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Model specific boards => Golf mk4 => Topic started by: sonyboy on 16 December 2010, 13:45
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hi, i have 1.8T agu engine, chipped to 195bhp, and it lost all its boost.
checked no boost leaks, no vac leaks, try to put new n75j and DV 710N but nothing, changed g62 coolant sensor and spark plugs, changed line from inlet manifold to PCV valve, all vac lines changed an tied with metal ties, maf reading normal around 2,9g/s idle, around 142g/s at max, no ecu errors over vagcom, lambda is +15% at group 06 MULT field(second field) seems normal, changed vac line from brake system to inlet manifold, cleaned IAT and MAF, even try to disconnect all sensors, and even disconnect from battery. checked PCV system, PCV valve is fine blocking in one direction. fuel consumptoin is fine with or without boost.
I have no boost at all, i cannot hear it any revs in any gear. Sometimes i have all its power and running for few days, and suddenly its just loss at its power and sometimes when i start car in the morning i have half of my power. same problem is when temp. is 25C or -5C.
So when car sometimes running great, turbo is sucking air you can hear it, its very strong suck of air, and pull is amazing.
help please
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i dont really no much but sounds like u have done a fair bit like ........maybe a turbo problem??? :undecided:
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Faulty MAF
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i can say when it is running its running amazing, i have no bad sounds and oil consumption so its not turbo, sometimes its running normal and there is strong sound of sucking air from turbo when spools, it is hard that turbo is sometimes working sometimes not. so its spools little bit at 1k you can barely hear it and than disapears.
i tried to disconnect maf but nothing, even cleaned it. i ordered new maf, should get it soon.
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+15% is a little too lean for my liking. There are various reasons why that may or may not be related to your boost issue though. MAF is a good start because they can be a b!tch to diagnose when the issue is intermittent especially on AGUs. You seem quite capable with vcds so try logging block 118 which will give you requested vs actual boost but probably more importantly n75 duty cycle. You could also check that your actuator is moving freely without any "sticky" spots.
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my engine is AGU, there is no groups past 35 as i notice, agu cannot measure boost. i will check wastegate thx.
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haha, yeah im tripping.. my bad. I forgot yours was agu in the space of one sentence (i blame lack of sleep). :laugh: you should still be able to log duty cycle (block 25?) and engine load req/act. Output tests are also useful, n75 should produce a healthy click.
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i connect my pc to my car over vcds and i got three messages, #1 Mixture adaptation( adaptation limit (add) exceeded, #2 n75 - output open, #3 intake manifold pressure - control limit not reached.
so i went and look at n75 and it was one of the two wires was broken at back of connector, so it was really hard to put wire back because only 4mm of wire was out of connector. i use a sort of wire clamp and solve it, when i cleared error message over vcds it didnt came back.
so ran car everything was like before, outside temp was -2 to -5, everything was fine.
even problem was solved, but i'm afraid that this not going to last long, problem is somewhere else because last time everything was fine no any errors no nothing and turbo did not want to spool. probably this was my mistake where i broke this wire trying to solve problem whn i was try to change n75 valve.
even from this view, let say small amount of power is needed from 1K to 3K, because before car ran amazing even from 1,5K you could spin the wheel in 2nd gear, now i need 3K at any gear except 1rs to make it spin wheels, it is small amout of boost al low revs only noticable for owner who drives car for a long time.
thanks, this was best forum ever i've visited, your answers where fastest and pleasant from any forum that i posted my problem.
i will let you know if any thing changes, or any error message apears, or my boost vanishes.
big thx
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Keep an eye on the fuel trims over the next few days. Avoid clearing the fault codes as that will reset the trims to 0. You should be able to get a new plug/repair wires for the n75 from a vw dealer
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i've already check group 6, second field lambda ADD is zero, means that idle is fine, third field lambda MULT is pulsing from +5% to +20%, this means that during drive car runs lean, so ecu is able to adapt to -+25%, in this case it is from +5 to +20% adapting. i'll try to solve it.
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dunno if uve fitted it yet but i had a very similar problem in mine, i take it when u unplugged ur MAF ur car refused to run as mine did...which is normal as for some reason most if not all AGU engines wont start once the MAF is unplugged unlike other cars which will simply run on a default factory setting..my MAF was the cause of a month or two of tinkering which finally ended in what i should of had checked more thoroughly...if u go to ebay u can pick a new one up for about 40 quid ish...just dont get ripped off as theres a tonne of people advertising the correct fitting MAF and they send you a different one...i got mine from a place called Europarts for 60 quid brand new...with the aid of a pack of security bits my power issues were solved! ill see if i can find a link to my old post with my description on it of what my problem was see if its anything like yours
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http://www.golfgtiforum.co.uk/index.php?topic=166128.msg1539688#msg1539688 as promised lol...thats pretty much what was going on with mine when the MAF was dodgy...intermittent fault...but it ran like a dog when it was on an off day
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The car should run on basic fuel/air settings with the MAF unplugged even on an AGU. I know mine does. I would say there is a problem if it doesn't
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nah mine doesnt, its not an issue just a problem with certain MAF types etc im told...some just refuse to start outright with it unplugged =\ i could be wrong however lol
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Get a genuine exchange MAF from TPS. Dont bother with ebay reps as people have had alot of problems with them.
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Sorry guyz problem not solved ;)
I have the same problem like before, i fix that wire on N75 valve and it ran fine fews days.
But this morning again no turbo, i look at errors over vagcom, but there is no errors at all.
Few days ago i had strong turbo spool and achieve 170 km/h uphill, this morning couldnt reached 100 km/h up hill. Same problem no turbo sound, no power from 1K to 3K, after 3K it ran good to 4.5K but not a bit like before, same problem. no idea.
Even i changed all vac lines from inlet to FPR and line to metal pipe from DV valve.
Lambda is fine from -4 to +7%, not bad for now.
I have no idea, i'll try change MAF and ordered Ignition Amp.
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Changed MAF, put brand new OEM. Two days it was running good, very smooth, no cold start misfire or so, and today i've lost half o my boost. suddenly i just feal that gas pedal is not under pressure, and i hit it to the floor and i got same situation like before, car was dead until 3K, and then there is 30 40% of boost. i can hear turbo but no max boost,
also i notice there is strange shake of engine at idle. car is shaking like mad but revs where constant at board no change?
i bought ignition amp i'm going to change it right now.
new maf did not solve the problem, but it is running better when cold very smooth during drive and after cold start.
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air leak? tried all the pipes including the one under the inlet manifold?
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few minutes ago i changed the ignition amplifier, no improvement. As I notice when i start the car and temp was aroun 2C, ca ran very good and there was strong sound from turbo of sucking air etc., as more as i drive it it getting worse.
even pipe between inlet manifold and PCV valve of breathing system is new. I checked air leak with air compressor no shhhhh sound no leaks, even changed vac line for FPR and DV valve.
everything is changed maf, ign. amp, g62 cooland sens, n75 tried J, DV tried 710n, vac lines, test leak, cleaned IAT sensor, pcv valve checked, connectins to sensors checked, wastegate is moving, turbo is running great when it is running there is strong suck of air.
Only what could be is lambda snesor, it is only one that is not changed. so is it possible when lambda is warming and warming that is getting worse for perfomanse. i have good readings from lambda at idle and running.
two pipes i dinot checked, that is from n75 to wastegate, and some kind from turbo to oil breathing system or pcv system ?
any new ideas???
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sounds like you no your stuff mate but have you thought about taking it to a garage....you must of spent hundreds :sick:
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again solved i have my power back, last time was wire on n75 and this time is second wire on n75. my mistake trzing to solve problem.
i have full power back when turbo is at max boost, only what i notice is loss of power and strong boost on low revs from 1.5kto 3k, after 3k pull great but before to much time to wait from 1.5& to hit max boost and car start pulling,
ideas????
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I have notice that when i start car, its running great even from 1K, specially pulls great from 1,5K revs, as much as it warms its lossing boost from low revs. one minute after cold start, much of boost is lost in low revs, but its fine from 3K as usual. so if i drive in 3rd gear from 1,5K and floor it to the ground i can barely hear turbo until it reached 3K and then pulls great, but when car is just started and when is cold in 3rd gear pulls great from 1,5K revs and you can hear turbo is spooling from low revs very strong.
any ideas about this, is there a way that lambda can cause this after warmup. I've tried with new DV it is the same situation, its no DV, N75,MAF, CTS that cause problem, all new.
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lambda could be a possibility, also have you changed the temp sender?
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lambda could be a possibility, also have you changed the temp sender?
+1
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temp sender changed, i have two it is same situation. lambda is not new, but dont seem to causing problems!
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Problem with narrow band system is they are hard to diagnose. you need to match the sensor idle readings with what VCDS is seeing. In the stock mapping the idel lambda should just be on the lean side of stoich around 14.7:1 - 15:1 AFR or narrow band volt reading of 0.6v to test the reading you need to use a wideband lambda probe up the tail pipe to compare (mot testers can read these for you)
What is your injection ms ratio to 2.9g/s? should be around 2.04ms with 2.5bar on the FPR.
The best way and fastest way to fix you problems in run the car up in the dyno and external log the IDC injector duty cycle with wideband lambda and fuel rail pressure. Steady state dyno testing at a held rpm of 3000rpm 4500rpm 6000rpm will show you exactly whats going on with the fuel system, plus using reverse maths using rpm, displacement and power, then we can work out how much air the car is using to produce that power and the given rpm and work the back from Lbs/min to g/s to compare the MAF scales.
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my fpr is stock i think it is 3bar, my idle is 2.9g/s and think it is around 2,5ms
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every morning car runs great, there is strong sound od turbo in any gear at 1.5K and car pulls great from low revs, as it warms for about few minutes sound of turbo from low revs dissapears and car pulls very poor from low revs, you have to hit 3K to hear turbo.
So some part is failing when it is warm, if it is pipe or some plastic pipe it cannot be warmed in a minute.
I tried to disconnect battery for about 15 20 minutes, and car ran few miles great with full power, and power is dropping as much as i drive it everydays, and after week or so power drops for about 30%, so only element that can lean the car could be lambda. bu i have good readings from lambda no errors or so.
this is my opinion, some element leans car and power drops as much as i drive it when i disconnect battery, no error over vagcom.
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today found leak at old DV valve, i tried to suck and blow air through DV and there is air shhhh sound when i blow through it. so i put new DV 710N and got little better boost from low revs. so even try to change N75 stock with new N75J it is little bit better in mid revs but i got big boost drop past 5K.
I notice more boost from low revs and i can hear stronger air suck and turbo spool in low revs but not in all rev range. i'm still looking for that loss of power, car doesnt pull like before not even close, so i'm thinkg of changing lambda but lamba seems fine in vagcom reading, voltage is fine, correction, mixture.
last thing what is not changed is lambda and turbo, there is a 220K kilometres on board, so turbo maybe weak. can this ko3 turbo last for about 220K with agressive driving????????????
any ideas may help!!!!