89 240sx SOHC sputtering/bad idle

[xKnownShadowX]

I have made a thread about my idle I think but this one is mainly about the sputtering. I have search and found threads but they all end with no reply of fixing or nobody posts the right info.

My problem is when I turn the car on it sputters/mis fires I guess you can call it.I hit the gas and for .1 second it sounds like as if one injector or plug was unhooked then revvs.When I drive, going into first gear it sputters then goes back to normal. If I floor it it'll get up and sputter ridiculously at the same time.

Reading the other threads they all said to change injectors and MAF. If I unplug my MAF the car just dies. I have swapped the injectors like 3 times already and problem continues. I have gone through 3 IAC and problem still remains. I have swapped the TPS twice and problem still remains. I even tested my MAF with my cousin's and still problem remains. When I replaced my plugs they came out with the tip a bit white as to the cylinders probably running too hott. My wires are brand new as well and the cap and rotor are semi new. I replaced fuel filter yesterday back to the 240 original one instead of a 300zx one. My FP seems to function correctly but who knows how old it is, but it has been replaced before.

I was thinking maybe I should double check my timing again and make sure it's correct perhaps.

As for my idling, let's just say it's a headache. I disconnect the TPS and adjust the idle screw and it lowers it but keeps it at 1500RPM if fully closed. I plug the TPS back in and it will just jump to 2000-2500RPM unless I face the TPS all the way down towards the front of the car. I tap it back a bit and it rises again. If I try to adjust the screw with the TPS at that position it does nothing, not even a tickle to the idling.

I can't seem to find any vacuum leaks since I only got like 3 or 4 since I removed my emissions. IDk if it can be a wire but if anybody here can really help me out that would be great. Engine has like maybe 1-2k miles on it since rebuild and it sucks because I was hoping it would be good and running fine for once but in reality runs worse then my last engine I screwed up.

Just incase you need to know my modifications here's a list:
-Injen Intake
-4-2-1 Header
-Emission removal
-3inch test pipe
-3inch cat back

Thats all that I know regarding anything with the motor and I still have my SCV installed just hooked up to a vacuum line which opens as I give throttle.Thanks for reading I hope this all makes sense your help is very much needed.

[breadbox]

When was the last time you checked out the fuel tank? I'd hate to think sediment got into your injectors.

What do your plugs look like/smell like.

[xKnownShadowX]

Smells like burned/died up gas perhaps.I was researching and I'm beginning to think it can be my Fuel Pump going out.I haven't replaced it since I got the car 2yrs ago.I have a spare one so I might swap it for temp until I come up with money and get a walbaro.Might change plugs again too and redo timing just incase.I will also check out the tank make sure nothing is sitting inside.Thanks will update tomorrow morning.

[xKnownShadowX]

This cars like ratarded I swear. I popped out the Fuel Pump and it was a Walbaro so I put it back in.Tried to adjust the idle a bit but once again it won't idle below 1000rpms unless the TPS is nose down all the way towards the front. W.E. so I put it normal and it idled at 1500RPM. Car had same problems so I just now swapped the Walbaro for a OEM working Fuel Pump. Same thing and no difference and also now when I hit the brakes my ilde drops to 100RPM and it also stalled earlier. Pulled plugs out and they look normal. I wanna replace them but knowing that nothing I'm fixing is working I don't wanna throw my money away. I got no clue why the car won't idle or stop stuttering. The ECU throws code 35 Exhaust Gas Temperature Sensor but my harness has that plug with a cap. I didn't have a sensor there to begin with. I also had another intake mani that had a sensor there too but had to throw it out cause I removed the butterflies and it gave me a leak so I put the old one back. This one has no sensors. I did that resistor 100k or w.e. trick and code still pops up. I still gotta get my hands on a timing light anybody got any idea what it can be? It's really upsetting me the engine had 1k or so miles and it's giving me a headache like my last motor.

Perhaps the Injen Intake is giving me this issue? Would a leaking header gasket cause this too? What about a bad o2 sensor? Mines like 2months old though?!

P A T I E N T S thanks in advance.

[compactfean]

I think you have a huge vacuum leak. The hardest one to diagnose....brake booster and/or booster ckeck valve. Plug it and test drive it.. be careful, no power brakes.

[xKnownShadowX]

I was thinking maybe my brake booster is out as well but never came to mind. So let me get this correct. Remove brake booster hose and plug it, then test drive? I forget where the boost check valve is or is it in the booster? I was thinking maybe I do have a leak because my previous engine started doing the same thing before I swapped it out and then this one has been since 1mile.

[compactfean]

The check valve is on the firewall dead center up top between. Booster and im.

[xKnownShadowX]

Whats the "ïm"stand for? Hmmmm perhaps a picture if you got one? So I plug that and drive it? Even though I took brake classes I'm confused. Been doing this all day hahaa....

Thanks.

[compactfean]

Sorry ...intake manifold. And don't know how to put pics up on here from my phone. The valve is inline and is in a bracket thing right above your valve cover.

[xKnownShadowX]

Okay got ya.I know what you talking about.So I should remove that and plug both lines together or plug em both and test drive?

[bladetech8]

There is a possibility that the Walbro fuel pump you had on there had overpowered the stock FPR and caused it to dump too much fuel and hence why your plugs are smelling like fuel and your car runs/idles like crap..

[xKnownShadowX]

Well I pulled my plugs today and it smells normal.I swapped the rail and injectors after it smelt like fuel.

[compactfean]

Just the one to your intake manifold. It really doesn't matter though as long as air is blocked from the booster that way if it fixed your problem. You know the problem lyes within the booster. All your doing is plugging a vacuum leak. ( boosters under vacuum aren't supposed to leak) it just sux that if it is the booster you can't just leave it plugged for your engine to run better.

[compactfean]

There is a possibility that the Walbro fuel pump you had on there had overpowered the stock FPR and caused it to dump too much fuel and hence why your plugs are smelling like fuel and your car runs/idles like crap..

That happened to me too! 50psi at idle! Pig rich and did. The "babababaaaaaaaah" as I took off.

[xKnownShadowX]

^^^mine does that sometimes.Could it have messed up all three of my FPR?

[compactfean]

Idk it happened on my 240 and my 200sx ser. Both I put afpr's on and both are great now. You don't have a fuel gauge?

[xKnownShadowX]

Nope.Not tryna spend hella money on something wen my car runs ratarded.

[compactfean]

14.95 harbor freight.

[xKnownShadowX]

my budget right now is $0 hahaha....i'll look into it.what should it read?

[compactfean]

34 at idle with vacuum line hooked up. Plugging that vacuum line is free! That will tell you something but that something will involve money eventually lol

[compactfean]

Booster vacuum line that is

[1KleenS13]

I think you may have a wiped cam lobe. The oil nowadays doesnt have any zinc in it, and unfortunately flat tappet motors are failing left and right because of this. I know the inventor of ZDDPlus and he showed me that the SOHC KA24de are the worst motor for wiping the lobes, and the Turbo Buick engines were second. http://www.zddplus.com/, its not just another snake oil, although I make fun of him for it. Im just throwing this idea out there.

[xKnownShadowX]

Interesting.Well I'm go do that booster thingy test.I'll update in a bit.

I'll read all his info later thanks.

[xKnownShadowX]

Check that and I plugged the hose.Nothing still the same thing.It idles good cold but when it gets hott it revvs up.I put the TPS facing down in the front and it's idling like before and when I hit the brakes my idle doesn't drop.I'm thinking its the damn o2 sensor once again???Perhaps???This is so annoying.....

[xKnownShadowX]

Forgot to mention I also replaced coolant temp sensor.

I was looking up pre-ignition timing or pinging and it kinda sounds like mines doing it but again could be the chain.Though that was replaced too?!?!?Hmmm....

[compactfean]

You replace the tensioner with the chain? I would pull the valve cover and double check chain tension and bring it up to tdc and see if the can is aligned. While your in there check your can lobes.. you know come to think of it my girls Honda was doing the same thing when her valves tightened. Valve adjustment and done. Then again did the same s*** when coil was on its way out. Too.

[xKnownShadowX]

I changed my Ignitor thingy and I also replaced the Spark plug wires today since one broke off.I will check my timing again but what should I check on the lobes?We can't do valve adjustments can we?I also forgot when I put the head on it was like new everything was gray even had speckles on the springs.It was not burned or brown looked fresh to me but I never know.Chain and tensioner are tight, I checked it when I did my valve cover gasket.Well I hope my cars not pre-igniting or anything.

Once again can a leaking header/intake gasket do this?I mean there is no leaks except I think my header one is leaking so IDK.

Also was looking and you know that module thingy that goes hooked up to the IACV, if it goes out or bad can't that be a problem too???



edit:I think if this was a english paper it'd be a FAT F!!!

[xKnownShadowX]

Just now I decided to disconnect my IAC thingy, basically everything plugged to that, and well the car idles better and I can set the TPS correctly but car still miss fires and sputters.I found a cracked vacuum hose on my FPR so I swapped it out and still not difference.Any ideas?Still gotta check timing which my friend has but I kinda don't wanna trade a clutch job for a timing light.

I also checked my injectors one by one and all are in working condition.I'm gonna clean my MAF see if it does anything.Other than that only thing left is timing.

Edit:
Cleaned MAF and made sure intake is tight secure with no leaks.Same thing and now when I turn hard my car sputters too. Beginning to piss me off now.

[xKnownShadowX]

Anybody?I been searching on google all day and all I find is threads that never get replied or finished.I feel like yanking everything off....

[240nessx]

You removed your EGR? If you used a block off plate make sure it is sealed correctly. I had a sputtering idle and when i checked the EGR block off plate i made, it was leaking. I got a new gasket and new bolts and put it back together and the idle is perfect now. Hope this helps