For the past month, my car has been stuttering at stoplights. It's most prevalent with the a/c on. The problem is intermittent though...sometimes it idles perfectly, others, it dips down to 500 rpms and back to 700 for the duration of the light cycle.

After a lot of searching on here and other websites, i started replacing parts.

New Idle air control (bwd)
New engine coolant temp sensor (duralast)
New throttle position sensor (set via nissans specs, 500ohms at closed throttle, 4K ohms at wot)
Newish mass air flow sensor (junkyard)
Cleaned the throttle body
The battery was unhooked to let the computer reset after every part was replaced.

*note*
The car is a 97, automatic. I did install an ebay short ram intake w/ an aem dryflow filter. The car also has a warpspeed y-pipe if that makes a difference.

Any help is appreciated before i suck it up and go to nissan.

Thank you

 

How many miles?
Any SES light?

From what you disscribed it sounds like you have a vaccum leak or are low in fuel pressure at idle.
Start by pulling the vaccum line off of the fuel pressure regulator if fuel comes out replace it.

The. Start the engine and spray carb spray everywhere there would be vaccum.

Report back

 

When you spray the carb spray watch the idle for any dips or if it shoots sky high
That will indicate a vaccum leak

 

~170,000 miles.
No CEL

I'll try the FPR in a few minutes and buy some carb cleaner while i'm out. Thanks for the tip.

 

there wasnt any gas leaking from the fpr...but while attempting to drive home from the car wash a few minutes ago, the car died at the stoplight. cranked right back up, and immedietly died again. I ended up having to keep my foot on the gas and dropping it into gear.

at the next light, it idled perfectly. **** this lemon...

i'll try the carb spray later if i can calm down.

 

My guess...
You either have a misfire do to a failing coil or a fuel injector that isn't spraying so good.
A vacuum leak would raise the idle speed (more air). You have dip in idle speed.
Try some fuel injector cleaner, see that makes any difference at all.
I've used Techron and Marvel Mystery Oil in a full tank with good results.

 

wouldnt a failing coil throw a cel tho?

 

Not until it's really toast.

 

My money's on a vacuum leak.
If its a coil and it stops running that would fall into a really bad coil and trigger a light.
Make sure you spray around the upper and lower manifold really good

 

having to keep your foot on the gas means its struggling to get enough air, fuel or spark. Your newish MAF might be the problem. Could of got wet at the junkyard. When my MAF went bad I had to keep my foot on the gas so it wouldn't die.

 

Ok just making sure. Mine is throwing a code cause a non Nissan coil was put in..can't remember the number I know it's famous tho lol.

 

he should clean that ****

 

Did some checking a few minutes ago. When i started the car, there was a clicking sound coming from the IAC. While i was near the car, i also did the ecu diagnostics and found a hidden P0505 code. (IAC)

i attempted to start the car, and it would turn over, start, and immediately die. It did this 5 more times. In an attempt to keep the car running, i gave it some throttle. it sputtered a lot and eventually caught idle.

did more .org research and found that if you unplug the IAC and then start the car, and it runs fine, the iac is to blame. So...I unplugged the IAC and the car started and idled fine. I plugged it back in; and...the car idled fine.......

fml

i'm having oreilly warranty out this IAC in hopes that i just got bad one. I'll install it tomorrow night (when it gets here) and report back. Thanks for y'alls help.

*tomorrow night, i'm going to also steal '1cleanGLE's MAF and see if that makes a difference. And to GGENIUS, i did clean the "new" maf with maf cleaner.

 

good to hear!

 

I had a similar problem. I replaced my plugs with NGKs and it went away.

 

Just wanted to come post that I had a similar problem. At stop lights, it would randomly putter and the RPM's would dip. I also had a slight misfire under heavy throttle. Just replace all my plugs with a new set of NGK Plat's and it has mostly gone away.

 

Quick update.

Replaced the IAC again. No change. Also did the idle relearn several times. It would idle fine, and start messing up as soon as I would start driving it.

She is very temperamental. Anyway, it started stuttering last night after a test drive. I popped the hood and started tapping sensors with a screwdriver. When I tapped the mass air, the car died. Afterwards, I would get a crank, no start. Tapped the mass air again, and she started right up. Seems my junkyard mass air was crap also.

Gonna mess with it tonight. I'll keep people that search for this updated.

 

Took it to the stealership...turns out coil #3 was not working at all and 4 others were on the verge of failure. Bought a coil at oreilly and she's running better, but not great. I'll be replacing coils the next couple of paychecks i guess...

 

OEM COILS OEM COILS OEM COILS. If you keep replacing them with junk aftermarket ones, you'll run into this same problem shortly down the road.

 

oem coils had to be ordered by the dealership. I needed at least 1 coil just to get the car running decent. The oreilly one is doing fine, no cel. I'm honestly not even worried about the cel for having an improper coil, i just want the car to run like it's supposed to.