Hey everyone I'm new to the forum but hoping someone can help me.

I have a '95 LT1 Trans Am automatic and while I was driving it i suddenly lost most of the power from the engine. While on the highway at around 65-70 the transmission suddenly shifts from 4th to 3rd (because of the power loss). And if I stop and try to accelerate away the engine simply acts as if it has lost at least half of its power and pickup is very slow until around 2500 rpm where the power comes back. If I push it a bit from a stop the engine shudders and vibrates the car as if only some of the plugs are firing, and then eventually smooths out as the revs increase. This only happens after the engine has warmed up for at least 15-20 min.

Related, I've found that it only happens when the engine temp reaches around 225 and higher or so which is kinda hot. Coolant level is good and I just got an oil change too. I went under the car and found the front bumper flap hanging a bit and blocking some airflow to the radiator. After fixing this the temperatures decreased to below 210 on the highway but occasionally it still happens. Heat definitely has an effect on it. No error lights on the dash and pressure gauge is normal, voltage is just under 13.

Could it be cracked wires or the optispark or something?
I know its not the trans => just rebuilt this past summer

Any help or ideas would be great.

 

Hey my car is doing this too, it wont shift up sometimes and is running really rough and shaking alot. Chevy told me its the distributor cap, so im guessing it is????????

 

I'm hoping a mechanic will stop by and reply to this thread.
It sounds sort of like the low rpm hesitation that I see a lot on here but it is definitely some what different. I don't know where to start. As for now im just trying to keep the temp down. I think my optispark and wires are stock I should replace them, i have a 100k miles.

sabedra, does your car vibrate on the highway when it doesnt shift? Mine goes from 4th to 3rd and just stays at a higher rpm but doesnt vibrate abnormally.

 

Don't know if this will help or not but mine was doing the same thing. I cold barely get it going in first and at time seemed like it was only running on half the cylinders. I found - by accident - that when I touched the wires going to the MAF sensor the car would shudder or quit altogether. I replaced the pigtail today and it runs like a champ!!! Just a thought!!

 

I would start with a coil wire replacement.

 

160 degree thermostat would help the car run cooler. The opti with 100K miles could be it for sure. My temperature sensor was bad and when i fixed it some of my power was back. I also replaced the maf and got hugh power results. Cleaning it could be all your might need. Fuel filter, air filter, plugs, wires, O2's could all be in need of replacement if there origional. Good Luck.

 

Yes my car vibrates really bad when i try going over 45 then it shifts up then down again, i dont think i can go faster than 80 mph cuz my RMPS just stayup at 6000. Also my speedometer doesnt work sometimes it acts like the Rpm gauge and thats when my car start bugging out.

 

Thanks for the help BLDun.

I'm a newbie so does anyone know exactly where the MAF sensor is? Like a picture of the engine bay or something?

I want to try doing what BLDun did and see if anything happens.

And I'll probably try seafoaming it. Cheap, need to do it anyway, and couldn't hurt right?

 

You can find pics for almost everything part on your car at shoebox's site - he is one of the Fbody gurus that is indespensible on this site. Just go to http://shbox.com/1/4th_gen_tech1.html

The MAF sensor is located in the middle of the large tube that leads to your throttle body. It measures/detects the amount of air coming into the engine in order to calculate the air/fuel ratio. The three-wire plug that hooks up to it is the one that went bad on my car.

Also you may want to develop a sig that shows up at the bottom of your posts so when you have a question a lot of basic info can be gleaned from that such as year, make, mods, etc.

As for the seafoam thing. If you do a search you will find that there are as many pros as cons on it. There have been many cases in which the O2 sensors were fouled because of it and there is still some debate as to how much good it actually does. Do a search and read up on it and you will see.

 

Hey i found out the answer to my car. My water pump was a little leaky so apparently it dripped a bit on the opti and that caused it to be sometimes shaky and only some of the cylinders fire. It also explains why the problem wasnt there when the car was cold and got worse as the car heated up.

Hopefully this will help any of you who have a similar problem