Intermittent limp mode and other issues.

[Spence_12]

For the last few months my 04 182 has been going into limp mode very intermittently with revs capped at 3000, but absolutely no pattern to when it happens. When the fault occurs the engine light is on but there are no other lights on the dash bar the ABS light (which i believe is an issue for a separate post).

Took the car to a bloke recently and code p0120 was showing up. He swapped the throttle body and pedal over for second hand ones that were working and test drove the car before telling me it was fixed. I picked up the car and straight away it goes back into limp mode.

I'm a bit stumped as to where to go next. I've had the large white connector under the fuse box apart and cleaned up any dirty pins i could see with a file but that hasn't worked. Am i right in saying there's also another connector somewhere near the washer bottle that can cause problems?

Another thing it might be worth mentioning is that approximately 18 months ago i removed my sub from the car and inadvertently left the live wire touching one of the others in the boot, which completely drained the battery. Since then if i wait more than a few days between driving the car the trip computer/clocks all reset upon starting, as if the battery has lost charge. I'm not sure if this could be related because it happened so much earlier than the limp mode problem i'm getting but it may be helpful.

Thanks

Tom

 

[bloke]

does abs light come on when it goes into limp mode? no electrical fault light?

 

[STEVE.M]

The trip computer reset is indicative of a weak battery.

 

[Spence_12]

The abs light came on a couple of times over the last few months but always went away when the ignition was turned off and on again (a couple of times I could feel the abs kicking in at low speed).

The abs has now been on constantly for a couple of weeks and is on regardless of the limp mode issue. When the mechanic's scanner was plugged into the obd port the n/s front sensor was reading 0mph all the time and the n/s rear was reading crazy high (600mph+). The other two read at 0.2mph when the car was stationary.

The electrical fault light has not come on at any point. Mechanic suggested it could all be an ECU or abs unit issue.

 

[bloke]

so he might of well just said 'your car is faulty' as it's that vague saying what he did.

did it bring any actual does up? what did wheel speeds show when he drove the car?

 

[Spence_12]

I guess so. I'm guessing that was meant to say codes? If so it brought up a code for throttle position sensor circuit A coherence between track 1 and track 2, and also one for the brake switch.

With regards to the wheel speeds he drove me round the ground outside the garage at slow speed with the scanner connected. Both off side sensors appeared to read correctly though as I said when stationary they were still reading 0.2mph. The near side front read nothing at all and near side rear read extremely high, over 600mph when doing about 5mph.

 

[bloke]

so a sensor and check/clean main connector in fusebox under bonnet and take it from there.

 

[Spence_12]

Ok thanks. So would that essentially be check the abs rings and clean them up along with checking the condition of the sensors and associated wiring?

I've already checked the white plug for corrosion and cleaned up any I could see on the pins. I guess there could still be corrosion on them where each pin in crimped onto its wire but is there any way to get around that if so?

 

[STEVE.M]

Ok thanks. So would that essentially be check the abs rings and clean them up along with checking the condition of the sensors and associated wiring?

I've already checked the white plug for corrosion and cleaned up any I could see on the pins. I guess there could still be corrosion on them where each pin in crimped onto its wire but is there any way to get around that if so?

I solved my limp mode problems with a liberal dose of SERVISOL SUPER 10 to the 90 pin connector to the ECU & the ECU pins, after having no luck with the engine

bay fuse box plugs.

https://www.ebay.co.uk/itm/Servisol-Super-10-Switch-Cleaner-Lubricant-Contact-Cleaner-Mixing-Desk-Studio-PA/202077401067?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[Spence_12]

Thanks Steve, I'll have a look at that area this week and try and give it a clean up. I've got some IPA electrical contact cleaner spray so hopefully that might do the job.