los of acceleration on a hard pull.

[trnsman]

On a hard acceleration from 70 mph Tac gets above 5 grand and drop down to about 3 grand during which there is no acceleration, why?

[pajeff02]

Possibly your knock sensors are kicking in and the PCM is pulling timing... although that would have to be extreme. Other possibility is a fueling issue and it is running out of gas, which causes a lean condition... which is very bad.

[RCH33]

Just had a tune where the knock blocker would retard the timing 8 degs and then start bringing it in again. You can definitely see it on the Dyno chart. As Jeff says, fuel would do the same thing. Check the fuel,pressure readIng and see if it drops or not. See what your timing is at that load and rpm. You can retard timing a little and enrich the air/fuel at that point to keep it away from the knock block. A tuner can make the PCM add timing back a little faster than stock also. My tuner likes to keep everything right below the knock block to keep a good steady pull. I only lost 1hp and 1 ft/lbs of torque with a tune that keeps it out of knock block and feels much better. Probably better on the engine too.

But, again as Jeff says: 5 grand to 3 is a big drop and seems like there might be something else. How fast does this take place and when do you start feeling the rpm's rise again.

[SMWS6TA]

any back fires? smoke in the exhaust?

[0rion]

need more info on this....like specifics about what exactly the car does.

[1998 T/A]

I will bet you a thousand dollars it's a fuel pump