Grand prix S/c 1997 no power, cant spin wheels....

**guimond47** · 06-07-2011

Hey guys i had a bad crank sensor so i changed that out and then i had a misfire and i ended up having a bad coil pack. so i got another ICM and 3 coil packs from a regular 3800 not supercharged and through that on my supercharged 3800. got no more misfire. but the car is now powerless, cant spin the tires, but it goes and runs good. just no power. i figuered its the cat because when i drilled my hole in front of the cat there was alot of pressure coming out compared to after the cat. im gonna change the cat and see if thats the issue. i was able to do smoke shows the day before i had a bad crack sensor.... soo now its gonna be a pain to figuer out. if anyone has sugestions on what can cause the no power issue the pointers would be great. thanks

Steph

**FordMan77** · 06-07-2011

How old are your plugs/wires? Last time a tuneup was done? Is the CEL on?

I'd also look for vacuum leaks. And save for a new trans

**guimond47** · 06-07-2011

plugs and wires are new. tune up i donno i just did an engine swap with with as well as the matching tranny that came with it. Wat is a CEL? . the funny part is it did have alot of power a few days ago. like i said theres alottttt of presure infront of the cat converter compared to after it. i went for a test drive and from a dead stop i floored it and its like it holds at 2500 rpm for a second oor soo then it climbs.

**torq455** · 06-07-2011

Scan it.

**guimond47** · 06-07-2011

there no codes...

**Fivefingerdeathpunch** · 06-07-2011

wanna test the for a clogged cat...

take the top o2 out and screw in a pressure gauge in the o2 hole, then start the car, see what the PSI reads, if its more then about 1psi its clogged end of story.

Backpressure is a myth, cars make less then 1 psi with a free flowing exhaust system.

**guimond47** · 06-07-2011

there like no pressure after the cat. i drilled a hole before and after. before the cat there alot of pressure and after it theres like none

**Fivefingerdeathpunch** · 06-07-2011

do what I said to just make sure. I have a feeling the cat is clogged.

**guimond47** · 06-07-2011

which means something is clogged into the cat to be holding all that pressure in the front

**guimond47** · 06-07-2011

theres no pressure in the back , theres like over 20 psi in the front of the cat , how hard is that to understand. did u ever test a cat before? drill a hole in front and after it/ and if there alot of pressure in the front that means theres a resistance into the cat and something is restricting the air flow pass the cat and that lead no presure at all after it. kinda like this is wat im talking about :

YouTube - ‪How to check your vehicle's catalytic converter.‬&rlm;

**Fivefingerdeathpunch** · 06-07-2011

Are you for cereal?

What kind of ****ing idiot drills holes in the exhaust to test for a clogged cat, I told you just take the UPPER o2 sesnor out and stick a pressure gauge in there to see what the numbers are.

I know exactly what I am talking about, I a friggin auto mechanic.

Since you already know the issue, go fix it.

**guimond47** · 06-07-2011

im cutting the cat off tomarrow and straight pipping it. i had a terrible misfire before fore a few days and all the un brurned fuel must of ruined that cat. mis fires apparently ruin cats. my mis fire was so terrible that the car barely moved and the engine light was flashing for a 60 min ride home.

**Fivefingerdeathpunch** · 06-07-2011

fyi, you will need to tune out the rear o2 sensor, becuase its going to throw a code and your mpgs will prolly suffer.

**guimond47** · 06-07-2011

tune it out? usualy you just drill a hole in the pipe and weld a nut and screw the o2 sensor into the pipe and the pcm reads fine from what ive heard

**Fivefingerdeathpunch** · 06-07-2011

tune it out as in, delete the code forever and tell the PCM that the car is doing perfectly fine for its air/fuel ratio's.

You can try and make the o2 bung a little longer to try and fool the sensor into thinking that the cat is still there. The sensor wont be as close to the exhaust gases and can possibly read it ok.

**guimond47** · 06-07-2011

yea i know what you mean , but where can i buy a extension piece to bung it out? , i live i a place where theres a canadiantire and a parts soure as our main automotive center