Newbie - Help needed, got boost issues with my LCR

[JBRADY95]

Hi everyone,
My names John, I have recently bought myself a 2004 Mk1 Leon Cupra R BAM. Paid just £1400 for it which is cheap, its in fairly good condition for its age however it was cheap because it has boost issues, I am confident home mechanic, being able to do clutches, head rebuilds, all suspension, brakes etc so I thought it would just be a sensor or something simple.
It starts fine hot or cold, runs fine etc just no boost, its just flat and wont rev over 5000ish rpm.

So first thing I did was plug it into my OBD reader and it was coming up with a Coolant temp sensor fault and Lambda Sensor 1 bank 1 fault.

I got a new temp sensor and fitted it that cleared that code, and I fitted a new lambda sensor but the code came back again and still no boost. So thought well I'll try a few other sensors to see if that does anything.
Changed MAF sensor, MAP sensor, N75 valve, N249 valve (has been bypassed but still plugged in), checked the fusebox on the inside of the drivers door but not sure if theres another fusebox to check? But still no boost. It sometimes boosts to 0.5 bar for a few seconds but then cuts again, and I have had it boosting at 1.5 bar once or a second but cut again. When I got it, the nuts on the actuator were loose so I tightened them, not sure if theyre in the wrong place its possible for it to not boost at all? Ive tried adding preload and playing with it but no luck.


So I'm back to the Lambda sensor, tried 2 second hand sensors now both working in previous cars and then Ive tried a brand new one from Euro Car Parts and still throwing up a code, sometimes itll come up with P0030, sometimes P0031 and sometimes P0032. All wiring looks to be fine, it still has the cats in so not because of a decat but it has been remapped. The guy had it running fine up until a few weeks before i got it, I also know the person who owned it before the guy i bought it from too and he said its not changed since he had it and it was fine when he had it too.
So where do i go from here, im stuck. Had the full front end stripped, checked for any leaks or splits in intercoolers and boost pipes and vac lines etc and all ok.

Any ideas or help would be appreciated as I want to get out and enjoy it!

 

[JBRADY95]

Can anyone help


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[Connorg115]

sorry to hear you're having trouble!

them codes are very specific to the pre cat lambda sensor.

It was the pre cat sensor that you changed wasnt it?



BTW I am not a mechanic, im just trying to help

 

[JBRADY95]

sorry to hear you're having trouble!

them codes are very specific to the pre cat lambda sensor.

It was the pre cat sensor that you changed wasnt it?



BTW I am not a mechanic, im just trying to help

Hi
Yes the precat Sensor I changed, at the back of the engine bay


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[JBRADY95]

Could a bad fuel pump cause this issue?

 

[verbal_kint]

It is possible that the lambda is faulty but you should first check for air leaks in the system, a smoke test will do that.

The MAF can be cleaned rather than buying new, buy new if cleaning fails.

Lambda sensors can also be tested for continuity and correct working - need multimeter.

The retaining nut on the actuator rod will not help at all, most likely it has vibrated down and basically not opening the turbo enough so no boost.

Resetting the actuator is not too bad but you will need a vacuum pump.

 

[Gaz20VT]

Some good points above but just one small correction to this:-

The retaining nut on the actuator rod will not help at all, most likely it has vibrated down and basically not opening the turbo enough so no boost.

Resetting the actuator is not too bad but you will need a vacuum pump.

The actuator on the LCR is a pressure-operated one - so a small pressure pump is needed.

On the petrol turbos, applying pressure to the WG actuator opens the WG - so reduces boost.

On the Diesel turbos with Variable Nozzle Turbine, applying vacuum to the actuator closes the vanes, so increases boost.

If the preload on the actuator rod is too low, the WG will open too early - underboost. If the preload is too much, the N75 will have more difficulty controlling the boost, and an overboost condition could occur.

Hope that helps.

 

[JBRADY95]

It is possible that the lambda is faulty but you should first check for air leaks in the system, a smoke test will do that.

The MAF can be cleaned rather than buying new, buy new if cleaning fails.

Lambda sensors can also be tested for continuity and correct working - need multimeter.

The retaining nut on the actuator rod will not help at all, most likely it has vibrated down and basically not opening the turbo enough so no boost.

Resetting the actuator is not too bad but you will need a vacuum pump.

How/where can I get a smoke test done? Car is currently SORN until its working right so cant really drive it anywhere

Ive changed the MAF for another one already and no change but may still try cleaning.

 

[JBRADY95]

Some good points above but just one small correction to this:-



The actuator on the LCR is a pressure-operated one - so a small pressure pump is needed.

On the petrol turbos, applying pressure to the WG actuator opens the WG - so reduces boost.

On the Diesel turbos with Variable Nozzle Turbine, applying vacuum to the actuator closes the vanes, so increases boost.

If the preload on the actuator rod is too low, the WG will open too early - underboost. If the preload is too much, the N75 will have more difficulty controlling the boost, and an overboost condition could occur.

Hope that helps.

Where do I put the pressure pump/how do i do it?

 

[Gaz20VT]

If the actuator was that far out of adjustment you should see an underboost or overboost code.
I would concentrate on the Lambda codes first.

The pressure is applied directly to the actuator hose fitting, a few psi (5-7) should start to see the actuator rod extending as the WG moves off it's seat. Don't apply the full force of a compressor to the actuator, you'll pop the diaphragm.

 

[JBRADY95]

If the actuator was that far out of adjustment you should see an underboost or overboost code.
I would concentrate on the Lambda codes first.

The pressure is applied directly to the actuator hose fitting, a few psi (5-7) should start to see the actuator rod extending as the WG moves off it's seat. Don't apply the full force of a compressor to the actuator, you'll pop the diaphragm.

What can I use to apply this force? Apply a few psi and once it moves, tighten the nut until it stops venting it out?

 

[verbal_kint]

Thanks for the correction Gaz, was applying my diesel knowledge.

All garages can do a smoke test, or make one yourself with an old paint can (metal) or similar and a bit of tubing and sealant. What you are trying to do is push dirty air (smoke) through your system and see where it comes out.

Another way is to spray carb cleaner or similar around a running idle engine. The test here is that a fault in the vacuum will suck in the cleaner and the propellant in it will make the engine revs raise.

The obvious problem with the latter is risk of fire so like all the advice here it comes with a disclaimer!.

https://youtu.be/qTzDY95aqXg

Also look for smoke tester there.

 

[Connorg115]

I made my own smoke tester, it’s proper ghetto af but it got the job done!

I put some smoke pellets in the can and attached to the throttle body and blew and smoke came pouring out from under the intel manifold!

 

[JBRADY95]

Okay so haven’t done a smoke test yet but changed fuel pump tonight, Lambda code still showing. Checked wires and got voltage and continuity to and from the lambda so that’s okay.

So if the lambda circuit is low, what could that mean?
Getting fed up now


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[verbal_kint]

Checked wires and got voltage and continuity to and from the lambda so that’s okay.

How did you test it?

 

[JBRADY95]

How did you test it?

With a multimeter, unplugged it and tested both plugs, tested the continuity and power. Obviously on the lambda side there was no power as it was unplugged but there was continuity and no resistance and on the loom side there was 3-4 volts? And no resistance


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[JBRADY95]

Could it be the turbo itself? Broken wastegate or something?

 

[verbal_kint]

Just read your original post again and missed the codes bit before.

All those P0030-2 codes point to a problem on the heater control of the sensor. You need to test both sides of the heater control wire/s as it is likely a problem of broken wire or connection.

You will need to check the sensors wiring as depending on type and maker they could be white/white, grey/white or red/white but could be more.

 

[JBRADY95]

Just read your original post again and missed the codes bit before.

All those P0030-2 codes point to a problem on the heater control of the sensor. You need to test both sides of the heater control wire/s as it is likely a problem of broken wire or connection.

You will need to check the sensors wiring as depending on type and maker they could be white/white, grey/white or red/white but could be more.

I have checked the wires on both sides, both sides are good. Wondering if the lambda codes are coming up due to the turbo not boosting so running very rich, not burning clean? And the issues lie with the turbo itself?

 

[verbal_kint]

The turbo would not do anything to get those codes. They are specific to the heater control for the sensors but please check this on Gendan and Ross's sites.

I think you have 2 separate issues and looking for a common solution.

Have you checked the air filter is not blocked and checked the turbo wheels for excessive play, any smoke from the exhaust, unusual smell from the exhaust (fish is usually someone having fun), blocked exhaust (failed Cat)? Again a smoke tester can check for such a block.