcohol....If built like mine, the active part is just a tiny shiny string in the path of the airflow. It was covered with a coat of clay like material that did not belong there......

THe 3.1 does not have a MAF sensor: it uses a MAP (manifold pressure) sensor.......
EGR valve is also an easy culprit to investigate, very very often the cause of serious engine irregularities.

Thank you LMP,

Mine is a 3.8, I looked at the manifold and one picture (www.avigex.ca/xport/maf.jpg) looks like what I have, it does have about 3 screws to hold to the area, do I have to unscrew it and clean it or what's the area to clean?

Thank you much in advance to your replies!!

[LMP]

I did remove it from the car. That was some time ago, I do not remember all the details...just take care not to loose the bolts and nuts.
As said, the critical element is a small metal wire across the throat: this is a electrically heated wire and its resistance changes with temperature and thus with cooling by the air flow, and that is what tells the air flow. Mine was covered by kind of clay and that impaired direct air contact hence the trouble...but again, it was my fault since I had run the car without an air filter for a time.
Again too, consider the EGR alve is a definite possibility and for an easy try, I would disconnect it and see what happens. If sections are blocked open, that would not change much to the problem,though.But this is more related to erratic idle , not wo wide open throttle conditions.