Is it a 3100 thang

[supreme_style21]

With both 3100's I've had... I do a LOT of long distance highway driving. After about an hour or so, I make a pit-stop. After the hour (and any time after that) of highway driving, the car is a pure dog. Summer, fall, winter, doesn't matter... any type of long distance trip has killed my 3100's. The older 3.1's I've owned have never been phased by this. Whats up with this? I've always been curious. I fuckin hate driving this car for awhile, getting into some town, and have it move like a 3-cyl. Geo. The two 3100's I've owned have done this. I want to say its an ECU programming issue, but I'll pick the brains of those experienced.

[Brian P]

I don't know what to say regarding that, because my 3100 does the opposite! I'm tempted to say the catalyst if you have one, maybe when it gets that hot after a long drive it restricts a little?

[19Cutlass94]

I duno, I kinda know what you mean, but then again maybe its just from going so fast, now going slow, to fast again (if getting back on highway) or just slow ( going on city streets) but Ive really never noticed it. If anything, it seems my 3100 runs a little better once taken out for a long drive. I usually go about 3 hours at a time before I make a pit-stop, but even if its after 3 hours or just 10 minutes on the highway, I cant say its a dog.

[gp90se]

when was the o2 last changed?

[manitcor]

ive noticed the same thing even with the 3400, I think it may be an ECM/O2 thing as others have said.

[scorpion_x9]

I can agree. But, I think it was my ignition coils. I made the BIG mistake of buying Wells ignition coils... Cheap $20 static electricity makers. I put GM factory coils back on and runs like a champ. It felt like I gained 20 HP back when I put stockers back on. I ran a 17.00 in 1/4 mile with those junkers on at the drag strip.

[Prospeeder]

I duno, I kinda know what you mean, but then again maybe its just from going so fast, now going slow, to fast again (if getting back on highway) or just slow ( going on city streets) but Ive really never noticed it. If anything, it seems my 3100 runs a little better once taken out for a long drive. I usually go about 3 hours at a time before I make a pit-stop, but even if its after 3 hours or just 10 minutes on the highway, I cant say its a dog.

 

its called Velocitation, we leanred it in Drivers ed, where it seems ur going slow after driving at higher speeds

[f_399]

i have taken my car to Florida twice and drove to Canada from Dallas Fort Worth and no problems

 

I dont really notice performance because its just set on cruise... the times i need to overtake it does the job pretty well

 

sometime i even hit the limiter and its all good

 

got 140,000 miles on it now

[manitcor]

 

its called Velocitation, we leanred it in Drivers ed, where it seems ur going slow after driving at higher speeds

 

I would tend to agree but if the orignal poster is talking about the same thing I see, the car actually looses its low end pull. It may be harder to tell on the 3100 but with my mods Ive got some pretty badass low end and after a long time on the highway and the car is really warm a lot of that is lost.

[jeremy]

I don't know what to say regarding that, because my 3100 does the opposite!

 

my cutty was the same, it seemed stronger as it got warmer

[runt]

I don't know what causes it, but i know on some of the long trips I took in the cutty with the 3100, it would do the same damn thing. Even if I ran the car for a little while and stopped at a gas station and let it run for maybe 5 min while I was inside, it'd do the same thing. I don't have a rhyme or reason for it, but just letting you know that you aren't crazy.

[supreme_style21]

I knew I wasn't losing my mind.

 

The oxygen sensors are fairly new.. they didn't make a difference on it.

[GP1138]

I know what you're talking about, and I've always wondered if the ECM is pulling timing because the engine is warmer. The Lumina I had started out with retarded timing and was a dog until I fixed the knock sensor.

 

Just a thought, probably wrong, but a thought.

[19Cutlass94]

Mine just seems to run stronger.

[Dannymik]

my 3100 did that crap as well...my 2.8 was even worst, heck lots of vehicles fall into that problem

[TeeJay3800]

I have the same thing. My 3.1 feels stronger when cold, and I notice the same lack of punch when its hot, especially after just getting off the freeway. Maybe having no cat and just a straight-pipe has something to do with it.

[SigEpCutlass]

I don't know what to say regarding that, because my 3100 does the opposite!

 

my cutty was the same, it seemed stronger as it got warmer

 

me three! I don't have the problem you guys are talking about. However, I will say that on a few hot days this summer in stop & go traffic, she ran hot, but I didn't notice a difference when it opened back up.

[supreme_style21]

Well if some notice it and others do not, I would say that it isn't related to an ECU/PCM issue. I'm not sure where else to look. Things kind of point to the cat.

[runt]

The times I experienced this was when I had over 85-95k. When I got the car it was not too bad. Probably a plugged cat that just got heated up, or maybe not plugged totally, but somewhat...you know what I mean.

[Dannymik]

reading your 2 post above you guys might be onto something...does heat create a lag in our cars if your cat is clogged or does it not matter how hot your car is

[Turbocharged400sbc]

a monolithic type cat flows best when brand new after a few thousand miles a few of the passages get plugged up with carbon etc and it gets worse with age...

at some pint the matrix doesnt expand uniformly and you can get cracks in the ceramic matric that will continue to widen with thermal cycling unit a chunk or a few chunks break off and clog the rear section of the cat or clogg up the flow paths in the muffler...as to whether this might be causing the problem you will need to check exhaust backpressure with a gauge at cold/hot and then duplicating your condition you usually tap into where the O2 sensor goes (unplug it and the computer will substitute a value and it will still drive fine) anything over 1.5 to 2 psi is a restriction....whether it be the cat or cat material/rust clogging the muffler...

 

James