Mildly warm start problem
Discussion
Hi all, just wondering if anyone has had a similar issue. Had the 350i for a few years now. Always on the button, whether cold, hot or somewhere in the middle. I've used it several times this last week and if the engine has cooled down from a run, maybe for 2 hours, then it churns over, picks up on a few cylinders after say 10 seconds churning and then after another 10 or 15 seconds runs clean again. There is also a very strong smell of petrol under the bonnet accompanying this start up period but no obvious leaks. After a few minutes the petrol smell clears and all is good. The car pulls like a train with no issues.
The car has never suffered from vapour lock, and given the fact that the issue is after the car has sat for say 2 hours I don't think it is this. The fuel pressure regulator holds pressure when the engine is turned off so again there doesn't appear any signs of fuel leakage and emptying of the fuel rail.
HT electrics appear fine and as it starts from cold and from hot without a moments hesitation I don't think this is the issue. I've pulled the plugs and mixture looks spot on.
Could the infamous CTS be the fault, maybe thinking the engine is colder than it is and over fueling it? One thing I have noticed of late is a lot of air gurgling around the engine and header tank/ bottle when I switch the engine off. It doesn't use any water but I can hear a load of trapped air moving back into the header tank. Could it be trapped air around the CTS confusing it? If the CTS is sat in an air pocket rather than warm water could this make the difference?
Thoughts would be appreciated. Cheers.
The car has never suffered from vapour lock, and given the fact that the issue is after the car has sat for say 2 hours I don't think it is this. The fuel pressure regulator holds pressure when the engine is turned off so again there doesn't appear any signs of fuel leakage and emptying of the fuel rail.
HT electrics appear fine and as it starts from cold and from hot without a moments hesitation I don't think this is the issue. I've pulled the plugs and mixture looks spot on.
Could the infamous CTS be the fault, maybe thinking the engine is colder than it is and over fueling it? One thing I have noticed of late is a lot of air gurgling around the engine and header tank/ bottle when I switch the engine off. It doesn't use any water but I can hear a load of trapped air moving back into the header tank. Could it be trapped air around the CTS confusing it? If the CTS is sat in an air pocket rather than warm water could this make the difference?
Thoughts would be appreciated. Cheers.
Convert said:
Keith, if swan neck was empty, then CTS will probably be reading temp of fresh air rather than coolant, and as such might overfuel.
Are you losing coolant anywhere?
I do hope it's not blowing it out of the expansion tank, that's how my HGF started.
That's what I was thinking re the CTS. If it's sat in fresh air it may well cock up the fueling. No obvious coolant loss, it just seems to have relocated itself. The header tank level is usually down about 60mm but today despite a cold engine the header was brimmed up to the radiator cap yet the swan neck was totally empty. The engine temperature is also rock solid mid way up the gauge.Are you losing coolant anywhere?
I do hope it's not blowing it out of the expansion tank, that's how my HGF started.
Now thinking about it about a month ago I did lose a load of water from the header tank. I checked the radiator cap and the rubber seal was very worn so fitted a new cap and had no loss since. I'm wondering if the swan neck emptied at that point and could all be down to an air lock? Fingers crossed tomorrow when I run it up and see what happens after a couple of hours. Cheers.
Hi gents, well after much investigation I have found the reason for air getting sucked into the swan neck and it was a perished small hose for the plenum heater. I did fit a new radiator cap and blanking cap which made no difference and also checked all other hoses. The plenum one is tucked out of sight. Although it didn't appear to leak water it was certainly so perished that air was getting drawn into it. That's the good news.
The bad news is that despite now having water submerging the CTS and thermotime sensors the car is still a pig to start unless it is stone cold. Starts first crank in the morning, every morning. If the car has stood for a couple of hours and even up to 8 hours, as it did today in the sunshine, when I try and start it is stinks of fuel out of the exhaust and appears to be flooding. I drove to work this morning at 8.00 but when I came to start it at 5.00 it just churned and churns and spluttered. Eventually I disconnected the cold start injector, floored the throttle to try and get some air in it and it did catch and immediately ran clean. I then had a very spirited run home chasing a 500 Abarth and the car didn't miss a beat.
This evening I've pulled half of the plugs out and colour is spot on. There's now no water loss, no bubbling into the overflow bottle, nice clean oil, big fat spark, obviously a shed load of fuel. Something is telling the ECU to pour fuel in. Would this be the CTS, thermotime or could it be related to the auxillary air valve?? The car had a new CTS last year but we know they all fail eventually. I've spares of all three items so wondering where I should look first? Any help would be appreciated. Thanks.
Edit - just had a look at the Vintagemodelairplane website and it does state the following:
"A faulty thermotime switch can cause uncontrolled over-fuelling during cranking if the internal contacts are permanently closed. Also the cold start injector can cause over-fuelling if its injection orifice is corroded or contaminated causing it to leak fuel continuously".
I'll try the thermotime first then unless anyone has any other suggestions?
The bad news is that despite now having water submerging the CTS and thermotime sensors the car is still a pig to start unless it is stone cold. Starts first crank in the morning, every morning. If the car has stood for a couple of hours and even up to 8 hours, as it did today in the sunshine, when I try and start it is stinks of fuel out of the exhaust and appears to be flooding. I drove to work this morning at 8.00 but when I came to start it at 5.00 it just churned and churns and spluttered. Eventually I disconnected the cold start injector, floored the throttle to try and get some air in it and it did catch and immediately ran clean. I then had a very spirited run home chasing a 500 Abarth and the car didn't miss a beat.
This evening I've pulled half of the plugs out and colour is spot on. There's now no water loss, no bubbling into the overflow bottle, nice clean oil, big fat spark, obviously a shed load of fuel. Something is telling the ECU to pour fuel in. Would this be the CTS, thermotime or could it be related to the auxillary air valve?? The car had a new CTS last year but we know they all fail eventually. I've spares of all three items so wondering where I should look first? Any help would be appreciated. Thanks.
Edit - just had a look at the Vintagemodelairplane website and it does state the following:
"A faulty thermotime switch can cause uncontrolled over-fuelling during cranking if the internal contacts are permanently closed. Also the cold start injector can cause over-fuelling if its injection orifice is corroded or contaminated causing it to leak fuel continuously".
I'll try the thermotime first then unless anyone has any other suggestions?
Edited by KKson on Wednesday 15th March 22:01
Edited by KKson on Wednesday 15th March 22:02
Edited by KKson on Wednesday 15th March 22:08
ElvisWedgeman said:
I had a similar hot start problem when I first bought the car which developed over several weeks. It was the ignition module on the side of the distributor. Replaced it with a good quality item, not a cheap one from the fleaby. It starts first time hot or cold and never had a problem since. That was two years ago.
Tony. TCB.
Thanks for the reply. I've a known good spare àmp also so thermotime first and then I'll try swapping the amp. Cheers.Tony. TCB.
Right had a further play with it tonight.
Even from cold it wouldn't start, which is a first, so something is breaking down further.
1. Tried disconnecting the cold start injector - no good.
2. Swapped the thermotime switch for my spare - no good.
3. Replaced the CTS and the car started but was misfiring badly.
4. Swapped the ignition amp with a known okay one - engine ran a little sweeter but fluffed every time I tried blipping the throttle.
I took some resistance readings - installed thermotime had a resistance of 48.8 ohms and spare that I then fitted 50.8 ohms.
For the CTS I have the installed plus three spares. At around ambient 15C the installed unit fitted in the engine had a resistance of 3490 ohms and the three on the bench were at 3310, 3280 and 3290 ohms.
I fitted one of the spares and ran the engine up a little to I'm guessing 45C and resistance of installed one dropped to 980 ohms. All resistances generally look about right compared with the info on vintagemodelairplane website.
For peace of mind I'll buy a new ignition amp and CTS so at least I can rule them out. Any other ideas??
Even from cold it wouldn't start, which is a first, so something is breaking down further.
1. Tried disconnecting the cold start injector - no good.
2. Swapped the thermotime switch for my spare - no good.
3. Replaced the CTS and the car started but was misfiring badly.
4. Swapped the ignition amp with a known okay one - engine ran a little sweeter but fluffed every time I tried blipping the throttle.
I took some resistance readings - installed thermotime had a resistance of 48.8 ohms and spare that I then fitted 50.8 ohms.
For the CTS I have the installed plus three spares. At around ambient 15C the installed unit fitted in the engine had a resistance of 3490 ohms and the three on the bench were at 3310, 3280 and 3290 ohms.
I fitted one of the spares and ran the engine up a little to I'm guessing 45C and resistance of installed one dropped to 980 ohms. All resistances generally look about right compared with the info on vintagemodelairplane website.
For peace of mind I'll buy a new ignition amp and CTS so at least I can rule them out. Any other ideas??
ElvisWedgeman said:
Your symptoms sound very similar to mine. At first it was harder to start when hot, then it got even harder when hot, then eventually wouldn't start even when cold. Spread over a couple of weeks. Notice there was an improvement when you replaced the ignition module. It's possible you may have a secondary fault as well as the ignition module. If you replace the ignition module make sure you get a good quality one. My one was made in Italy and cost over £30 from local motor factors. That was two years ago.
Tony. TCB.
Thanks Tony - certainly the ignition amp made a difference. I've just found an original old stock but new Lucas amp which I've bought. Cost a few quid but it is an original so we'll see how that goes. The temporary amp I've fitted was a Powerspark three pin unit with two wire adapter which was running okayish last year but not ideal. I've also got a couple of spare coils so may well try one of them on, BUT I will only replace one item at a time so I know which is the culprit. Thanks for your advice. You looking for another Wedge or moving on to something different this time?Tony. TCB.
mrzigazaga said:
Sounds more like something has/Is working itself loose??.....Check the plug connector on the resistor pack on the wing, If its loose then a couple of cable ties help to hold it in....Also check the ECU plug is firmly home....You could use some contact cleaner on them both and clean up the pins on the ECU...Especially pin 13.
Hi Mark, I checked both of them thanks and did blast them with contact cleaner, and the AFM multiplug. Earths appear good. There obviously was an air leak in the cooling system so the top of the engine wasn't getting enough water around the top pipes, even though the temperature sender was submerged as that never showed an elevated temperature, so wondering if it's cooked anything? I'll plod through one thing at a time, the same as I did 2 years ago............ At least I have a full garage loft of spares!
Well still not found the root issue with the 350i but a new CTS and ignition amp are due tomorrow so fingers crossed they might be part of the problem. I did have a good look at wiring etc. I did a full earth check of all components - AFM, power amplifier thingy, coil, block, ancillaries and all had a good earth with virtually no resistance between the components or back to the battery earth so not that.
Going on Marks advice to check wiring condition I did peel back the CTS connector and did find three cuts in the wiring insulation, two next to each other just as the wires exit the rubber shroud. I've cut the connector off and soldered in a good replacement. I was hoping this might be the cause but sadly not. Checking the wiring back to the ECU again with the new connector there's virtually no resistance so I know the wires are good.
The engine now just churns but doesn't wire, even though there is a spark and loads of fuel. The spark however does not appear to be as strong as it has been, despite a fully charged battery.
Going on Marks advice to check wiring condition I did peel back the CTS connector and did find three cuts in the wiring insulation, two next to each other just as the wires exit the rubber shroud. I've cut the connector off and soldered in a good replacement. I was hoping this might be the cause but sadly not. Checking the wiring back to the ECU again with the new connector there's virtually no resistance so I know the wires are good.
The engine now just churns but doesn't wire, even though there is a spark and loads of fuel. The spark however does not appear to be as strong as it has been, despite a fully charged battery.
Hi Mark, answering your questions:
CTS connector - yes I did double check and ensured it is wired correctly. I've got two spare looms so I did check one of them also.
I'll check unplugging the CTS. I did try unplugging the thermotime when the engine was running the other night and as you say as soon as the connector was pulled it died.
I've two spare thermotime switches and all three show pretty much the same resistance. I did try swapping one out but it made no difference.
No fuel leaks but when it tries to start the exhaust stinks of fuel as if its flooding.
I've removed the air filter and fingered the flap (oh err) and the fuel pump kicks in. However when the car is trying to start the fuel pressure is lower than usual, despite the stink of fuel. When/if the engine does fire then pressure is back up to normal. I have pulled the cold start injector and it's not leaking and to be honest appears bone dry as if it's not actually cold enough for it to kick in. I am wondering if it could be a sticking AFM flap? I've three spare AFM's so I'll swap that out also as a check. How about a sticking fuel regulator? I've got a spare one of those as well so I'll put that on the list also.
I've not touched the timing so that shouldn't have moved. In order to stop it pinking it is around 2 to 3 degrees BTDC. If I try static at 8 degrees then it pinks too much and always has done. I'm suspicious that my TDC timing marks on the pulley are slightly out.
I've got today off but still waiting on the Postie for my new CTS and ignition amp.
On a couple of occasions last night it fired and once warm then runs fine. If I turn the engine off then again it's a pig to get re-started.
Further investigations will continue this afternoon, AFM in particular, followed by fuel regulator...... Cheers
CTS connector - yes I did double check and ensured it is wired correctly. I've got two spare looms so I did check one of them also.
I'll check unplugging the CTS. I did try unplugging the thermotime when the engine was running the other night and as you say as soon as the connector was pulled it died.
I've two spare thermotime switches and all three show pretty much the same resistance. I did try swapping one out but it made no difference.
No fuel leaks but when it tries to start the exhaust stinks of fuel as if its flooding.
I've removed the air filter and fingered the flap (oh err) and the fuel pump kicks in. However when the car is trying to start the fuel pressure is lower than usual, despite the stink of fuel. When/if the engine does fire then pressure is back up to normal. I have pulled the cold start injector and it's not leaking and to be honest appears bone dry as if it's not actually cold enough for it to kick in. I am wondering if it could be a sticking AFM flap? I've three spare AFM's so I'll swap that out also as a check. How about a sticking fuel regulator? I've got a spare one of those as well so I'll put that on the list also.
I've not touched the timing so that shouldn't have moved. In order to stop it pinking it is around 2 to 3 degrees BTDC. If I try static at 8 degrees then it pinks too much and always has done. I'm suspicious that my TDC timing marks on the pulley are slightly out.
I've got today off but still waiting on the Postie for my new CTS and ignition amp.
On a couple of occasions last night it fired and once warm then runs fine. If I turn the engine off then again it's a pig to get re-started.
Further investigations will continue this afternoon, AFM in particular, followed by fuel regulator...... Cheers
adam quantrill said:
Just in case you missed it. Belt and braces.
Hi Adam spent the afternoon doing point to point tests and all wiring is good. New Cts fitted and no difference. I think it may well be the bloody ignition amplifier after all. I plugged in my set of spark plug tell tails (red in line neon things). When I crank the engine there is a spark but it is really feeble. If it catches and runs then immediately the spark goes to big and bright and then the engine runs as sweet as. Stop the engine, crank it again and back to feeble spark. I've swapped the coil out and that's made no difference. Could it be that the ignition amp is failing and only when it gets additional voltage when the alternator kicks in that it delivers a pukka in your face spark?
Good news I suppose is that at least I've double checked my wiring, my AFM has been taken out and given a lovely clean and I have a new CTS now fitted.
Still waiting on my new ignition amp so as soon as it arrives I'll see if that is the culprit.
So new but old stock genuine Lucas two terminal ignition amp eventually arrived today. Plugged it in and car fired first turn of the key. I've had a spirited run around the lanes, tried leaving the car for an hour and every time it starts on the button. The old amp was only 18 months old, but not a genuine Lucas unit. Many thanks for all your replies but also to Tony for pointing out the potential culprit.
Last night I also fitted new front wheel bearings on the 390 so as of tonight I have two Wedges and both are bloody working - amazing......! A glass of red in celebration I think.
Last night I also fitted new front wheel bearings on the 390 so as of tonight I have two Wedges and both are bloody working - amazing......! A glass of red in celebration I think.
adam quantrill said:
Good stuff - label all the other parts you've tried as "good substitutes" before you mix them up with your other spares!
Hi Adam, yes spare thermotime and CTS sensors put away safely and two duff ignition amps now in the bin. I also know that my spare ECU and AFM's both work fine too. I've added the neon spark plug extenders into the essential boot kit so I can easily see if I get a weak spark in the future. Cheers.
adam quantrill said:
Can I have your old amps - if the bin man hasn't "bin" and they are not covered by potato peelings already ;^)
Being of an electronicy bent I'd like to take them to bits to see how they tick.
Adam no problem they are still in the garage bin which gets emptied annually! Ping me an email with your home address. My email is kej.knight@btinternet.com Cheers.Being of an electronicy bent I'd like to take them to bits to see how they tick.
adam quantrill said:
Can I have your old amps - if the bin man hasn't "bin" and they are not covered by potato peelings already ;^)
Being of an electronicy bent I'd like to take them to bits to see how they tick.
Adam no problem they are still in the garage bin which gets emptied annually! Ping me an email with your home address. My email is kej.knight@btinternet.com Cheers.Being of an electronicy bent I'd like to take them to bits to see how they tick.
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