Check engine light / slow car

I have a 91 Turbo MR2 and for some reason my Check engine light comes on whenever I start driving and my car feels really slugish. Im sure its not hitting fuel cut, because I have the HKS FCD installed and have been boosting 12psi for months with the blitz boost controller.

Im going to try the diagnostic check that I read in another post and see what code it gives me, but does anyone have any ideas what may be causing this because I have to wait till tomorow until I can check.

Another thing I noticed is that my HKS instake sounds like its sucking in WAY more air when the light is on, and my boost controller shows that I am reaching 12psi faster than usual but my car is actually driving much slower than usual.

Mods include:
HKS FCD
HKS Intake
Apexi S-AFC
Blitz Boost Controller

All was tuned and running great for a couple months, until now.

My guess is going to be that you are going to get Code 52 for the knock sensor.

Good guess, Code 52 was it, I had 3 codes stored but reset my ECU, drove around for a while and re-jumped the diagnosis, and got code 52 only.

So whats the next step, replace the knock sensor?

Yeppers ... the sensor should be just over $100 from Toyota. It is simple to replace.

It just has one electrical connection going into it and it is held onto the block with one huge 27 mmm nut. It's less than a 10 minute job to swap it.

The concern you should have is WHY did you blow the knock sensor? ... how old are your ignition pieces? What type of fuel do you use?

I believe the ignition peices are as old as the car, as for the fuel, I use 91 chevron (premium) I live in CA so its the best I can afford.

Im boosting 12-14psi so Im thinking that may be one of the problems.

I would suggest replacing your ignition components ASAP ... I promise you will get instant power back. I am sure your power is down.

I replace my cap, rotor and wires once a year and I change my plugs every 3000 miles.
Of course, you need to get a new knock sensor as well.

If the best you can get is 91 octane, I would highly recommend you look into getting a water injection system. I use the aquamist system and I only use 94 octane gas on the street (110 octane when racing).

I ordered the knock sensor, I Im about to order the cap, rotor, wires, and plugs, but I just wanted to check and see if there were any wires that you suggest.

Also is about $40 correct for the cap/rotor together?

I think Im going to go with the NGK 6097 to replace what Im using now.

Use TOYOTA wires.
$40 sounds right for the cap & rotor. Wires are probably around $70.

NGK 6097s area great choice.

cool thanks a lot for the help, I ordered toyota wires, caps, and rotors, and the NGK 6097 for about $90 total. Plus the knock sensor for apox $100.

You mentioned water injection, I dont really know much about it, is there a company that sells it, or can I drive down to my local shop and have them order it and install it, if its not an easy install?

If you want some info on water injection, this is a good place to start reading:
http://www.aquamist.co.uk

ok I installed the cap rotor and wires, but I ran into a problem with my wires.

The #1 wire (longest one) isnt quite long enough, but the wires I bought came with something extra that I attached to the #1 wire which seemed to extend it, making it long enough.

Not sure if that makes sense, but I hope theres nothing wrong with that.

I assume that if that setup is incorrect the car wouldnt start?

Did you buy TOYOTA wires? It doesn't sound like it.
Toyota wires are the only ones you want in there.

There is no way they should not have reached. I would not trust some sort of "extension" piece.

Did you buy TOYOTA wires? It doesn't sound like it.
Toyota wires are the only ones you want in there.

There is no way they should not have reached. I would not trust some sort of "extension" piece.

Thats what I was thinking I ordered, the guy at the shop assured me they were over the phone, Im gonna take em back this afternoon.

Look at my engine bay photos on my site ... those are Toyota wires. They are red and would have the date of manufacture painted on them in white.

If you did not buy them from a Toyota dealer ... chances are they are not Toyota wires.

OK!!!! All work is done, I went to the toyota dealership to pickup the oem wires, and knock sensor, installed them along with the cap and rotor and plugs.

Car is running perfectly now, any advice on how to troubleshoot what caused the knock sensor to go bad, so I can prevent it from hapening again?

1. What octane fuel are you using? (should be 93 or more)

2. How hot/cold outside was this when it happened? You are more likely to detonate at the extreme temperatures.

3. Your worn ignition components could have easily contributed to this.

4. Were you running more than 15 psi of boost on the stock turbo?

1. 91 - I live in California so higher octane is hard to come by

2. It wasnt very cold or hot, its been relatively nice outside.

3. Fixed

4. I was running 14 on the stock turbo.

If you were running 14 psi for any length of time (several months) with no worries ... then I wouldn't stress it. Chances are your ignition will help a lot.

I assume you have noticed the car being smoother and peppier with the new ignition pieces?

Its been running much smoother until last night when the CEL turned back on, so I reset my ecu (to clear the saved codes frm before) and sure enough code 52, and this is only about 4 hours after installing the new sensor.

Is there any possibility that I tightened the sensor on to tight? Because I noticed the old sensor wasnt on very tight at all.

Im really stumped on this one and hope that I dont have to go buy another sensor, (cost me $155 at the toyota dealership).

It is more likely that the sensor would blow from not being on tighteenough.
If they are not on tight, they could wiglle around giving off "knock" (metal vibration).

Dam, so I guess Ill buy another one and put it on as tight as possible

I am really concerned that you knocked loud enough to break it ... unless you think it was installed loose.

Maybe you should get your engine checked out?
At least a compression check.

Do you have an aftermarket boost gauge that reads vacuum? If so, what is your vac at idle?
Does the car run well? Any smoking?

I didnt think the sensor was loose at all.

Taking my car to a shop in about 5 minutes to get the motor checked out especially because of an oil leak.

My vac at idle reads -20 and the car ran perfect while the sensor was intact, but as soon as the CEL turns on it runs like crap.

And there is a little white smoke when I turn on my car, Thats burning oil I think, and taking my car in to get that fixed.

Is it possible that the sensor is still good, only loose, and only needs to be tightened?

I also have a new knock sensor next to me (the GM one from ATS) should I just install that one?

Is it possible? ... sure. Can't hurt to try. It's free. :)
Just remember to reset your codes.

DID you reset your codes when you installed it?

As for the ATS GM knock sensor, I am not that familiar with them. I know you need an adapter to put it on the car. Did you buy that? A lot of people use them.

Yeah I did reset the codes after installing the adapter the first time. Tightening the adapter didnt help either.

I was able to install the ATS sensor (I bought the adapter with it) and so far everything works. Im taking it to get tuned later in the week