Hey there, I am new to the forum and would just like to say what a great site and thank you.
Anyway I am currently having trouble with my 2001 TJ Magna Advance. I have a rego inspection coming up and there was a fair amount of old oil on the engine I wanted to clean so washed the engine "carefully" with good quality degreaser and a light pressure garden hose. After his my car will start perfect idle perfect and rev fine at low speeds but wont rev out too high 2-3 grand or when driving wont go above 40-50 k's. Above this range the engine sounds terrible like its running on 2-3 cylinders, I believe its in "limp" home mode.

OK that's the story so far and to solve the issue which I believe is going to be a sensor or something electrical.
this is what iv done so far-
I have dried the engine with a blower and the sun over the last two days
Unplugged nearly all the sensors again
Unplugged the negative battery terminal to reset the ECU
all no luck
OK so here is my question (at last)
I have read on the internet that it is possible to use a voltmeter or test light for diagnostic purposes, plugging into the correct terminals on the diagnostic plug will give some sort of pattern that will tell me what's wrong. Firstly I am not sure if I have found the diagnostic plug (Black sinlge line plug with 8 blade female connections located just under the left drivers side near centre conso) and if so which plugs do I use ? that's if there really exists a plug for the 3rd gen magnas and as iv also read they use the check engine flashes as code instead. That brings me to my next question, on my dash there is no check engine light coming on, why? there is obviously a problem most likely electrical hence the limp home mode.

any advice or suggestions would be very welcomed
thank you
Scott

Remove dust cap and dry inside the dist, 99% this is the issue

Thanks for the speedy reply. I was just wondering how it could be the distributor as the car idles and revs at lower range perfectly. Im only asking as the dist cap is kinda a pain to pull off by looking at it.
thanks

Does anyone know if it is possible to connect a voltmeter or test light to the diagnostic plugs with 3rd generation magnas, I read somewhere here that grounding terminal 1 will cause an error code to be produced in the check engine light?

Forget the diag port, is 3 screws.......check that first as diag port will prob tell you sfa

Forget the diag port, is 3 screws.......check that first as diag port will prob tell you sfa

Yup. We always assume that the ECU will have an error code in it every time something goes wrong. Unfortunately, it's just not the case much of the time. Sure there are somethings which show up but other things don't trip codes.

If you were to write some error handling code for a car ECU to cater for every possible failure type, the code would be longer than the instructions used to make the engine run. Newer cars are getting there though.

Pulled distributor cap off but was bone dry under there, used a blow drier just in case but still seems to be in limp mode. Any other suggestions much appreciated

Just tried grounding the diagnostic plug and found the engine light came on in constant flashes which means no error I believe, so why would limp mode be enabled and how to get out of it?

Just found an old post with the exact same issue as mine and funny enough the resloution was as you said the distributor. I guess ill need to replace it then, though seems weird i could kill it just by washing my car. Is there any way of repairing the dist. or not?

I have a similar problem with my KH. There's a connector near the transmission dipstick, down to the right and lower. It's to do with the transmission. Water gets in. Just pop it off and blow out the water from both parts of the connector. There's a clip that holds it on, I think you have to push the clip.

Happens every time, although takes a day before it locks into limp mode, so must seep in slowly.

Just tried grounding the diagnostic plug and found the engine light came on in constant flashes which means no error I believe, so why would limp mode be enabled and how to get out of it?

ECU doesnt not have a dedicated Limp home mode - in the sense that it limit speed, cyl, etc. About the only thing it's smart enought to do is determine that its getting an incorrect signal from a sensor, throw an error, then use alternative tables with failsafe values. (e.g. missing maf will use an alterative fuel map that is TPS vs RPM rather than Load vs RPM)