super boggin... with lack of power!

[iamtheyi]

I have a 95 s14 with a KA and some stupid stuff has been happening with it. Some details:
1. Bogs on idle
2. Bogs/farts during WOT in all gears and at any RPM
3. Bogs/farts when under 2k rpms to about 2.2 before it kind of "clears up" (also clears when I let go of the gas pedal and accelerate somewhat slowly)
4. during all the bogging/farting, there is an immense lack of power and I don't go faster than my current speed
5. No bogging at higher speeds, like highway cruising. only happens when I go WOT again.
6. I cleaned the MAF and sprayed intake cleaner into the IACV sprout thing.
7. Check Engine Light is not on
8. I think it's making the sound that people describe when their injectors go bad, like the WRX exhaust note. Sounds like my car is gurgling something :P

update: my car does it more often after warm-up. When it's cold, little to no problems.

I replaced the spark plugs sometime in June and have basically new NGK spark plug wires. I also replaced the fuel filter thinking that might've caused the problem. The problems didn't start until after I changed my exhaust from a ~2.5in straight pipe to a 3" catback. But I doubt that's the problem.
More, possible irrelevant, info: I have leaks in the exhaust and a leaky valve cover (need to replace gasket).
Please help. This is really starting to bug and I don't want to throw more money at it ><. Thanks in advance :}

[KoukiDrifter240]

if your stock you should have kept 2.5 inch with cat u need back pressure n/a you will lose power if you exhaust is to big unless your turbo then 3" no cat good it could timing or your trannny is bad are u auto or manual?

[iamtheyi]

if your stock you should have kept 2.5 inch with cat u need back pressure n/a you will lose power if you exhaust is to big unless your turbo then 3" no cat good it could timing or your trannny is bad are u auto or manual?

I'm manual. I also saw a thread on here where a guy dyno'd a 2.5in exhaust and a 3" and the KA makes more power with the 3" stock. I have no cat either, it's gutted. My tranny is fine. I don't think that would make my exhaust fart no matter how bad it is. Timing is a possibility as I have timing chain rattle but having it clear up after letting go of the gas doesn't make sense then. it should be doing it regardless in certain RPM ranges.

[iamtheyi]

and an update. my car does it more often after warm-up. When it's cold, little to no problems.

[xsidewayzx]

Check your timing if not it maybe you alt. I had the same issue all fixed now.

[iamtheyi]

my alternator is good. I'll check my timing today or tomorrow. Where do I have to spray the intake cleaner for the IACV. I might've sprayed it in the wrong hose.

[Schassis707]

Take the tube off the intake that connects to the metal tube that goes in between the plenum of the manifold.And spray in there.

[Pirate_Freder]

Is ur pcv still hooked up to ur intake? If so that valve cover leak is a vacuum leak and that gave me serious problem when I had it. If u cant fix the leak right now just take the pcv out of that T of hoses by routing a hose from the intake to the iacv tube. Pcv cant vent to atmosphere but will most likely shoot a bit of oil, no biggie, I lived with it.

[Bigsyke]

Sounds like it could be a break in the Knock sensor harness. However it sounds more like timing. Incorrect Distributor timing will make similar symtoms when the CTS registers ~160f.

Check the TPS voltage and fuel pressure. Also the o2 sensor would be another culprit, which could also be caused by exhaust leaks

[iamtheyi]

hmm... i'll be getting on everything straight away.

[iamtheyi]

ok. Basically thought it through and, a break in the knock sensor will throw a code. and so will a o2 sensor getting a weird reading.

My last few options being considered are fuel pump and timing.
I figured when I did timing, I would clean up the tensioner and take off the upper guide while I was at it. When taking off the Timing belt cover off, is it really necessary to make the silicone bead that specific? the FSM or [forgot what it's called but it's the auto shop program with DIY info] gave a super specific bead sizing etc. is it really necessary or can I just guestimate?

[klits562]

ok. Basically thought it through and, a break in the knock sensor will throw a code. and so will a o2 sensor getting a weird reading.

gave a super specific bead sizing etc. is it really necessary or can I just guestimate?

My exhaust manifold had burned up my wire for the o2 sensor(wasnt broken but severaly damaged), and i wasn't throwing a code.

Just stay as close as possible to the size the program said. I believe its to ensure you dont use to much and cause it to get all gunked up in your timing cover.

Also i was reading through your symptoms and it kind of sounds like what mine does, but mine does it when cold. I start to accelerate and the engine will hit a wall at about 2.2-2.5 rpm(before 2.2 it drives mostly normal) and the exhaust does change note sounds like crap along with plenty of popping backfire. If i push the gas in more not much happens, it wont pick up speed it just gets a little louder untill above 2.5k rpm then it drives pretty normal, if im right on the border of 2.5+/- my engine goes nuts! it will throw me back and forth in my seat, its like the engine launches with power for a second then completely loses all torque and it throws me around lol.\

Anyway just yesterday i figured out my problem, i unplugged my CTS(coolant temp sensor) and it ran 95% better when cold, but once it started warming up and the warmer it got, the worse the engine started to perform again but not nearly as bad as when the cts is on and the engine is cold. So i ordered a new CTS hopefully when i put it on all my problems will go away.

BTW even with the faulty CTS plugged in i dont have a CEL, but once it is unplugged it will throw a code.

[iamtheyi]

^ huh... alright. Well let me know how it goes with the CTS and get back to me.

also.. when i spray intake cleaner into to IACV do i have the car on and idling or off and just spray that stuff in there? I'm really leaning towards the timing right now but I will check my o2 and CTS and see what's up.

[iamtheyi]

finally i have figured it out. In the process of doing a compression test (just cause lol) I destroyed one of my spark plugs. I told my friends to check out my spark plugs to see what happened and one of them noticed that ANOTHER one of my plugs had the tip missing. When flipped, it would pop out. Guess the combustion in the chamber forced it inside the plug lol. Last time I'll ever buy Pulstars.

[hingamatt]

finally i have figured it out. In the process of doing a compression test (just cause lol) I destroyed one of my spark plugs. I told my friends to check out my spark plugs to see what happened and one of them noticed that ANOTHER one of my plugs had the tip missing. When flipped, it would pop out. Guess the combustion in the chamber forced it inside the plug lol. Last time I'll ever buy Pulstars.

Spark plugs? Thats it? Dammit I have the exact same issue and I already checked my plugs and they are fine.

[iamtheyi]

Spark plugs? Thats it? Dammit I have the exact same issue and I already checked my plugs and they are fine.

lol I'm kidding. It came back with a vengeance about two weeks ago lol. been trying to figure out ever since. I narrowed it down to a fuel pump, spark plug wires, a sensor and the entire car hahaha. I'm at loss with this one.

[hingamatt]

Anyone heard of 240s having a dual voltage fuel pump? I heard somewhere that our cars run a lower voltage to the pump during light driving but when you get on it the pump kicks up to 12 volts. It was proposed to me that my car could be having problems switching from low to high voltage and that's why it bogs and loses power.

I have never heard of this before, anyone else?

[nddavis2]

Have you checked fuel and spark for each cylinder? My car did something that seems similar just last week and an injector had crapped on me. Replaced it and it's good to go. Check them when it's running bad and not better of course. Mine would run fine when it was cold but when it warmed up any the problem came back.

[nismoman]

Anyone heard of 240s having a dual voltage fuel pump? I heard somewhere that our cars run a lower voltage to the pump during light driving but when you get on it the pump kicks up to 12 volts. It was proposed to me that my car could be having problems switching from low to high voltage and that's why it bogs and loses power.

I have never heard of this before, anyone else?

300zx has this setup , 240sx does not

[iamtheyi]

Have you checked fuel and spark for each cylinder? My car did something that seems similar just last week and an injector had crapped on me. Replaced it and it's good to go. Check them when it's running bad and not better of course. Mine would run fine when it was cold but when it warmed up any the problem came back.

oh shnaps! How did you find out which injector was bad?

[steve1040]

Might be a dumb question but have u tried to plug in an obd scanner and pull the codes? I know you said that your check engine light is not on but sometimes it doesnt come on even if you are throwing a code. I was pretty much having the same symptoms on my '95 with no check engine light on. I checked spark, fuel, and even changed the fuel pump but the problem was still happening. I plugged in the scanner just for giggles n lo n behold, I had a code saying my knock sensor was bad. I read somewhere here on the forum that not all codes make the engine light come on.

[iamtheyi]

Might be a dumb question but have u tried to plug in an obd scanner and pull the codes? I know you said that your check engine light is not on but sometimes it doesnt come on even if you are throwing a code. I was pretty much having the same symptoms on my '95 with no check engine light on. I checked spark, fuel, and even changed the fuel pump but the problem was still happening. I plugged in the scanner just for giggles n lo n behold, I had a code saying my knock sensor was bad. I read somewhere here on the forum that not all codes make the engine light come on.

huh. I'll try that. It may just be my savior :]. Just found out yesterday that my injectors are pulsing normally.

[driftr240sx]

i had the same problem on my coupe. bogging, no power backfireing, etc. It turned out to be that my #2 cylinder injector was bad.

way to test injectors is to unplug your injector clip, and with a volt meter check your OHMS resistance. all should be just about the same. (i cant remember off the top of my head what the OHMS is sorry)

I swapped my injectors out with another set and BAM! i had power no more bogging etc, etc. Well a week later i had no power and bogging again. i suspected another bad injector but no all was good. I replace fuel filter plugs, wires, nothing worked. I had a hunch it was my fuel pump but everything checked out with that as well. i drove it as it was and all of a sudden my power was back. No bogging or anything. i was dumbfounded. I pulled my pump out to check my gas tank for debris or anything and my fuel pump sock was off. It wouldnt stay on so i relaced it and havent had a problem since.

Not saying that is what your problem is but that is what mine was. A bad injector and a old dirty fuel pump sock.

[nddavis2]

Sorry to just get back but you've already found your injector voltage was fine so that's not the issue. When an injector is bad the car will sound like a subaru because you're only running off 3 cylinders. driftr240sx already mentioned how to check injectors so that's covered. Any luck yet?

[iamtheyi]

Sorry to just get back but you've already found your injector voltage was fine so that's not the issue. When an injector is bad the car will sound like a subaru because you're only running off 3 cylinders. driftr240sx already mentioned how to check injectors so that's covered. Any luck yet?

lol I just did a sound test not a voltage. Where you put something against the injectors and listen for the pulses. It can't be a fully nonfunctioning injector cause I don't get the subie noise all the time. Just sometimes and WOT right after a upshift

[driftr240sx]

Mine didn't sound like a suby either. The injector was dumpin fuel onto the cylinder, so when I shifted it would backfire because of the extra fuel left in the cylinder. It would fire in the exhaust stroke causing the backfire.

[iamtheyi]

update: I seafoamed the car and it got rid of the bogging substantially. It would fart only a couple times during normal driving and would kick in pretty hard the first time I did a hard pull on the car. Didn't try it again after that but it would rev up smoothly with the occasional fart.

I just put in 91-octane gas from 76 and it CAME BACK! WTF?!?!?! I don't even realize how that's possible. I don't know whether or not I should just seafoam the car again or burn all the gas in the tank and go to Shell..... >:[. Advice?

[hingamatt]

Have checked your fuel filter? My car had similar issues and after replacing the fuel filter all the bogging and loss of power was gone.

[iamtheyi]

Ahh~ I forgot to update this.

I have found my problem to be nothing to do with fuel. I replaced fuel filter and checked fuel lines and pressure and nothing was wrong. What was wrong however was the spark plug wires. I have no heat shield on my exhaust manifold and it was creating a higher than normal resistance in my wires creating misfires. I replaced them with Magnecor KV85's and it is now perfect. Thanks for everyone helping me out :].

[ks98240]

I have a reason that your car is running like You explained. I had the same exact issues! Bogged and slow. I took my 98 240 to the shop for diagnostics and found out the problem.the INTAKE MANIFOLD GASKETS were shot! They replaced them, all previous codes were cleared and car ran like a champ. 600 dollars said and done, totally worth it. See if this is your issue, my car had 101000 when this happened.

[iamtheyi]

^ lol thanks for the input but I figured it out :P

[NismoDriverS13]

I have a reason that your car is running like You explained. I had the same exact issues! Bogged and slow. I took my 98 240 to the shop for diagnostics and found out the problem.the INTAKE MANIFOLD GASKETS were shot! They replaced them, all previous codes were cleared and car ran like a champ. 600 dollars said and done, totally worth it. See if this is your issue, my car had 101000 when this happened.

u paid a shop for replacing intake manifold gasket? 600 bucks? besides i dont think that its a huge problem to cause bogging.

i have light bogging too, but im pretty sure it has something to do with my shit wires to the maf. missing one metal port out of three and getting shitty connection.

but hey glad u got ur car working op

[iamtheyi]

I have to agree with you ^. $600 for intake manifold gasket is wayy overpriced. You can do that outside your house for a lot less ><. and codes aren't too hard to clear. Just got to find out what the problem is, fix it, and it'll go away after time. And if you really don't want to wait, Just disconnect the battery and your good to go :P

[Corey121]

Since you already figured out what the problem was, im going to tell you what fixed my problem, i bogged at wot replaced spark plugs, and fuel filter, i narrowed it done to the fuel pump bought me a 255lph pump and replaced it and havnt had any problem since.