New Member - KA Build

[fixius]

Hey everyone!

I'm a new member from Florida. I've had my '91 240sx hatch for close to two years. The first year was spent trying to get the motor that was in it to run/fixing electrical issues and the leftover #aintcare of the owner prior to the guy I bought it from. Eventually, it got to a point where I had it running, but it was running super rich and would overheat, so I voted to pull it and build it for a KA-T setup about this time last year. I've learned a lot about this motor, and this is honestly the first motor I've ever built/gone through entirely. Not going for a whole lot of power as I plan to use it partially for street partially for track, and want to get used to how the car drives/handles before I stuff a ton of power in it, (it is my first 240). I've always been a huge fan of the schassis, mainly the s13, so this has been pretty killer. Here's a breakdown of what I've done to it since I got it (it was in rough shape):

- Had motor bored to 90mm, acid bathed, 3-way grind on the valves, machined crank.
-90mm Weisco pistons 9:0:1
-Eagle Rods
-ARP head studs
-ARP rod studs
-Cometic headgasket (90mm bore)
-ISR Fuel Pressure Regulator
-Walboro 255 Fuel Pump
-Z32 Fuel Filter
-Replaced all fuel lines
-New OEM fuel injectors
-New OEM radiator (Aluminum rad set aside for now)
-Electric Radiator Fans [wired to a switch]
-Bypassed heater core (It was plugged, and didn't feel like getting a new one at the moment.)
-Silicone hoses for radiator, and all new heater hoses
-New timing chain guides and tensioners
-New Cap and rotor
-NGK Spark Plugs
-Import Direct spark plug wires
-KA24DE Engine Harness from Wiring Specialties
-New stock MAF
-s14 o2 sensor
-New TPS
-New Coolant Temp Sensor
-New water pump
-New oil pump
-New thermostat
-Terrible eBay front and rear strut tower bars
-eBay 4-2-1 headers (figured it's getting swapped out for a turbo exhaust manifold later, so why spend a bunch).
-Nismo 60mm extended wheel studs
-Had to get a different OEM KA24DE ECU because the one I had was shot. This fixed a lot of issues.
-Competition Clutch - White Bunny clutch kit
-New outer tie rods

Car came with:
-Megan Racing motor mounts.
-Some sort of 3" catback exhaust (can't find any sort of engraving on it)
-Slotted & drilled rotors
-A ton of spare parts and some spare wheels


(I don't have any good pictures of it at the moment, sorry about that)

It's a slow project and I'm working on restoring it (I don't intend to keep the missile look forever). I haven't had a fun car in some time, and it's nice to have both a second vehicle as well as something I can pretty much do whatever with. My aim was to build this thing to be pretty much bulletproof/ready for boost. I'm in the process of breaking in the motor, and am leaving the turbo setup out of the picture until it's broken in.

Anyways, the motor is back together and running like a dream (for the most part). It's been a matter of working out bugs as I run in to them. So far I haven't had any issues, until the past few days. I've been driving it to work occasionally [to break it in], being that work is a good 25 miles away. Drives great, doesn't have any issues with cooling, idle, acceleration. It's not running rich or anything either. It has a strange issue where after 3-5 minutes of driving, the engine will hesitate/bog for a couple seconds [sometimes less/just a slight flicker], and the RPM gauge appears to lower, then bounce. Then it continues on the rest of the drive like nothing happened. I've checked all electrical, because that was one of the first things that crossed my mind/I've had issues with that in the past that were similar, and everything appears to be fine. All sensors are connected. Does anyone know what might cause something like this? It's not a constant issue, but for the past two trips to work and home, it has happened a few minutes in to the drive without fail, and never again during that trip. I'm a tad stumped, but I'm still checking things over/looking for possible causes. Not a lot of free time due to work, so progress with this thing has been slow to begin with. Just wanted to get some opinions to see if anyone has experienced this before.

[centralcoaster33]

Cool car, welcome to the site and post some pictures of your engine please. All that hard work and we can't see it.

I don't know the cause of your last described situation. When I do projects, I do them in stages, with completion and testing in between, that helps me reduce the areas I might have to look if it's not working properly when all is done. Easier typed on the internet than actually done right?!

Anyway, I've had similar issue to what you describe and it was a bad injector. I see you have new ones in there, but maybe you could test them or have them tested and if one is bad, it's hopefully new and still under warranty. Other guesses/ thoughts are idle and or auxiliary air valves being sticky, the egr vacuum switch thing or the egr vacuum solenoid thing not working at the correct time. I am also thinking this is happening right around the time your car and it's computer think it's warmed up to operating temperature, so maybe looking at the FSM for what happens before and after warmup will generate some clues.

Be sure to keep taking mental note of what you're doing (gas, brake, clutch, steering inputs, gear selection, key position, lights on, off or brights, stereo hitting the bass notes, etc.), where you are (flat, uphill, downhill, hard right turn, at a stop light) and what your car is telling you (gauges, vibrations, clicks) when your issue shows itself again.

[fixius]

Cool car, welcome to the site and post some pictures of your engine please. All that hard work and we can't see it.

I don't know the cause of your last described situation. When I do projects, I do them in stages, with completion and testing in between, that helps me reduce the areas I might have to look if it's not working properly when all is done. Easier typed on the internet than actually done right?!

Anyway, I've had similar issue to what you describe and it was a bad injector. I see you have new ones in there, but maybe you could test them or have them tested and if one is bad, it's hopefully new and still under warranty. Other guesses/ thoughts are idle and or auxiliary air valves being sticky, the egr vacuum switch thing or the egr vacuum solenoid thing not working at the correct time. I am also thinking this is happening right around the time your car and it's computer think it's warmed up to operating temperature, so maybe looking at the FSM for what happens before and after warmup will generate some clues.

Thanks!! I tried to do this in stages for the most part, but I ended up backtracking here and there to correct little things I missed, so I got a little sidetracked, lol. It sat parked in the driveway for a long time while I worked the bugs out and went through each system after hooking it up.

Thanks for the input! I know a local shop that tests injectors, so I can have them checked out for sure. They are new in the aspect of not having been used much after purchase, but I bought them right before I pulled the motor and started the overhaul, so I wouldn't rule them out completely. They were run briefly on the motor before it was pulled. Will check the other suggestions as well. It does seem like it could be right at that point where it just hits its operating temp.

I have some pics of the build as it progressed and of the engine on my PC at home, so will post a few later tonight or tomorrow for sure!

[PapaSmurf2k3]

It may be when the vehicle is switching over to closed loop feedback as opposed to running off a map.

How do you like the Megan Racing motor mounts? I have some in my cruck, and notice they translate a lot of vibration to the chassis.

[fixius]

It may be when the vehicle is switching over to closed loop feedback as opposed to running off a map.

How do you like the Megan Racing motor mounts? I have some in my cruck, and notice they translate a lot of vibration to the chassis.

That's probably what it was. The issue seems to have gone away recently, but I'll keep an eye on it.

As for the Megan Racing motor mounts, it's hard to say because I've never driven a 240sx outside of this one, and it came with them, so not sure what they feel like as opposed to stock. They do seem to transfer a good bit bit of vibration to the chassis at idle. Driving though, it's less noticeable.

[jamescallowa]

Welcome to the club ! I'm new on this forum too and I am very excited to be here. I would love to see the pictures of your engine. I have a 95 Nissan 240SX and I am trying to hunt for a SR20DET swap from S15.

[PapaSmurf2k3]

Driving though, it's less noticeable.

Yup, I agree!