lost power

[TAckhouse1]

So last week I had the knock sensors replaced in my car (1994 Toyota Camry V6). It was a PITA to have done, since the knock sensors were $165 a piece (one in each cylinder bank) and then another $380 in labor since they are under the intake manifold. But it was causing a check engine light, and the car wouldn't pass a upcoming emissions test with the light on.

The issue is that the shop replaced the knock sensors, and there is no more check engine light, but now the car feels down on power. It just doesn't push me back like it used when under hard acceleration.

The power delievery is also not as smooth. It seems to bog somewhat around 3k, and then surge are 4.5k rpm, it never used to do that.

The problem is I don't know how noticeable these issues are. I notice them, becuase I have driven the car for the past 100,000 miles. the bogging and surging isn't drastic, but I notice it. The idle is still smooth.

I'm just worried that the shop isn't going to be able to figure out what the problem is, or that they will tell me that everything is fine. I am pretty convinced its not. A little bit of me worries that it is just in my head (since I don't have anything concrete to point to, other then how it "feels")

Any ideas of what could be wrong?

[v-cam]

Reset the ECU, see what happens after that.

[shingouki808]

I second v-cam's advice. If that doesn't work, when they removed the intake manifold did they clean it? If they left the intake manifold in the open it might have gotten all kinds of crap in it when they put it back. Clean that and the throttle body.

[TAckhouse1]

Originally Posted by v-cam

Reset the ECU, see what happens after that.

How do I do that? Is it just a matter of disconnecting the battery?

[abew330]

i had my engine light on too.. i just did emissions 2 months ago and they told me that they wouldnt touch my car until the light was gone..

went around the corner disconnected the battery went back to the same place and my car passed!!! hahaha

but anyway i would start off cleaning your TB and IAC

did you have the codes read before you changed the knock sensor? stupid question but maybe work code

if you searched theres a few on peeps here on TN with the same problem, (were it bogs down)
but i dont think anybody found the problem

[geoff5093]

Originally Posted by TAckhouse1

How do I do that? Is it just a matter of disconnecting the battery?

You could disconect the battery for say, 5 minutes or so.

[Eye8Pussies]

ah, damn...too bad you already got the job done and paid a fortune for it as well....

it has to do with the sensitivity of the ecu to the knocksensor signals in the 94 1mzfe. and NO, you are no imagining the power loss.

I advise that you start learning how to work on your own car, otherwise you will have to live with this problem....or pay another pretty penny to get it fixed.

read my threads:

knock sensor relocation:
http://toyotanation.com/forum/t157503.html

dyno after relocation:
http://toyotanation.com/forum/t158255.html

[Axel Kain]

it (i hope not) could be that the mechanics didnt properly seal your intake parts. and the engine is not mapped for the excess air it's getting. but i also recommend trying the ecu reset first!

[Eye8Pussies]

^ nope...it wouldn't be that....and generally speaking, power loss isn't too great with vacuum leaks, especially during WOT, since the ecu id dumping fuel anyway.

but more so, it'll be obvious during idle


and you can try resetting your ecu, but if it's knock sensor related, if there's no code, then resetting the ecu won't do anything- and if there is a knock sensor code, then resetting will nothing as well. it will just come back on once the throttle is touchec

[mike6466]

it could just a loose cap or something. try changing your gas. that what i did and my light went away.

Originally Posted by abew330

i had my engine light on too.. i just did emissions 2 months ago and they told me that they wouldnt touch my car until the light was gone..

went around the corner disconnected the battery went back to the same place and my car passed!!! hahaha

but anyway i would start off cleaning your TB and IAC

did you have the codes read before you changed the knock sensor? stupid question but maybe work code

if you searched theres a few on peeps here on TN with the same problem, (were it bogs down)
but i dont think anybody found the problem

[geokor]

do thorough check of vacuum hoses, make sure they are connected properly and none of the fittings are broken. Also, check distributor wires (looseness, damage etc). I can't tell you how many times i got car back from dealer repairs with loose hoses, wires. Fortunately, i don't bother with dealers anymore.

[bronzemaxell]

Originally Posted by geokor

do thorough check of vacuum hoses, make sure they are connected properly and none of the fittings are broken. Also, check distributor wires (looseness, damage etc). I can't tell you how many times i got car back from dealer repairs with loose hoses, wires. Fortunately, i don't bother with dealers anymore.

hmm, i didn't know the 1MZ-FE has distributor wires.
my 94 V6 was in the shop for inspection, and the mechanic said it was severly under power, i am thinking i need a tune up, but don't know where to start. . . .
spark plugs, fuel filter, clean throttle body, coolant flush, do i need to change the spark plug coil?

[Eye8Pussies]

the 94 doesn't.

but the 96 and up have sparkplug wires that run off the other three coils.


and if a car is severely under powered, there is something wrong and a tuneup won't fix it. if a car is feeling a bit more sluggish, then a tune up could help.

and you shouldn't have to change the coil packs unless it dies

[geokor]

Sorry, I meant sparkplug wires. You can check resistance of wires and check coils.

[TAckhouse1]

Thanks for the responses guys. I took it back to the shop. They checked everything and made some adjustments. The car seems to be driving better now.