tentonhammer 10 Posted January 9, 2012 Revs jumping from 1000 - 1500 approx / Intermittently whilst idle and at 12mph, causing the car to lurch and bounce around. Hi guys I'm hoping you might be able to help me. I used the car this morning and noticed that the car is sitting at and jumping between 1000 and 1500 rpm approx whilst at idle and at low speeds. I'm sure revs should be lower than this when at idle? Revs certainly shouldn't be jumping up and down (rhythmically) as it is! Lurching / rev jumping is stopped by putting my foot on the gas or easing the clutch out (at low speeds only. Car does not lurch when at idle, just the rev needle is bouncing up and down). My initial thought was that it could be the timing that was out but logic would have it this would be across a wide range of revs, not just at 1000rpm. I suspect it's probably the coolant temp sensor or an air flow problem. Anyone got any ideas / had the same problem? Cheers, Ten Ton Corrado 16V 2.0 ---------- Post added at 11:46 AM ---------- Previous post was at 11:37 AM ---------- Possibly a throttle issue perhaps? Cheers, Ten Ton Quote Share this post Link to post Share on other sites
Jim 2 Posted January 9, 2012 I'm gonna go with the classic Idle Stabilisation Valve.. I'd try cleaning your one, or replacing it with another (normally a few on eBay, VR6 ones work as a replacement also - new ones are prohibitively expensive) and see if that helps. Bouncing revs is something I experienced with mine when the ISV was faulty! Quote Share this post Link to post Share on other sites
Roger Blassberg 0 Posted January 9, 2012 Have you disconnected the battery or replaced the throttle position sensor recently, and then not carried out the Basic Settings routine? If so, there will be a lack of coordination between the throttle and various fuelling and ignition timing settings. Look at the Basic Settings routine in the Knowledge Base for the procedure. Are you getting high fuel consumption? Maybe a lambda sensor/wiring fault. Is your MAF (Mass Air Flow) meter known to be good? Disconnect it at idle; that should cause the engine to splutter and stall if it is working well. Take it off, clean the connector block with contact cleaner and spray the fine platinum wire inside the body with contact cleaner too. Otherwise, check for air leaks in the induction system. Are there any loose clips, are there any perished hoses, is the small diaphragm valve on the intake trunking/cylinder head junction split? Best wishes RB Quote Share this post Link to post Share on other sites
swiftkid 1 Posted January 9, 2012 Think you're getting confused with a VR Roger. The 9a doesn't have an MAF Anyway, I'd check for air leaks, make sure all the rubber hoses are connected and not perished anywhere because those engines are a nightmare for air leaks, as Jim says check the ISV and give it a good clean. Also check the plug underneath the throttle body, I had a right problem with the wires being really manky, caused the revs to be all over the place! Have you done anything to provoke it to do anything like this? Literally the smallest thing could give us a clue, like changing the oil... maybe you've knocked something off in the process? Quote Share this post Link to post Share on other sites
tentonhammer 10 Posted January 9, 2012 (edited) Ah yes... the ISV. Makes perfect sense. Jim - Looks like you were right on the money mate. Just had the bonnet up, located ISV, and one of the wires has come away from the unit! Literally fell out of the terminal when I touched it. A simple re-solder and a clean up should hopefully sort it ;) Roger & Swift - I HAVE recently disconnected the battery actually, had to throw some charge in it a week or so ago. First time I have driven the car since the bat was put back in. Replaced a couple of fuses as well when the battery went back in - Nearside dipped headlight and nearside tail light. "Look at the Basic Settings routine in the Knowledge Base for the procedure" Would really like to know the correct setup procedure after batt installation - Where would I find this? Will def check all hosing etc for air leaks, as well as the plug / terminal under throttle body - Looks pretty filthy to be fair. Ten Ton Edited January 9, 2012 by tentonhammer Quote Share this post Link to post Share on other sites
swiftkid 1 Posted January 9, 2012 TenTon (like the name, reminds me of TinTin lol), the correct setup procedure relates to a VR6 because its electronic engine management, nothing to worry about with a 9a. By the sound of it you might have sorted it with the ISV which I'm betting you will have knocked as you took the battery out so fingers crossed for you! Might be worth just giving it a clean out anyway whilst you're fiddling, can't hurt! Quote Share this post Link to post Share on other sites
Roger Blassberg 0 Posted January 9, 2012 Yes, sorry for leading you up the garden path with VR6-related stuff. I'll make it another New Year Resolution to read ALL the information provided before jumping in with both feet............. Anyway, it looks as though you have found a very likely cause for your woes, which is good news. best wishes RB Quote Share this post Link to post Share on other sites
Jim 2 Posted January 9, 2012 Does sound very likely indeed. Keep us updated! :) Quote Share this post Link to post Share on other sites
tentonhammer 10 Posted January 10, 2012 Thanks guys, Aim to get this sorted out today, will get back. Ten Ton ---------- Post added at 08:33 AM ---------- Previous post was at 08:25 AM ---------- Roger - BTW no worries, I now know something about the VR6 I didn't know before ;) Quote Share this post Link to post Share on other sites
tentonhammer 10 Posted January 16, 2012 Ok so finally got round to sorting this out and after re-soldering the cable that had come away from the ISV - The car now idles as it should. Took all of half an hour to do and cost me f-all! As ever, couldn't have done it with out the forum and my partner in crime - My ol' man. Thumbs up to all involved. BTW - Drove in this morning and noticed temp light on dash is now flashing at me? Not sure whether this is related to ISV fault or not. Car isn't over heating, needle indicator on dash sits just above 75 degrees. Temp sensor perhaps? I could have knocked it when sorting the ISV. Will check Any ideas? Ten Ton Quote Share this post Link to post Share on other sites
swiftkid 1 Posted January 16, 2012 Glad to hear you got it sorted! I do enjoy an easy, cost free fix which is quite rare these days. Anyway light flashing is not overheating its low water, check your water bottle to make sure you have enough water in, sometimes its quite deceiving and it looks like its full but when you pour some in it drops the level. The sensor is the one plugged into the side of the bottle, maybe check the connections are fine and you havn't knocked anything. Quote Share this post Link to post Share on other sites
tentonhammer 10 Posted January 16, 2012 Fixes like these are few and far between though, lets be honest! Quote Share this post Link to post Share on other sites
