wildejon 7 Posted August 12, 2006 I have had to set my idle to about 1400 to ensure my engine does not stall. When I'm driving it, everything seems ok, apart from the revs seeming to take longer than I would have expected to come down once you release the accelerator... but when I stop, it revs at 1400 for about 5 secs and then drops to 500 and gradually pulls itself back to 1400 and continues to repeat this so I have to sit there with my foot on the pedal a little to keep the revs up. Any ideas? It was rr'd about 6 months back but in another car. Therefore, I cant see it being the timing and we have set the afm mixture correctly so I'm a bit stumped. The only thing I can think of is an air leak somewhere but I cant find anything. It does make a strange sound, like a manifold gasket blowing a bit but they have just been replaced... Seems to do this most when the engine is under load at low and mid revs, its fine at the top end, just sounds quite loud Anyone have any ideas of either where I may find an air leak (I've tested the inlet gasket from the top of the engine but not underneath) or anything else that may be causing this? Thank you! Share this post Link to post Share on other sites
jim21070 2 Posted August 14, 2006 A favourite spot is the bolt on the side of the inlet manifold by No.1 injector that holds the oil tower in place. Often the oil tower floats around in free air and the bolt is lost. The bolt hole goes right into the inlet manifold and causes a massive air-leak and emits just the noise you describe. Share this post Link to post Share on other sites
wildejon 7 Posted August 14, 2006 Nope, its not that (thanks anyway). Just ran down to have a look. It wasn't doing it in the other car so it must have been something that got moved I guess. Or knocked loose I suppose. It's sooo nearly there, just got to fix this idle and then its all good! Thanks for your input mate. Share this post Link to post Share on other sites
arry 0 Posted August 14, 2006 mine is doing exactly the same and has been since I bought it - the previous owner has raised the idle to 1500rpm too, to prevent stalling Share this post Link to post Share on other sites
jim21070 2 Posted August 14, 2006 A leak anywhere downwind of the AFM can cause this and there are a multitude of places. The manifold gasket is favourite and only careful checking will find it. Have a check of all orifices that radiate out from the mainfold, like the fuel pressure regulator sense pipe, the servo take-off and the SAD pipe inlet right underneath the manifold and of course the SAD piping. They can be a sod to find but you have noise to help. Try listening through a stethoscope made from a piece of hose... Share this post Link to post Share on other sites
madspikes 41 1 Cars Posted August 14, 2006 Did you change the inlet gasket? I had simular issues and it turned out that the inlet gasket was wrong! It was a pattern part, and just was cut wrong. It basically blocked off the injectors squirting directly into the head, so fuel only flowed properly at high air speeds, and not very well at idle. Just a thought. Also check the pipe on the bottom of the inlet, mine split and I could see it. Share this post Link to post Share on other sites
wildejon 7 Posted August 14, 2006 Inlet gasket has not been changed, so it shouldn't be that. I'll have a check of the pipes mentioned and see how it goes. I do reckon there is something funny going on somewhere... Cheers all! To check the SAD and piping do I just squeeze the pipes when its running and hot? It shouldn't change the revvs right due to the SAD supposedly being closed right? Thank you! Share this post Link to post Share on other sites
saveloy 8 Posted August 14, 2006 Correct Jon. I would arm myself with a can of brake parts cleaner and start spraying around the inlet,pipes ans injectors. If you don't get an increase in revs, then it sounds like it's running very rich. Which points to an AFM problem. Share this post Link to post Share on other sites
Rob_the_Sparky 9 Posted August 15, 2006 A clean of the inside of the AFM can work wonders on idle mixture, depending of course if it is dirty to start with! Also idle mixture screw may help. Share this post Link to post Share on other sites
wildejon 7 Posted August 15, 2006 Funny you said that Saveloy, a friend of my Dads (who works on Imprezzas) tried that and it set on fire and melted the plastic cover over the dizzy I was proud of that, my old engine didn't have one! Luckily it didn't stay on fire for long but I wasn't too impressed... Maybe when its colder eh? I'll have a look at the SAD and the pipe work tomorrow and see what I find, cheers guys! Is there anything other than brake cleaner that I can use?! Share this post Link to post Share on other sites
Rob_the_Sparky 9 Posted August 16, 2006 I used WD-40(!) but only cause it was the only thing to hand... Share this post Link to post Share on other sites
wildejon 7 Posted August 16, 2006 Thats what I used last time (already checked the top of the inlet gasket) but it don't half smoke!!! Not sure it did my lungs any favours. Maybe when the engine isn't quite so hot it will be ok Share this post Link to post Share on other sites
pug_ham 242 3 Cars Posted August 16, 2006 Check the throttle switch; A Works, test procedure is in Haynes & I've posted it before on here. B Is set correctly, some set it so it doesn't click closed at idle. C The throttle body, AFM & breathers are as clean as you can get them. Remove the brass adjusting screw from the throttle body and clean it with Brasso or some metal polish until it gleams and spray some carb cleaner through the hole it fit's in to. Count the amount of turn's out take's to unscrew it form the throttle body and retighten it by the same amount. You can also clean through the bleed air screw housing on the throttle body with the carb cleaner, remove the idle speed screw and with the engine running at a high tickover (use the quadrant on the throttle body). With the nozzle straw in the hole, cover the hole with your thumb or finger an spray a bit at a time. Keeping an ear listening for the car starting to struggle and be ready to give extra throttle if needed. Keep the hole covered or the car will stall. After this stop the engine and refit the idle speed screw and set your tickover as it was before and you're done. IMO carb cleaner is best for this as it will make the engine rev even from the residue aftewr cleaning when it is all back together.(only momentarily). Graham. Share this post Link to post Share on other sites
wildejon 7 Posted August 16, 2006 Something for the weekend then... What is the brass adjusting screw on the throttle body? Are you referring to the idle screw? (Just so I get this right...) I'll have to get myself some carb cleaner before I give it a go... Can I use that to check for leaks around the gaskets too? Thanks for the advice Share this post Link to post Share on other sites
Rob_the_Sparky 9 Posted August 16, 2006 I took all the relevant bits off and cleaned with WD-40 or carb cleaner and a tooth brush before replacing. Watch for the top connection on the throttle body blocking up, there seem to be 2 designs, one of which is commonly blocked where the small pipe from the oil filler cap connects to the TB. Rob Share this post Link to post Share on other sites
wildejon 7 Posted August 16, 2006 Cool, cheers. So much for having a weekend off! Thanks mate Share this post Link to post Share on other sites
pug_ham 242 3 Cars Posted August 17, 2006 What is the brass adjusting screw on the throttle body? Are you referring to the idle screw? (Just so I get this right...)I'll have to get myself some carb cleaner before I give it a go... Can I use that to check for leaks around the gaskets too? Yes to both questions, idle speed screw & carb cleaner will help find any leaks. Graham. Share this post Link to post Share on other sites
wildejon 7 Posted August 26, 2006 Turns out it was the vacuum advance... Replaced that and all it nigh on perfect now. Still sounds like a tiny air leak somewhere but I certainly can't find anything. I'm going to sbc in 2 weeks for a rr tune so hopefully they'l find whatever else is wrong. Sounds LOADS better now, like a pug should! I'm sure its faster too, although that might be just the exhast noise creating an illusion... Cheers for your advice everyone (enjoy your weekends!) Share this post Link to post Share on other sites
Super Josh 4 Posted August 26, 2006 Still be worth cleaning out the Pies, TB and AFM etc. before your trip to SBC. You'll get the most out of the RR seesion then and it should idle spot on Josh Share this post Link to post Share on other sites
wildejon 7 Posted August 27, 2006 I know.... I'm a bit lazy and also have a multitude of knocking sounds to sort out before we go... Hopefully I'll have time to do it all Cheers Jon Share this post Link to post Share on other sites
