'99 stutters/hesitates, no CEL on though

[oakback]

I bought this truck a few months ago, and it had a bad injector. I replaced that, and cleared the codes, and the CEL hasn't come on since then. But I feel this stumble/stutter/hesitation, whatever you want to call it, both while idling and cruising. It runs completely fine otherwise, it doesn't ever stall out or cause problems, the hesitation is very quick (doesn't effect speed any noticeable amount, can still accelerate).

Either it's getting worse over time, or it't getting worse as it gets hotter outside, I'm not sure. Without a CEL, I'm not sure where to start.

I use premium gas every time, if that makes a difference.

 

[Cannon88]

Sounds similar to what I had when I had a bad coil pack, but that should make the CEL come on. You can also remove the intake tube and check your throttle body. It may be dirty and sticking a little, which would produce the same symptoms. A quick clean up on it is fast and easy (air filter clean as well?), and so is the changing of coil packs if thats the issue.

 

[Sandroad]

X2 on the throttle body cleaning. Without a CEL, that's pretty likely to be the problem.

 

[re_guderian]

Could be a lot of things. Here's a few more to check...

https://forum.ih8mud.com/threads/in...fire-on-2000-lc-no-codes.592303/#post-8713523

Most common is a coil pack on the way out, but there are several other potential causes. I haven't noticed any change at all with a throttle body cleaning, but that's just me.

 

[fumanchu]

In reference to the link on the above post.... All 8 of my plugs were loose. This truck was dealer serviced too. I think they loosen up over time and need to be rechecked which is a pain. Also the plugs are the type with a crush washer so you really need to make sure that the washer gets compressed fully when putting the plugs in. Truck runs better with tight plugs!

 

[96crooser]

Have you replaced your fuel filter

 

[dnp]

Could be a lot of things. Here's a few more to check...

https://forum.ih8mud.com/threads/in...fire-on-2000-lc-no-codes.592303/#post-8713523

Most common is a coil pack on the way out, but there are several other potential causes. I haven't noticed any change at all with a throttle body cleaning, but that's just me.

Did yours stop doing it altogether after you tightened the plugs?

 

[re_guderian]

Did yours stop doing it altogether after you tightened the plugs?

Yep, this was my 2000. Not a single problem since.

 

[kelly saad]

I have had the same problem for 3 months now. Once its totally warmed up it stops. No engine light. The mechanic at Toyota said that the only thing that doesn't kick on an engine light is the fuel pump when it goes out. He checked it and mine is fine though so we are trying different things. He said he found a slight misfire on #4 but not enough to turn on the engine light, so we tried a new coil, no luck. I cleaned my throttle body 6 months ago so thats not it either. I really just don't know. I guess move on to the injectors. Maybe check your fuel pressure, perhaps its the pump. Its the only time in my life that I actually want my engine light to be on. So funny.

 

[oakback]

Thanks, I'll check plug torque and move on from there.

 

[oakback]

Just finished replacing all the plugs (I wasn't sure when they were last changed). All plugs torqued to 13 lbs. I haven't taken it for a test drive, that'll have to wait till tomorrow. But here are a couple of the old plugs that I thought looked suspect, what do you think?

 

[oakback]

It still stuttered again, on my morning commute. I'll replace the fuel filter next.

I sorta half-assed cleaned the throttle body, as I was running out of daylight real fast and hungry for dinner. I sprayed some carb cleaner around the plate and scrubbed with a brush, but didn't really inspect it or get thorough (I was hoping the spark plugs were the problem). I'll do that more thorough as well.

 

[Mohammedqur]

I'd buy a coil and replace it one at a time. I got the same issue awhile ago without codes. Changed the filter and cleaned the TB. Didn't help. I inspected the coils one by one and found the 4th havibg burn marks. I knew it was it and the truck ran great after that.

 

[oakback]

I'd buy a coil and replace it one at a time. I got the same issue awhile ago without codes. Changed the filter and cleaned the TB. Didn't help. I inspected the coils one by one and found the 4th havibg burn marks. I knew it was it and the truck ran great after that.

When I bought it, it has a code for misfire on cylinder #3. The previous owner had several coils to give me with the vehicle, 1 brand new (not sure on the other 2, but I kept them). I replaced the coil for cylinder #3, and the code was still there. I replaced the fuel injector, and that fixed it.

Not sure if that matters, just thought I'd give the full background. All the coils looked fine to me, I didn't notice any burning. But if the fuel filter doesn't improve it, I'll do what you suggested. I figured it can't hurt to replace the filter anyway, not knowing when it was done last, and it being so low cost.

 

[BMWSTOY]

X2 on the coils. Mine just went out after replacing it in 2007, would act up, then stop. very erratic.
I erased the code and it worked for a month or so, then I received the code again. The coil looked fine, but it was going out, slowly.
Hope it clears up for you. have you run nearly out of gas to eliminate bad fuel. I know you said 91, but it still could cause this if bad. My 2000 does not run on bad fuel very well - 89 or 91. I get better performance from good 89 then some 91's.

 

[WGermer]

@oakback any update on the stutter/hesitation? I'm having a similar issue with no CEL.

 

[camino70]

@oakback any update on the stutter/hesitation? I'm having a similar issue with no CEL.

I would explain my situation similarly, it wound up being a coil pack or two. It will eventually throw a code, but you could unplug one coil pack at a time to see if the issue changes.

 

[oakback]

I never bothered to change the fuel filter, and it still stutters, I just try to ignore it (rather than sinking money into diagnostics). It comes and goes, it seems random. It's more noticeable when it's really hot out, and when I have a load on it (trailer, both a/c's running). Never real bad, not bad enough for me to do much about it. No CEL.

 

[WGermer]

Thanks for the quick replies. I think I'll have to try and change out a coil pack systematically. My stutter lessens when its warmed up/hot, but doesn't go away entirely. Its especially noticeable when cold, and when starting from a stop sign or stop light. My wife is getting on my case to get it fixed!

 

[ibrahim83]

coil pack. oe is the way to go.