1998 Nissan 180SX • 136,000 miles

My nissan 180sx wont idle after been driven. The revs fall the engine struggles and dies when it is clutched at a junction? Will idle fine if not driving once driving you have to keep the revs up with the accelerator?

its an sr20det engine. Not smokey runs great but un-drivable with its idiling problem. The car has a few moddifications.

does not have an air flow meter on the intake instead it has a map sensor with a vacuum pipe attached. Have checked for vacumme leaks also there are none. I hope this helps and I hope you can help me!
thanks : )
Steve fits
November 23, 2011.

Check the Idle Air Control Valve, near the throttle body on the intake manifold. Also check the Throttle Position Sensor, on the throttle body.

Throttle position sensor seems fine. When unplugged the car stalls. The idil air control valve I also taught would be fine considering that the car will idil until u rev it! Thanks for the reply any other ideas? : D

Steve fits
Nov 23, 2011.
Check the fuel pressure and fuel pressure regulator. It should be around 35 PSI at idle and go up 10 PSI when vacuum is removed. I am not sure how a boosted car handles fuel pressure regulation as the boost would not work right with a standar fuel pressure regulator. It works on vaccumnot boost, so you must use an electronic regulator that gets a boost or electrical signal from the regulator to the ECU.
I never really thought of that until I just thought of it as it is something I have never paid attention to or had to work on in a boosted car. However the signal may work, 2 things could be happening. The base fuel pressure is low and that means the fuel pump is weak or there is blockage in the fuel lines. If the regulator does not increase pressure with the increase in RPM or boost, the fuel curve will be wrong and either starve or flood the cylinders.
Check the fuel pressure. There is a port on the fuel rail that will work with a pressure test gauge. Advance Auto and Auto Zone have test gauge kits on a loaner basis. They have adapters in them to mathc most fuel rails which are pretty standard threads.
Let me know how it goes.

I think myself that it is a fuel problem alrite. Ill do that and ill let you no. Thanks very much for the help its such a fustrating problem but I hope to solve it. If you think of any other reasons in the meantime please post them as I need all the help I can get : D thanks again ; D

Steve fits
Nov 23, 2011.
Your very welcome.
It is a very frustrating thing to work on even a slightly modified car as seeking help is hard to find since your setup is somewhat unique. You ca't go buy a Haynes manual and solve the problem. Often, you can get a lot of information from joining an enthuisasts forum. I have been a part of many and there are other members who have been in the same place you are now and willing to give you there advice. You can also seachr different threads and see if there are any archived posts on the subject. As popular as the 240/180 SX is, you would have no problem finding an enthuisiast forum.
I built a 1990 Integra that I swapped a 1998 Interga GSR with VTEC motor into. I had to change a lot including the wiring harness and I bought an OBD2 package from HMotorsonline and was stuck as going OBD0 to OBD2 was not something that was being done. I found a place called the swapshop, I tried Rywires. Com but they had a huge backlog and I still needed an ECU which they did not carry, and they hooked me up with an OBD1 ECU and flashed it with a Type R program. I had problems starting it and could not figure it out. I was a member og HondaTech. Com which is a huge enthusiast forum and I could not find help there as a no start after doing a swap like that could be so many things. I got the answer after I called the swapshop guys a few times as I was running high impedance injectors and the old engine had low impedance injectors and ran a injector resistor to make up the resistance neccassary. I had left the connector hangin and it needed to have all the terminals tied to gether. I found an end cap which did so and it started, but the RPMs were like 200+ at idle. I also had a catch can that I set up wrong and it sucked a quart or so of oil into the fresh motor I had just got. I had forgotten to put a PCV into the circuit and the vacuum was too high. The idle was just a problem with the throttle cable bracket. I had to make one by had that would work until I got a Type R which worked. Then I had a vibration problem at 45+ MPH which felt like the axles. I eventually figured it out and had to change the ride height to keep the axles from binding but they had been damaged by then and I had to send them back to the DriveShaft shop as they were warranteed. I was too tired of messing with it and put off the axles as it was not bad an I sorted out a few things. Then I had a really bad accident in it and totalled it. I mean I hit a telephone pole and the engine almost came through the firewall onto my feet. The fenders blew off the car and one was in a tree. I hit my head I am guessing, between the dash and steering wheel a few times and got knocked out so hard I was out for a week and have no idea how I wrecked. I am still recovering. The point is I got the car straight and I am guessing that I was going fast and must have lost traction, it would turn the wheels shifting into second even with the factory LSD tranny. Cheap tires, so I guess that might have had something to do with it.
It is a frustrating business being a gearhead sometimes. You are bound to have issue when you mod a car. You will eventually figure it aout and may have other issues that take some time too. But, in the end, you created a beast of a car and there is no other feeling like turning the key, going out and beating V-8s, I tore a new Mustang a new as@#%ole, and getting into the throttle of something you made.
So, don't let it frustate you as it is bound to happen. Find an enthusiast forum, if you have not already, to get help and they usually have used parts for sale and advice on what vendors to use for new parts. Be lotal to the parts places you buy stuff from. Always post comments that are positive about there store or shop, don't say anything unless you can say something nice, and you might not always get the best deal but if you buy from one place they usually price match. They will also give you a general discount over time and do other things for you. I buy all my stuff from Summitracing. Com, horsepowerfreaks. Com, (Really good place with smart sales guys and good clearance deals), theswapshop. Com, (they aren't rywires, but they are nice and will do things for you that other places won't), and sometimes usautoparts. Com, but the loyalty factor there is zip but the prices are awesome, and fatbrakes. Com, really nice guy who owns it and if it is not listed, he will make any setup you want.
The other thing is to get through the period where you finally have it running good and keeping yourself from racing everyone who will, speeding, testing the limits, ( I got up to 120 in my car and had a gear to go and 500 RPM), and don't end up like me.
I lost my pride and joy right after I sorted it all out. I think that hurts more than the metal in my ankles. The car you are building will be so quick and so fast that you will not notice how fast you are going, just like when I hit 120 MPH, that you really have to find out what the car can do, but hold back. I lost my car, all that money and almost died and my body will never be the same. I don't know if you have issues like me but most gearheads do, we change when we get behind the wheel. You don't worry about tickets as much, but you might have your car taken away as it will go over 100MPH so fast that you won't notice and most states will impound your car and you will have to go to court and maybe prnation before you get your car back.
Wrecking can happen easier as the HP you have in such a light car, I had the Integra down to 2200 Lbs, with a full tank of gas and me in it, that losing it when you are getting on it can happen. You may not have these issues, but I do and I just wnated to say it, sorry I wrote so much, becasue I don't want to see anyone go through what I have. Handling your foot in such a high performance machine is hard, but there are too many things on the street that will make you lose your car and you might get hurt or hurt someone, thanks God I did not hurt anyone else.
So, I apologize for the long and whiney story. I just know how frustrating it can be, but you will get it straight. I know that your set up will be a handful to drive and capable of more than most $60-70,000 cars can do. And more. I also know what it is like to lose that and if it was a few weeks like me or years, it will really get to you and you will always think about it.
So, just keep a handle on that puppy and hopefully you are more mature than this 42 year old man who has little self control and all of this you have read has been un-necassary, except for vendor loyalty and places where to get advice like enthuisast forums, becasue you are building something that you can't ever truly replace.

I do think the fuel issue is the next thing to look at and I don't have as much knowledge as I should about how boosted cars regulate fuel pressure. So, please let me know if you use a standard vacuum type regulator, maybe you don't run the vacuum line or there is another way it is handled. I really should know and want to know.
Also, let me know how everything turns out as I am interested and hope this is all that stands between you and riding the streets.

Take care.

Dr. C