Thread: NOT your basic idle issue.

Alright, so I just finished my highport motor swap into my b15, using the b15 everything. I can turn it over, it starts, but idles like it's missing all the time.
No matter whether I unplug 1,2,3 or 4th cyl., it basically runs the same. It sometimes also backfires but not unless I give it some gas when I turn it over. I can't for the life of me figure out why it's not running.

After ignition, it revs up to about 2k quickly, then dropps like a brick down to about 500-700, stumbles violently and then after 5 seconds, just stalls. Same thing over and over. Any ideas would be helpful. Thanks guys

So an additional peice of information: because they both have different throttle bodies, I fabbed up a plate to convert the previous air regulator spot (highport b13 engine) into the idle air control valve (relocated from previous throttle body from b15 automatic engine) spot. Also, because of the swap, I had to extend the wires on the thermistor and coolant temperature sensor.
So, hopefully that helps, I can't for the love of me figure this **** out.

I would think that if it was some sort of idle air control issue, that pushing the throttle open more would keep the idles high, but no matter what I do with the throttle, it doesn't change a thing, still very very violently idles, then stalls.

alright so I used the plugs from the 01' engine in the 91, and it's .043 on the 01' and .031 on the plugs for the 91. I'll try tomorrow to see if that's why it's idling so ****ty.

One other question: is it possible to put the distributor in backwards? I saw that it looks like not, but if I'm using a b15 distributor on a nx engine, perhaps?

I had this same problem on my low port to high port swap. It started as a Mass air flow sensor being out... Once that was replaced it still ran really rough. I resolved a vac line issue and made sure all the EGR stuff was set up. After that it ran like a champ and purrs like a kitten getting its tummy rubbed.
Seriously, double and triple check your vac lines.
Verify your TPS voltage and coolant temp sensor also. Also verify you have replaced sensors that go with the computer on the car. Make sure you are using the correct coolant temp sensor, sender, TPS and EGR. A cool way to verify this is to load the two cars into Autozone's website. Search for a part with one car, hit the dropdown and select the other car. If the part numbers don't change, there is a strong chance the parts are compatible.

interesting...there was a backfire that caused a bit of smoke from behind the intake manifold somewhere, I'm not sure where though. Is there a way to check that without removein the intake manifold? I can't figure out where else it would come from

You can try disconnecting the MAF and starting the car as a test. If it run smoothly (but idles high) it's more than likely a vac (or air) issue. Did you replace all the gaskets on the new intake setup? Are you confident that the intake isn't not leaking?
With this test, you can at least tell if it is running smoothly when bypassing the MAF. keep in mind the rpm may escalate as the car tries to find its idle. Also, it will be in "safe mode" so you won't be able to rev it past 3k.

it revs with or without the maf up to about 3-4k seemingly fine, then drops like a brick down to 400-700, chugs violently and then shuts off.

worst part is, if Miko says he would never swap a highport into a sentra se, I'm in trouble.

I actually have the same thing going on with a B14 low port. the rotor button tip was bent and chewed up the distributor cap, replace those and still idles like a crap. strange thing is take it down the road and it will run like a champ if you keep the rpms over 2 - 3k. but its funny that its really is doing exactly how you described. It really acts like its getting to much fuel and flooding out.

P.S. sorry if a jacked your thread just in the same boat buddy

ok, so here's the new situation.

I fixed all intake leaks. now, with all vaccum lines plugged, it doesn't start. great! plugged in, and it starts/idles briefly. sounds like it's idleing fine, no missfires, or stumbling, then after 15 seconds of running, it dies.

I've tried it with and without the maf plugged in, does the same thing. I've measured the voltage on the tps at closed throttle (REMEMBER THIS IS A B15 with an auto tranny, so the tps is a 2 connection thing) - It reads 5.12V at closed throttle. I think this might be the issue but I have no idea how to test it. Any ideas?