Changed Knock sensor... Still CEL and No power

[dnbmovement]

Well we pulled a knock sensor code and decided to change it. The knock sensor was blown to bits and i thought it'll fix the problem. After the install the CEL came on and car still ran slow as if i have no boost. When codes are tried to be pulled, the computer reads normal. car also runs really rich and gets bad gas mileage. Any help would be appreciated.

 

[abaum565]

easy check:
1. Plugs
2. Wires
3. Coil
4. Boost leaks
5. Vaccum lines

I would check these first. I had a similar problem and went through all these steps to find out it was 2 bad plugs. Keep us posted

Also I did a quick search on knock sensor and here is what i found.
http://www.dsmtuners.com/forums/showthread.php?t=230381&highlight=knock+sensor

Hope this helps

 

[dnbmovement]

well the plugs are new and the wires as well. and why would a bad plug send a cel signal?

 

[abaum565]

a bad plug will not trip the CEL, but you need to start eliminating things. Have you got the CEL checked yet? you could go to autozone to get it scanned it's easy and free. After you get it scanned post the CEL code. I see you have a 92 talon, i believe that they are OBDI i am not sure if autozone can scan it. but you could try or find out how you can get it read.

 

[dnbmovement]

Autozone only has OBDII. We have checked the codes and the first time it oull 13, 14, 21, 23. The second time it added another 2 codes. Finally we reset the ecu, drive, and pull the codes and i only got knock sensor code. We pulled the sensor and it was all damaged. Didnt fix the problem. This whole thing happened within a 6 hour night with the car off. I went to sleep woke up and the car didnt run a fraction of what it did.

 

[abaum565]

I believe these are the codes for what it read. you need to start by checking these out. If you don't think that these are the problem then you need to check the wiring, from there i would check ECU.

13=No difference seen between the engine MAP reading and the barometric (atmospheric) pressure reading at startup. Indicates a problem with the MAP sensor vacuum system.

14=MAP sensor voltage output is outside the acceptable range.

21=O2 sensor does not detect rich or lean condition, or O2 sensor input voltage too high. DRB will indicate which side with dual sensors. The O2 sensor signal should fluctuate under normal conditions.

23=Intake air manifold temperature sensor is out of range. Check sensor.

make sure you check the plug gap (.28)

I hope this helps.

 

[dnbmovement]

i really appreciate the help.... the only thing i dont understand is why did they all show up in one night. The ecu looks fine, no corrosion, no leaky or swollen caps. But i guess ill start off with the knock sensor i did today. Next O2 Sensor

 

[donmagicjuan]

I see that you reset the ECU before replacing the knock sensor, but did you reset it again after replacing it? Kind of an idiot check, I know, but I didn't see you mention it. Codes can take an unbelievably long time to clear on their own.

 

[MrBoxx]

Codes can take an unbelievably long time to clear on their own.

40 warm-up cycles with no instance of a recurrant trouble code on most cars, if the literature is correct. If the 40 cycles are completed with no sign of trouble, the code gets cleared out on its own (usually).

 

[dnbmovement]

yeah ther computer was reset after the knock sensor install. and its not only the CEL on. i still have no power

 

[donmagicjuan]

Still no power to what?

 

[dnbmovement]

still no power in general. The car is slow. like really slow and it feels like it has no boost although it does. I just pulled the codes and the knock sensor code came back up with a new knock sensor!

 

[donmagicjuan]

Sorry, I thought you were talking about an electrical problem. With a CEL, your car will run in a safe mode, which involves lowering the boost if you still have the stock BCS. In my experience, the fuel pressure solenoid is also kept shut, meaning that you will see higher than normal fuel pressures whenever vacuum conditions exist in the manifold, although I can't confirm this for all CEL codes. However, this could likely be the cause of your reduced power and fuel economy.

If you know that the knock sensor and its wiring are good, check the ground connection. The sensor is designed to ground with the engine block when it is threaded into its hole properly. This permits the ECU to detect when the sensor has come loose from its location or has been plugged in but not installed. It would help if you had a logger to inform us what knock value you are getting from the sensor.

As a helpful FYI, the torque spec for the sensor is 14-18 ft-lbs. They tend to get a little unruly if you don't adhere to this.

 

[dnbmovement]

the sensor is grounded. screwed in tight but not to tight. should be working properly. i not only got code 31, i also got 13, 14, 21, and 25. everyone is gonna say go change all of those sensors but i dont see how all of these will go bad in just one night when the car wasnt even on. just parked. WTF!@! my rx-7 never did this

 

[donmagicjuan]

I guess I need to wake up. I coud've sworn I read that you were able to get the other codes to clear. I seriously doubt you have 5 independent faults-- if all those sensors are in fact bad, then it is probably the result of an underlying problem. I think it's time to take a look at your ECU and its connectors.

 

[dnbmovement]

took ecu out checked it no leaky coapcitors or rust/corrosion damage... is it possible that its still gone bad?

 

[donmagicjuan]

Sure, it's electronics. ESD can fry the crap out of an IC, and just by looking at it you'd never be the wiser. I wouldn't jump to the conclusion that you burnt up your ECU just yet, though. Did you verify that all the connectors were plugged in correctly? In other words, have you done anything to mess with the ECU between the last time the car was running normally and now?

 

[dnbmovement]

nope i took the ecu out after the car started to act up... most of the sensors mentioned were changed and yes the knock sensor was torn to bits but its still slower then all hell. like i mean so slow that wot feels like im and old lady

 

[dnbmovement]

help anyone?

 

[donmagicjuan]

If you have access to another one, you can swap out the ECU to narrow it down. If not, you can start checking the continuity of the wire connectors in the meantime. Perhaps one of the ECU gurus that we have can chime in and lend their expertise.

P.S. It's against the site rules to bump your threads. Next time, just give it a little while until someone comes along that can help.

 

[dnbmovement]

well im bidding on one on ebay. the description says no leaky cap and in full working order so if i get ahold of that, then ill know if its the ecu. what do u mean by checking wires how do i go about that?

PS: Sorry about that

 

[dnbmovement]

okay update... just changed the ecu and nothing still CEL, Still Weak, and the comp wont gimme codes. what now? im going to crash the car into a tree

 

[dnbmovement]

so yeah. i just got done working on the car and turns out my wastegate was stuck half open and half closed? i dunno some PB Blaster and my pair of Ideal Electrical Pliars took care of that. Still CEL do have power just boosting 20 PSI???! Well yeah its reads knock sensor so any ideas will help. 14B PoWAH!!