FAQ: Hesitation, Stutter(Studder), Shudder, Stumbling, on Acceleration/Load

Glad you found it. FYI the engine will not rev past 4k in park/neutral, that's on purpose.

deekster_caddy wrote:

Glad you found it. FYI the engine will not rev past 4k in park/neutral, that's on purpose.

well at least thats good to know. Just happy now that its a nice smooth growling motor again without the sputter.

Well I fixed the belt jumping off, the alternator was out of line. Now I have another problem!!!! I can be cruising at 45 mph in 4th gear but upon hard acceleration the engine shudders, if I take my foot off the gas and lightly accelerate I can do so to whatever speed I want without the judder. Sometimes if I put my foot hard to the floor engaging the kick down I can also accelerate with only minimal judder happening. The check engine light then comes on and when read it indicates" multiple engine misfire" I have new plugs and wires so are there any more suggestions please.

What other modification have you made to the car besides the 3.4" SC pulley?

It still seems ignition related to me. If you can afford an extra coil, I'd buy one and swap it out one pack at a time. Even if it doesn't fix you'll have spare for future troubleshooting. Dounle check your wires and plugs are installed correctly and still in good condition.

Whose wires and how long since you put them in has this been a problem?

Thanks AAron and Albert. I replaced the plugs and wires with premium quality products just after I noticed the juddering about 3 weeks ago. I will certainly invest in a coil pack and do a swap out check..A chap at my local friendly shop said that it was the torque converter but I really dont think so since the car goes through all the gears smoothly under light acceleration, another was talking about manifold gaskets oxygen sensors and catalytic converters etc but like you Aaron I think it is ignition related and will post back after the coil pack change out.

Lenrapkins wrote:

Thanks AAron and Albert. I replaced the plugs and wires with premium quality products just after I noticed the juddering about 3 weeks ago. I will certainly invest in a coil pack and do a swap out check..A chap at my local friendly shop said that it was the torque converter but I really dont think so since the car goes through all the gears smoothly under light acceleration, another was talking about manifold gaskets oxygen sensors and catalytic converters etc but like you Aaron I think it is ignition related and will post back after the coil pack change out.

The chap at the local shop could be right.

I just rebuilt my transmission for a similar problem. It was running fine until 2 things happened. One, a newer tech at the local transmission shop instead of doing a drain and fill with Dex 6 like I asked, refilled with Dex III and an additive. NEVER refill a transmission with Dex III after changing to Dex VI. Refill with Dex VI whenever you want, though. When this was done the 1-2 shifts got mushy but nothing else changed much really over time so I ignored it...

So what happened later - i had replaced brakes with a set of reman calipers from NAPA back in I think 2006 or 2007. After the third I think set of pads and second set of rotors the calipers started binding. They bound just enough to get the torque converter clutch to engage and disengage more or less by itself... a lot. It eventually hammered itself to death.

What does this mean to you?

Offer to pay the local friendly mech for an hour of time. what to have him do:

- check if one or both front brakes are dragging or if the brake hoses have collapsed. I had one hose that had collapsed internally. When this happens it acts like a 1-way valve and holds brake pressure on... you need to know if this might be happening. You may have to drive the car a bit (20-40 stops) to get them to act up.

- check if one or both front calipers are binding.

- check if the new wires are arcing, you would be far from the first to buy new wires only to find that the Riv's high energy ignition blew them out. Really, thinking about past posts the wires to get are the GM/ACDelco wires, Delphi wires, or one of the higher end spiral wound wires (Magnecor, Taylor). If you are thinking "premium quality" rhymes with a name brand such as Bosch or Autolite or some suck, the thing to do is pull those wires and check how the terminals are swaged on. You may find that the carbon impregnated fiberglass conductors in the middles of one or more wires have been compromised at the terminal crimps.

- check the primary resistances, and the secondary resistances, of each of the coils and compare to each other. the values are somewhere on this site but they almost never all go bad so if you check them against each other any marginal one(s) will stand out. They are all working or else you woulda set a code. But if one is marginal it will measure much different from the others. Mech may want to use an old sun machine and run a "cylinder balance test" instead, I guess that would be OK.

My guess is it may well be the torque converter and brakes. The problem will be that the TC will send shrapnel thru the transmission, messing up the valve body and putting grit in the fiber disks. Bad scene.

All fixed, turned out to be two faulty coils. Changed all three and now she is running perfectly.

Did the coils fail from age or did bad wires do them in - any idea?

Albertj

Two of the coils had failed due I think to old age as the wires and plugs I replaced were in very good condition. I changed the plugs and wires as part of an elimination process and was getting to the coils when friendly mechanic put me off the scent when he mentioned the torque converter. I resumed my investigation when a friend read the check engine codes and multiple miss-fires were highlighted and it made sense then because if it was the torque converter the code would have been a transmission code.!!!!!!!!!!!

96 Rivie shutters on straight hard acceleration

Wonder if you're thinking this is wheels, axle or engine banging around w/busted mounts.

Wires.

Ignition wires!

bigdave wrote:

Ignition wires!

while you are at it, check the coils for physical signs of failure (body cracks, not likely) and clean the ground plane of the ignition module and wipe with dielectric grease.

ok heres the problem, if i rev my car in park or nuetral it spits and sputters way before redline. if i stomp on it while drivin it also does this. im thinking maybe my cat is stopped up? any ideas for me to try when i get back to my car? ive been lookin into a new tranny but since it does it in park and neutral also i dont think thats the prob.

maybe it's time to get your heads rebuilt? mine did that too and after they were rebuilt it went away.

First thing id do is run some seafoam then go from there.

joshuadalegrimes wrote:

ok heres the problem, if i rev my car in park or nuetral it spits and sputters way before redline. if i stomp on it while drivin it also does this. im thinking maybe my cat is stopped up? any ideas for me to try when i get back to my car? ive been lookin into a new tranny but since it does it in park and neutral also i dont think thats the prob.

How many miles on your car total, how many miles you put on it last year, and what regular maintenance (plugs, wires, oil change, fuel filter) have you done in the past year, and have you checked for stored codes (or is your check engine light on and you just did not bother to tell us)?

If you rev in park or neutral, it will not redline. It has a built in rev limiter. Don't do that, or at least don't take any meaning from it.

If you are in Drive and go full throttle, exactly what is happening? Loss of power? Misfire? Is there a check engine light? Does it reach 5500 RPM and shift into 2nd?

Can you scan operating parameters and post? Or at minimum have a passenger take a ride-along video so we can see what you are trying to describe?

Neutral revs are like 10X worse for your engine than revs under load. Car is protecting itself from being destroyed.

In drive, stuttering can be caused by old ignition wires. I'd start there and install a fresh set of plugs while you're at it.

Wait.... so putting your car in P or N and revving is bad? ....

mass air code is only one and its getting fixed with new sensor and as soon as i find them wires.

plugs are new, wires are not

seafoamed it about 3 months ago

165xxx miles ive put 35xxx since i bougt it a lil over a year ago. all reg maintence done plus new front hubs, new fuel pump, repaired fuel lines, radiator has been flushed when i put in 180 thermo, thats all i can think of and when i get back to atlanta next month ill do a video of what its doin

Quote :

Wait.... so putting your car in P or N and revving is bad? ....

Let's just say it's not good. You probably won't hurt anything by doing it, but one day if the engine blows, you'll wonder why it happened and probably won't consider the neutral revs as a contributing factor. Every abusive thing you do to an engine shortens its lifespan a bit.

One reason neutral revving is bad: think about when people usually do it - when the engine is cold. The coolant temp might be at 200, but the oil takes a bit longer to warm up. The engine isn't fully warmed up for a few more minutes.

Another reason it's bad: you could slam it into gear by mistake. Neutral drops are definitely bad for the trans.

The engine can burn more oil in N because there's less pressure sealing the piston rings against the bores. Not harmful, but it's just one more thing.

The PCM limits RPM in N because if you're driving and you knock it out of gear with your foot on the gas, it would instantly red-line and destroy the engine. Revving without load the RPM builds much faster than when in gear. The inertia from such a fast rev means RPM can continue to climb even after you release the throttle. This is why it cuts out before red-line, imo.

It's like smoking - not healthy, but not going to kill you if you only do it a few times. People are going to do it once in a while, and probably no harm will come of it, but there a higher risk!