sometimes sluggish somtimes not

my intigue is a 98 3.8L with 83k miles. i just rebuilt the motor from the ground up. it has about 1500 on the rebuild. it had the infamous intake leak and sucked in antifreeze and ended up with the dreaded rod knock. since the rebuild the car has been running perfectly.but in the last week i have noticed that sometimes it is a little hesitant when cruising and even trying to increase speed to the point that the rpms are going up but the power is just not there. then there are times when it runs like a raped ape. i can not figure it out. i thought that the a/c compressor might be the problem but it does it with a/c on or not. it is not throwing any codes either. does anybody have any ideas?:confused:

If I were you, I'd be leaning towards the tranny, I'm afraid. Unfortunately, this transmission is well know to go south at a very early age. My first was at 90K, another at 180K,and just put in #3 at 245K. Problems are searchable in the index, but the bottom line is that the '98 was a bit early for the Shortstar and it's far better transmission, and Olds gambled alot on the first year ECM controlled automatic, result was the trans was not very robust, gears were too soft, etc. Biggest problem is that the trans was only used on the car for 1 year,and they are starting to get a little hard to find. I really don't mind putting in a trans every 50K, right now it is easier and a whole lot less painful than a new car note!

How does the Shortstar have a different transmission? There might be a few small differences, but its still the same 4T65-E transmission that the OP has in his/her 98.

That same transmission also debuted in 97, and was used for many years.

I suppose I could be wrong, but I do believe all Intrigues use the same transmission, a 4T65-E with either 3.05 or 3.29 gearing. Im sure the TC might be different between the two engines. But I would strongly venture that they are the same internally.


Also, you might want to check the condition of the catalytic converter, smack it with something relatively heavy, a jack handle is my preference, and see if you hear anything rattling around.

I meant that the case is different, and later models won't mate up to the 3.8. Yes, the trans is a little improved for the '99 year on, but for the '98 it really doesn't match the reliability of the engine...

Knock sensor(s)?
Fuel Injection (pulse)
Fuel Pump
Timing?

Is it faster or slower when hot or not? Crankshaft sensor out of whack just enough but not enough to throw a code. Difference to throw a code could be a range of 20% or so from optimal even with ODBII.

Maybe having it read with a Tech II computer will yield dividends for your piece of mind?

Good luck!

run some injector cleaner in the gas (maybe 2), I'm also wondering if burning coolant could knock out an oxygen sensor.

Air filter-check
Fuel filter-check

i have all new filters in the car after the rebuild. i does not seem to matter either if it is hot or cold when it happens. i ran 2 bottles of injector cleaner thru it after the rebuild also. the crankshaft sensor is new as of last year. would a bad oxy sensor cause this problem?
i have not checked the cat yet. i had a truck once with a bad cat. it lost all highway speed until it choked it self. emptied the cat out and it ran better. i thought about the fuel pump too but i have no way of checking the psi right now.
if it is the trans is it fixable or is it better to swap it out?

thanks for all the replies.

If it is the trans, it would be fairly apparent at almost all forward speeds. I'd lean towards a plugged cat, especially if there are no codes set.

well i did a through inspection of the cat and this is not the problem. i am sure now that it is the trans. 2.5 motors and a trans...........i hate this car!!:banghead:


thanks for the help guys!!

Old tranny fluid will cause your slippage also.
-tranny fluid low (use the instructions in the manual)

Don't feel bad, you are in good company. I have replaced my trans 3 time now, each time I can find a reasonable one for about 3-5 bills at the junkyard, and then my mechanic does the R&R for about $400 labor. It seems like a lot of dough, but when you look at the cost of a new car, it's peanuts. 'Course, you could rebuild the tranny with all heavy duty parts, but that will cost you about 3-4 thousand, and what with everything else, I'd rather put another used one in it every 50K or so miles. At leas the 3.8 I've got in mine is still good, the interior is mint, and the body is good. Fortunately I make enough in a week to cover the cost of the trans replace...:runaround:

i just changed the fluid about 2000 miles ago.
this car is in really good shape also. it was grandma's car. it must have sat too long or something. have had nothing but problems since i bought it. thought i was getting a deal. what i have in to this car i could have bought a 2 year old car.