need some help

[Oatmealman]

hey guys,i got a 1989 240sx stock engine and transmission,and it will not run right,it runs on 3 cylinders most of the time sometimes less,i've checked the timing,distributers in right place,i have spark on all of them,i have gas,injectors and opening and closing,but i haven't checked if there pumping,made sure there's nothing clogging it,ummmmmmmmm,haven't pulled the codes on it yet but i just can't figure it out,i've checked everything,just let me know what u think it is,my dads a mechanic and he's helped me until now were he couldn't figure this out and said screw the car,so i need help figureing it out,btw it's suppose to have black top injectors(my specific vin# was made for only a month then problems happended and they quit making them),i found newer same year red top injectors.so give me some ideas,i've tried switching injectors from diffrent cylinders to the cylinders that won't run,and yes i have 140psi of compression on all the cylinders pls help getting old enough to drive soon and i need to get this running

[Oatmealman]

bumpizzle

[240DRFT]

isnt 140 kinda low? i thought they were suppost to be kinda higher even for the min.

[Oatmealman]

i didn't think so,my dad said thats plenty for a gas engine

[Oatmealman]

bumpizzle

[Oatmealman]

bump damnit some one help me figure this out

[ricebike]

check for codes... &/or goto nissan online mechanic section...

[phuphyter]

My best guess would be the injectors, but since you've tired swapping them, I don't know what to tell you excpet maybe trying to run seafoam in the gas tank to see if it can unclog anything. I'm having trouble running on 3 cylinders too and its a b*tch, but I found out that its my No. 3 injector. Im gonna have to replace it soon. good luck finding out your engine's problem.

[Oatmealman]

thanks i'll try seafoam i think there may be dirt build up in some of the injectors,i'll try that,and is 140 low for compression on all the cylinders meaning i have 140 on each and everyone cylinder

[phuphyter]

From the FAQ's on http://www.240sx.org:

Measurement of Compression Pressure

1. Warm up engine.2. Turn ignition switch off.3. Release fuel pressure (See How to Change Fuel Filter)4. Remove all spark plugs.5. Disconnect distributor center cable.6. Attach a compression tester to No. 1 cylinder.7. Depress accelerator pedal fully to keep throttle valve wide open.8. Crank engine and record highest gauge indication.9. Repeat the measurement on each cylinder as shown above.Note: Always use a fully charged battery to obtain specific engine revolution.

Compression Pressure kPa (kg/cm2, psi) / RPMStandard = 1,236 (12.6, 179) / 300Minimum = 1,040 (10.6, 151) / 300Difference limit between cylinders = 98 (1.0, 14) / 300

10. If cylinder compression in one or more cylinders is low, pour a small amount of engine oil into the cylinders through the spark plug hole and re-test compression.

* If adding oil helps compression, piston rings may be worn or damaged. If so, replace piston rings after checking piston.

* If pressure stays low, a valve may be sticking or seating improperly. Inspect and repair valve and valve seat.

* If compression in any two adjacent cylinders is low and if oil does not help compression, there is a leak past the gasket surface. If so, replace cylinder head gasket.

140 psi does seem kinda low

[Oatmealman]

k i'll print that out and try that on friday after school

[Oatmealman]

did a leak down test and figured that my engine is fine,so it's the timing chain