check engine warning dual fuel 97 prado

[Bewitch Lurker Find all posts View Profile Close Bewitch]

hi the check engine light is on my 97 prado its dual feul was throwing knock sensor code so had them replaced and all timing and drive belts replaced done plugs and leads,ecu,maf sensor and still cant get rid of it and its now throwing no codes.
some days i can go 15km before it will come on but other times it comes on straight away.
only diffrence with light on is it lacks power and have no hope of towing with it and is using alot of fuel the light comes on weather running petrol or gas .
its doing our head in and costing the earth has anyone got any other ideas of what to look at next or had the same problem.
thanks in advance

[brissy Member Find all posts View Profile Close brissy]

have you tried crank and cam sensor , I remember a post on here somewhere someone had a similar problem, sensor signal seamed ok until it was put on an oscilloscope which showed the waveform was slightly out

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

I'd suggest pulling the codes again for it. Wouldn't surprise me if it's a knock sensor code again. Typically on these motors the sensor doesn't fail but the wiring to it does.

When it throws this error it will retard the timing like crazy, which will chew juice and cause a big loss of power.

Depending upon how you drive.... it may not always come on.

[Bewitch Lurker Find all posts View Profile Close Bewitch]

It always comes on its just a matter of how far I can get before it does and the knock sensors had melted due to a bad over heat and when I had them replaced they checked all wiring and it doesn't throw any codes now the annoying part is I have only had this car for 6mths and traded a perfect good van with half the kms for this car which from day one had trouble with because 20 mins after buying it the diff blew up and has been one problem after the other and only reason we brought it is to be able to tow my daughters horse which to date we haven't yet been able to do and have already spent thousands trying to figure this pesky light problem

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Stick with it mate. Sounds like it may not have had the best life prior to you. But once you get it sorted you won't regret it. It'll tow the horse float beautifully when sorted as well.

[tonyrey35 Lurker Find all posts View Profile Close tonyrey35]

Hi did you get this problem sorted .I am having the same problem had the knock sensor changed but the engine light still coming on

[Bewitch Lurker Find all posts View Profile Close Bewitch]

Nah not yet it's currently at the mech getting heads and sensors done will update if that fixes it

[Bewitch Lurker Find all posts View Profile Close Bewitch]

Well I'm about to give up heads done crank sensor done timing belt done knock sensors done and the light is still coming on over $5000 so far and still no luck

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Get a new mechanic?

Did you replace the actual knock sensor harnesses? This is so often the fault. They get dry and brittle and crack internally. Especially now that they've been moved during the sensor replavement. You can't just look at them, they actually need to be metered. 90% of this failure is the harness and not the sensor.

[Bewitch Lurker Find all posts View Profile Close Bewitch]

Yeah replaced the actual sensors have since had it back in and still not fixed over $6000 later were can I buy the harness for the knock sensors or even just the clips the wreakers in Adelaide don't have any and I have no idea were to buy new

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Not sure where to buy the harness from, other than toyota. I made my own using shielded cable.

[Bewitch Lurker Find all posts View Profile Close Bewitch]

Well still have the pesky light so far done heads,knock sensors
Knock sensor wiring,crank sensor,tps,secondhand gearbox,timing chain,secondhand ecu,maf
Have no idea what else to try as it loses power after check light comes on
Just about to give up as it has cost nearly $8000 and still not fixed

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Is the car at an auto elec or a mechanic? It needs to see an auto elec.

You never did tell us, what are the actual codes that its throwing?

I'd love it if this car was in Melbourne! Id sink my teeth into it in no time flat!

[Bewitch Lurker Find all posts View Profile Close Bewitch]

It's throwing codes 52 and 55 and that's why we're trying to get it fixed cause we have to drive it to Melb
With 6 kids on board and don't wanna get stuck this car does my head in

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Ok so its throwing both knock sensor codes. With new sensors and new harness under the intake manifold we can assume that the sensors are in fact ok but for some reason the signal is not reaching the ECU.

1, check for corrosion in the harness plugs.
2, using a multimeter, check the resistance of each sensor to ground. The resistsnce should be very high. Certainly should not be a short.
3, Verify the input going into the ecu by using an analog multimeter on the two knock sensor inputs on the ecu.
4, Verify continuity between the sensors and the ecu on both sensor wires plus the shield.
5, Consider running complete new wiring to the sensors from the ecu. Balanced microphone cable works very well in this regard.