Yet another hesitation thread, but I'm at my wit's end!
 

Soooo ... grab a beer ... this may take a while. :)

I've searched the forum plenty of times and came up w/ a whole lot of diffrent scenarios, but I was wondering if the gurus could provide some step1,2,3 input...

99 SE, 166K miles.
About 3 weeks I noticed it hesitated for a second while I was at a stop light. I figured, meh ... I'll change the plugs ... hadn't done it in almost 2 years. Ended up getting Bosch platinums since the auto store didn't have the usual NGKs at the time. Swapped them out like I've done puh-lenty of times. Made sure the gap was in spec (.044). Car starts up fine no probs. After about 5-8 miles I notice that it's not picking up like it normally does. So I floor it a couple of times to check, and it seems really sluggish. After about the 3rd time going WOT the check engine light starts to flash, but goes away. By the time I've driven it about 15 miles and get home the check engine light comes back on STEADY. I read the codes and they come up as 0325 (the lovely Knock Sensor) and 0301 (Cylinder 1 misfire). So obviously I think that the coil may have gotten screwed up, and since I wasn't quite clear on how to check a coil if it's good or bad, I did the logical thing and swapped it with the one next to it on cylinder 3. Sure enough, the code followed it and now when the car was misfiring, the code was 0303. I went and bought a new coil pack (only one) and I was sure thatthat's the end of the issue, but after about 5 minutes of running the car, it started missing again. This time the code was 0305. I figured stranger things have happened so I went and bought another coil to replace that one. Unfortunately, the car still ran like crap after that. So I went and replaced ALL the coils. I cleared the codes and drove around. Same story. After I go WOT the check enginr light flashes, but doesn't go steady. I can I can make it go steady after ragging the car in stop/go traffic and going WOT from every damn light for about 20 minutes. Then the code reads 0300... Multiple misfires.
I got tired of that BS and I actually went back and put back the OLD plugs and the old coils (since I was sure that the coils weren't bad). The Car is running the same right now. The check engine light is NOT on, but when I'm at a stop light, it hesitates every 15-20 seconds.
Out of sheer desperation I took it to Nissan to see if they'd pull a Yoda on me, but after charging me $120, they told me "Oh, it's saying Multiple misfire. CHange all the coils" ... I told them that I already had, and that's NOT it... but you know how those fockin stealers are.
So ... I know I can go ahead and replace everything under the hood, and eventually I might hit the one or 2 things that are actually bad, but any insight would be good.
Of course swapping everything is not a viable solution because money's tight. I've been told that it could be the coils, O2 sensors, crank sensor(s), Plenum gasket... (am I leaving anything out .. no that's it). Of course no one is guaranteeing that that's it, and if I get all that replaced/ do it my self it's a lot of $$ which I don't have...
(Oh did I mention that the vacuum hoses have been checked too .. they're fine)

BTW ... if you guys have any input as to what I can check/do, please let me know. I'm by no means an expert with this engine :(

NGK Platinums only

thats it...take out the Bosch's and go soemwhere to buy the NGK's (New ones). Problem will be solved

P.S. Use yoiur new coils too..lol

^^ I already went w/ the NGKs and changed all the coils.
Still same issue.

Check all the plugs on the coils & harness, make sure you didn't bend a pin. Spray contact cleaner on all the connections as well. Put new NGK plugs in and see how it runs. If the misfire still exists, replace your coil packs. The 99's are notorious for them going bad. I've had 4 out of 6 on my 99 replaced and I'm at 160K miles. Pretty much the same as you.

fuel filter?
 

We had a suburu once that that would hesitate badly under load. It eventually just began stalling. Replaced the fuel filter and all was well.

A clogged filter could lean the mixture enough to cause misfire.

Does it ever seem hard to start after sitting for more then a couple of hours?
Also change the Knock Sensor...if its bad, and not working the car's timing wont be optimal and thus performance will be down.

Back to the misfire, I had a leaky injector that caused hard starts...a misfire code once replaced it was good to go.

I would check ckps(ref,pos), cps

and +1 on ngk's but you could get the v-power if you want to stay on the cheap side.

I just had this problem recently. I put new NGK V-power plugs and cleaned the coils. Reset the ECU and no more problems

Infinitiblast - It always starts up fine. Infact, the first 5-10 minutes from cold, it runs damn perfect. It's always AFTER she's been running for a few minutes, when the lil hiccups start.
I'm going to install new NGKs and re-check all the coils .. now I just have to dig up the how-to on checking the coils...

Thanks for all the info guys!

i had a problem jsut like this in another car i owned. It ended up being MAF. Replaced it and it ran perfectly. It was in a chevy blazer so i realize its not really the same but its a similar problem.

I have a 99 and had similar bouts with my car.

Things you should do, regardless. You're at 160k and probably haven't done half of these.

1) Clean the grounds behind the passenger headlight (on the frame), driver headlight (in the fender well), and below the air filter box (on the strut tower, close to the tranny).
2) Replace fuel filter with 300ZX (95 non-Turbo) filter
3) Replace air filter - I prefer Nissan OEM from the dealer
4) Check the two ground wires on the front of the upper intake manifold (after my coils failed and were replaced, this was also an issue as I had done some work and the bolt wasn't tight)
5) Run some Chevron Techron, Gumout, or Seafoam through the gas tank (when the tank is almost empty, pour in a bottle, fill up, drive) - about $7
6) Do a half bottle of seafoam through your brake booster line - follow instructions on bottle - another $7 or so
7) Put in the NGK's and the new coil packs. It's time. Your car has 160k. If your other coils are still good, sell them cheap.
8) Clean your throttle body and IACV with Throttle Body Cleaner (CRC makes it) - about $7
9) Clean your MAF with MAF Sensor Cleaner (CRC makes it as well) - about $6

All the above might cost you around $80 for supplies but I can bet your car will run much better after all is said and done.

Go ahead and replace that Knock Sensor too..that will remove some of the hesitation issues then you can focus on the rest.

I know you said you had replaced all coils and still had the problem, my question is does the coils come with new boots to attach to the plugs, I would imagine they do, if they do or don't you might want to try this regardless. Get electric tape and wrap it around all the boots at the buttom where the piece that rest on the plug connects to the shaft, over time this joint tends to fail. Believe it or not, I once had this same problem you are experiencing and it was a torn boot, the electric tape solve the problem until I purchased a new boot kit from Napa. Just thought I'd share this with you and good luck

I just had 0304 code, plugs and coils were replaced, then found out injector 4 was bad. fix the miss fire problem

Well his CEL followed the coil pack when he moved it, so I doubt it's an injector.

Hello,

My 99 Max has similar symptoms. Today I replaced all the spark plugs with NGK Platinums. That seems to have done the trick. I drove around a lot today and didn't notice any hesitation or stutter.

I do have a question though, could a bad knock sensor cause the engine to stutter at low idle?

I ask because last month my car failed the emissions test. The CEL had been on for a long time. The codes came up as a bad o2 sensor and bad circuit on the knock sensor. We replaced the o2 sensor and got retested. It passed. At that point I figured the stutter was being caused by the knock sensor but after finding this thread I opted to change out the plugs instead (car has 100k on it, I am pretty sure the plugs were original).

Thanks

No.

Thanks again for all the input guys ...

btw .. if I had left something out, my apologies, but to add, I had previously gotten a new Air Filter and had run Sea Foam through the gas tank ... as per Ilyak's recommendation, I checked the ground wires ... they seem to be fine.

I just got new NGK Plats in it with all new coils. Still no diff. Btw ... I don't have the Nissan coils - I got mine from Napa and AutoZone ... is that a no-no?

I'm going to go ahead with cleaning the MAF first and then the IACV.
I'm going thru this one by one so when and IF I do finally get the car running properly, I'll know exactly what fixed for future reference...

Thanks again!

*sigh* :)

this might be a little late, I've tried everything except for a lot of things here. But, how's your A/c compressor because my bad one caused an electrical issue. I'm replacing it now, and hopefully it will take it away. Just stuck on a bolt.