240sx bogging
 

Mods: cat back exhaust, stage 2 clutch and light flywheel.


1995 240sx the car idles fine and under slow acceleration the car will rev up
but any acceleration past like 15% throttle the car stocks bogging really bad
and will die if not brought back to idle. No check engine light on. Last thing
changed on the car was the clutch and flywheel was about 4 months ago.

Things i have tried cleaned the maf,replaced fuel pump and filter,replaced plugs and wires,check ohms on injectors and pulled plugs off one by one but made the engine get worse,checked for vacuum leaks,checked fpr, hooked up fuel pressure gauge got 40psi idle 50 55psi when bogging, pulled exhaust off and ran just headers to see if the cat was clogged.

Any idea would be helpful

anyone with an idea?

Ohm the knock sejsor, should be ~550k ohms. If not. Replace or bypass. Check fuel pressure. Check O2 sensor and CHTS.

Did you mess with ur ignition timing or pull the distributor out? Also check intake system and make sure you have no leaks, ka's dont like any air leaks especially after the maf

checked the ignition timing which was good. Did a fog test over engine bay no leaks.

Try cleaning the maf and check for possible loose grounds on the engine, if the ground on the rear left of the cylinder head is loose, it will cause a problem like that. The bracket that holds the o2 sensor wire also mounts there, possibly do a compression check also see if you dont have a burnt exhaust valve

Thanks for the help.

Replaced the Maf 2 days ago also I checking the grounds by removing them and removed any dirt/grim still the same. Guess i will try a compression check next.

get a wideband o2, that'll help you determine if the bogging is caused by too much air, or not enough.

Put new distributor in and car now runs fine but when i press the pedal more then 50% the car picks up and then acceleration is very slow.

Knock sensor. Did you check it?

No i didn't wouldn't that trip a code?

Yes. But no check engine light.

K I will check out the volts and ohms today

You still have an EGR?

Yes I still have the egr

So i got my hands on a scan tool and got P0325 and P0110 but when i went to reset the codes they were gone? Drove around for 30min checked and got code P0325 this time i stopped the car to reset it but it was gone again. PO325 is the knock sensor and PO110 is intake air temp right?

replace the air intake temp sensor

I was going to say it might be sticking, but if you're getting codes for the AITS and knock sensor, change those... The knock sensor is easy if you fish it in with a coat hanger or something... You don't have to take your intake mani off like the FSM suggests.

The knock sensor is troublesome on these cars. Bypass it

/?/..................

Already bought both 100$ shipped

Thanks for the help everyone I will let you all know how it goes when the parts are in.

also something minor to check is ur plug gap make sure ur gappings are correct

Well both parts came in today installed them cleared the codes started it up drove it around and it did help a little bit but still doing it. The knock sensor was cracked down the side of it.

Ever check the cylinder head switch? Injector seals?

What the temp switch? Haven't checked them yet

Cylinder head temp switch. Two sensors on the front of the head near the rad hose outlet. One has one wire. That's for the temp gauge. The other has two wires. That's the cylinder head temp switch. If it goes bad it can make the car run real screwy. It's only about $8 .

I will take a look at it as always thanks for the help.

From the looks for where it is I might as well change the coolant or is the fluid level not up that high when not running.

The coolant always does touch the sensor. When the car warms up and the thermostat opens . The sensor changes resistance with temp telling the ecu how to trim the fuel and timing. The one on my girls car was cracked, causing a high idle, hesitation and hot running. When you remove it not much coolant comes out.Dont use Teflon tape or any other sealant on the sensor.