low turbo boost

[guncharmer]

hello to all,this is my first post, tonight had diagnostics on my terrano 2 2.7tdi swb as have had the mil light on since buying the truck a month ago,its had new oil.air and fuel filters,nissan parts.changed the maf after it conked out in 5th gear,when it did this i opened the air filter housing and thats when i noticed how dirty it was,it restarted and the mil went out for appx. 500 yards and then came back on. got a maf off ebay,it drove fine for half a mile then into what seems like limp mode,wont go over 2k revs,put the old one back in and cleaned it with carb cleaner and meths,drove ok with the occasional misfire,so got a bosch maf and drives without hiccup but a bit gutless.with the original maf one trip it was flying and could feel the turbo coming in,i really thought the new bosch maf would sort everything but definite lack of power,drives smooth with mil light always on. so back to tonight i have a PO235 code and am told it is low turbo boost,i dont know where to start,the truck was first reg sep 2001 and the fuel pipe on top of the fuel pump fixes to another bolt about 1 and a half inches long and this screws into the fuel pump,just thought i should mention this as have read about the mini filter,any help much appreciated,not sure where to start !

 

[scott301004]

You never bought your maf of a seller called Theairflowmetercompany did you cus I had one of them through e-bay and it got here today and the pissing thing wont rev when the sensor is fitted yet once the old one is back on the car revs fine.

 

[Toolbox]

Hello guncharmer and welcome.

Could you tell me how many pins your diagnostic connector has is it 14 or 16?

Just trying to establish if you have OBD1 or2.

 

[guncharmer]

hello and thanks for replying, its a 16 pin,

 

[extreme-4x4]

You never bought your maf of a seller called Theairflowmetercompany did you cus I had one of them through e-bay and it got here today and the pissing thing wont rev when the sensor is fitted yet once the old one is back on the car revs fine.

why dont people go and buy a nissan one... ebay's good but i wouldn't buy a maf from there:doh:doh:doh:doh:doh

 

[guncharmer]

You never bought your maf of a seller called Theairflowmetercompany did you cus I had one of them through e-bay and it got here today and the pissing thing wont rev when the sensor is fitted yet once the old one is back on the car revs fine.

hello,got mine from username partsdome 99.7% positive feedback,was in ireland at the time so had it posted to uk address then on to ireland,after 7 days no returns, well 9 days had gone before i got it!,i read somewhere the copy ones are no good and the impedance or something doesnt match properly or somethi
ng,got my bosch one from andrew pages in hometown york as my nearest nissan dealership is 20 miles away, 62.66 plus vat and old one required in exchange,nissan quoted 75.00 plus vat without exchange,the bosch one from pages is identical to the old one except no nissan part number or nissan stamp,still have a niggly feeling i should have gone to nissan.

 

[extreme-4x4]

hello,got mine from username partsdome 99.7% positive feedback,was in ireland at the time so had it posted to uk address then on to ireland,after 7 days no returns, well 9 days had gone before i got it!,i read somewhere the copy ones are no good and the impedance or something doesnt match properly or somethi
ng,got my bosch one from andrew pages in hometown york as my nearest nissan dealership is 20 miles away, 62.66 plus vat and old one required in exchange,nissan quoted 75.00 plus vat without exchange,the bosch one from pages is identical to the old one except no nissan part number or nissan stamp,still have a niggly feeling i should have gone to nissan.

still have a niggly feeling i should have gone to nissan .... that will be the guarantee with nissan

 

[ern1e]

try these www.fuelparts.co.uk we use these at work thay do pattenor gen parts

 

[Toolbox]

hello and thanks for replying, its a 16 pin,

Thought so, its OBD2
P0235 is an OBD2 code and listed as Turbocharger Boost Sensor Circuit Malfunction, this does not suggest you have low pressure just that there is a malfunction in the electrical circuit.

You will have to look around the inlet manifold to see if you have such a thing fitted as the pre 2000 models do not have one fitted and I am not sure if you will have one either.

 

[Terranosaurus]

still have a niggly feeling i should have gone to nissan.

There will be a guarentee with pages too - never had any problems with stuff off them.

BTW guncharmer whereabouts are you from? I'm in South Milford, south of Tadcaster.

 

[guncharmer]

Thought so, its OBD2
P0235 is an OBD2 code and listed as Turbocharger Boost Sensor Circuit Malfunction, this does not suggest you have low pressure just that there is a malfunction in the electrical circuit.

You will have to look around the inlet manifold to see if you have such a thing fitted as the pre 2000 models do not have one fitted and I am not sure if you will have one either.

thanks again for replying,any clues as to what it may look like and if i dont have one have you heard of anyone correcting this fault code,cheers.

 

[guncharmer]

There will be a guarentee with pages too - never had any problems with stuff off them.

BTW guncharmer whereabouts are you from? I'm in South Milford, south of Tadcaster.

hello, am in york itself

 

[guncharmer]

had all the turbo pipes off today and all seems ok,turbo impeller spins nice and freely,disconnecting pipes makes no difference to running,going to take the intercooler off and inspect next. does anyone know where the turbo charger boost sensor is?,or even if it exists as thats what the po235 diagnostics code is suggesting is at fault ,i have not found anything electrical attached in this area yet,also i read somewhere on the forum to be careful when removing the intercooler,can anyone tell me what to be wary of?,will be grateful of any replies

 

[Darwin]

dont worry about anyone saying about no returns , you are covered by the sale of goods act and the distance selling act.

 

[guncharmer]

mil light etc.

hello again,i posted earlier under low turbo boost,here is an update.
checked all pipes and had the intercooler off,all clean and airtight,mil light on,have had running problems ,all fiters and oil changed,new bosch maf,runs ok without misfire but seems a little down on power and doesnt rev freely above appx. 3500 rpm,feels constricted.checked the maf voltages as per download section,all ok and voltage increase with revs 4 volts plus. with the intercooler off and engine revs increased the turbo outlet pipe blasts air out proportionate with increase in revs.
now this is what has me baffled,the throttle control valve and the egr valve have no vacuum present at idle and according to a manual the throttle control valve spring should move up and down with an increase in revs,this does not happen ,even more baffling is the fact with the maf disconnected it drives exactly the same. i have checked the breather air circuit,no problems found,i dont know where the vacuum in this pipe system is supposed to originate from .having spent in excess of 30 hours plus reading and googling am non the wiser, turbo spins freely,no noises.
one thought i had was if the turbo was overboosting would the ecu reduce fuel because of this,the actuator rod on the wastegate lever moves when gripped with pliers,again the absence of a vacuum at idle which it seems should dissipate gradually with engine revs is troubling me as i dont understand what should be happening or what ought to produce this vacuum,please help!

 

[guncharmer]

mil light etc.

the fault code causing the mil light is po235,turbo boost sensor circuit A malfunction,i am now pretty sure i dont have a turbo boost sensor as i cannot find it on any wiring diagrams,this is a fault code on all obd2 ecu's and generally seems triggered by something else,

 

[Toolbox]

Hello again Guncharmer,

Firstly I have merged both your threads together to make them easier to follow.

Have you followed/ traced the vacuum line back to make sure the tube is sound and not blocked? It may have been blocked in the past purposely to prevent the EGR from working.
You could also try testing the operating voltages as per the manual.

If the Turbo was over boosting, with out a boost pressure sensor the ecu wouldn’t know.

 

[scott301004]

I had A series one escort rs turbo when I was much younger and that had an overboost prob and it used to cut the engine of until pressure had dropped.

but then that was a classic sports car not a pulling machine that should do a trains job

 

[guncharmer]

thanks toolbox for sorting my threads, i have now found vacuum pump,there is a pipe leading from it connected to 2 of the 3 solenoids under the air filter housing,prior to the solenoids it branches out to the brake servo,vacuum is present in this pipework right to where it attaches to the solenoids(pulled off pipes here) .however there is no vacuum coming out of the solenoids(engine at idle),the two pipes comong out from the solenoids connect to the egr and the throttle control valve,the manual is telling me there should be vacuum when idling,all the pipes seem to be connected properly as they are colour coded.tested all for leaks,no probs. the manual i refer to is online and i access it by going to members tips,page 2,thread by captlimey(workshop manual for terrano)and clicking on the link. so i am thinking is it likely these solenoids are duff or is there an electrical problem telling them not to pass the vacuum through? could anyone tell me if they see the throttle control valve plunger spring mechanism moving up and down with engine revs,mine is always open(had intercooler off and looked in)though it moves freely by hand ,also would an egr valve stuck open cause a lack of top end performance or indeed any effect.
now just to make this more confusing the jeep drives ok,no misfires since changing maf,filters etc,however it STILL drives ok with maf disconnected ,there is no change at all,its just down on acceleration and not revving freely above appx. 3300 rpm.same as when maf connected(maf checks ok) its a 2001 terrano II 2.7TDI SWB COMMERCIAL,96k,nissan history to 72k,since then its had oilchanges etc,a clutch and recent full exhaust,this was before i got it and i mention the work in case there are sensors etc close to where the mechanical work has been carried out. also whilst searching the net a site topic was shown on google saying , diesel ecu,bosch 0281 prone to throwing po235 codes,couldnt find any info when i clicked on it,the site was a repair outfit, bba. something?next i am going to check wiring earths(any tips cos i will have to look for them,i still think it may be something simple thats got the ecu confused or i think i mean i hope it is as i have no pennies for the main dealer,cheers,any thoughts welcomed.

 

[lacroupade]

was it an old wives tale about disconnecting the battery overnight to see if it loses its all its little bad memories?!