Cold Starting Probs
Discussion
Have seen a previous thread re cold starting, but wondered if anyone can advise me or had similar issues.
Mine is a series 1 350i and has always started after a couple of cranks hot or cold.
However recently if I leave it for a day or two or longer, it just won't start when cold. I have checked all the usual, leads, plugs (new), rotor arm and points and all are fine, and recently new coil.
I have experimented, by blipping the throttle incase it wasn't getting enough fuel and then the opposite by unclipping the cold start injector. But I can't seem to resolve the problem.
I tend to get it started eventually, but can't seem to find the best sequence.
The only recent work I've done, was a replacement valley gasket, where I had to remove the plenum chamber and fuel rails, but on complettion of work it started first time.
Any ideas chaps ?
ps: the battery is on trickle charge so plenty of volts.
Mine is a series 1 350i and has always started after a couple of cranks hot or cold.
However recently if I leave it for a day or two or longer, it just won't start when cold. I have checked all the usual, leads, plugs (new), rotor arm and points and all are fine, and recently new coil.
I have experimented, by blipping the throttle incase it wasn't getting enough fuel and then the opposite by unclipping the cold start injector. But I can't seem to resolve the problem.
I tend to get it started eventually, but can't seem to find the best sequence.
The only recent work I've done, was a replacement valley gasket, where I had to remove the plenum chamber and fuel rails, but on complettion of work it started first time.
Any ideas chaps ?
ps: the battery is on trickle charge so plenty of volts.
I havn't checked compression, but think I have good fuel supply as it tends to smell a bit after some cranking. As I've changed the valley gasket (inlet manifold) I am starting to think it might be a leak on the inlet manifold somewhere. I used a high quality silicone and copper based sealing compound on the gasket and all joining surfaces. Are there any particular tips for this job, as I'm thinking I might have to strip it all again and refit.
When there is a suspected leak on or around the inlet manifold a mechanic once taught me an old trick. Mix a small amount of washing up liquid and water and place it in one of them household spray bottles with a trigger. Start the car up even though its difficult to start, while it is still startable. Whilst the engine is running, before it gets too hot, spray the liquid mixture around the inlet manifold and any suspected air leak areas. If there is an air leak you will see bubbles rather like a childs bubble machine. That way you will know if there is a leak and where. If I have managed to solve your problem, all donations to the BBWF charity. All the best and good luck.
Tony. TCB.
Tony. TCB.
Lean Machine said:
When there is a suspected leak on or around the inlet manifold a mechanic once taught me an old trick.
Tony. TCB.
How about a new tip from an old mechanic? Tony. TCB.
Simply buy a can of spray ether. It is normally sold in auto stores under the name "QuickStart". Once your car is idling, spray the upper engine components with brief bursts. When the idle changes..you have found a leak (unless you have sprayed the stuff in your air intake).
+8
It would seem from your description that blipping the throttle did help giving only a partial solution, enriching the mixture when the engine is cold. Winter-time does make it more difficult tho'.
It has to be a possibility that your work on the inlet manifold valley gasket has breached and you have a gross air leak developed, thereabouts.
Moving on, a system induced, non starting issue may also be due to a couple of usual suspects.
But lack of rich starting mixture can also be due to a few more possibilities.
It has to be a possibility that your work on the inlet manifold valley gasket has breached and you have a gross air leak developed, thereabouts.
Moving on, a system induced, non starting issue may also be due to a couple of usual suspects.
- Cold start injector not firing during cranking
- A bujjered coolant temp sensor
But lack of rich starting mixture can also be due to a few more possibilities.
- Rogue air leak into the plenum chamber causing grossly weak mixture.
- Failed Fuel Pressure regulator unable to achieve the normal 36 psi.
- Crud in the fuel supply system, including tank, pump and filter
plushuit said:
How about a new tip from an old mechanic?
Simply buy a can of spray ether. spray the upper engine components with brief bursts.
+8
But surely if the liquid ether ignites from a spark you'd be left there looking like one of the dancers from the 'Black and White Minstrels Show' ;-)Simply buy a can of spray ether. spray the upper engine components with brief bursts.
+8
Tony. TCB.
plushuit said:
How about a new tip from an old mechanic?
Simply buy a can of spray ether. It is normally sold in auto stores under the name "QuickStart". Once your car is idling, spray the upper engine components with brief bursts. When the idle changes..you have found a leak (unless you have sprayed the stuff in your air intake).
+8
Simply buy a can of spray ether. It is normally sold in auto stores under the name "QuickStart". Once your car is idling, spray the upper engine components with brief bursts. When the idle changes..you have found a leak (unless you have sprayed the stuff in your air intake).
+8
I believe carb cleaner does the same thing.
Cheers HonestJohn, some good advice. I would like to think my work on the inlet manifold was OK, as I'm pretty particular, but as you say, I can't rule out a possible leak. But because I can't start the engine, is there any way of checking for a leak. I will firstly do a compression test and spark test, and if thats ok move onto your other advice re cold start injector and temp sensor etc. My thoughts are it's not an inlet air leak as the problem from memory was present prior to replacement, but not as severe, so seems to be something which has deteriorated/worsened. There seems to be plenty of fuel from the smell when cranking, so I keep coming back to a simple electrical fault. I understand the cold start injector could be stuck open, so even if I unplug it, it will still overfuel. Is there a way of clearing excess fuel, I believed it to be by holding the throttle wide open when cranking ?
Anyway, cheers for all the advice and help from everyone. I knew I shouldn't have quoted that in 24years of ownership it has never broken down !!! That's why I know so little, it has caused so few problems for me.
Anyway, cheers for all the advice and help from everyone. I knew I shouldn't have quoted that in 24years of ownership it has never broken down !!! That's why I know so little, it has caused so few problems for me.
braddeztvr said:
My thoughts are it's not an inlet air leak as the problem from memory was present prior to replacement, but not as severe,
There seems to be plenty of fuel from the smell when cranking, so I keep coming back to a simple electrical fault.
I understand the cold start injector could be stuck open, so even if I unplug it, it will still overfuel.
Is there a way of clearing excess fuel, I believed it to be by holding the throttle wide open when cranking
The guff in my prior post was addressing the reported signs and symptoms pointing to the probability that there was a lack of enrichment when starting - such as - CTS crocked, CSI not injecting, Air Leak causing weak mixture, FPR not providing fuel pressure and blocked fuel supply.There seems to be plenty of fuel from the smell when cranking, so I keep coming back to a simple electrical fault.
I understand the cold start injector could be stuck open, so even if I unplug it, it will still overfuel.
Is there a way of clearing excess fuel, I believed it to be by holding the throttle wide open when cranking
However, from your observations above emphasising you suspect over-fuelling. ie, noticeable fuel smell, CSI maybe stuck open and needing the clear excess fuel, can point to a different scenario.
And to support that - as you surmise, any simple electrical problem preventing preventing sparks will result in loads of excess fuel being squirted from the CSI during repetitive cranking.
But then, even with sparks, the same can happen, ie - repetitive starting, loads of squirting and a super rich non combustible starting mixture. One of the by-products of repetitive starting is a low battery voltage and this can affect the strength of the sparks.
Inspecting the condition of the spark plugs, one from each bank, will tell you if the engine is flooded.
To clear the combustion chambers of excess fuel on an Efi is NOT best achieved by holding the throttle wide open as this invokes extra fuelling from the acceleration and full load enrichment circuits as well as the injectors on full bore. That's a lot of fuel.
Perhaps the easiest way would be to disconnect the engine running signal from coil negative to the ECU AND electrically disconnect the CSI, and providing its not actually leaking, you can now crank the engine with throttle wide open to blow out excess fuel and no new fuel can be added to the chambers.
Strange tho', trying to address a weak mixture and excess fuel (flooding) in the same diagnosis but if an engine will not start and run when cold due to a weak starting mixture and/or weak sparks, it can rapidly be overtaken by repetitive cranking, squirting and pumping creating a flooded engine.
Finally to support your suspicion that an electrical fault exists, be aware that over 80% of all RV8 Efi problems are due to electrical connection issues and rogue air leaks and combining that with the possibility of weak or non existent sparks you might want to have a look at the health of your ignition system here
Have done compression test, and all are between 155 and 165 PSI(I presume thats OK for an old engine). However whilst doing this, have now checked and there is no spark at the plugs? This is odd as a week or so ago I had the same starting probs but when it did start it ran and drove OK. I will continue with the diagnosis as per the attached link you provided, re electrical probs.
Lean Machine said:
plushuit said:
How about a new tip from an old mechanic?
Simply buy a can of spray ether. spray the upper engine components with brief bursts.
+8
But surely if the liquid ether ignites from a spark you'd be left there looking like one of the dancers from the 'Black and White Minstrels Show' ;-)Simply buy a can of spray ether. spray the upper engine components with brief bursts.
+8
Tony. TCB.
But no, that can't happen. Think of it this way, a widely sold product that instructs to spray into the air intake while trying to start your car, is not brewed to explode when you spray a bit on the plenum and surrounding hoses. Gassing Station | Wedges | Top of Page | What's New | My Stuff