1998 Infiniti I30 "hiccups" and hesitates

Hi everyone,

I’ll try to provide as much information as I can. I have a 1998 Infiniti I30 (Automatic, V6, ~112k). I’ve noticed in the past week or so that the car hesitates and actually hiccups when accelerating. By the sound and feel of it, I think it’s definitely coming from the engine. It’s as if the car is trying to rev up, but can’t, and then tries again. I can usually get through it by giving it more gas. These “hiccups” never lasts too long (a few seconds) but it happens most often at certain speeds/shift points: ~0mph (parked), ~20mph, ~30mph, and most often at ~40mph. I’ve also experienced it at ~60mph. The probability of hiccups also increases when going up a hill (even a very slight incline)

These hiccups happen sporadically, and engine temperature doesn’t seem to make a difference. It also doesn’t seem to matter how long the engine’s been running. (I made a two hour trip last night, and it happened both at the beginning and end of the trip.)

There are a couple of causes that I considered. One, it has been really cold (temperatures in the teens, at the lowest point). Second, it could also be fuel.

I read on the Car Talk site that the octane that you fill up with doesn’t matter too greatly because the engine’s computer will adjust accordingly. My car’s manual recommends premium fuel, but I’ve been putting in mid-grade for about two years with no problem. Two fill-ups ago I tried putting in regular. The car seemed to be a little rougher, but no “hiccups”. My last fill up was with mid-grade, and it was soon after that I really started noticing problems. (My next fill-up with be premium.)

I’ve also considered spark plugs/wires (I bought the car at 83k and haven’t changed them – not sure if the previous owner had), fuel pump, and ignition (I doubt it.)

Do any of you gearheads have a take on this? Is it a bad tank of gas? Did I mess things up by using a tank of regular octane gas? Do I need new spark plugs? New fuel pump? Should I try a fuel additive? Is it something else?

Thanks in advance, and Merry Christmas!!

Yes, start with the expensive guesses and work down to the least expensive ones.
Or, you could change the spark plugs. Drive. Still misfiring? Change the fuel filter. Still misfiring? Opps, time to do some troubleshooting unless you want to throw that fuel pump in there?

Hi hellokit,

Thanks for your worthless and unwarranted reply. I posted my question to the forum because I wanted to get some constructive advice on this issue from those more knowledgeable than I. If you had bothered to read my post, you would have seen that I have done as much troubleshooting as I can, given my limited knowledge of cars. I turned to the forum because I don’t know what the most likely culprit is, nor do I have any idea how much things will cost to repair.

If you have any constructive ideas then I’m all ears, but if not, don’t you have anything better to do than post snarky replies?

Merry Christmas all the same.