p_gliddon Posted August 25, 2010 Report Share Posted August 25, 2010 Hoping for some advice here on a 1999 APY S3 87k... Car seems to be running well unless I floor it in lower gears, 2nd or 3rd where this problem is really noticeable. Car pulls well in these gears except after about a couple of seconds or at higher revs (not sure if time based or rev based) there is a spike in power. I haven't really noticed it before (owned the car 6 years). Seems either like a low boost problem or turbo lag getting worse somehow. -No faults showing, -I've disconnected the MAF and that makes no difference, -just replaced the DV as the old one had died and this hasn't seemed to have made a noticeable change. The old one was definitely nackered and now have the uprate 710N one. Would have thought i should notice a difference with this?? Maybe the vacuum line to it not controlling it correctly? My thoughts are either checking the vacuum lines again or maybe a N75 issue. Read somewhere the N75 solenoid on the turbo does not always throw a fault and might be slow controlling the waste gate? If its the N75 are they a cheap easy fix or not? The only other part that I though it might be is the engine coolant temp sensor but monitoring this through the AC display it rises constantly up to 90 degrees. Not sure if this could cause the fault described. I still have the old style black sensor not the uprate green one. Another £30 i dont want to spend if it doesn't sure anything though! What else could I look at? Really appreciate any help. Thanks Paul Link to comment Share on other sites More sharing options...
James Blonde Posted August 25, 2010 Report Share Posted August 25, 2010 I've had a similar problem on my A3 1.9TDI, that I'd put down to needing a new clutch (which its going in for on Friday...)....?! Problem appears in 3rd, 4th and 5th around mid revs when I put the foot down to overtake - the car over-revs before falling back, feels like the clutch is slipping, but the problem doesn't appear to have got worse, and doesn't appear in lower gears. The car doesn't feel like its been pulling as well as it used to either. If someone can give a definitive answer before Friday, I'd be most greatful!!!!!! Link to comment Share on other sites More sharing options...
p_gliddon Posted August 26, 2010 Author Report Share Posted August 26, 2010 I've had a similar problem on my A3 1.9TDI, that I'd put down to needing a new clutch (which its going in for on Friday...)....?! Problem appears in 3rd, 4th and 5th around mid revs when I put the foot down to overtake - the car over-revs before falling back, feels like the clutch is slipping, but the problem doesn't appear to have got worse, and doesn't appear in lower gears. The car doesn't feel like its been pulling as well as it used to either. If someone can give a definitive answer before Friday, I'd be most greatful!!!!!! Hi James, Yes it could be your clutch that is worn, they generally last for 80-120k miles. If it is an 8L chassis consider getting the clutch slave cylinder checked though as this could be leaking onto the clutch giving the same symptoms. They are known to fail. Whichever is causing the slip I would consider replacing both. This is far different to the problem described in this thread though. Regards Paul Link to comment Share on other sites More sharing options...
p_gliddon Posted August 27, 2010 Author Report Share Posted August 27, 2010 Logged requested boost vs actual in the file attached. Anyone able to look at it and tell me whats wrong? Shows hard accel through all the gears. MAF readings peaking at 80 (expecting 140-150) and now when i disconnect the MAF its seems to cure the problem. Ordered a new MAF. Question is does this rule out a vacuum/boost leak? Thanks Paul Link to comment Share on other sites More sharing options...
p_gliddon Posted August 28, 2010 Author Report Share Posted August 28, 2010 Just to close this thread - it was the MAF, put a new one in today and now MAF readings are twice what they were, peaking at around 165g/s. This equates to 78% of the engine original bhp which is about right I believe. Feels like i have a new car! Link to comment Share on other sites More sharing options...
SAiLO Posted September 23, 2010 Report Share Posted September 23, 2010 I am having the same problem on my 2.0tdi. There's a massive lag when I change to 3rd gear and want to quickly accelerate, then the boost kicks in and the car pulls nicely. Going to replace the MAF on Saturday, just need to find out how to do it. Link to comment Share on other sites More sharing options...
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