SR20DET issue, breaking up at 4400rpm

[southernontarian240]

Hi guys! I recently bought a 89 nissan 240sx with a sr20det swap. When i take it down the road it goes good through 1st shift light comes in around 5700 or something like that. Then when i shift into 2nd it breaks up around 4400rpm and continues to do so in any higher gear at this rpm or more. I have no idea whats going on. Very new to 240s and sr20dets. Any help would be much appreciated. Will post list of mods and pics. Thanks.

[PapaSmurf2k3]

I'd start by checking your plug gap. I'm guessing this happens under boost? If you slowly creep up the RPMS, will it go passed 4400rpm?
You should also check for boost leaks.

[southernontarian240]

Thanks for the response! I will check plug gap today. What is the appropriate gap for this motor? The revs will increase past 4400rpm but no more power gains after that and its very rough and stuttering. Ive searched for boost leaks, found one going to boost gauge. Also the vacuum line that goes from the wastegate actuator to manual boost contoller was okay, but line from boost controller to front side of turbo was completely disconnected.

[PapaSmurf2k3]

That is NO BUENO. Did you hook it back up?!
If not, it could be going into overboost protection or something. Do you have a boost gauge? Do you know what boost you are running?

Try gapping plugs down to about .030" or .75mm