Slight jerk at highway speeds

[onespiritbrain]

Okay I’ve got some serious anxiety building up because on the interstate moments ago my vehicle jerked probably 4-5 times in the span of about 5-10 minutes.

 

The jerk feels like a very short loss in forward momentum followed by an opposite reaction as the momentum returns. I’m so worried it’s the transmission I could die. Not really but I’m going to die if it’s the transmission.

 

I thought I ran over a bump the first time it happened and I couldn’t tell if I let up on the gas slightly and returned my foot downward on the pedal the next couple times. The last time I had my foot down on the gas pedal and it jerked real good and is definitely something.

 

Any insight is greatly appreciated because not knowing is going to eat me alive today.

[03TroutFinder]

Hey bro. Mine was doing that a few months ago because my drink spilled all over the shifter and apparently caused an intermittent short in the overdrive button. I purchased a new shifter but it did not work for my truck due to the connector being different. So I ended up buying a aftermarket shifter knob and I have not had a problem since. You may want to check that first just to make sure that's not it. Let me know if you need any help with anything since I'm local to you. I'll be glad to help in any way as time permits

Sent from my SM-J327P using Tapatalk

[onespiritbrain]

That’s what I’m afraid of. I haven’t spilled anything and I’m worried the lockup solenoid is failing.

My wife’s MDX would do this same sort of thing on the highway except it would super slam so hard the tires would bark instead of a slight jerk.

I have noticed an intermittent misfire recently. It’s so slight I didn’t pay it much attention. I guess a little misfire under load on the interstate could feel like a jerk.

[onespiritbrain]

Oh man... it didn’t shift out of 1st from a stop just a minute ago... it did shift after I let off the gas but it’s never done that before.

I very recently went up a large mountain and I’m worried that my external trans cooler couldn’t keep it cool enough.

What are the chances that the oil could be “damaged” or thinned out so badly that it’s not allowing for proper operation once it gets hot again??

[onespiritbrain]

Well the oil is perfect. Pink as it was the day I put it in..

I cleaned the MAF and plugs for the MAF, TPS, and dizzy.

I also rotated the TPS forward a bit.

The drive home today was basically flawless except for a couple jerks on the highway and after cresting a hill.

It seems to happen much more often when coasting right after having the engine under heavy load. I am starting to suspect the dizzy for the jerking.

Now the shifting issue today was quite a shock but I’m sort of wondering if I was doing something weird with the gas pedal.

[onespiritbrain]

It did whatever it’s doing this AM and I tipped in on the gas several times until lockup let go altogether and I coasted downhill at 55mph in OD with no lockup. Lockup engaged again after I got on the gas at the bottom of the hill.

I could feel it lightly letting go and biting again leading up to a good grab at the top of the hill mentioned above. I watched the RPM very close while it was doing it and the stronger jerk showed a 100-150rpm rise and drop as it occurred.

It’s the TC lockup. I’m not sure exactly what’s going on but I am confident it’s a solenoid related issue. Might even be trans comm plug or TPS related.

I’m gonna set the TPS with feeler gauges here in a minute and I’ll clean every comm plug connection.

[Slartibartfast]

TPS would be my bet, too, especially with that delayed shift. If you haven't yet I'd check it with a scan tool (live data) or a meter (looking for a smooth change in resistance with no bumps/spikes/dead spots). Any trouble codes? Seems like the computer would notice if a solenoid was going out.

 

Hopefully it's not internal. I'm sure you're sick of anything transmission-related at this point.

[onespiritbrain]

I just set my TPS per these instructions:
http://lyberty.com/car/Maxima_A32_docs/EC-engine_control/NTB99-053b.pdf

I couldn’t get 0 ohms. I got it down to 9 ohms but the difference between 9 and 0 felt like it must have been .00001”

The little piece below the thing that the throttle cables hook on to which has a small adjustment screw was making the throttle cable thing not to sit down all the way on the adjustment screw that you’re not supposed to touch. I got that adjusted and I got the TPS as close as I could get it so we shall see.

The TPS was slightly ill adjusted and slightly on that thing is miles off so maybe it’ll make a difference.

[onespiritbrain]

Absolutely flawless drive after work. No skipping and no jerking.

 

I ran the scantool and saw spikes all over the place... except on the TPS haha.

 

I wonder if my ECU is on the fritz after I took it swimming one of those times.. I may try to grab one at the junk yard next time I go.

 

Edit: woah wait a minute! I see engine load high and throttle position flat as a pancake.

[mjotrainbrain]

Kinda whacky, but it's progress

[Slartibartfast]

Some weird spikes going on there for sure. Loose wiring maybe? That's a hell of a spike on the MAF. Good to hear the TPS adjustment calmed down the trans issue.

I'd check the EF&EC section of the '99 manual on the off chance it explains the different resistance to what you saw in the '96-'98 instructions. (Also thanks for the link--another tech writeup for my hoard! I can stop any time I want to...)

[onespiritbrain]

It ran very good today. It seems to be shifting quicker than it has since installing this transmission. TC lockup disengages at less throttle now and seems to stay unlocked longer before going into lockup again.

I think I’m going to buy a new TPS. The last junkyard TPS I got was a turd so this time I’ll grab a new one.

I am pretty confident the adjustment made everything operate better but I think the jerking issue was actually resolved by tapping the crap out of the gas pedal that day on the hill. I’m guessing maybe the TPS wiper flicked away some copper powder inside of it or something. Or maybe not who knows..