Hesitation/Jerking under acceleration
The car is a 90 NX2k with a sr20det swap. Mods are Greddy profec e-01 boost controller set at 9-10psi, stock turbo, stock injectors, walbro fuel pump, large front mount intercooler, 2 1/2in exhaust, arp headstuds, Brian Crower stage 3 272/272 cams, BC valve springs and titanium retainers, and copper NGK R's gapped at .028.
First, the car won't idle by itself until it's warmed up. Then it will idle a little below 1k, but it's very rough.
I just recently installed the BC valve train, so I'm thinking the rough idle might have something to do with that, not the dieing tho.
Under normal acceleration shortly after starting the car, it starts jerking pretty bad around 1000rpm-4500rpm or so, almost as if a person who has never driven a clutch is driving it. As soon as I hit 4500-5000rpm it quickly smooths out and will slam you back to the seat very hard with medium to heavy acceleration.
Once the car reaches the halfway point on the coolant temp gauge, it runs fairly normal.
I was also having an issue with the radiator fans where they wouldn't turn on and I would start to overheat. I unplugged the CTS clip and the fan turned on. I replaced the sensor yesterday, and when I drove to work this morning, it never passed the halfway mark. Highest I saw was about 160 degrees under acceleration. When I got to work I left the car running to check the fans. They weren't on. Either the sensor wasn't my problem, or it was cool enough that the computer didn't think it needed them yet.
Ok, so when the car is warmed up and running as normal as it will right now, it hits full boost and pulls the very very hard right at 5k through redline in every gear. It has the stock t25 with an a/r of 0.8 and is only seeing a max of 9.5-10 psi. My a/f ratio's are kinda weird too. When just driving normally or with very light acceleration, i'm seeing 15's. Under heavy boost it pretty quickly drops down to 10 or 11.
It has clear exhaust until i hit boost, then it gets some black in it.
So my main concerns are why it's dieing at idle, why the ecu isn't turning on the fans when it's warm, why it has the bad jerking and hesitation under acceleration, and why it spools up sooo slow.
I'm thinking it has something to do with the coolant temp sensor, but I'm not sure what else to try since the sensor didn't fix it.
I've pressure check the intake system and have no leaks, replaced the dizzy, cap, rotor, and plugs. I've swapped the idle air control valve, but the set screw on the replacement one is messed up, so i'm hoping that it might help once i get a new set screw. The one that is in it right now won't go in very far, it's backed pretty far out. I've cleaned the MAF and TPS and tried uplugging each while the car is running and it nearly or does die so i don't think those are faulty. If I unplug one of the two connectors on the IACV, the rpm drops for a second then steadies out. Should it do more than that?
The only other things that I can think of to check is the electrical timing and to try a different coil pack. I recently had the head off too, so I know my mechanical timing is dead on.
I guess that's a little more than my title said haha..
Thanks for the help guys
First, the car won't idle by itself until it's warmed up. Then it will idle a little below 1k, but it's very rough.
I just recently installed the BC valve train, so I'm thinking the rough idle might have something to do with that, not the dieing tho.
Under normal acceleration shortly after starting the car, it starts jerking pretty bad around 1000rpm-4500rpm or so, almost as if a person who has never driven a clutch is driving it. As soon as I hit 4500-5000rpm it quickly smooths out and will slam you back to the seat very hard with medium to heavy acceleration.
Once the car reaches the halfway point on the coolant temp gauge, it runs fairly normal.
I was also having an issue with the radiator fans where they wouldn't turn on and I would start to overheat. I unplugged the CTS clip and the fan turned on. I replaced the sensor yesterday, and when I drove to work this morning, it never passed the halfway mark. Highest I saw was about 160 degrees under acceleration. When I got to work I left the car running to check the fans. They weren't on. Either the sensor wasn't my problem, or it was cool enough that the computer didn't think it needed them yet.
Ok, so when the car is warmed up and running as normal as it will right now, it hits full boost and pulls the very very hard right at 5k through redline in every gear. It has the stock t25 with an a/r of 0.8 and is only seeing a max of 9.5-10 psi. My a/f ratio's are kinda weird too. When just driving normally or with very light acceleration, i'm seeing 15's. Under heavy boost it pretty quickly drops down to 10 or 11.
It has clear exhaust until i hit boost, then it gets some black in it.
So my main concerns are why it's dieing at idle, why the ecu isn't turning on the fans when it's warm, why it has the bad jerking and hesitation under acceleration, and why it spools up sooo slow.
I'm thinking it has something to do with the coolant temp sensor, but I'm not sure what else to try since the sensor didn't fix it.
I've pressure check the intake system and have no leaks, replaced the dizzy, cap, rotor, and plugs. I've swapped the idle air control valve, but the set screw on the replacement one is messed up, so i'm hoping that it might help once i get a new set screw. The one that is in it right now won't go in very far, it's backed pretty far out. I've cleaned the MAF and TPS and tried uplugging each while the car is running and it nearly or does die so i don't think those are faulty. If I unplug one of the two connectors on the IACV, the rpm drops for a second then steadies out. Should it do more than that?
The only other things that I can think of to check is the electrical timing and to try a different coil pack. I recently had the head off too, so I know my mechanical timing is dead on.
I guess that's a little more than my title said haha..
Thanks for the help guys
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