One reason you can`t splice or use a Universal sensor is because one of the wires is hollow and detects the ambient or surrounding temperature, so if you cut and solder or whatever the signals cannot get through.

So because the last owner has cut my wiring up next to the fuse box and put a electrical choc block in between lambda and wiring there even if i get a genuine volvo one it will still not work a 100% or cause me issues ?

Would I be better replacing the whole wiring I'm guessing that could be a pain to do :(

If you buy a new lambda it will come with wiring and correct connector to just plug in.

Ah just removed the plastic cover on the bulkhead and found all the connections :thumbs_up:

After doing that it is the rear lambda that has been spliced in to and a aftermarket sensor fitted.

The front one is orginal and hasn't been changed.

Is the 2nd lamba as important as the front one ?

No it's not as important as the front one. Some people say it is critical for fuelling but it's mainly there to ensure the cat is working. I was told this by the guy with the most powerful T4 in the country. When my old one was duff I didn't even notice the difference tbh. I only noticed when I got a code thrown. Obviously it's worth replacing just to be 100% the car is running A1.

Been out having a fiddle with the actuator again wound it back out more to see what it did found boost a bit slower to come on and higher up the revs it then kicks in but still hitting 1.1 bar and spiking right up to 1.5 sometimes as well :stormy: worried its going to damage something going to drive very slow until i can get it sorted.

Disconnected the bcv drove it and hit 0.6 bar and wouldn't go over that plugged it straight back in as was only for a quick test then back to 1.1 upwards again so looks like that is working ok should be as only just replaced from volvo.

code reader should hopefully be here this week so see if that brings anything up.

Don't wind it out past the point where it lines up with pin otherwise your wastegate will be slightly open hence taking longer to build boost. I've always used a MBC but the BCS is the safer option so keep it fitted if you can (although I find MBC more fun and never let me down). I do have the luxury of forged rods and pistons though. It must be the BCS struggling to reign in the strong actuator. I'm glad you didn't buy the really strong one that I think someone suggested. 1.5 is a bit much on stock injectors, about 19psi is said to be the max. It's trial and error with aftermarket actuators when using the stock BCS, esp as your car has an unknown map and turbo.

I would say your options are either

Send it back and get the one rated at slightly less pressure and run your old actuator for time being. (ideally)
It didn't cure your 4000rpm problem anyway did it?
or

Fit a MBC and run whatever boost you choose (less safe on stock engine)

Ps if it makes you feel better my car is giving me headaches to. Waiting on the postman for sensors atm. Fingers crossed it fixes it.

Going to scan for codes first then see what that shows up

Should the car not hitting standard boost as nothing has been turned up or would the new actuator increase the boost even when the arms at it's lowest setting as me adjusting it seems to make no difference hits same boost levels everytime and overboosts ?

Depending what that shows might then try a mbc and set it at 1.1 bar as would be happy if i could get that through the whole rev range without it dieing off after 4000/5000 rpm

Apart from this issue the car runs great and no other problems so hopefully i can get to the bottom of it soon :thumbs_up:. Everytime you try a new fi and it doesn't work makes you feel just that little bit more gutted.

Hope you get yours sorted out soon :thumbs_up:

Heres a quick explanation how I understand it. The stock ECU thinks you have a stock actuator. The BCS duty cycle is within the ECU's map and is mapped for a stock actuator. To control boost the ECU knows how much it needs to alter the BCS duty cycle for the stock actuator. With your stronger uprated actuator, the ECU is still using the old settings as it doesn't know you have replaced the actuator for a stronger actuator and therefore struggling to keep boost low enough. I know the EMS2000 has the ability to learn but I'm not sure how much adaption it has to alter the BCS.

A MBC isn't ideal as you remove one safety parameter, but without sending your actuator back or returning to stock it's better than running 1.5bar as your ECU can't seem to control boost anyway with the stronger actuator! Just start MBC at the lowest boost setting and adjust from there. Keep the boost sensible and you won't have any problems. My MBC is made by Turbosmart and works fine.

Sorry it's not sorted yet but still better than spending £200 on a stock actuator from Volvo!

The only good thing about all the problems on my car is I have learned so much about it and the basics of turbocharging, mapping etc in general. I bet you have learned quite a bit just from this one problem lol

Looking at your pic. of the wiring and now you say you have found the connectors on the engine bulkhead. Vadis says they BOTH go to this panel but they don`t ! they don`t on the `98 T4 anyway

The front O2 sensor is the first connector looking at it on the left but the rear O2 sensor connects with a smaller plug after going through the floor above the cat. and plugs in a small connector behind the centre console.

To me it looks as though the previous owner got confused as he could not find the connector, but if when you get the rear sensor you will see the small plug on it together with a rubber grommet for the floor pan hole.



I do know what you say Mitch, but it doesn`t matter who told you that the rear O2 sensors only looks after the cat., because your own actual experiences are the ones that count.

When i bought the `98 T4 the lamda light was on and i was told it was the front O2 sensor, i had no code reader then so had no idea of P0...number

So i replaced the front one and after £146 (3yrs ago) the car still performed the same exactly and the light was still on.

Then learnt there was another sensor the rear one but i had now bought the scanner and the codes told me it was the rear one faulty, so i paid another £146 from Volvo fitted it, the light was out and the car went like the proverbial rocket it didn`t even have to learn the new parts were fitted.

So just believe me it does make a difference if you want the motor to perform to have things all correct and just don`t listen to those that may not have it happen the same way. As they said in the War years talking is dangerous!!

You don`t have to take any notice of what i say as i am only here to help others learn and also give my own practical experience.