Car slightly blocks when accelerating

[DaveLS]

Hey everybody, I did search before posting. The closest thread I found similar to my problem is this one :
http://www.lincolnvscadillac.com/forum/archive/index.php/t-85272.html . Unfortunatly the guy didnt have the exactly same problem that I have and therefore that is why I am posting this thread.

Before explaning my problem my LS is a 04 and has the v6 engine. SO, my little ``problem`` is that when I accelerate the rpm will ``block`` just over 2500 rpm and it is only when I push the gas pedal down to certain point that my rpm will go over that 2500 mark. After my rpm has passed 2500 everything is fine though. I don't know if this could be helpfull to find the probable cause of my problem but I noticed that mostly happens when I'm in 5th gear (80km per hour and over / in lower gears I usually go pass the 2500rpm mark without any ``blocks``. I can also say that this ``problem`` happened before and after I changed all of my coils/plugs ( I drove about 5k kilomtre since I changed them). Oh and by the way I don't need to push down my gas pedal all the way down to go over the 2500rpm mark, just push on the gas pedal a little more.

No check engine light on.

Any ideas on what the problem could be ?

 

[joegr]

IMT?
VCT?
Catalytic converters?

 

[Telco]

Would you describe it possibly as a dead spot in the pedal?

 

[LS4me]

Would you describe it possibly as a dead spot in the pedal?

Which would lead me to believe either the electronic throttle (gas pedal) or the throttle position sensor (maybe one of Joe's acronyms).

 

[joegr]

Which would lead me to believe either the electronic throttle (gas pedal) or the throttle position sensor (maybe one of Joe's acronyms).

Maybe, but it seems like that would trigger ETC failsafe.

 

[FDR]

` Grave accent on the left
Apostrophe/Quoatation marks on the right ' / "
`1234
QWERTY
GHJKL;'


Or are you just making the quoted words stand out?

 

[RigsLS]

Come on, cut him some slack Frank!

at least he doesn't get on your nerves with hitting 'enter' at the end of each line, or putting silly hip-hop music in LS exhaust videos.

^ sometime I like to start of a sentence without capitalization. That be alright?









~ just teasing (bored again)

 

[LS4me]

Come on, cut him some slack Frank!

at least he doesn't get on your nerves with hitting 'enter' at the end of each line, or putting silly hip-hop music in LS exhaust videos.

^ sometime I like to start of a sentence without capitalization. That be alright?









~ just teasing (bored again)

Cold getting to you?
It's supposed to be 70°F and sunny today.
Should be upper 70's by mid-week.

 

[RigsLS]

Cold, huh? No, I'm indoors silly!
I have some time off for good behavior believe it or not.

 

[FDR]

Come on, cut him some slack Frank!

at least he doesn't get on your nerves with hitting 'enter' at the end of each line, or putting silly hip-hop music in LS exhaust videos.

^ sometime I like to start of a sentence without capitalization. That be alright?









~ just teasing (bored again)

Honestly, the Grave Accent and manual line breaks were genuine curiosity. I remember the days where you had to write <br> in forms and wonder if people don't realize programming has advanced from there.

But as for "exhaust" videos, I just want to skip to the part where I decide which exhaust manufacturer s getting my money in the Spring (or Canadian Winter Lite).

 

[DaveLS]

Would you describe it possibly as a dead spot in the pedal?

Sorry for not responding earlier I was OT for a couple days. Now that you mention it,yes the feeling of a dead spot is quite accurate.

 

[DaveLS]

Maybe, but it seems like that would trigger ETC failsafe.

ETC failsafe mode was not triggered recently. It did happened a couple time but end up it was because of a bad ABS speed sensor. Changed it and did never happened again.

 

[DaveLS]

If one of you guys could show me how to quote more than 1 people in the same reply would be great. I must say that the past week when I really noticed that my problem was more obvious then before the temperature was around -20 Celsius (don't know how much it is in Fahrenheit). No need to say that it was cold as F***. Maybe that could be one of the cause of my problem ?

 

[RigsLS]

If one of you guys could show me how to quote more than 1 people in the same reply would be great.

As many - "Multi-Quote This Message" - as you need,
then on last post - "Reply With Quote".

Piles them all in the "Quick Reply" console.
then you just place cursor in between Quoted messages to reply individually.

GL

 

[Telco]

I wouldn't count on a dead spot in the throttle system causing an ETC error. Unless it picks up an actual open it won't see a problem. When those sensors wear they make metallic flakes which eventually can mess with the resistance inside the variable resistor that is a TPS. The effect is a constant resistance value across that section. Once the swing arm passes the bridged portion, it suddenly jumps to a new resistance value which appears to the car that you hit the gas hard, nothing more. No matter though, simple enough fix if this is the problem.

There is probably a method to test both somewhere on the Deneau site. If you replace I would go with Motorcraft sensors. A TPS goes for the 60-80 dollar range, new gas pedal somewhere in the 120 dollar range. I didn't check but Tasca likely has both available.

 

[joegr]

The TPS is indeed a single potentiometer, but a dead spot in it should result in an ETC fault since the processor would see the throttle as not moving (although it was moving) when it knew it should be moving.
The gas pedal, on the other hand, has two or three potentiometers. They would all have to have exactly the same dead spot for the processor not to pick it up as a fault. Also, the dead spot would always be at the same pedal position, not the same engine RPM.

The IMT (intake runner control) and VCT (intake valve timing control) are two things that do specifically change positions at particular RPMs.

Of course, the whole system (engine and transmission control) is complicated enough that it could be anything mentioned so far, or something else altogether. Without some measurements and diagnostic equipment hooked up, these are all wild guesses...

 

[DaveLS]

Thanks for the help everyone ! I'm going to bring my car in a garage as soon as I have a few hours of free time. I'll keep the hints you gave me in mind and tell that to my mec. Hopefully, with a test drive he'll be able to put the finger on the problem. At least for now it's not a significant problem (still can drive with no problem) and no CEL light on. I'll keep this thread updated when I'll be back from the garage and hopefully it'll help someone else who might have a similar problem.

 

[Telco]

The TPS is indeed a single potentiometer, but a dead spot in it should result in an ETC fault since the processor would see the throttle as not moving (although it was moving) when it knew it should be moving.
The gas pedal, on the other hand, has two or three potentiometers. They would all have to have exactly the same dead spot for the processor not to pick it up as a fault. Also, the dead spot would always be at the same pedal position, not the same engine RPM.

The IMT (intake runner control) and VCT (intake valve timing control) are two things that do specifically change positions at particular RPMs.

Of course, the whole system (engine and transmission control) is complicated enough that it could be anything mentioned so far, or something else altogether. Without some measurements and diagnostic equipment hooked up, these are all wild guesses...

That would point towards the TPS being the problem then. The symptoms mostly fit a failed TPS (didn't know there were multiple pots on the pedal) and it may be that the error hasn't set in long enough for the ETC to recognize it as a fault yet.

It is true that these are guesses (not necessarily wild) but then that's about all one can do when troubleshooting on a computer instead of on the car itself. All we can do is make suggestions based off what's been seen before that fits the symptoms.

 

[DaveLS]

Didn't have time yet to get at the garage but it is a lot warmer than last week (0 Celsius instead of -20 Celsius) and I can see a noticeable difference. Right now the ``dead spot`` is barely noticeable.Still going to go at the garage and try to found out if it is a real problem or if it was because of the temperature.

 

[regiment1]

Didn't have time yet to get at the garage but it is a lot warmer than last week (0 Celsius instead of -20 Celsius) and I can see a noticeable difference. Right now the ``dead spot`` is barely noticeable.Still going to go at the garage and try to found out if it is a real problem or if it was because of the temperature.

What if your throttle body is a little gummed up?