Engine problem

ONLY for ADVANCED technical discussion about the 240sx!
mosilvia
Posts: 5
Joined: Thu Jan 03, 2008 11:01 pm
Car: 96 Nissan 240sx

Engine problem

Postby mosilvia » Thu Jul 08, 2021 1:15 pm

I have a question.The moment I drive on the gap between the street and the free way,
The engine speed drops from 500 to 1000 rpm for a moment.
What could be the cause of this?
Last edited by Rogue One on Thu Jul 08, 2021 7:21 pm, edited 1 time in total.
Reason: Duplicate post deleted


User avatar
NukeKS14
Posts: 213
Joined: Wed Apr 10, 2019 2:50 pm
Car: 1995 240SX SE - KA24DE-T
2014 Camaro SS 1LE

Re: Engine problem

Postby NukeKS14 » Thu Jul 08, 2021 5:15 pm

More information on your car would help.

So if I'm understanding your problem, the engine stumbles and when you try to rapidly accelerate. Is that correct?

What engine are you running? Have you performed any maintenance or modifications recently. How long have you owned the car (has it always done this?) Is there an aftermarket ECU? Do you have a wideband and, if so, what do your AFRs look like when this happens?

We really don't have the info we need from you to help at this point.

User avatar
NukeKS14
Posts: 213
Joined: Wed Apr 10, 2019 2:50 pm
Car: 1995 240SX SE - KA24DE-T
2014 Camaro SS 1LE

Re: engine problem

Postby NukeKS14 » Thu Jul 08, 2021 5:17 pm

engine-problem-t629394.html

Please don't create duplicate threads for your issue. Just because everyone's at work and didn't reply to your question for 3 hours, be patient or bump it with additional info if you need, but creating more threads only creates confusion and makes it more difficult for people to keep track of everything if they're trying to help you.

mosilvia
Posts: 5
Joined: Thu Jan 03, 2008 11:01 pm
Car: 96 Nissan 240sx

Re: Engine problem

Postby mosilvia » Fri Jul 09, 2021 12:11 am

I am sorry I posted it in a different place and didn't know how to erase it. My Car is 96 s14 300000 miles No engine modifications No ecu modifications Complete stock MAF air temperature sensor iacv replaced with original parts 8 years ago Alternator TPS fuel filter distributor cap and rotor 2 years ago Battery is brand new. When you run on a step, the engine speed drops by 500 to 1000 for a moment. It returns to its original state in a moment (about 0.5 seconds), and the engine is still working well. I thought Fuel pump or fuel injectors issues in the beginning but the issue happens when drive on a step so like a electric ?

User avatar
NukeKS14
Posts: 213
Joined: Wed Apr 10, 2019 2:50 pm
Car: 1995 240SX SE - KA24DE-T
2014 Camaro SS 1LE

Re: Engine problem

Postby NukeKS14 » Fri Jul 09, 2021 5:31 am

When you say 'run on a step' do you mean you're stepping on the throttle? I'm assuming you mean that you're tapping the throttle here is that right?

That's tough, could be a few things. How do the spark plugs look? That's a lot of mileage. May try pulling and cleaning the MAF. How does the air filter look? Is the intake and tubing from the MAF to throttle body in good shape?

Does the car smell of fuel like it's running rich?

At what RPM does the engine idle? Should be about 700-800 RPM.

How long since the coolant has been changed/flushed? It's a really long shot but, if it's REALLY really old I've seen coolant actually conduct small voltage which throws all of your sensors out of wack. Here's how to check for that as an issue. I wouldn't freak out if it comes to this; you don't need to replace everything just flush the coolant and I would replace the coolant temp sensor in this case as well, they're not expensive and absolutely vital as an input to your engine's fueling and warmup enrichment tables.(make sure it's the CTS and not the sending unit for the dash. The CTS has 2 wires, sending unit only has 1)
https://www.familyhandyman.com/project/ ... ultimeter/

We can do a few checks to see if something has gone bad. I would check and adjust the TPS. Thats fairly easy. Its a long shot but check the ECU for codes. This is separate from OBD2 (which your car may have if it's late model 96).

Checking/Adjusting TPS

How to check codes on S13/S14 ECU

mosilvia
Posts: 5
Joined: Thu Jan 03, 2008 11:01 pm
Car: 96 Nissan 240sx

Re: Engine problem

Postby mosilvia » Fri Jul 09, 2021 11:49 am

"When you say 'run on a step' do you mean you're stepping on the throttle? I'm assuming you mean that you're tapping the throttle here is that right? "
I mean driving at a constant speed and when driving on a bumpy road, road surface with steps, RPM drops by the number steps for a moment.The accelerator is in the state of being stepped on.
The engine is good condition. Compressions are 185~190psi. Idling is 750rpm but running rich .
The coolant was changed 3 monthes ago but CTS replaced 8 years ago so I will change new CTS.
I will fix what you have taught me one by one.

mosilvia
Posts: 5
Joined: Thu Jan 03, 2008 11:01 pm
Car: 96 Nissan 240sx

Re: Engine problem

Postby mosilvia » Fri Jul 09, 2021 11:54 am

NukeKS14 Thank you for the huge help

User avatar
NukeKS14
Posts: 213
Joined: Wed Apr 10, 2019 2:50 pm
Car: 1995 240SX SE - KA24DE-T
2014 Camaro SS 1LE

Re: Engine problem

Postby NukeKS14 » Fri Jul 09, 2021 12:11 pm

I think I did misunderstand initially; you may have a broken or loose wire somewhere.

Check for codes as before and see if anything comes up.

How are your battery terminals? Make sure they are in good condition and not corroded. Check engine grounding wires too.

mosilvia
Posts: 5
Joined: Thu Jan 03, 2008 11:01 pm
Car: 96 Nissan 240sx

Re: Engine problem

Postby mosilvia » Fri Jul 09, 2021 1:13 pm

ok


Return to “240SX Technical Forum”