I’ve got slow sluggish acceleration on my auto max; it’s pulling 11+ secs from dead stop to 60mph. I got a new stock air filter but it made no difference, so I decided to check the ECU. It gave me back a code for a faulty knock sensor, so I guess this could be the culprit, but I wouldn’t have thought it could affect acceleration by so much?

I’ve always used 98 octane fuel and I don’t notice any pinging, the car has about 150k miles on it and is pretty much completely stock. Basically, if I’m launching from dead stop there is a decent take off until about 3k, where it sort of dies, then going to second it’s really sluggish. If I’m cursing at 35 mph and punch it, when it kicks back it feels really underpowered and takes ages to get to 50-55mph. Also, there isn’t much of a response at all after pushing the accelerator more than half way, it wont accel any faster, in second after 2.5k rpm it dies. It feels like my mums 4cyl corolla. Aren’t the average VQ auto’s capable around 8’secs to 60mph?

What do you guys think? Is the knock sensor the cause if this?

 

yes that prob is the cause. knock sensor is a ghost code and wont make the cel come on. there may be something else tho, because i dont think it has that much of an effect to make your car that slow. but change ure KS and you should be ok. i think u can get them on ebay for like 60-70 bucks.

 

I'd put a lot of blame on the KS too. and it sounds like your transmission is the problem
can you really get 98 octan in MS or was that a typo? my max can do 0-60 in around 7 seconds, and its stock.

 

My knock sensor died on me a few months back. I noticed a big power loss, but not nearly enough to make me accel to 60 in over 11 seconds. But like everyone else said, replace the ks and see how it goes from there.

 

Hmm, trans shifts pretty smooth and quick, don't notice any slipping really, but if replacing the knock sensor doesnt result in much diff then ill get it checked out furhter. Was a typo, meant 93 octane, sorry.

 

It could be a dying MAF sensor that will cause u to lose power at strange RPM levels.

 

well since everyone else is stating the obvious, like the KS and MAF. I'll state the worst case scenario, check and see if all your cylinders are firing and have the correct pressure.

 

vaccum lines?? with out those your car wont run right.. if its not that or anything else people have been saying, it sounds crazy but maybe your E-brake is somehow stuck on and after all your torque is gone (after 3k rpms) your car might get held up from that.. one way to check that is to see if your E-brake handle is really loose until the very top of its pull. idk just a thought

 

i was counting 11 secounds but it wasnt using a watch i have an auto with y-pipe bpipe intake and two row radiator.

i replaced my knock about 6months ago

 

98 octane?!?! damn!

 

Vaccum leak should through a code....shouldnt be have anything to do with that. E-brake light would be on if it was stuck. No chance that the e-brake would be stuck and the light/sensor would be out too. It's going to be your KS. Fix that and see how the car rolls. If it still lacks power then it could be something else.

 

Actually, regarding the e-brake, if the caliper is seized in any way, it would slow you down, and no light would appear on your dash. One easy test is to stop after some driving and check the heat from your wheel wells. If the rears are hotter, or one of them is hotter, then you've probably got a seized caliper.

 

That's very true. I forgot about that.

 

another way to tell if your calipers are seized is feel the rim after a drive, when my rear left caliper seized my rear left rim almost burned you if you touched it, while the rest of the wheels were cool/warm. I remember when the knock sensor went on my auto, it was really sluggish, replace the KS and it should make a huge difference.

 

also you can jack up the back side and see if the wheel spins freely.

 

I think this is my same issue. I am at around 10 secs for 0-60, and the car had more pwoer than like the van I am used to or the focus that my friend has, but it still should be running under 9 seconds, and it is not. Could a KS lead to bad MPG too?

 

Yes, KS can cause bad MPG. Whether that is a PCM running rich issue, or operator applying more throttle to make up for the lost power, no idea...

 

I jacked it up today, and all wheels spin freely, so i think the break calipers are alright. Ill be getting a knock sensor on thursday this week so i'm hoping it will help quite a bit. The engine doesnt feel like its missing, it runs quite smooth and idles pretty good....

Ill see about the MAF sensor, although wouldn't the ECU be reporting a bad MAF if i had one?

 

possibly but the ECU is like any other computer and doesnt need an excuse to mess up on you. sorry im just reffering to my pc experiance... you might have bad ecu but doubt it.

 

Depends on how far out of spec the MAF is. The ECU allows a range of operation for the MAF, it may be on the edge. The MAF could be causing a rich condition, with out causing a fault. You could also have an issue with a coolant temp sensor, if the ECU thinks it is colder than actual temp you could also run rich. I would start with the knock sensor first.

 

my gas mile per tank has gone from 360 to 250. could that be my knock sensor? or something else. i havent changed driving habits or gas type. i hacked my air box though...

 

new info from my car... i had the o2 sensor code go off a while ago, and then the cel went away.

but now the car is acting really weird. weird rpm's and this morning the car wouldnt even go into gear without turning off (automatic).

im guessing its the o2 sensor even tho the cel is not on, the light has been on and off for the o2 for a while now.

try your o2's too! i bought an o2 from ebay for like 22$ with shipping, i will see if its worthy soon as i get it.

 

Clean your MAF. It only cost about $10 to go buy some electrical contact cleaner. Make sure you take the MAF off the car and spray about half the can inside. That might help.

 

will bad cv axels also cause issues? i need new ones for sure because of all the noise comming from em.

 

Update: I changed my knock sensor today, my old one was cracked down both sides. I also took apart the MAF and sprayed electric contact cleaner on it, as well as clean the throttle body. I must say, low end has lots of improovment from what i can notice in my short test run so far. Before, i could barely get any wheel spin, it basically had to be raining, but now i almost get to much of the spot in the dry! Also, a very slight idle vibration that i use to get has disappeared in D and R, now the steering wheel feels like the car is basically off when idling in D.

I raced a mate today who use to beat me by half a car length, to test the accel after the new knock sensor. Off the spot, i got a ****load of wheel spin (quite unexpected) so he got the jump, but i caught up pretty fast and was basically in front by half a car by the time we reached the speed limit and slowed (45mph). I haven’t tested it from 0-60mph yet, but i suspect if i dont get wheel spin, it should be quite a bit better. I'll see if i can get a time tomorrow, to compare with my 11 secs.

 

Did you have a KS code? I am not getting one, but I am leaning to believe that this might be one of my problems. Does it always trip the CEL if it(the KS) is not performing like it should be? Maybe I have the same issue(s) that you do...

 

Where did you get your knock Sensor from? I believe I need to replace mines, cause I notice my low end isnt like it use to be, but when my rpm gets above 3 all the power kicks in

 

ebay.....$64

 

Yeah i was getting it, even after resetting the ECU, it would come back almost straight away. Since i've changed it, the code hasn't appeared, so i think my old KS was pretty stuffed.