Stuttering at freeway speeds, stalls at idle.

[gotta240]

1996 240sx, 0BD2. Stock KA, about 100k. miles, injen intake/custom exhaust. Just passed smog with flying colors(numbers were super low actually)

This is a very intermitant problem. It usually occurs on the freeway between the rpms of 3k and 4500. Doesn't matter if i'm flooring it or just cruising. Every once in a while it will also stall out at a stop light or when i just start if up and back out of a parking space.

When it stutters it feels like i loose spark or fuel, the car stutters for 2 or 3 seconds, then picks back up as normal. The car shows NO CELs...

I have TWO track events this weekend, so getting a little desperate.


Already replaced

Fuel Pump (with another used one)
Fuel Filter (was good, but replaced anyways)
Primary 02 sensor
Secondary 02 sensor
Intake filter is k&n, and fairly clean.
Cap, rotor, plugs, Plug Wires are a year old with about 5k. miles.
Gas is new, and always 91 octane

[240on430]

clean the MAF?

[gotta240]

will try. thanks for the suggestion.

[SR240DET]

if that dont work then... give this a shot because its cheap and free for the most part

http://www.zilvia.net/f/showthread.php?t=139980&highlight=s14+mafs+repair

[gotta240]

thank you sir.... will look into that!!!

[pbcstylez]

yah i r/p my MAF once already for the same problem and yet to fix it

[gotta240]

MAFS replaced and MAFS PLUG replaced.

Still having the same problem.

[idlafie]

Check the ground wire directly above your oxygen sensor. It's towards the rear of the engine block on the driver side next to the firewall. Make sure the ground wires are firmly connected to the metal grommet that is bolted to the engine block and to the firewall. An intermittent short in the grommet & those wires can cause stumbling or worse yet not allow your car to start. You might have to cut the grommet off & resolder the wires to a new grommet.

I had this problem several years ago with my 95 S14. My car had been stumbling and stalling for several days while driving it. After doing some maintenance on it, I couldn't get it to start. Prior to working on it, the ECU didn't show any codes at all. After doing a tune up, swapping out the fuel filter, spark plugs, distributor cap & rotor, and cleaning out the air intake, the car didn't want to start. It was after doing all this work that my ECU started throwing MAF, Distributor, Fuel pump AND ECU codes. Turns out the engine block ground wire had a short. It took 3 weeks AND a trip to the stealership to figure out what the problem was.

It was funny cuz the dealer tried to tell me my ECU was bad, to which I brought in my friend's 95 S14 along with a spare ECU and demonstrated to them that the ECU in my car wasn't the problem. I knew there was a short, I just couldn't figure out where!!...

Anyhow, hope this helps...

ID

[gotta240]

I'll check on that.... Thank you!!!

[pbcstylez]

gotta240, did this fix your problem? i got a CEL today and it stumbled like all hell on the freeway

[slothonaleash]

vac leak(s)

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[gotta240]

No vac. leaks... Followed all lines and found a vaccume leak(from intake pipe to intake manifold) but that didn't fix the problem.

Only thing left to try is EGR... Suggestions?

[lswang]

i have the exact same problem on my car. it's been a year and i still haven't figured out the problem. LMK when you figure it out bro! :)

[Zenki_S14]

Might wanna check that used fuel pump. You'll might as well dish out $100 for a brand new Walbro. Haha.

[gotta240]

I have a new walbro waiting to go on... The chances of getting two bad fuel pumps that cut out during the exact same circumstances is very low though..

I'm betting my fuel pump isn't the issue.

[lswang]

just for reference, this is what i have checked/changed so far so you can compare with me. i've check fuel pump, fuel filter, changed spark plugs/cap/rotor/wires, changed maf, cleaned maf connecter with electrical spray. and still, i haven't solved the problem :(

[pr0ject TRUENO]

Clean the EGR and IAC. My old S13 had the same problem and when I cleaned it out worked like a charm.

Might also be your fuel pump.

[pbcstylez]

where can i find this $100 walbro pump?

[pr0ject TRUENO]

all over ebay

[gotta240]

forget 100, i paid 85 bucks...

I believe they are a sponsor on this site... If you tell them you were reffered from zilvia, or use "zilvia" as a code, you get 15 bucks off... I just can't remember the name of the site!!! Someone else remember?

[pbcstylez]

anybody anybody? sorry for my lack of motivation to look around this stuttering issues have caused me to abandon this project temporarily

[Canaduh]

Whoa whoa whoa. NEVER stop your project. =D

I had a similar issue, and i threw in a new fuel pressure regulator and it's never done it since. I recommend finding a used one, or jack one off your friends car, just to make sure before you go replacing parts. I work at a part store, and the part number for a new one is PR59, but you'll need to get it interchanged if you go for a new one.

[arkive43]

yea check/clean ur iacv that should help....

[Canaduh]

i could have sworn your IACV valve doesn't do a whole lot while cruising at 3500rpms.... i know it affects IDLE issues. News to me if that would fix this problem. Maybe i'm completely wrong though.

[vvtisupra]

bad ground dafdafdafda

[Zenki_S14]

What about your distributor? If you have oil leaking into your distributor, it can cause a misfire as well. I'd take off the cap and look to make sure nothing's disrupting inside. Just a thought.

[gotta240]

Grounds are good. All the grounds had about .05 resistance. Just to be sure i removed them, cleaned, and replaced.

The dizzy has no oil in it. As a matter a fact i JUST put in a new cap and rotor...Still no fix.

Also seafoamed through the brake vaccume. got a little black smoke and more white smoke, but nothing substancial. Still no fix.

I disconnected the egr by unplugging the vaccume and capping the line. Not sure if this will fix it. Also went out and got a Fuel pressure tester... I'm getting upset and ready to do something crazy!!! lol.

[slothonaleash]

by now i would have thought the problem would have been fixed lol...

maybe bad fuel pump relay?

[pbcstylez]

do the crazy!!!! i'm there with you....

[Dream240]

The two things you should always check first is fuel pressure, and spark/timing.

Once you get the fuel pressure checked and that's not the problem, check your TPS voltage and kohms readings per the FSM.

You might also want to inspect your Crank Position Sensor. This problem sounds like a bad ground, and not necessarily a body ground. Your TPS has a ground wire connected to it, as do some other sensors. You might have some corrosion in a connector that's causing the short.

[pbcstylez]

if that dont work then... give this a shot because its cheap and free for the most part

http://www.zilvia.net/f/showthread.php?t=139980&highlight=s14+mafs+repair

Hey I tried to do this, instead of soldering new connections I got lazy and just sprayed electro-wash "electronic pcb cleaning solvent" and it seems to idle and drive better... I'll have to give it a week before having a definite answer to whether this is a fix or not. I sprayed the whole board inside the MAF as well as the hot wire.