TR5tar Posted August 17, 2016 Report Share Posted August 17, 2016 (edited) Been out in the garaging tinkering again . . . when will I learn. Out at the weekend, I noted that as the 5 got hot sitting in traffic the idle speed went up to around 1400 rpm. I've read on the forum that a slight increase is not unusual as the engine gets hot, but I thought this figure seemed a bit too much. Also, out of traffic and giving it a bit of welly on the way home, there was one occasion when the car stuttered and backfired. Anyhow, someone said that perhaps I should try adjusting the air/fuel mix, so I just tried that. Turning the screw away from me the idle revs when warm dropped a little to about 800 rpm and for a while it ticked over fine, no choke, but then conked out. At the moment I can't get it started again. There is a strong smell of petrol, so I thought it might be flooded, but looking at one of the plugs I see it's bone dry. I'd have thought it would be wet if flooded, wouldn't it? I've adjusted the screw back to pretty much where it was before and I'm now waiting for the car to cool down before trying again. Does it sound like it's just flooded, or might I have bu**ered up something else? Fingers crossed. Darren Edited August 17, 2016 by TR5tar Quote Link to post Share on other sites
boxofbits Posted August 17, 2016 Report Share Posted August 17, 2016 HI Darren Not knowing that much about the Pi engine, I would still say you've probably not got a lot to worry about apart from maybe flooding if you over-richened it, but that doesn't necessarily account for the stuttering and backfiring before you adjusted the mixture. I know the injection pumps give trouble on these as you probably know, so are you certain you are getting a good fuel supply in the first place, especially if your plugs look dry - before you go looking for electrical. I doubt it is anything drastic. Kevin Quote Link to post Share on other sites
openroad Posted August 17, 2016 Report Share Posted August 17, 2016 Hi Darren, I too got hotter will I'd, in good, but I had been checking my advance and retaRd, maybe check yours before you start playing. Cheers, Conrad. Quote Link to post Share on other sites
TR NIALL Posted August 17, 2016 Report Share Posted August 17, 2016 What Screw did you adjust? Quote Link to post Share on other sites
TR5tar Posted August 17, 2016 Author Report Share Posted August 17, 2016 What Screw did you adjust? I'm tempted to say the loose one Niall, but I believe it's the "air valve". Thanks Conrad, if readjusting the air valve doesn't help, I'll look into that. Hi Kevin, I've not checked that I'm getting fuel at the injectors, but the fuel pump sounds as it has always done. So, just to demonstrate how much of a novice I am. Am I right in thinking that turning the valve away from me (which reduces the revs) means that the mixture is leaner? Cheers, Darren Quote Link to post Share on other sites
TR NIALL Posted August 17, 2016 Report Share Posted August 17, 2016 If you turn it away from you you are closing of the Air Supply if you close it fully the Engine should Stall,you should set the Tick Over with it open at about 800 rpm. Quote Link to post Share on other sites
Guest ntc Posted August 17, 2016 Report Share Posted August 17, 2016 Darren Remove pipe engine running from the airbox put your thumb over the end does it stall? Quote Link to post Share on other sites
peejay4A Posted August 17, 2016 Report Share Posted August 17, 2016 Screwing the air bleed screw in clockwise when viewed from the front allows less air to bypass the butterflies and reduces idle speed. It doesn't alter the mixture as the MU takes care of that according to how much vacuum the engine is making. As Neil points out, if you blank it off completely the engine should stall. If it doesn't then you have an air leak somewhere, maybe badly seated butterflies, manifold gasket leaking, vacuum pipe to MU leaking or MU diaphragm leaking. Quote Link to post Share on other sites
Guest ntc Posted August 17, 2016 Report Share Posted August 17, 2016 Screwing the air bleed screw in clockwise when viewed from the front allows less air to bypass the butterflies and reduces idle speed. It doesn't alter the mixture as the MU takes care of that according to how much vacuum the engine is making. As Neil points out, if you blank it off completely the engine should stall. If it doesn't then you have an air leak somewhere, maybe badly seated butterflies, manifold gasket leaking, vacuum pipe to MU leaking or MU diaphragm leaking. Yep spot on and also the valve can leak as it goes into the manifold. Quote Link to post Share on other sites
Peter Cobbold Posted August 17, 2016 Report Share Posted August 17, 2016 Darren, "..giving it a bit of welly on the way home, there was one occasion when the car stuttered and backfired". That could be from ignition , as Conrad #3 suggests. Maybe the points gap has closed up. More tinkering: check the points' gap. Peter Quote Link to post Share on other sites
TR5tar Posted August 18, 2016 Author Report Share Posted August 18, 2016 (edited) Thanks all.I imagine I'd closed the valve too much and that what's made it conk out. After leaving the car to cool down for a couple of hours, I tried it again and I'd hardly turned the key before it sprang into life, so I'd obviously flooded it earlier (pump ran for a few seconds when the car conked out). Anyhow, I've adjusted the valve closer to where it was originally, so tick over is around 800 rpm (just slightly lower then where it was before) when warming up, no choke.Took it out last night, and it ran nicely . . . no stutters or backfires. Of course, it was cool last night and at no point was I sitting in traffic, so I suppose I won't know if there's an improvement until I replicate the circumstances when the problem occurred.Niall, you say I "should set the Tick Over with the valve open at about 800 rpm." By that, do you mean I should open the air valve fully, and then alter the advance/retard to adjust, or do you just mean that I should adjust the air valve until I get to 800 rpm, as I have been doing? Neil, I've not tried your recommendation yet, but I'll give it a go. Is the pipe you are talking about the one that runs from the plenum to the air valve? Pete, I didn't realise that altering the air valve doesn't actually alter the mixture. I'd mistaken thought that I was making the mixture leaner or richer by turning the valve. Peter, no points for me, I'm on electronic. Cheers, Darren Edited August 18, 2016 by TR5tar Quote Link to post Share on other sites
Guest ntc Posted August 18, 2016 Report Share Posted August 18, 2016 Neil, I've not tried your recommendation yet, but I'll give it a go. Is the pipe you are talking about the one that runs from the plenum to the air valve? Yep Quote Link to post Share on other sites
TR NIALL Posted August 18, 2016 Report Share Posted August 18, 2016 By just adjusting the Air Valve till your happy with the Tickover. 800 on your Rev Counter might not be 800 but you'll be near enough. Quote Link to post Share on other sites
TR5tar Posted August 18, 2016 Author Report Share Posted August 18, 2016 Yep Thanks Neil. I'll give it a go and see what happens. By just adjusting the Air Valve till your happy with the Tickover. 800 on your Rev Counter might not be 800 but you'll be near enough. I see, Niall. That's good, because it is what I've been aiming for. One problem is that the rev counter needle bounces around (700-1100 rpm) quite a bit at tick over, so I'm having to estimate that the correct reading is in the middle of that. Cheers, Darren Quote Link to post Share on other sites
Tom Fremont Posted August 18, 2016 Report Share Posted August 18, 2016 Hi Darren, Glad you got it back to where it was . Here's what 550 rpm idle sounds like, PI cam but Webers ( sorry, can't help myself ): Cheers, Tom A US TR5 idling.MOV Quote Link to post Share on other sites
TR NIALL Posted August 18, 2016 Report Share Posted August 18, 2016 Thanks Neil. I'll give it a go and see what happens. I see, Niall. That's good, because it is what I've been aiming for. One problem is that the rev counter needle bounces around (700-1100 rpm) quite a bit at tick over, so I'm having to estimate that the correct reading is in the middle of that. Cheers, Darren Can be set Bang On with the better type Timing Lights that have the Built In facility. Quote Link to post Share on other sites
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