Dreaded stutter problem (1 Viewer)

[ultra_runner]

I've been reading the threads and FAQs and trying a few things but now at the point of reaching out for input.

2000 LC with 323K on it. Runs solid and smooth (typically) and leaks no fluids.

In the past year I've had the following work done on it:

- Power steering pump replaced
- Starter replaced
- Alternator replaced
- New plugs
- New front axles
- New front rotors/pads
- New fuel filter
- New (all) O2 sensors​

A few weeks back I towed a trailer up to Sacramento and back. Maybe 260 miles with highway hills and AC on. No problems really. I was pushing it to make time but nothing crazy.

Later that day my son used the car and he said it was hesitating on the highway and it concerned him. Next day I felt it. It was a very infrequent "miss" or stutter, only occasionally. As I continued to drive it (days) it got progressively worse to the point that one night I thought I would not make it home.

First I thought transmission. Did a drain and fill and the outbound fluid looked and smelled fine (not burned). Problem continued until I could feel the stutter even at idle, not under load in neutral so I scrapped the idea of anything transmission or driveline related.

Pushed it one day and had flashing CEL on dash while it was stuttering bad going up hills. The CEL finally stuck and gave me a "Misfire on Cylinder 1."

Cleared the code, read the threads and thought coil packs as I was still running the originals. Replaced all coils with new Denso and checked the plugs at the same time. Plugs (iridium) looked fine and in the right temp zone. Engine had more response with the new packs but stutter persisted.

Last weekend I replaced all 8 injectors, new PVC, cleaned MAF, new air filter while I was at it. Problem persisted.

Last night I pulled both battery connections and shorted to do an ECU reset. NOW - this morning to and from work it ran very smooth with almost no stuttering. I actually tried to push the revs to drop a gear and put it under load on highway to try and replicate the stutter it did quite well despite it not having the throttle response I am used to. This evening, the stutter returned. Fluke? Don't know.

I have a new TPS that arrived today and new fuel pump arriving tomorrow to attack those this coming weekend.

Other ideas I have come across; ground cables to engine/transmission, FPR, MAF, Fuel relay. I thinking it is fuel delivery or spark (electrical) related.

I would like to get a list of all the Toyota "form-fit" vacuum lines so I can just replaced all of those (as opposed to buying and cutting bulk unfitted hoses, etc). If anyone can point me to such a resource - much appreciated.

I've seen many threads on similar issue but not seen a whole lot of concrete solutions. Open to ideas and suggestions.

Thanks.

Scott C.

 

[fooldall1]

You added new plugs- but check the COILS... Make sure the top center of the coil isn't swollen or cracked.. Sounds to me like you might have a coil going bad.

 

[Battleship]

You replaced all 8 coil packs with new, or just cylinder 1?

 

[Dwight S]

And by all means DON’T buy the cheap Ebay or Amazon coils that they sell 8 for the price of one good coil. Everyone here will say Denso and I don’t disagree. But I ran into a couple of situations where I had to go with a AutoZone Duralast coil. It’s been 2+ years and they’re still working. So at least go that route if you’re replacing coil packs.

 

[ultra_runner]

Regarding the coil replies - replaced all 8 at the same time and they are genuine Denso.

 

[Eicca]

I’d suspect vacuum leaks if those haven’t been pursued already. Check your main intake hose and the resonator first. I replaced all my Lexus vacuum lines with generic stuff from the parts store and it’s fine.

Also check your wiring harness and plugs for kinks/breaks.

Not sure how you would check them, but cam/crank position sensors also come to mind.

 

[ton504]

Stop throwing money at it. Keep driving it until check engine light comes back on. If its not a big deal, light will just come on. Its a big deal if the light is flashing, so stop when it is safe to do so. Report back with the code. OR when it is fuel pump related, it usually never gives a check engine light. And if it is a fuel pump, it usually acts up under heavy load or after driving some miles(heat).

 

[ultra_runner]

Stop throwing money at it. Keep driving it until check engine light comes back on. If its not a big deal, light will just come on. Its a big deal if the light is flashing, so stop when it is safe to do so. Report back with the code. OR when it is fuel pump related, it usually never gives a check engine light. And if it is a fuel pump, it usually acts up under heavy load or after driving some miles(heat).

This is the advice my indie gave me. Said "They're built like tanks so drive it until it throws a code." I did that and it threw a P0301 - Misfire cylinder 1 which then got me to the coil and injector replacements.

I agree with your point on fuel pump and that is my next line of attack. Saturday morning swap.

 

[ultra_runner]

I’d suspect vacuum leaks if those haven’t been pursued already. Check your main intake hose and the resonator first. I replaced all my Lexus vacuum lines with generic stuff from the parts store and it’s fine.

Also check your wiring harness and plugs for kinks/breaks.

Not sure how you would check them, but cam/crank position sensors also come to mind.

The main intake is cherry with no cuts or splits. Will go with some generic hoses and chase down all the lines.

 

[ultra_runner]

Problem solved and I win the dumb azz of the year award.

Plugs were gapped between .058-.060. No bueno.

Ran down to the store before they closed and grabbed some old school NGK copper core plugs was was able to swap out 4 before calling it a night. Test drive tells me this was the issue.

HOWEVER - having new coil packs and injectors makes a world of difference as well. Happy again.

 

[Wilsil]

The main intake is cherry with no cuts or splits. Will go with some generic hoses and chase down all the lines.

Did you change all hoses?
I am thinking of doing it but I don't know what type of hose to use.

 

[2002TLCyes]

Problem solved and I win the dumb azz of the year award.

Plugs were gapped between .058-.060. No bueno.

Ran down to the store before they closed and grabbed some old school NGK copper core plugs was was able to swap out 4 before calling it a night. Test drive tells me this was the issue.

HOWEVER - having new coil packs and injectors makes a world of difference as well. Happy again.

Are you saying you had bought the wrong new spark plugs? I don’t follow as to what the conclusion of the main problem here is.