I've had a bit of an issue with the car over the last couple of days and couldn't quite work out what was up....symptoms were confusing... idle was a little erratic... would sit high when cold (1600) and only drop down to about 1200 when warm, this after a sudden drop to around 800 before settling at 1200. The exhaust was burbling a lot more too and not just on overrun, but idle too. Add to this a flutter under load but not on high boost which would kick in about 4 out of 5 times with no signs of flutter....this confused me a little clearly I had an air leak but also seem to have a boost leak too, were they linked or were they a coincidence that was leading to further confusion. I could not find any sign of hoses being loose, or such
Today being a nice sunny day I decided it was time for a road test to hopefully find the problem, a quick blast up the A41 was what the doctor ordered. Before getting to the main road I noticed that the flutter was still there (on and off) and that it would still boost when no flutter making think that the hoses were ok. Once on the A41 I could push a little harder, the car was fast but didn't feel as fast as it usually is, I applied more throttle than I ever have before and although I was accelerating rapidly it still felt slow, the solenoid was clicking away as per usual.
It then dawned on me that something was missing, other than the usual very rapid acceleration that is...there was no 'blip' from the boost gauge to say that I had hit 1BAR? I have this set as a warning to stop me getting carried away as with the duty cycle set as it is(85%) the boost can spike to very high levels. Usually, this blip sounds within a second or two of hitting boost and here I was sitting on an empty stretch of A41 moving quickly bust no blip? I floored it (96%) car ran perfectly, nice and smooth but no sudden push into the seat as was the norm and I looked at the boost gauge that was fixed at 0.9BAR, it would not go higher. Aha, I say there must be a boost leak somewhere although in the past the car wouldn't run so smoothly with any of the hoses lose.
I stopped at my son's in Tring and over a coffee took a closer look at the car, at first I couldn't see anything but then noticed that the intercooler connection to throttle hardpipe had slipped off the pipe and yet was in such a position close to the lamp pole that it blended into the hard pipe, I mean it was up tight against the edge of the hardpipe and thus was sealed but clearly the hose was flexing under boost, especially when high. Great I say and after a bit of juggling I had the hose repositioned and tightened up ( note to self, make the proper hardpipes up and ditch these supposedly temporary ones). That left the idle issues to sort, again after a little rooting around and checking the most obvious items i discovered that the throttle idle valve's seal was looking a little hard. I had some 'O' rings in the car (part of my classic car tool kit) and found one that wasn't perfect but close enough, I wrapped some PTFE tape around the thread and reset the idle to 900rpm.
Result?...what a difference.....I had my amazing speed machine back with all of it's horses running together again, it's amazing the difference between 0.9BAR and 1.2BAR... don't get me wrong the car was still very fast with the issue, it just didn't have that..OMG feeling as you try to hold on to the steering wheel.....I was good and didn't take it to the 1.5BAR that the overboost protection is set at...
I'm a happy boy again and it was such a simple fix even if a little confusing having two separate issues at the same time....
So, if anyone else with a modified turbo has similar problems hopefully this post may help.......
Pete