Couple more issues with the Q4

wrinx · 12-04-07, 22:57

Ok, think I'm getting on top of the little things and lack of turbo boost, will ignore the clutch release bearing for now

But, two more things...I'm getting a strange deep "dry" creaking sound when I turn the steering wheel. I'm wondering if it's the top strut bearings but have never heard the sound they make.

Other possibility is steering rack but I'm looking at the cheaper option first, especially as there's what looks like a leaky shocker so I may have to take the strut out eventually.

So, what do they sound like?

Secondly, when I start the car, from hot or cold, it backfires

What could this be?

A quick chat with Speedy (on 155.org) the other day, he suggested timing, my thought was fuelling...any advances? Seemed worse today with the heat...air temp sensor may be suspect too.

wrinx

Juan AR155Q4 · 13-04-07, 00:02

I'd check fuelling.
Do you have an A/F? Check the lambda sensor.
Do you smell fuel in the exhaust at idle?

**Steve Webb** · 13-04-07, 06:29

Hi Wrinx,

my steering rack didn't make any noises when it was giving up the ghost, just started leaking. I did get some noise when a top mount was on its way out though. I always find the power steering bloody noisey though.
Just a thought, but you could take the covers off your topmounts, give them a drop of 3-in-1 oil then see if you still get the noise.

With regards to the backfire at starting, is it a proper backfire out of the exhaust, or is it a blowback into the inlet system?

Also when was the car serviced last with regards to filters\plugs etc? And what plugs are in the car? Shouldn't make a difference at startup but once you start tuning the engine you really need to swap the plugs for something abit more meaty to deal with it.

My only experience of really bad timing was when I had the belts replaced and the exhaust cam was one tooth out !!! . Brilliant low range torque but no puff at all, the funny thing was that the car ran smoother than normal.

Before getting the timing/valve shims checked, I'd got round and check the air and water temp sensors. I'm pretty sure there is a check procedure in the workshop manual.

If you have got a plumbers merchant near you, you might want to go and get a decent pressure gauge and check the fuel pressure, (procedure also in the manual) it should be 2.5 bar normally, but not sure what it needs to be set to with a squadra chip. The Evocars chip needs 3 bar pressure.

On a boost note, you could always link the two small bore hoses coming into the bottom of the pierburg valve together with a straight through union. This would give you the overboost function permanently and so you should be able to tell if the pierburg valve is working or not. It might be that the wastegate has been set incorrectly and you are only getting 0.4bar base boost.

Few things for you to think about in there.

Steve

wrinx · 13-04-07, 09:20

:shock: Thanks guys....

wrinx

wrinx · 13-04-07, 13:29

Ok, looks like I've sorted he backfire and SOME of the turbo pressure.

No backfiring today and I've got 0.9 boost. Slightly more than base boost but still not up to the 1.5/1.6 I think I should be getting as the car is Squadra'd.

Will be messing with hoses...also can't hear the wastegate chattering which may be linked (but the actuator moves)???

wrinx

**Steve Webb** · 13-04-07, 14:10

No backfiring today and I've got 0.9 boost. Slightly more than base boost but still not up to the 1.5/1.6 I think I should be getting as the car is Squadra'd.

Whoooaaaa!!! don't even think of going to more than 1.4bar with a standard head gasket and head bolts. As thats all they can safely cope with.

Sounds like the Pierburg valve is not working, standard base boost is 0.7bar, which goes to 1.1 with the overboost function. Sounds like your base boost has been turned up to 0.9, giving 1.3 on overboost with the squadra.

Steve

q4fatboy · 13-04-07, 14:32

Wrinx, what did you do to find the extra boost ?

**AlfaJack** · 13-04-07, 15:33

Mine is the same as wrinx - 0.9 with a squadra - is there a way to test the pierburg?

**Steve Webb** · 13-04-07, 17:10

Seems like its about time I put together an article about the turbo/wastegate and pierburg valve. How it all works and how to test it. In the meantime I'll dig through the manual and see if there is a quick test procedure.
However from looking at the schematics the pierburg modulates the overboost by bleeding boost pressure from the inlet back round to the wastegate actuator to keep the pressure differential down and allow the turbo to make more boost.
I did think that you could just join the small bore hose from the inlet to the pierburg straight through to the wastegate actuator, but thinking more on this it would theoretically allow boost to build to unlimited levels, (well limited by what the turbo could produce)
You could try this, but it would be at your own risk, and only really suitable to see if the turbo could make more than the base boost level, for short periods as there are no safeguards.

First place to check if you are only making base boost is the small bore hose from the pierburg to the wastegate actuator.

Steve

wrinx · 13-04-07, 18:43

Originally Posted by q4fatboy

Wrinx, what did you do to find the extra boost ?

..err, replaced a split pipe

But not just any pipe, oh no....the GREAT BIG one for the intake

*muffled cries of you muppet wrinx!!!*

wrinx

**AlfaJack** · 13-04-07, 21:49

Originally Posted by Steve Webb

Seems like its about time I put together an article about the turbo/wastegate and pierburg valve. How it all works and how to test it. In the meantime I'll dig through the manual and see if there is a quick test procedure.
However from looking at the schematics the pierburg modulates the overboost by bleeding boost pressure from the inlet back round to the wastegate actuator to keep the pressure differential down and allow the turbo to make more boost.
I did think that you could just join the small bore hose from the inlet to the pierburg straight through to the wastegate actuator, but thinking more on this it would theoretically allow boost to build to unlimited levels, (well limited by what the turbo could produce)
You could try this, but it would be at your own risk, and only really suitable to see if the turbo could make more than the base boost level, for short periods as there are no safeguards.

First place to check if you are only making base boost is the small bore hose from the pierburg to the wastegate actuator.

Steve

You can make the turbo give about 1.5 bar by pulling one of the pipes off as I found out recently :shock:

Brul(tm) · 13-04-07, 23:30

Originally Posted by AlfaJack

You can make the turbo give about 1.5 bar by pulling one of the pipes off as I found out recently :shock:

And run in to trouble..... safty precaution from the ECU. You will get a fuel cut at this figure

At least from the standard and Squadra chip.

Greatings,
Marc

wrinx · 14-04-07, 08:05

Whoooaaaa!!! don't even think of going to more than 1.4bar with a standard head gasket and head bolts. As thats all they can safely cope with.

8) I got the figures wrong

Originally Posted by Steve Webb

Sounds like the Pierburg valve is not working, standard base boost is 0.7bar, which goes to 1.1 with the overboost function. Sounds like your base boost has been turned up to 0.9, giving 1.3 on overboost with the squadra.

Steve

Ahh, I see, butno way of testing it without a sillyscope afaik???

wrinx

wrinx · 14-04-07, 08:06

Why don't quotes work with the author's name?

wrinx

Brul(tm) · 14-04-07, 11:43

Originally Posted by wrinx

Why don't quotes work with the author's name?

They do work

wrinx · 14-04-07, 11:57

Originally Posted by Brul(tm)

Originally Posted by wrinx

Why don't quotes work with the author's name?

They do work

Just not for me....typical

wrinx

**AlfaJack** · 14-04-07, 19:35

Very wierd! The quotes code looks fine

wrinx · 14-04-07, 19:38

Yup, that's what I thought...tried playing with the code and only removing the poster's name works...but means there's no name of course

wrinx

Brul(tm) · 15-04-07, 00:35

Originally Posted by wrinx

Just not for me....typical

That's odd.... This post I typed everything instead of using the quote button to reply

As you see, no trouble at all

Greetings,
Marc

wrinx · 15-04-07, 05:59

Originally Posted by Brul

That's odd.... This post I typed everything instead of using the quote button to reply Confused As you see, no trouble at all Very Happy

Testing...

wrinx · 15-04-07, 06:00

Nope....that was typed.

wrinx

Brul(tm) · 15-04-07, 10:52

Originally Posted by wrinx

Nope....that was typed.

I realy haven't got a clue what's going wrong here

Qouting whitout the name of someone does work?

Greetings,
Marc

**AlfaJack** · 15-04-07, 22:19

Originally Posted by AlfaJack

Mine is the same as wrinx - 0.9 with a squadra - is there a way to test the pierburg?

I take it back, today I saw 1.1 - I was doing 50, floored it, after a few seconds I saw it climb to 1.1 and the speed had hit 80 pretty quickly - although there was not much inertia the speed does rack up nicely

Perhaps I wasnt being persistant enough on the throttle to make it hit full boost

I nearly went in to a Fiat Bravo doing this, slammed the brakes on big time - best to test the turbo on a quiet road rather than the M25!!! :shock:

markgq4 · 27-04-07, 08:39

i got evo`s chip and if i floor it in high gear goin slowly it makes nearly 20psi for a few seconds then drops back to around 14

mind you it did blow the end cap of the intercooler the other day

wrinx · 29-04-07, 09:21

Originally Posted by AlfaJack

Mine is the same as wrinx - 0.9 with a squadra - is there a way to test the pierburg?

I take it back, today I saw 1.1 - I was doing 50, floored it, after a few seconds I saw it climb to 1.1 and the speed had hit 80 pretty quickly - although there was not much inertia the speed does rack up nicely

Perhaps I wasnt being persistant enough on the throttle to make it hit full boost

I nearly went in to a Fiat Bravo doing this, slammed the brakes on big time - best to test the turbo on a quiet road rather than the M25!!! :shock:

The throttle has to be floored...iirc I've seen a similar figure, but only briefly. Will have to test it some more :twisted:

wrinx