Stuttering sometimes when driving

Today I took an extended trip and put another 60 miles on the Riv today. I had been cruising at about 70-75 mph easily the whole way in TCC lockup. The gas pedal was at the same level it always was and randomly the car makes a thumping kind of shudder - like there was crap in the fuel. It did it immediately after that again about a second later.

Thinking it may have been crappy gas, I punched it up to 85 and got back off. Ran great again. So I'm driving along, THUD. It did it again, only once this time. What is causing this? I just filled the car up on overpriced Shell V-Power 93 octane, which is not my regular fuel. Normally I use premium at Pilot and have no problems (So much for that great gas Shell - thanks...).

Is this crap in my gas tank or is it something else? Is an injector going bad? Something else in the fuel system afoul? This worries me as the Riv has been running good for the last several thousand miles. I can't afford for it to do anything stupid on me when I'm going to school.

Is it random, or is it when the car goes up a hill?

How new are your ignition wires and plugs?

It seems random, although there was a very slight incline in some areas (Nothing to stress the car more than normal though). No idea on the wires or the plugs, I think they're the good plugs that last like 100k (or so they say). My dad had been talking about swapping over his brand new wires and plugs off the GTP onto mine since they obviously do his car little good with a blown motor.

Good idea to swap over the wires, and get 6 new plugs - no need for 100k mile (lol) platinums, though.

I personally think it may be the gas. I don't like additives. That's probably 91 or *gasp* 90 in your tank. If it feels like there's an absence of power, that's definitely it.

Thing is, I used to fill up at BP since they're the cheapest in town(the Sunoco I praise is a good 3 miles farther away), but all of a sudden they started putting an additive called 'invigorate' in all their fuels, from 87 to 93. Well, when I filled up with that stuff, all hell broke loose. I lost all my bottom end torque, some good horsepower, and that definitely wasn't 93. It was probably 89 with a boost. Another good reason why I use Sunoco. It was recommended by the factory for my dad's 1970 Mach 1, and is the sponsor of NASCAR racing, and it definitely has more getupandgo in it than other fuels for more money around here, so yeah.

Run that tank dry and go back to what works. See if it happens again. It may not seem like it, but that's the least expensive way to troubleshoot this problem, haha! Full tank of gas being the least expensive way...heh, at least it's not as close in price to the wires as a month ago!

If this were an issue of wrong octane, it wouldn't create the symptoms Kevin is describing, imo. I also have experimented with many brands of fuel, different additives, and never noticed a difference. I did notice once with a 30-year-old carbonated car, but that engine was lucky it ran anyway. On a more modern fuel injected engine, all fuels should work unless there is some water contamination. In that case, I wouldn't suspect it would be so random as described.

So how many miles are on this car? With original wires and plugs, if you're past 100k, that's likely the problem right there.

i have a 1992 pontiac bonneville it has the series one 3.8 but it did the EXACT same thing. i ran injector cleaner and all threw it. it helped for awhile but it happened again.. i talked with my dad(auto mechanic) and the mass air flow sensor gets tiny tiny particles of carbon built up on it. we had another 3.8 that we had just replaced laying around so we took the MAFS off that and the problem was fixed. If you do not wanna buy a new one right now their kinda spendy i think you can blow them off. but be CAREFUL dont break the two strands that run across it. or with a electronics cleaner spray it from a distance and let it dry and replace. hope this helps, let me know

Cleaning the MAF sensor with electronic parts cleaner never hurts. Takes about 10 mins with the right tools. It's an expensive component, so be careful like rivboy says.

The last time my dad cleaned the MAF on our Volvo 850 GLT he broke it and that was a nice $300 we had to spend. I don't think he's going to want to mess with it after the last time he messed it up (And I sure as hell don't).

well with that kind of mechanical attitude... I guess you'd better take it somewhere to get it fixed... It's just a MAF cleaning. It's not that delicate.

Do you have any way to scan? It would be nice to see operating parameters while it's stuttering... But it really sounds spark related.

Nope, I don't have any scanner of any sort. No idea where to even get one around here. And yes, the MAF is that delicate. He just blew air on it and that screwed it up. Not even cleaner AFAIK.

if u take time and handle it carefully u will have no problems

Wow, "just blew air on it"... Are we talking compressed air, or did he huff and puff and blow the MAF in? A sure-fire way to destroy the MAF sensor, imo. Was he trying to kill it? It's comparable to yanking really hard on a spark plug wire and wondering why it separated from the boot. "Damn cheap-ass wires!" Or, does anyone remember that guy who dumped a bag of sand in his Audi TT throttle body to clean out carbon? Probably a hoax, but still...

Kevin, why don't you try doing something yourself instead of asking your Dad. You'd be surprised at how simple it is to take care of a car if you just exercise a little patience and listen to those who know how. We're here to help you out.

I notice when I give enough gas when I'm on the expressway for the car to slowly kick into the next lowest gear (Not a full throttle stomp), the car likes to stutter a bit upon changing gears but then smooths out. I'm thinking spark plugs, is it possibly anything else?

might want to reset the PCM by disconnecting the battery for an hour or so.

Albertj

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I've noticed today it's doing it under harder acceleration. Also, I put it in neutral and it seemed to do it at around 2k. Very disconcerting. It also did it when I put it in park in the driveway and revved it up. I can hear the slightest sound like a "tick tick tick tick" but it's not that pronounced - almost like it's a belt making the noise. It is dependent on the RPMs as well. That ticking sound has been around longer and is most noticeable when I'm in a drive through next to the building. It's not the A/C either.

And so when are you going to try resetting the PCM?

And when was the last time you had the transmission serviced? Could be that a clean filter and fresh fluid will correct your problems, truthfully... it's harder to push fluid thru a dirty filter. And if your fluid is brownish, time 4 a change anyway.

Albertj

Sounds like bad wires to me, check plugs and wires.

We had to go out to eat tonight and I was in too much of a hurry to unhook it then. That won't mess anything up by unhooking it will it?

Also, I thought transmissions aren't supposed to have the fluid changed if they never have been before. I doubt the elderly owners before me did it and I know we never have. Since I will be robbing the sparkplugs from the new ones that were put in the GTP before it died, I'll have to wait until my dad can help me - I'm not sure that the motor blowing up didn't foul one of the sparkplugs in the process.

Shintsu wrote:

We had to go out to eat tonight and I was in too much of a hurry to unhook it then. That won't mess anything up by unhooking it will it?

Also, I thought transmissions aren't supposed to have the fluid changed if they never have been before. I doubt the elderly owners before me did it and I know we never have. Since I will be robbing the sparkplugs from the new ones that were put in the GTP before it died, I'll have to wait until my dad can help me - I'm not sure that the motor blowing up didn't foul one of the sparkplugs in the process.

Dont use used plugs.
Get new plugs, same with the wires. You start swapping out parts with used stuff and the next thing you will have is another problem and you will never figure out what happened.

Bert

No no, these parts were put on the GTP and it drove a distance of maybe 15-20 miles and then blew up. My dad bought these brand new and just put them on the GTP and it blew up. They're not used like you're thinking they are.

Hmmm... the only problem from unhooking battery might be a need to enter the TheftLock code on your radio, if you have it enabled (the red light blinks when engine off)

Albertj

albertj wrote:

Hmmm... the only problem from unhooking battery might be a need to enter the TheftLock code on your radio, if you have it enabled (the red light blinks when engine off)

Albertj

Where can I find that code? In the service manual somewhere?

Shintsu wrote:

No no, these parts were put on the GTP and it drove a distance of maybe 15-20 miles and then blew up. My dad bought these brand new and just put them on the GTP and it blew up. They're not used like you're thinking they are.

Then especially don't reuse them!!! Seriously, the plugs should be considered junk at this point. DO NOT use them.

The insides could be cracked, causing all kinds of ignition oddities, or worse, pieces falling off and damaging your pistons or valves.