THE BOX Posted July 29, 2010 Report Share Posted July 29, 2010 I have an 88 TSI with a few mods. I have a 1G BOV crushed down and 2.5 inch down pipe both have been installed for years. Im running 15 psi on a hallman mbc. I pulled the car out of storage this spring and it has a new habit. When i hold steady acceleration it sometimes has a small surge to it. It is pretty random which isn't to big of a problem but now anew issue has crept up. When i boost and let off the throttle right after to just coast the car stumbles and idles very low around 400 rpm. It will recover but it takes a few seconds. Just wondering what anyone thinks about it and what i could look at first. Thanks in advance for any help. Link to comment Share on other sites More sharing options...
dmyers151 Posted July 29, 2010 Report Share Posted July 29, 2010 Sounds the BOV to me, the low idle is caused by a rich condition due to you venting the BOV to atmosphere. If you shift and continue driving, you don't notice it. All the stockish cars running a BOV do it, nothing to really worry too much about. Link to comment Share on other sites More sharing options...
Cobalt60 Posted July 31, 2010 Report Share Posted July 31, 2010 Even though this may be normal for the OPs current setup, what would the solution to the issue be? Link to comment Share on other sites More sharing options...
dmyers151 Posted July 31, 2010 Report Share Posted July 31, 2010 Replace the BOV with a bypass vavle that re-circulates the air back into the system. Or remove it altogether and just run a stock style setup. Link to comment Share on other sites More sharing options...
mikec Posted August 1, 2010 Report Share Posted August 1, 2010 Quite possible a vacuum hose or the rubber diaphragm inside the BOV have rotted while the vehicle was in storage. Thus you end up with an air leak in the intake tract... that screws StarQuest air:fuel calculations a lot. Old gas doesn't help either; old gas degrades to varnish. Have you run the storage-gas out of the tank yet? Old/varnished gas a) doesn't burn very well and gunks up the fuel pump, the injectors, etc. That gunk makes the injectors stick open, leading to excess fuel getting injected. mike c. Link to comment Share on other sites More sharing options...
UlrichWolf Posted August 1, 2010 Report Share Posted August 1, 2010 I've never much cared for the 1G BOV. They seem to leak boost, and that creates issues too. I switched over to a HKS SSQV ( a real one), and since it is pull type, it helped quite a lot of the issues. Tim Link to comment Share on other sites More sharing options...
THE BOX Posted August 18, 2010 Author Report Share Posted August 18, 2010 I did check with brake cleaner and was spraying around but no idle change i could notice. I figured it would be a condition attributed to my BOV venting to atmosphere bleeding off metered air. I'm still interested in any input on the surging problem. it doesn't do it too often and doesn't seem to be connected to the blow off scenario. only seems to happen on longer trips and on the highway. I don't notice it happening when i have the cruse on just when I'm holding a steady speed with my foot like when I'm waiting to pass. Again any help is appreciated. Link to comment Share on other sites More sharing options...
Indiana Posted August 18, 2010 Report Share Posted August 18, 2010 Rev the motor up to 3000-3500rpms and hold it there steady. Put your hand over the BOV and see if it leaks. As the rpms get high enough without boost the volume of low pressure air can easily be enough to suck open a BOV crushed or otherwise. Once a spring is mashed that doesn't mean it can't open just the same way it means its range of movement is less and it might take a bit more to get it to move but in the end you can't make that spring stronger by doing that. There's DSM links for 1G BOV mods so that they do not leak, just google that. Link to comment Share on other sites More sharing options...
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