timing retardation and sensors.

Post by **Alex** » Fri Jan 28, 2011 11:57 am

hey guys,

im after a strait answer here as its really starting to flip me off.

My liberty my02 2.0l n/a is being a pain in the bum at the moment.

It had a suspected knock sensor issue, so i swapped it out.

Previously it would retard power when cold and throw the engine light on, with it going away once warmed up.

I swapped it out, but now it runs magnificent whilst cold, and only throwing the engine light on once its well warmed up (after 25-30mins of driving) the light stays on and i have constant timing retardation and terrible fuel economy.

Basically im going to hang out until Paul RSR gets back to perth to chuck the ecu reader on it and see what code(s) is coming up with.

The wire on the knock sensor is quite tight, could this be causing it to throw an error? Im thinking about extending the wire, it has always been tight.

What other sensors on the car will cause it to retard timing? o2 sensor? maf? the maf in my case is built into the trottle body i think.

just wish my car was like the old ones with flashy ecu lights but you need a obd2 reader or whatever theyre called.

any help or ideas would be much appreciated

thanks

alex

littlewhiteute · Post by **littlewhiteute** » Sat Jan 29, 2011 8:36 pm

Is the engine noisy?

Knock sensors will log codes for mechanical noise if the ecu can't determine the difference between abnormal combustion and abnormal engine noise.

Gannon · Post by **Gannon** » Sat Jan 29, 2011 9:01 pm

A gen3 liberty non turbo should still have the green plugs, as they are not OBD2.
To be sure, non OBD2 models have one oxygen sensor in the front of the catalytic converter and have the IAT (intake air temp) integrated into the MAP sensor on top of the intake plenum.
OBD2 models have 2 oxygen sensors, one in the front and one in the rear of the front catalytic converter and have an IAT sensor on the air filter box.

Your green plugs will be taped up against the loom (mine was taped with blue tape)

RSR 555 · Post by **RSR 555** » Sun Jan 30, 2011 6:12 pm

Alex.. It sounds like you had more than one issue and there is a process to follow when trying to diagnose sensors. After reading your post and how the engine is using excessive fuel, I'm going to say the oxygen sensor is not working correctly. There is also other things that can cause this.. electrical is one off the top, so I'd like to help you as soon as I get home.

Cheers,
Paul

littlewhiteute · Post by **littlewhiteute** » Sun Jan 30, 2011 7:14 pm

Don't discount abnormal engine noise.

I've seen many parts, knock sensors, harnesses and ECMs thrown at cars with noisy valvetrain or piston slap etc.

The last car I had with an "irrepairable knock sensor issue" had a failed roller lifter which ruined the camshaft, yet NOBODY I knew at the time was interested in the noise from the engine.

RSR 555 · Post by **RSR 555** » Mon Jan 31, 2011 3:02 am

I hear ya Gaz will have a close listen when Alex comes over

Post by **Alex** » Mon Jan 31, 2011 9:45 am

there are definately no engine noises.

im running afew extra tanks of ultimate thru her at the moment, thinking maybe it was bad fuel.

i'll have a look to see if i can find the plugs tonight.

thanks for all your help guys.

littlewhiteute · Post by **littlewhiteute** » Mon Jan 31, 2011 12:33 pm

That's good, now you can concentrate on the fault.

Could be fuel related, get a sample and check for water contamination.

Post by **Alex** » Fri Feb 18, 2011 1:03 pm

update

suparoo, you are dead right.

im a tad confused. It has the plug for the OBDII reader, thanks heaps Paul RSR for reading them for me and helping me out so much!

It came up with some random codes, crankshaft sensor and maniford pressure sensor.

changed out the sensor on the manifold(just next to the coil) this is a few sensors in one i believe, map sensor and manifold pressure sensor, this made the problem not go away but it was better with the light flicking on and off randomly but not staying on. Last night i swapped the crankshaft sensor, but to no avail, the light still came on and stayed on once at full operating temp, it didnt turn off so its back to the worst it ever was.

Now the confusing part.

My car also has the green connectors, I have plugged them together and this threw 3 codes. Knock sensor(changed out), o2 sensor, and vss (vehicle speed sensor)

the knock sensor was changed afew weeks ago (its obviously just a memory code)

this afternoon im picking up a new o2 sensor and going to swap that in.

its REALLY doing my head in now.

which codes do i believe?

just trying to do this on mega budget, dont want to swap every sensor until i find the REAL problem.

Heres to hoping its the o2 sensor!

anyone else got ideas?

alex

steptoe · Post by **steptoe** » Sat Feb 19, 2011 1:03 am

Tell you what , some cars have thrown some really pissy error codes and answer has been damage to the wheel the crank angle sensor reads off, like a broken toof, which may be read as TDC in some systems, giving ECU two TDCs to play with !!

Post by **Alex** » Mon Feb 21, 2011 11:52 am

okay, so after doing heaps of research i found my solution.

I changed the 02 sensor and the light still came on after a spirited drive, then the computer was only throwing the knock sensor code.

basically took out the knock sensor and ditched it.

wired in a 560k ohm resistor in place of the knock sensor and hey presto, three days of driving and the light hasnt even thought about coming on, power is better than ever and she runs like a dream.

happy!

alex

RSR 555 · Post by **RSR 555** » Mon Feb 21, 2011 3:25 pm

Awesome.. Do you want to come over and clear out the codes? and did you keep that knock sensor I sold you? I'll give you back your dollars if you bring it back

Post by **Alex** » Mon Feb 21, 2011 3:39 pm

its cool, i'd like to hang onto the knock sensor, just incase (if thats okay)

we will have to sort out something with the other sensors i have of yours. I have a new camshaft sensor coming in the mail and i might swap my original mainfold pressure back on and see its actually faulty or not.

RSR 555 · Post by **RSR 555** » Mon Feb 21, 2011 3:41 pm

No probs.. let me know this weekend or when ever

Post by **Alex** » Mon Feb 21, 2011 3:42 pm

sweet as man!

Gannon · Post by **Gannon** » Mon Feb 21, 2011 7:26 pm

Do you plan on replacing your knock sensor?

A resistor might be ok for now, but if you get a bad batch of fuel, and on a hot day, with your radio on, if you dont hear knocking, you could end up with engine damage. Subaru installed the knock sensor on for a reason.

Post by **Alex** » Tue Feb 22, 2011 11:14 am

i will when funds allow.

RSR 555 · Post by **RSR 555** » Tue Feb 22, 2011 5:20 pm

If got another one if you want to try it?

Post by **Alex** » Tue Feb 22, 2011 5:36 pm

yeah can do. My new setup is patrially permenant, but can mod it suit.

Post by **Alex** » Mon Mar 14, 2011 4:18 pm

suparoo...youre dead right.

filled her up to the brim with 91 octane yesterday (for the first time since bodging the knock sensor)

only to have her pinging almost instantly. It seems the knock sensor is used in tuning the engine.

I read on the net this might happen (but only overseas with 87 octane fuel)

chucked a bottle of octane boost in her, was slightly better but still pinging when driven hard. I'll put another bottle of octane boost in just to be safe and run a tank of 98 octane thru her next fuel up.

In the mean time i'll be saving for a new knock sensor. Problems always come at the worst time! Just spent 800bux on new tyres and a stupid amount at the tiffany jewellery shop for the girls birthday!

alex