t0m541
Veteran Member
Hi everyone, it's been a while since I have posted on here, so Happy New Year to all.
Before you all slap me down for my thread title and tell me I should be in 101, it is performance related.
As you will see from my cars spec sheet I have done a lot of mods and the old shed has been running well till late, after last Kerma chips It was pushing about 165whp, and I was quite happy, so I just left it at that.
About 5-8 weeks ago I began to notice that at WOT and full boost, my boost gauge is marked to 25psi and the needle would fly past it to the stop, the engine would lose power, turbo would drop to nothing, then jump back to life and boost would come back, not slowly but instantly, like flicking a switch, 3-4 times in quick succession, so I would back off the throttle and just drive "normally".
It was getting more and more frequent so I just kept on driving around gently, I did notice a whistling sound when boost came up like air either escaping or a blockage boost side of turbo, as I had the IC piping blow off on the M-Way a few months ago I decided to have a look in them to see if anything was "laying" around and causing a restriction, and apart fom a piece of cord, that I had used in making the seals, wrapped around the anti shudder flap, lucky it stopped there. The only other stuff I could see was a good deal of oil in the pipework.
After a while I began to notice the car was less reluctant to go to full boost and I would have to feather the throttle to get it there, but when it did it would take off and leave a huge cloud of black smoke which it has never done since the remap, it has always run clean.
I was putting the intermittent power fluctuations down to the turbo playing up, maybe sticking vanes, but as the car was always driven in a lively manner I cant really see that happening, then most recent, when the temperature dropped in December, the car would lose turbo completely going up hills at about 2k revs and struggle up till I could cycle the ignition.
I Vag-Com the ECU and it said bad MAF so I dioded it out, which helped a little, the power loss got a little less frequent but still happened, so I had a look on here and found Canadian Grizzly's limp mode diagnosis thread.
So I checked and changed vacuum pipes, swapped N75 for EGR controller which gave a little more boost but still got power loss, (limp), so I replaced N75/EGR controller back where they should be and plugged them into harness so the ECU would still see them and bypassed the N75, vacuum straight to turbo, (max vanes), but was still only getting 10-15psi boost pressure and still power was cutting back once 15psi was reached, I assume the ECU cuts fuelling to try to reduce boost.
This lead me to the MAP sensor possibly reading high or failing causing the ECU to read overboost, so have tried driving with it unplugged, the car struggled to make any boost, and plugged in but taken out of pipework and hole plugged so it reads atmosphere only, car drove better until it reached the 15psi limit then power backed off, ECU reduced fuelling?, which is restored by cycling ignition.
So how does the ECU know that the boost is reaching the 15psi limit to back the fuelling off, when everything is disconnected and also is there a electrical mod/bypass for the MAP, or even some kind of workaround for this.
Any input or new angles on where the fault could be would be helpful, the hybrid turbo was reconditioned about 18 months ago so the diaphragm should be good although I have not got under and checked if actuator is moving, damn snowy weather.
I realise I could just spend cash and buy some new sensors/N75 but I want to buy the right ones as I have been pricing the devils up and they aint cheap but if I have to do that, 3bar map sensor is probably a good idea, (part nos. and where from please if anyone knows).
So guys what do you think??
Cheers
Tom
Before you all slap me down for my thread title and tell me I should be in 101, it is performance related.
As you will see from my cars spec sheet I have done a lot of mods and the old shed has been running well till late, after last Kerma chips It was pushing about 165whp, and I was quite happy, so I just left it at that.
About 5-8 weeks ago I began to notice that at WOT and full boost, my boost gauge is marked to 25psi and the needle would fly past it to the stop, the engine would lose power, turbo would drop to nothing, then jump back to life and boost would come back, not slowly but instantly, like flicking a switch, 3-4 times in quick succession, so I would back off the throttle and just drive "normally".
It was getting more and more frequent so I just kept on driving around gently, I did notice a whistling sound when boost came up like air either escaping or a blockage boost side of turbo, as I had the IC piping blow off on the M-Way a few months ago I decided to have a look in them to see if anything was "laying" around and causing a restriction, and apart fom a piece of cord, that I had used in making the seals, wrapped around the anti shudder flap, lucky it stopped there. The only other stuff I could see was a good deal of oil in the pipework.
After a while I began to notice the car was less reluctant to go to full boost and I would have to feather the throttle to get it there, but when it did it would take off and leave a huge cloud of black smoke which it has never done since the remap, it has always run clean.
I was putting the intermittent power fluctuations down to the turbo playing up, maybe sticking vanes, but as the car was always driven in a lively manner I cant really see that happening, then most recent, when the temperature dropped in December, the car would lose turbo completely going up hills at about 2k revs and struggle up till I could cycle the ignition.
I Vag-Com the ECU and it said bad MAF so I dioded it out, which helped a little, the power loss got a little less frequent but still happened, so I had a look on here and found Canadian Grizzly's limp mode diagnosis thread.
So I checked and changed vacuum pipes, swapped N75 for EGR controller which gave a little more boost but still got power loss, (limp), so I replaced N75/EGR controller back where they should be and plugged them into harness so the ECU would still see them and bypassed the N75, vacuum straight to turbo, (max vanes), but was still only getting 10-15psi boost pressure and still power was cutting back once 15psi was reached, I assume the ECU cuts fuelling to try to reduce boost.
This lead me to the MAP sensor possibly reading high or failing causing the ECU to read overboost, so have tried driving with it unplugged, the car struggled to make any boost, and plugged in but taken out of pipework and hole plugged so it reads atmosphere only, car drove better until it reached the 15psi limit then power backed off, ECU reduced fuelling?, which is restored by cycling ignition.
So how does the ECU know that the boost is reaching the 15psi limit to back the fuelling off, when everything is disconnected and also is there a electrical mod/bypass for the MAP, or even some kind of workaround for this.
Any input or new angles on where the fault could be would be helpful, the hybrid turbo was reconditioned about 18 months ago so the diaphragm should be good although I have not got under and checked if actuator is moving, damn snowy weather.
I realise I could just spend cash and buy some new sensors/N75 but I want to buy the right ones as I have been pricing the devils up and they aint cheap but if I have to do that, 3bar map sensor is probably a good idea, (part nos. and where from please if anyone knows).
So guys what do you think??
Cheers
Tom
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