304 215i Lost a boat load of power?? Flatspot

[pedrotski]

Hey guys. Since fitting a twin 2.5" exhaust system to my car, I have lost a ton of power over pretty much the entire rev range, Esp down low.

I didn't think it would be an issue with a stroker engine. Also considering the stock pipes are twin 2/8th inch, the power loss is insane. Must say im pretty annoyed atm, Even tho it sounds mint.

I also have a flat spot where i have almost no power in the higher rev range, The flat spot covers about 1500rpm before redline.

Any ideas?

I have changed plugs, reset ecu, oil change, gearbox service.

To give you an idea on the power loss, I could put my foot down in first and it would light up through the entire gear with 235's and then chirp/axle tramp into 2nd. Now it cant even light up 1st if i just put my foot down and it wont chirp 2nd because of the wild flat spot.








edit, bad tune?

 

[ari666]

only thin i can think of is O2 sensor. did it get knocked around in the changeover? what about your cat?

 

[GOTMYN]

Hmmm, mine does the same thing every now and then,
I blame it on fuel, like the engine has detonated and instantly the Knock sensors retard timing, then gradually increase it again.....

Try to use the same fuel every fill, and imo only use 98octane.

 

[delcowizzid]

if its a map based vs 5L its probably needing more fuel you will be flowing a lot more air into the engine

 

[greenfoam]

A you comparing the car to how it was before are you just imagining how it should be? because no stock stroker is going to make any power within 1500 rpm of the limiter and wont have much down low either

 

[GOTMYN]

A you comparing the car to how it was before are you just imagining how it should be? because no stock stroker is going to make any power within 1500 rpm of the limiter and wont have much down low either

I have to agree with it not making any power up top, as mine suffers from this :-(
But down low, on a good day, it's a tyre screwing monster

 

[FusionX]

Check that the knock sensor and wiring for it is still all in good shape. Few times have done exhaust or engine swaps and forgot to replug it in. Makes the car feel like ****.

 

[pedrotski]

Dunno if this well help someone spot my problem, But if im rolling and i drop the car into neutral, it will start hunting for idle.

Any ideas???

 

[ari666]

well, i dunno if this will help, but whenever a jap car pulls that hunting crap i reset the ecu and it usually does the trick.

to do it on skyline; disconnect battery, join the two battery terminals with a jump lead and leave it for 30 mins. reconnect battery terminals, start the car, leave it running for 1 minute, switch it off then start it again.

it works on a lot of different cars, but holdens i dunno bout.

 

[pedrotski]

two battery terminals with a jump lead and leave it for 30 mins

Yea ill be right hahah.

I have reset the ECU quite abit and it still does it.