90 240sx Ka24de idle/boggy problem

[Froskie]

Hey guys, this is my first post on Zilvia.net! I'm stoked to be a member. But anyways.

I just bought my first 240, and it had been sitting for around 7-8 months. I purchased the car last week and since then i have changed the fuel pump, changed out a injector, installed a new battery, spark plugs, fuel filter, changed the oil, filled up the tank and ran some sea foam through it, and ive driven the car maybe 150 or so miles since the day i bought it. It drove fine up until today.

The ka24de came out of a 1995 s14 and is rebuilt with 80k miles and new OEM pistons and rods. The car fluctuates in idle but not significantly. And when in gear, i press on the gas anywhere from minimal to medium or even 3/4 way down and the car seems to bogg and has a major delay in acceleration.

Any advice would be much appreciated! I'm gonna clean the MAF and IACV tomorrow and see if it doesnt help. Oh also. The exaust is welded all the way back from the header and at the resonator it has a small crack where it leaks. I ordered a new catback exaust today and when it gets here im gonna find a good header to use. ;)

[pacotaco345]

Wait.. So is the car N/A or turbo? Because you used the term KA24DET and header in describing the same car.

Oh, and welcome to the forum! Good job finding the right place to post, most people can't even do that...

[Froskie]

Yeahhh... Sorry about that. I posted it last night after studying for my literature test allllll night long. But it is NA. It's just a rebuilt ka24de out of a 1995 S14. And thanks man! i appreciate the hospitality. haha. isnt that the truth!

[Mitsubayati]

Unplug the MAF. see if it runs better.

Also, my car had a similar problem at low rpms. It was a simple problem but there was a hole in my intake pipe after the maf where the resonator for the stock setup goes. It was open to the atmosphere and causing the car to misread airflow thus causing it to bog. I taped it for a quick fix and it fixed the problem.

Also, check your distributor cap. Especially if the car sat for a long time, there could be corrosion build up on the terminals inside. If you pull it off and they are white or the rotor is white, just change them both. They are cheap and it's always good to "tune up" your car.

This problem happens a lot with 240s and sadly there is no one cure as it could be many things causing the same problem. Best advice would just be to check the basics first and find any potential problems. Change items that seem worn and don't replace expensive items unless you are 100% sure through diagnosis. In the end if you have changed out a good amount of things you will have less problems down the road and your car will run right. So, don't worry if you spend a few bucks changing things that ended up being unnecessary as they would need to have been changed at some point.


Most of the time these problems arise out of nowhere because the owner failed to do basic maintenance on the vehicle. Sometimes a simple tune up can fix these problems. 80% of the time, it's something simple. Finding out what that problem is though, isn't always as easy.

[pacotaco345]

Check all the things he ^^ mentioned, and also check vacuum lines. They're often cause for rough idle. In 20 years they get all crusty-like and leak lol.

[DJ-of-E]

Check all the things he ^^ mentioned, and also check vacuum lines. They're often cause for rough idle. In 20 years they get all crusty-like and leak lol.

Yeap. I had issues where my rpm drops down to 300 whenever I brake or accelerate. Drove me nuts for 6 months because it would shut down the car too at many times.

Checked the vacuum lines 3 times during the time period (just by squeezing the hoses), couldn't find anything.

After I took out the intake, I just went ahead and start bending nearly all the hoses much further. My power brake booster hoses (which looked conformed when squeezing and pressing) literally broke into dust when I bend it hard (rubber hoses, if it doesn't bend completely, it's no good (unless it is hardened or has hardpipe inside).

Replaced that power brake booster hose and never had that issue again.

I'm doing an engine rebuild sometime in 1 or 2 years from now (ahead of other project first) and you'd be an idiot not to replace all the rubber/non-hardline hoses.

[Froskie]

Thank you very much for all of the posts. Especially Mitsubayati! The person whom i bought the car from did a lot of good to the car, but the person before him riced it out and probably is the cause for all of the replacement being needed. I just went from a 88 civic hatch with a b16 swap and full bolt on set up to my 240sx with the rebuilt ka. So from owning a honda i learned a lot about changing out things and doing "tune-ups" myself. I replaced too many things on that car

But i agree! By me taking the spare time and money to replace small things on the car that could be potential problems it will be very benificial down the road. I'm going to put new plug wires on today, and track down the vacuum lines. There are two hoses on the car that are hard as rocks.. one goes to my power steering or my braking system i believe(would have to check again) and the other goes from the radiator to the block. I just havent got to replace them yet. I'm also running 87 octane on the car because thats all the previous owner used he said. He's a good friend of mine. And i only paid 1400 for it so i cant really complain.

But i'm going to check out the brake booster hoses as Dj-of-E said and see if their alright and unplug the maf and see what happens. Thats wild that they actually disentigrated at the touch! Wow haha.

And also the distributor cap terminals werent white, they were more black than anything. I scraped them off with a wire brush and the silver color came back. I'll let everyone know how the car's running once i get home and check it out. i get off soon so im just waiting!

[Mitsubayati]

DJ-of-E is probably the best example of what I was talking about. I had the exact same issue as him, but it turned out that my issue was with the corroded cap. Once that was swapped out, never again did my rpms fluctuate at idle.

I did forget to mention vacuum lines. While they can be the culprit sometimes having them unplugged could do nothing. It really depends. A good way to check is to get a can of brake cleaner and spray it all over the rats nest. While I'll admit it probably isn't good for the lines themselves, it will help you find the leaking one quicker. If you notice your engine run better once you've sprayed it in a certain spot, then it's highly likely you find your bad line. I did this before and it worked like a charm.

If you don't care about your emissions or smog, then it would be in your best interest to just eliminate the lines. I like to strive for simplicity on my track car and that was the first thing I did. All you need to do is remove your EGR setup, put the EGR block plate in place, remove all of the hardlines behind the motor along with the soft lines that run into the hardlines in the intake manifold. Then just put caps on the front ones and remove all of the emissions components. It will make your life easier if done right and could even solve your problem. Just make sure that any hose that goes to the intake pipe is capped off. I say cap the hardlines up front of the intake manifold because one or two them goes directly into the IM.

[Froskie]

Awesome! I'm about to leave the office right now and head home to check out the car. It drives quite well for sitting for 8 months, and is peppy compared to the ka24e s13's ive driven. But the power deffinately isnt where it should be... I can tell a major lag in acceleration. But like i said i still have things to replace and to clean up including some ground wires, and i need to change out my battery cables because their too short and get pulled out due to being tightened on the battery and its just barely close enough to fit. But that is a good idea. In the future i deffinately plan to do so. It would make it a lot easier on me if i got rid of the EGR set up. I know a good bit about car's in general, but i'm new to the ka and the nissan game. So all of this is a learning experience for me. But i'm always excited and ready to learn new things. I'll do a few things and check out the car when i get home like i said and i'll let you know whats up with it!

Also. i ordered a catback exaust for the car and i'm now searching for a good header and downpipe to get.. any suggestions would be appreciated! ebay of course. don't have much funding right now. But the header is old as dirt, and the exaust is crap. has three holes in it total. but i just figured i might as well change out the header when i do the exaust

[Froskie]

So far i've changed the plug wires, flushed the radiatior, checked vaccuum lines (none that i could see were damaged or in need of replacing), and i even ran some sea foam in my gas tank when i filled up last week. I let the car run out of gas and then i filled up completely just to make sure it wasnt particles or dirt in the gas tank. Still nothing. I know the MAF is a simple fix, but i just havent had the time to check it. I'm gonna go home and take it off from the intake box and check both the intake box and clean the MAF and see if it doesnt help.

[Froskie]

Well....... this isnt good. The car is back to acting weird via fluctuating idle and poor acceleration. But last night it drove like a champ. I've never felt it drive like that before. I had a friend suggest that theAIV Valve is clogged up and this is causing the problem. Also, the hose that goes from the stock intake box to the PAIR/AI valve is hard as a rock. Anyone cleaned this out before?

[Frank_Jaeger]

Well....... this isnt good. The car is back to acting weird via fluctuating idle and poor acceleration. But last night it drove like a champ. I've never felt it drive like that before. I had a friend suggest that theAIV Valve is clogged up and this is causing the problem. Also, the hose that goes from the stock intake box to the PAIR/AI valve is hard as a rock. Anyone cleaned this out before?
Step 1. Remove AIV
Step 2. Plug AIV pipe.
Step 4. Repeat steps 1-2 for EGR.
Step 5. Enjoy cleaner engine bay at the cost of decreased gas mileage and shitty cold starts :bigok:

[pacotaco345]

Step 1. Remove AIV
Step 2. Plug AIV pipe.
Step 4. Repeat steps 1-2 for EGR.
Step 5. Enjoy cleaner engine bay at the cost of decreased gas mileage and shitty cold starts :bigok:

I have neither and get > 30 mpg regularly. My car also starts fine on < 20 degree days.

[Frank_Jaeger]

I have neither and get > 30 mpg regularly. My car also starts fine on < 20 degree days.
http://www.meh.ro/thumbnail/2009_12/meh.ro2952.jpg

1. Manual or auto?
2. Cat or test pipe?

[Froskie]

So i removed the AIV components on the car and it DOES drive better, but the acceleration still suffers and isnt where it should be. It seems like its a fuel problem to me. But i'm not too sure. i can still drive it of course, but it doesnt pull for shit. and its a manual, and full 2.5" pipe all the way back, but im putting a 3" catback on the car next week