Forge TIP fitted - now boost problems (resolved!)

[gex18]

As per the title really. Me and a friend fitted the forge TIP to my Cupra a few days back, and where as before it was peaking at 1.4 / 1.5 bar (its running a Revo stage 1 map) it now refuses to go past 0.9 bar and is noticeably slower / less torquey

Suggestions?

All vac pipes seem ok and secured

 

[R1ch85]

Is everything done up properly? Did you use new jubilee clips? Did you put jubilee clips on everything?

It may sound like stupid questions, but thats the only thing that could be wrong I guess. It's literally a straight swap part.

 

[gex18]

Is everything done up properly? Did you use new jubilee clips? Did you put jubilee clips on everything?

It may sound like stupid questions, but thats the only thing that could be wrong I guess. It's literally a straight swap part.

Right, the problem gets ever stranger.....

The N75 valve is actually the wrong way round (so air is constantly being fed into the TIP). Swapped it round, the car only boosts to 0.4 bar. Linked it up to a battery to make sure it was working, its fine Tried another N75 valve, same problems.

So at the minute it seems to be the wront way round and is giving 0.9 bar (its in exactly the same position as it was with the standard TIP i,e, the wrong way and yet that was giving 1.4 / 1.5 bar).

Any suggestions? This is really bugging me now.

 

[EZ Tutty]

i've been helping ant (gex18) look at this fault, when fitting the TIP we noticed that the pipe from the N75 valve to the actuator had come off, but thought we must of pulled it off accidentally.

However I now believe the hose was never attached at all, and re-attaching this hose has caused the change in boost, so the problem may not lie with the drop in boost.

BUT whilst fitting the TIP i noticed the N75 was fitted backwards, the side that should go to the actuator was connected to the TIP, causing boost to be dumped straight back into the tip, and the Actuator not to be controlled properly, so we fitted it 'properly' with the long leg into the TIP,(as per some pics of other mk4 bays, and the same as my Mk3 Ibiza Cupra),

Then the boost only sits at 0.4bar, almost as if the N75 is never activated to bleed boost from the actuator line, or the ECU is in limp mode

Checked all hoses, tried the N75 off my Mk3 (all be it an N75J but it still should of done something, checked the voltage at the plug, and with the engine off, and the keys in at the 2nd click got 3.5v.. again same as my Mk3.

With the N75 in reverse, we still get 0.9bar.... Real confusing

 

[gex18]

Bump up.

The problem still seems to be there. Only boosts to 0.9 bar with the N75 valve the wrong way round, and only 0.4 bar with the N75 the right way round (it used to boost to 1.4 bar before).

Can anyone shed any light on the problem?

 

[Damoegan]

You can see my N75 valve in the top left of this pic, just to confirm the correct way it should be.

 

[gex18]

^ Putting the N75 that way round causes the car to only boost to around 0.3 / 0.4 bar, almost like its in limp mode, it feels very slow and sluggish. So currently it is plumbed in the wrong way round (as it was when we changed the TIP) and this enables at least for it to boost to 0.9 bar.

So just to clarify, when we changed the TIP we discovered :

- Acutuator Pipe wasn't attached to the turbo at all
- Melted 75 plug and wires (replaced and tested)
- N75 valve plumbed in the wrong way round (dumping air back into the TIP)
- N75 tested and working correctly (attached to a knackered car battery to test)

So atm I have a choice between 0.4 bar with the N75 correctly plumbed in and just 0.9 bar with it incorrectly plumbed in. Nowhere near the 1.3 bar I should be getting with the Revo Stage 1 map though

Help please!

 

[CJRamze]

I don't want to sound like a tit, But why dont you (For now) put the original TIP back on. If it goes back to the way it was before you've got a problem with the Forge Fitting/Pipe.

If it doesnt you know its something you've done between fitting things.

 

[gex18]

I no longer have the standard TIP, plus im 99% sure its not that causing the problems.

Any chance it could be the MAF at fault? The fact the TC light is on 90% of the time makes me think so, but this was replaced just 6 weeks back!

 

[Damoegan]

No, MAF wont cause this fault.

 

[gex18]

Damn.

Fault findings such a pain in the arse!

Will have to see what VAG com says I guess.

 

[gex18]

Finally managed to resolve this problem.

After linking up to VAGCOM there were 7 faults present, all open circuit faults too. Having replaced all faulty fuses (which had been left in place AND lined out, with the N75 swapped round and actuator pipe removed to give overboost), and swapping the N75 into its correct position, replacing the plug on the N75 and the wires all is good

Its better then before, holding peak boost until much higher in the rev range

A massive thanks goes out to Paul (aka EZ Tutty) for the help and resolving the problem for me - much appreciated mate

 

[Breezapom]

Glad its all sorted mate i hate it when u change something then something completely diffrent breaks

but at least people can check this fault first in the future

 

[Random1989]

did your car display any faults eg engine managemnet light on dash ?