ECU cutting boost with no fault codes present???

[MarkTurbo]

I've just put the engine back in my R after fitting a new clutch and gearbox, i noticed that it was only running 0.5 bar. Did the ecu fault code test and it came up with 13 (engine temp sensors)
I checked the 2 connectors (coolant i assume) on the water pump end of the inlet manifold and sprayed them with wd40, did the fault test again and came it came up 55 which means no faults.
Took the car up the road again and it was ok (running about 0.7 bar) but after a few minutes it went back to 0.5 bar again and the fault code test is still coming up clear.

Any ideas?

 

[Anonymous]

Have u put the boost restricot back into place?
cause if u dont u will run 7psi (0.5bar)

thats a thing to consider.

 

[MarkTurbo]

Whereabouts is the boost restrictor? Just out of interest. The restrictor must be there cos it did run at 0.7 bar for a while then it went back down to 0.5 bar.

 

[zia]

does it happen when the car is warm?

zia

 

[MarkTurbo]

does it happen when the car is warm?

zia

Yes, the car was fully warmed up when it cut the boost back to 0.5 bar.

 

[zia]

then it probably a bad connection somewhere start disconnecting and reconnecting the major bits like airflow meter/ temp/coil/dizzy etc.sorry carn,t be more helpful, recheck any pipe work you took off is the factory boost switch connected up correctly?

zia

 

[MarkTurbo]

I'll check the connections on all the main wiring connectors tomorrow, could just be that one of them has a bad connection and it only happens when i'm driving which might explain why the fault code check says everything is ok when the car is stationary
Also the boost switch is connected up the same way as it was before i took the engine out and it worked ok then.

 

[Boooooost]

This sounds like the same problem i've got I did my clutch and no the car runs to a bar then drops to .5 Powerstation reckon its the turbo but i'm not sure. I was wondering if it might be something to do with the boost solenoid or a waste gate problem.

 

[MarkTurbo]

I'm sure it can't be anything to do with the turbo or the wastegate, you said yours boosts to 1 bar then drops back to 0.5 bar, mine does the same thing (apart from i'm only running 0.7 bar)
Its gotta be the ecu detecting a fault somewhere and cutting the boost, i'm gonna look at all my wiring plugs tomorrow.

 

[Keira]

My mates was doing something similar.

No fault codes were showing, car was ticking over sh!te and wouldn't rev, managed to get it running properly twice by doing not alot but as soon as it was booted it would go sh!te again.

swapped ecus and the same thing :?: :?: Didn't ever get to the bottom of it and he hasn't bothered to get it in anywhere.

Its currently sat collecting birds poop whilst he gets saving for a full rebuild :evil:

 

[Edd]

but as Ian at hiteq quite correctly pointed out to me ( i had misfire on mine before it went to hiteq)

a rebuild won't necessarily fix the problem, he can rebuild it and still misfire, and he still has to track down the problem.

 

[Boooooost]

:roll: I must admit when I put it all back together I got 2 plugs the wrong way around and it wouldnt start but I swapped them back and it started ok and idles fine Ithink it must be an electrical problem myself but dont really know where to start :?

 

[Keira]

but as Ian at hiteq quite correctly pointed out to me ( i had misfire on mine before it went to hiteq)

a rebuild won't necessarily fix the problem, he can rebuild it and still misfire, and he still has to track down the problem.

The problem will obviously need sorting first but he's planning on getting it all done at once

Personnaly i'd get it running again before putting it anywhere as its abit of an open cheque book fault cos he hasn't got a clue whats wrong with it

 

[samellio]

I had this problem on ,y old car and never found out what it was..
It would be fine for a whole day around a track then for no reason would cut the boost.
Turn the car off for a minute then turn it back on and this should return boost to normal levels..

 

[GINGA]

The only sensor which causes the ecu to switch off the boost solenoid (and retard the timing) is the det sensor and it will only show up as a fault code if the readings are to far out of its range eg broken wire,short to ground etc if the det sensor is picking up det or back ground noise (or thinks it is) from the engine it will not show a fault code as its just goes into safety mode eg low boost, retarded timing
Easiest way to see if its doing this is when it drops boost again pull over turn the ignition off for a few seconds then restart and see if the boost returns to 0.7bar again :?: if it does you can be pretty sure the ecu is going into safety mode then you'll have to investigate whats causing it
Could also be a bad earth make sure the 2 earths on the inlet manifold have got a good conection as they are the main ecu earths.

 

[MarkTurbo]

Sorted now, my R's now boosting to what it should be again (all the way to a massive 10psi )

Took all the wiring connectors (that i could get to) off, airflow meter, coil, boost solenoid etc, had a quick look sprayed them with wd40 and put them on again and everythings ok now.

 

[ashills]

worry a few of u now lol
my det sensor kept showing a fault
retarded teh igntition etc
and when ehgine was stripped it turned out teh sensor was fine but was going into safe mod because of a cracked pistons causing its own knocking

 

[Boooooost]

Guess what i'll be doing this weekend Thing is it would be one hell of a coincidence if we both had a poor connection and the way my luck is at the moment the problem with mine will be impossible to find or expencive

 

[Anonymous]

Same thing happend to mine and...I fixed it!

1st check the earth to the airflow meter. add an additional one if required.
2nd DET sensor
3rd where I had cut the wires for my decat pipe when it got hot the outer sleve was expanding and shorting. trim it back and tape it up.

Job done!!!

Dunc