New Build - Hesitation On Acceleration

[aspekt9]

Just finished rebuilding my motor and went to start it up. I cranked the motor over without the MPI fuse until the oil light went away and then I started it up. I forgot to plug in the coil pack so I think I dumped a decent amount of gas in the cylinders because when I realized I forgot to plug it in I heard a loud POP out the back, which I attributed to the unburnt gas igniting. So after I started it up, I took it out for a drive and when I started accelerating the car would kind of hesitate and bog down but it would keep accelerating. On deceleration the car is perfectly normal.

Now the main reason why I had to rebuilt this motor was because the previous motor ran lean (injector duty cycles extremely high), could a high duty cycle mess up the injectors? On the previous motor there was a piece of the number 2 ring missing, is it possible one of the valves was bent in the process? Could a bent valve cause my symptoms? I don't really know what to think, how can I start narrowing things down?

 

[jen_cairo]

i would start by doing a vacuum test, use propane and a hose and open the valve and listen 4 a change of noise in ## engine. or you can use starting fluid and spray it on the hose. I would also check ## fuel pressure if u have upgraded fuel inj./pump/regulator..

 

[1gdsmftw]

make sure you didnt get any gas in the oil if you flooded the chambers and assuming you just redid the valve stem seals they could have leaked some gas in due to not being seated

had that issue on my old talon dl and i changed the oil and seals again and car ran like butter

 

[delta448]

I think your fuel delivery is not right. That could be due to any one of many things. I'd first double check settings in ECMLink. If you could attach a datalog in your next post that may help out a bit here too.

Do you still have the stock MAS?
How's your fuel trims?
Is your narrowband O2 cycling at idle?
Seeing any knock?

Now the main reason why I had to rebuilt this motor was because the previous motor ran lean (injector duty cycles extremely high), could a high duty cycle mess up the injectors?

A higher than expected duty cycle probably just means that the ECU thought the engine was running lean, it doesn't mean it actually did.

More likely causes of high duty cycle are that you either had a post GM MAF boost leak, or you've removed fuel-cut and are running more boost than your stock injectors could ever hope to keep up with.

Remember that the stock fuel maps target very rich mixtures at moderate to high rpm and over 12ish psi, if by chance you haven't tuned that area yet.

 

[321]

I take it that you inspected cylinder 2 cyl. wall. If a piece of the ring broke it could of ate up the wall. Also pull your plugs and make sure none of them are fouled. I guess th cylinder walls could be washed down.