jim21070 2 Posted February 28, 2007 It may just be me but my Activa seems to have a strange throttle response. Given this is the first petrol turbo I have owned since an MG Metro Turbo 20 years ago and the only other petrol engine I can compare it to is my 205GTi. Big petrol engines are completely new territory to this Diesel Head My Activa runs really well, starts instantly, idles perfectly always (now there is a revelation after the 205 Jetronic management ) and goes with plenty of vigour. However... When you snap the throttle shut, say between gear changes or running down to a junction, it seems incredibly slow to run back to idle. It always does but it just seems very slow to do it compared to the GTi which seems to fly back almost instantaneously. Even just revving it in neutral it seems to take a long time to run back down, almost as if it has an incredibly heavy flywheel on it. I confess I've not checked very deeply into this yet but I have checked very carefully for air leaks downwind of the turbo and all seems good. A very crude test I did was to disconnect the air trunking going into the intercooler and put my hand over it. Even at idle the rubber piping sucked itself flat under vacuum Likewise these seem no air leaks at the inlet manifold. I could see this effect being caused by a problem in the ICV if it were opening right up under power and taking a time to shut back down again. How does the ICV work on these engines? Is it a stepper motor or just a glorified SAD? I saw somewhere that it was a modulated solenoid like the boost control valve but that seems a bit outlandish. Speaking of the boost control valve, could that cause it given how it is "wired" in? Finally, the throttle butterfly seems to be closing right up (i.e. not a tight throttle cable holding it open a bit) but does it have a stop screw like the 205 TB thatmight be out of adjustment? I've not found one on casual inspection. Grateful for any thoughts from those of you running this same engine and apologies for the long post. Share this post Link to post Share on other sites
welshpug 1,657 Posted February 28, 2007 sounds just right to me, similar to diesels actually, my mum's 405 TD will lift revs quite quicly but lift odd the revs will ease down nicely not plummet, on a non turbo diesel they tend to drop rather quicker. might be the boost keeping it going? Share this post Link to post Share on other sites
Mikey S 29 1 Cars Posted February 28, 2007 sounds just right to me, similar to diesels actually, my mum's 405 TD will lift revs quite quicly but lift odd the revs will ease down nicely not plummet, on a non turbo diesel they tend to drop rather quicker. might be the boost keeping it going? its just a form of 'damper' thats all. on the 405 td there is a mini taigate strut that stops the throttle snapping shut to fast. renove it and the car will jerk violently when you release the throttle. on the xantia i presume it is controlled by the icv, its just a way of making the car nicer to drive. mike Share this post Link to post Share on other sites
sonofsam 5 Posted February 28, 2007 (edited) Speaking from experience I'll tell you what it might be. as I had a sticky throttle when I first ran my engine, the spring under the throttle spindle ( Black platic disc, were the cable atttaches to ) was rusty and binding, a few squirts of lube had it sorted again Throttle response is damn good on mine now, yes you have a certain amount of lag, but nothing major as its on a small turbo. Edited February 28, 2007 by sonofsam Share this post Link to post Share on other sites
jackherer 543 Posted February 28, 2007 My Activa was the same, the ICV is meant to behave like that I think. The ICV seems to be a lot more capable than the one on Mi16s for example. If you put it in first and raise the clutch (with NO revs) as the revs drop it will open the ICV enough to bring the revs back to 1000 or whatever and will drive without stalling. And then if you dip the clutch the revs will shoot up and take a while to settle. My 1.8 16v Xant is the same too, you get used to it but it is odd when you switch from a 205! Not as annoying as the wiper stalk going the wrong way though Share this post Link to post Share on other sites
jim21070 2 Posted March 2, 2007 If you put it in first and raise the clutch (with NO revs) as the revs drop it will open the ICV enough to bring the revs back to 1000 or whatever and will drive without stalling. And then if you dip the clutch the revs will shoot up and take a while to settle. Yes, I've noticed that effect too. Quite strange after a 205. Thanks all for your thoughts and now after driving the Xant for a couple of days after four soild days in the 205 I've grown accustomed to it. I have to agree about the wipers but on mine the strangest thing is the lighting switch. My phase II Xant has two barrels on the stalk, one for the main lights and another for the foglights next to it and so many times I go to turn on the fogs instead of the headlights All in all the Activa has been one big cluture shock so far... Share this post Link to post Share on other sites
jackherer 543 Posted March 2, 2007 haha, I'd forgotten about the light switch, I've been annoyed by that too have you tried to turn the radio down in the 205 with your thumb on the steering wheel yet? Share this post Link to post Share on other sites
