sr20 breaking up and hard start

[cnazzaro240]

I recently dropped an sr in my s13 and at first it ran great no problems but the problems came fast when the motor is warm at around 4.5k-5k it breaks up but when its cold most of the time it runs just fine, also it wont build boost alot when its warm, but the wideband reads normal always but when its breaking up the boost gauge twitches under 5lbs i disconnected my boost controller till i sort the problem out but it wont go up to 7lbs, but for some reason when its cold it runs just fine(most of the time). and im also having a problem with it starting, i have to let the key sit in 2 and pump fuel first it wont start, and the not starting problem started after i installed the gauges, idk how they would affect each other. but the breaking up problme has been there all along before i touched anything. please help. thank you

[2.5T_/<ouki]

Originally Posted by cnazzaro240

I recently dropped an sr in my s13 and at first it ran great no problems but the problems came fast when the motor is warm at around 4.5k-5k it breaks up but when its cold most of the time it runs just fine, also it wont build boost alot when its warm, but the wideband reads normal always but when its breaking up the boost gauge twitches under 5lbs i disconnected my boost controller till i sort the problem out but it wont go up to 7lbs, but for some reason when its cold it runs just fine(most of the time). and im also having a problem with it starting, i have to let the key sit in 2 and pump fuel first it wont start, and the not starting problem started after i installed the gauges, idk how they would affect each other. but the breaking up problme has been there all along before i touched anything. please help. thank you

Fuel pump? Which one are you running?
Do you have an aftermarket FPR? What's it set to?
Check spark plug gaps?

[cnazzaro240]

Originally Posted by 2.5T_/<ouki

Fuel pump? Which one are you running?
Do you have an aftermarket FPR? What's it set to?
Check spark plug gaps?

im running a walbro255, and i have a nismo fpr, i was told it was set correctly by the previous owner, but ill check it anyway, and ya im probably gonna get new plugs and make sure there gaped correctly. but i was told this problem could also be the CAS, i wanna be sure though before i buy one because there expensive, any thoughts on that? thank you

[2.5T_/<ouki]

I would start with the small/cheap stuff first. Does your FPR have a gauge? Pretty sure it's supposed to read 43psi with the vacuum line off. Also, get new plugs if yours are shot and make sure to gap them correctly. It could be CAS related however I would start with those first; process of elimination.

[cnazzaro240]

Originally Posted by 2.5T_/<ouki

I would start with the small/cheap stuff first. Does your FPR have a gauge? Pretty sure it's supposed to read 43psi with the vacuum line off. Also, get new plugs if yours are shot and make sure to gap them correctly. It could be CAS related however I would start with those first; process of elimination.

alright thanks ill do that first

[ultimateirving]

Also check to see the condition of your knock sensor. it can cause the ECU to retard the timing at higher rpm causing some of the symptoms you're describing

[Jay24/7]

Originally Posted by 2.5T_/<ouki

I would start with the small/cheap stuff first. Does your FPR have a gauge? Pretty sure it's supposed to read 43psi with the vacuum line off. Also, get new plugs if yours are shot and make sure to gap them correctly. It could be CAS related however I would start with those first; process of elimination.

Had very similary problem, turned out to be the fuel pump, change fuel filter as well if you havent done so already (300zx z32 fuel filter).

[hessianben]

Dealing with the exact same issue...
S13 type x blacktop.
runs great when cold, but after it warms up, cuts out under load between 3-4k.
feels like spark cut- bogging, popping...
once warm, hard to restart- cranking, cranking, backfiring...
if i press the gas to WOT, it will start fine, so i assume it's overfueling.
so far, have replaced the old fuel pump with a new aem 320lph fuel pump, z32 filter, new brk7 plugs gapped, stock everything else.
subscribed for any input.

[cnazzaro240]

Originally Posted by hessianben

Dealing with the exact same issue...
S13 type x blacktop.
runs great when cold, but after it warms up, cuts out under load between 3-4k.
feels like spark cut- bogging, popping...
once warm, hard to restart- cranking, cranking, backfiring...
if i press the gas to WOT, it will start fine, so i assume it's overfueling.
so far, have replaced the old fuel pump with a new aem 320lph fuel pump, z32 filter, new brk7 plugs gapped, stock everything else.
subscribed for any input.

my friend had a very similar issue it ended up being his CAS(cam angle sensor), but if it feels like an ignition cut out try checking your coil packs first with a multimeter should be 1ohm