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S4 Not Producing boost over 60 KPA HELP!


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Dear all,

I am hoping that someone can help with this issue I am having for the last 6 months trying to find why the S4 Esprit has lost its boost.....

Since this is a long story I will try to provide as vital information as possible to explain the fault.

I used a stock S4 to upgrade and test some performance parts starting with the chips available.

All went well till we got to the red hot number 6 chip which clearly showed on the dyno that the car was starving of fuel.

We replaced the Fuel pump and secondary injectors with higher volume units. The car at that stage produced over 250BHP.

At that point we decided to import a stage 2 WC turbo which was installed and run at the Dyno.

From that moment on the car never produced any boost and I must highlight that John from WC has been fantastic with this issue providing ideas to resolve it.

He has also offered to replace the Turbo with a stage 1 since the car was running at 150PSI compression test, and that we did.

Replacing the turbo once again did not resolve the issue.

The car before the turbocharger installed had some mods, eg: sport exhaust, K&N filter all that is showing on http://www.lotusesprit.com.au/s4engine.htm

Since the car lost its boost from that moment I have collected all the freescan data I can to resolve this issue.

What's then been tested or replaced..

Replaced sparkplug leads

Replace ECM including Mem-calm from a known working car

Replaced battery

Replaced Turbo WC stage 2 to stage 1 WC tourbocharger

Preplaced Chips

Installed a mechanical boost gauge ( the gauge is showing max of 60kpa under full thottle)

Checked for leaks vacuum (however some time tast is a little hard to complete as the car need to be under load)

Checked wiring on the ECM (earth and positive connection)

Tested wastegate (hand pump)

Future replacement parts:

Since I am getting no error what so ever on the ECM during the test runs I am picking something not normal on the freescan data which I am working to understand.

The Knock sensor is showing on freescan 65 to 170 knocks and the battery Voltage not increasing pass 13 volts however the Knock Retard is at 0 which tell me that the timing is not changing which may limit the boost.

By the way the car is not backfiring it starts normal keeping its idle as it always did....

Due to these readings I will replace the Knock sensor since its not producing any proper readings on freescan and also the Frequensy Valve sensor which controls the wastegate since I can

Edited by greekmixS4
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I only had this problem once and for the life of me couldnt figure out what was wrong after lots of testing but mine was a 89 carbed turbo model. In my case the Turbo housing had a small crack in it. But you have noted that yours is new ?? it can t be that either. A sad process of elimination <_<

Sorry not much help but good luck!

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Thank you both for replying.

The turbo has been replaced now and checked by WC enginnering I dont think we have a bad product there.

The water temp is at 82 to 87 which is normal the Mat sensor is also at 43 to 48 thats has also been serviced recently.

This fault must be so simple that I am unable to find since I have looked at all the hard areas.

I need to also mention that the Sport exhaust system is only a few months old and has been tested with a standard turbo and produced 250bhp so there is not Issues with that I hope.

The information I need to establish is the state on the frequency Valve sensor which controls the wastegate boost. I suppose if that is faulty and not closing the circuit the boost will not be generated and there will be no error in the system.

Does anyone know how to realy test this valve unit????

The sensor when the car is idling is open .. does anyone know if this is right? I was under the impression that this valve should be closed till it receives a signal from the ECM at .85 bar to open and release the wastegate..... ??????

When the wastegate is disconnected from that it does produce .6 bar which is normal however nothing happens after that when connected back to the solanoid.

Edited by greekmixS4
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You say that you are getting 250BHP? At the flywheel or at the road wheels?

A standard s4 delivers circa 264BHP and up to 285bhp under hard acceleration for short periods.

Caught between a rock and a hard place in a catch 22 situation, So its 6 of one and half a dozen of the other. Your damned if you do, but your damned if you don't so shut your cock!!!!!!!!!!!

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Lotus Elise S2 Sport 130

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Rocket63 The dyno was showing 250 BHP= Brake Horse Power which means readings at the wheels. However the car was starving of fuel after 5k since the secondary injectors and Fuel pump are not up to that !!

The vehicle started with 203 BHP as factory I believe the factory is claiming 263 at the crank but this figure changes depending who you speak to.

Anyway the vehicle now is producing 170 BHP so when someone helps me to understand where the boost has gone I am sure I can find an extra 20 HP to much the factory number.

Just for the record the vehicle has only 35k on the clock with engine compression at150 psi

Love to see some suggestions regarding the boost though as I know the engine is healthy

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Your car should be 264bhp, 203bhp is an erroneous figure, where did you get that from?

Can you post up the freescan log? Your knock count is massive, are you using high octane fuel and this is being caused by pinking? Also, the fuel pump and secondary injectors should be good for the job, you shouldn't be having problems with them.

88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

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Well thats all very confusing. A lot of this does not add up. Perhaps you need to go back to basics and start from the standard set up?

Caught between a rock and a hard place in a catch 22 situation, So its 6 of one and half a dozen of the other. Your damned if you do, but your damned if you don't so shut your cock!!!!!!!!!!!

Lotus Espirt Turbo S3    

Lotus Esprit S4 

Lotus Elise S2 Sport 130

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Bibs.... Thank you for replying.

The fuel on the car is a standard 98 octaine from the Shell pump.

The initial dyno test showed 203 BHP as factory standard configuration.

You can see the development stages with the dyno tests on this page.

http://www.lotusesprit.com.au/s4engine.htm

Going back to standard set up will be a little hard at this stage since the pipe has been replaced.

However I can take it back to the last known working configuration which means the only think I need to remove is the Turbocharger and replace it with the factory one... Some how I dont think the turbocharger is at fault but after I replace the Knock sensor and the Frequesncy Valve next week I may have to go that way.

IMPORTANT QUESTION:

I am trying to identify how the frequenscy valve sensor is working in the circuit talking to the ECM.

Does the ECM request it to close the valve when its reveiving all the right signals or the Valve closes to produce the extra boost its required then the ECM pick up the boost signal and turns on the Secondary injectors.

.. Not sure if I am making a clear point but I am trying to determent this since I have replaced the ECM and the boost is not generated and I have a feeling the Valve is always off which causes only mecanical boost to pass through.

I am also assuming there is no leak with the vacuums or pressure as well

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From my understanding, the valve is normally closed - in this state all manifold pressure is present at the actuator and will give the 0.6 bar or so of boost. When the valve opens (actually repeatably open and close very quickly) it bleeds off some of the pressure seen by the actuator and therefore the actuator will open at a higher manifold (boost) pressure. If the valve is stuck open, or there is a hole in the actuator pipe, then I would expect the car to overboost.........................this is my understanding anyway!

Phil

98GT3

Edited by Kimbers - Mod
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Phil,

Yes thats what I understand also... However if the valve stays always off even if the ECM is telling it to open then you will get no boost right?

on the other hand what drives the boost or build up of boost in this case. if the valve goes on becuase the ECM has send the signal then the ECM needs to be satisfied with the boost going through the manifold. or maybe is the otherway around?

Does the valve goes open firts before the boost build up then the ECM does its thing?

I asume there is not mechanical fault with the engine no leacks, ECM and wiring ok and turbocharger also good then what can stop the boost from happening... I am down to two components, Frequesncy valve and Knock sensor but if the ECM drives the Frequescy valve them my fault is before that so I am wasting my time looking et that department.

Does anyone know if we can test the manifold for leacks? Its very difficult to listen to those when the car is reaving at 6K.. and you are driving it as well

Edited by greekmixS4
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Hi,

detach the vacc tube from the solenoid to the wastegate actuator. You should then overboost to 1.7 bar plus. Only do this for a few seconds to avoid a blow. Then you know tjat tje system works, if it does. If this is so, the electronics try to prevent engine damage due to false sensor readings. Trial and error after that... And you are sure on the acuator settings are correct ?

Edited by Kimbers - Mod
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Olaf S400 project www.esprits4.de

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If pinching or disconcting the vac line to the wastegate does not help

that means no electronics problem, but mecanical, its wastegate or restrictions

in the exhaust make sure ur cat (if u have one) has not falen apart and plugged up the flow,

also check the intake plmbing hoses if they r tight and bov if you have one may be leaking

good luck

Edited by Kimbers - Mod
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Sorry,

I confuse that one all the time because we call it vacum hose,

but u r right it has positive pressure to push the gate open

Edited by Kimbers - Mod
tidy post, please use add reply when replying to a post that is just previous, not quote and reply - thx
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guys thank you for your input.

The BOV is taken off the car so I can clearly listen to any other noises coming from the engine.

THE PIPE AND CAT ARE NEW only 500 klm completed with most of them on the Dyno.

Please see the website for the upgrade stages completed showing on my previous post.

When I disconnect the wastegate from the frequency valve solenoid I get only mechanical boost to 0.6bar. that’s what freescan and the mechanic gauge is showing.

I believe that is wrong since the wastegate should release at .84 or so but I am getting mixed answers regarding this.

Maybe someone can clarify this for me.

PS: Once again remember the ECM has now been replaced.. so how can we have an electonic fault here? It has to be mechanical or the frequency valve is faulty which I will find out soon when the new unit arrives.

Edited by greekmixS4
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Please remember that the electronics can limit boost to the mechanical value if certain parameters are not met, for instance if the water temperature is below 72c I think. The official value for the wastegate opening pressure is 0.58 to 0.6 bar.

Phil

98GT3

Edited by Kimbers - Mod
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Hi All,

The mechanical boost setting is exactly 0.65 bar. This means, when you remove the electrical connector from the solenoid (=it behaves like a plain piece of pipe/tube) you should get exactly 0.65 bar boost.

Everything higher than 0.65 bar is done via ECU/solenoid.

In your freescan log you can see if the ECU is triggering the solenoid. IIRC its called Wastegate DC. Have you looked at this ?

The 0.84 bar figure is nonsense here ... old Esprit turbos had this setting as max. boost level.

Cheers

Marcus

guys thank you for your input.

When I disconnect the wastegate from the frequency valve solenoid I get only mechanical boost to 0.6bar. that

Marcus

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The numbers are duty cycle open time and are a percentage value ie. 100% would mean the valve would be being asked by the ECU to be open all of the time. If the figure approaches towards 100% it means that the ECU wanting the valve to be open to achieve more boost pressure, but it still isn't reaching it. I seem to remember (can't remember where though) that the duty cycle shouldn't really go above something like 70% to maintain proper control.

Did you disconnect the pressure pipe off the Actuator and see if you boost gauge goes higher? I wouldn't do this for more time than needed to qualify and warm the engine up first! Certainly DO NOT drive it like this! This will at least tell you if your system is capable of boosting above the base actuator setting.

Phil

98GT3

Edited by Kimbers - Mod
tidy post, please use add reply when replying to a post that is just previous, not quote and reply - thx
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Tony,

This tells us that the ECU is working properly. It triggers the solenoid up to 93% open time. But apparently without physical luck ...

-> maybe the solenoid is just bad

-> maybe you simply connected the wrong solenoid to the wrong electrical connector (there are three solenoids and three connectors ... ;o)

-> maybe the turbo (actuator) is bad (= spring too weak to stay sufficiently closed

... who knows ???

Cheers

Marcus

www.PUKesprit.de

Marcus,

The wastegate DC on the free scan is showing me numbers from 0 to 93.

I can forward these files if you wish.

Edited by Paula&Marcus

Marcus

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Marcus,

Since I have replaced the ECM its clearly showing the computer is not the problem.

I can only hope the solanoid is the fault ans I will prove this next week when the new solanoid and knock sensor arrives.

Believe me the connectors are in the right spot.

What really is strange is why both ECMs are not reading any higher the 13.1 volts (battery) when the car is going.. this is a mistery which I hope is not causing this fault.

Regarding the wastegate spring as I said in my previus post its has been tested with a hand pump and passed, however I also have the original wastegate which I will replace as a last resort before I replace again the turbo back to the original system if the sensor I replace will not show any fix.

I will keep everyone posted as I go.

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Tony,

if you by pass the wastegate solenoid and run the hose streight to the waste gate you should have

.65bar boost if everything is ok mecanicly no metter what engine parameters say

if u disconect the hose complitely from the wastegate no hose atached u should boost quick over

1bar all the way to the fuel cut out point if every thing is ok mecanicly no metter what engine

parameters say

if u dont reach these values ur problem is mecanicly,

if it does than ur problem is electronics

hope this clarifys

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The numbers are duty cycle open time and are a percentage value ie. 100% would mean the valve would be being asked by the ECU to be open all of the time. If the figure approaches towards 100% it means that the ECU wanting the valve to be open to achieve more boost pressure, but it still isn't reaching it. I seem to remember (can't remember where though) that the duty cycle shouldn't really go above something like 70% to maintain proper control.

Did you disconnect the pressure pipe off the Actuator and see if you boost gauge goes higher? I wouldn't do this for more time than needed to qualify and warm the engine up first! Certainly DO NOT drive it like this! This will at least tell you if your system is capable of boosting above the base actuator setting.

Phil

98GT3

Phil,

I am not relly following your instruction here regarding disconnecting the pressure pipe??

Do you mean disconnect the wastegate from the solanoid by commecting the wastegate directly to the turbocharger housing?????? because this has been tested and and there is still no boost.

Tony,

if you by pass the wastegate solenoid and run the hose streight to the waste gate you should have

.65bar boost if everything is ok mecanicly no metter what engine parameters say

if u disconect the hose complitely from the wastegate no hose atached u should boost quick over

1bar all the way to the fuel cut out point if every thing is ok mecanicly no metter what engine

parameters say

if u dont reach these values ur problem is mecanicly,

if it does than ur problem is electronics

hope this clarifys

Tony94S4.

Can you provide me with what you mean by disconnecting from the solanoid.. there are two hoses connected to the frequensy valve solanoid .. do you mean disconnet both of them and just have them hanging free ? will that give me bost all the time?

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OK, to make it a bit clearer for you, all you need to do is disconnect the pipe that connects onto the wastegate actuator capsule at that point - this pipe is about 7 or 8mm diameter. The pipe that you take off should have it's end blanked off really for the test. As I have said before, only do this test to determine that you can mechanically produce more boost - NO DRIVING!!! If you see 1 Bar or so then it is your electronic control system that is faulty - maybe just a jammed air soleniod - maybe something else, but you can't move forward without determining that the mechanical side is ok first.

Phil

98GT3

Edited by Kimbers - Mod
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