Hesitation Saga! i30 is a bit fussy.

[rhetoric]

I thought I'd keep a bit of a journal on my new to me 1996 Infiniti i30 hesitation issue. I'll update as I attempt fixes.

Problem: Very subtle, but noticeable sag/surge/hesitation problem under moderate acceleration. I notice it mostly from a start. It's hard to tell if it's surging or sagging, but it's a steady rhythmic problem until you get to cruising speed at which point it runs just fine. Most people in the car don't even notice it. It DOESN'T do it under very light acceleration nor under heavy acceleration. I notice it more when pulling up a hill than on the flat. Most noticeable in 3rd gear, but does it in 2nd too. It feels more engine than transmission to me, though what do I know?

UPDATE 10/09/09 As I said in one of the later posts, the slight hesitation has turned into slight hesitation and serious intermittent missing and chugging -- usually under load. Yesterday it was rainy, today, essentially teh same problem, but it's dry. It did seem worse yesterday, but I also didn't drive it as much.

Solution Attempts: Trying to do the cheap things first and happy for suggestions.

Premium gas: No change.Air filter: No change.Synthetic Oil: No change. (but I didn't really expect it, either)Fuel Filter: No change. (thought I had it with that one!)Spark Plugs: Pending...transmission Chage: Pending... (though the fluid is nicely pink)
Modified by rhetoric at 7:52 PM 10/10/2009

[MinisterofDOOM]

Injectors or ignition coils would be my next suspect. Check engine light on?

[rhetoric]

Nope. No engine light.

[NutriaforBreakfast]

How are the CV joints?

[turbocat]

tps ?

[rhetoric]

Chevron Fuel system cleaner: No change.

One of the CV joints was changed just before I bought it. I haven't checked the other. How does a problem here manifest itself w/ hesitation? Gears slipping?

What's tps?

(and thanks for the feedback)

[rhetoric]

New spark plugs (platinum/champion): No change and the other spark plugs looked just fine.

TPS (Throttle Position Sensor) is next, though from what I've seen, it would be far more troubled than a slight hesitation of the tps was bad

[rhetoric]

Major changes! For the worse. The slight surging turned in to bucking and missing! Driving today (in wet weather) it started chugging and bucking. I was able to keep going, but at idle under load it would groan a bit. Then if I tromped on the accelerator it would chug a bit, then catch and run just fine. Like before, it seems to be just fine at speed and easy acceleration.

Feels like ignition now, but what do I know. Will try to test the TPS and coolant temp sensor tomorrow.

[rhetoric]

Throttle Position Sensor (TPS) replaced: No change (it was easier to change than test -- that was $62 down the tubes.

Despite the heavy missing, still no codes. Might I show codes even if the idiot light isn't on?

[loystock]

The change for the worse may be due to Champion plugs. Nissan/Infiniti are designed around the NGK plugs - not Denso, Bosch, etc.. If the old plugs are OEM and still good, make sure they are clean and re-install them.

[rhetoric]

Temperature Coolant Sensor: No change.

It's getting worse and today on the highway it felt like it was running on 5, so I guess testing the coils is next.

It's not the plugs. The Japanese make a fine spark plug, but the "you have to use NKG" or "Champion plugs are tools of Satan" claims haven't been bourne out in my experience.

[Rendurante]

One of the coils might have been on its way out (before you recently changed the plugs). Everytime you disconnect/connect the coils to the plugs, the risk of damaging a coil increases.

Also, Mass Air Flow sensor cleaner is less than $10...I would pull the MAF sensor and give it a good cleaning. Just be sure NOT to touch the sensor element with anything other than the cleaner.

[loystock]

I'm sorry that you take my advice with derision... and I'm not evil. I've helped so many people in the NICO forum.

Non-OEM plugs are known to cause performance issues and even damage to VH, VK and other Nissan/Infiniti engines and the VQ engine is not an exemption. It's NOT a myth. Just do a SEARCH about spark plugs problems that other members have had. The truth will set you free.

[rhetoric]

Sorry -- I didn't mean to be derisive. I appreciate the help. I was actually referring to a thread (perhaps here, perhaps the maxima.org page) in which the whole issue of "off brand" plugs was debated and... not resolved! But anyway...

I'll give the MAF a try. I'm also going to do a fuel pressure test, though I'm not convinced it's fuel.

UPDATE -- Took the air assembly apart to look at the MAF sensor. The screen is clean, but I do suppose that little wire looks black. Could be carbon, I suppose. Will buy some MAF stuff tomorrow and see what happens. Seems hard to believe a big of carbon on that hair thin wire could slow down my 4000lb infiniti!
Modified by rhetoric at 7:26 PM 10/11/2009

[Rendurante]

Rhetoric,

Check the FSM for I-30 1996 at the link below. Page 97 through 102 of section EC (Engine Control) should be helpful with troubleshooting your problem

http://www.nicoclub.com/FSM/

Ren

[rhetoric]

MAF cleaned and replaced: No change.

Thanks, Redurante. I'll study.

[NutriaforBreakfast]

EGR valve?

[rhetoric]

Ghost codes?! Nobody told me about any stinking ghost codes!!!

On the whim that maybe my SEL light was burnt out I had the AutoZone persons run my codes and a "ghost code" showed up. 0325. Knock Sensor. I wasn't ready to plunk down 132 bills right then and there (as you can see, I'm not unwilling to treat symptoms w/ new parts, but...) so I've done a little homework and seen sensors for WAY less. I'll do a little homework, order online and give you a report later this week.

I know you're all on the edge of your seats, wringing your hands w/ anxiety.

[NutriaforBreakfast]

Got the PO325 code with the PO400 code (EGR Valve)I did not change the knock sensor and the PO325 code has notcome back. I did change several EGR related parts and maybeI will pass inspection this mo. And yes, I am wringing my hands.

[rhetoric]

Well, I finally got a knock sensor ($18!) and I think the problem is solved! The hesitation seems to be gone and it doesn't seem to be chugging (though it usually only does that when it's been run for 1/2 hour or so. Still, I'm optimistic!)

Let me add... I was able to remove and replace the knock sensor w/ only two six inch extensions. I didn't remove the manifold -- I didn't even remove the air intake plastic. Loosened the nut, removed it with the wiring harness, replaced it w/ the assistance of my daughter who was able to get her hand in the crevass and hand thread the bolt most of the way -- I just snugged it w/ the universal swivel socket. Took me 2 months to figure it out, but only 20 minutes to do the job. Runs like a top.
Modified by rhetoric at 5:07 PM 11/16/2009