Hesitation!

[GazzaG60]

first knock sensors.

put a bar on it and tap it lightly with a hammer when the engine is running. you should see/feel the engine stumble a little as it pulls timing.

if not look at the wiring and make sure of no splits in the wire or shield. they are sensitive to this. slighly loosening the sensor will make it more sensitive and tightening will make it less.

on the hoses do the **** test. give the hose a few pulls a couple of inch from the item be it fpr,ecu or whatever. if it feels weak it is. cut it back a little.

the screach could be boost leak or even knackered turbo.

[stevieyid]

If the turbo is knackered surely it would not pull any boost or if it did then would have gone by now? The turbo was second hand and looked fine when it was fitted

[GazzaG60]

the turbo would only stop putting out any boost if it couldn't flow more than the engine could suck.

its possible the fins are slightly touching the casing due to seal/shaft/bearing wear or play.

take a look in the coldside and see whats there.

does it have oil in the intake/exhaust

[stevieyid]

No il, that mean the turbo is doing as it should?

[stevieyid]

Put a new boost gauge on tonight and got no reading. This is the second one to do this. I took the hose off the t piece at the ECU and can hear the vacume etc. The pipe is possibly getting pinched somewhere. This owuld not affect the boost in anyway though would it?

[newsh]

If the boost gauge pipe is leaking it would really mess it up. Try connecting the gauge with a short bit of tube directly to the T piece.
I wonder if you have a leak inside the ECU? It has been known.

[stevieyid]

This is getting weird. Right got a small inch long bit of hose and connected the gauge to the ECU directly at the T-Piece. Guage reads -6, blip the throttle goes down to -0.8 blip it agin down to -0.9 and when driving goes to -1 bar. So i took the t-piece out and connected the gauge directly to the hose that feeds the ECU and it does the same. This must be the reading the ECU is getting even on boost! Any ideas?

[s2avant]

Are you saying that you only get vacuum on the guage and not boost pressure? When driving does the vacuum reading change? As in when it comes on boost does the reading on the guage go up or down?

If I'm reading it right then the hose to the ECU is connected to the wrong place on the engine. It sounds as though it is connected the wrong side of a 1 way valve (i.e a vacuum circuit that never sees boost - AC recirc or rear diff controller for example)

Can you trace the end of the ECU hose in the engine bay? I wonder if the vacuum lines have been reversed somehow. There should be two going through the bulkhead. One for the ECU and one for the rear diff (and AC if fitted). IIRC the ECU should connect into a t-piece on the back of the intake manifold. the other stem of the t-piece should go to the fuel pressure reg.

Edit: Also check by the ECU. On my car Carly managed to kick the end of the recirc valve on the AC and I was left with a vacuum line hanging down by the ECU. Could they have been accidentally swapped over? I know it sounds daft but sometimes it is the silly little things that cause the problem.

Ben

[stevieyid]

Yep thats right not getting any boost pressure reading on the gauge at all. All im getting is a vacume readingwhich eventually hits -1bar then does not move from there. Ill take a look at the hose if i can find it in there. Where abouts is the valve? Terrybullwon has been working on the car but im sure he has not had cause to touch that ill drop him a text.

[s2avant]

The AC valve is under the passenger side of the dash near the pillar. If you take the a-pillar lover trim off you can follow the pipe from the water trap to the ECU and also check it from the watertrap to the engine bay. Be careful with the trim though as they are obsolete.

I haven't got a diagram to hand but if you can check the hoses both in the car and the engine bay then we can tray and work out what is wrong and where.

Ben

[stevieyid]

Thanks Ben. Yeah ill try and take a look. I take it the gauge is reading the same as the gauge it would mess all the timing up etc? Seems to drive fine though except on full boost

[s2avant]

Someone is bound to be along in a minute to describe what the ECU does in the absence of a boost signal but with a vacuum only signal I would guess the ECU would try to get the figure up by increasing boost etc which would cause all sorts of issues.

Ben

[stevieyid]

Sounds about right. Any tips on getting the trim off without breaking it?

[newsh]

If there's a leak on that line to the ecu or its disconnected the car drives fine but runs really bad on boost, holds back and misses, I had this at the Donnington track day and only discovered the leak on the way home! I'd say you've found your problem mate.

[stevieyid]

Thanks John. How did you rectify it? Do you have to replced the whole line? Is it a PITA job? U about tomorrow night?