Firing on two at start up

[Geordie]

Hi all
Unfortunately part 2 of my problem ,,,car starts intermittently on two cylinders if you attempt to start it it will eventually start ok and run for sometimes days ,as an old school being used to plugs/points etc I’m a bit out of my depth- so upto now I have removed plugs (look fine ?) fit 2 new coils and as it’s getting worse I have managed to find out cylinders 1 and 3 is problem ,can any of you with a lot more experience with these engines give me some idea how to fault find my problem ? Please use correct names not abbreviations of parts as I’ve said I’m a complete novice on this engine ,I’m only hoping I can sort this as I don’t want to lose driving time ,
Cheers in advance
Geordie
Oh it’s a m100se in case it makes any difference

[Chas54]

Geordie

You may be short on replies as you possibly should have posted in "igntion and fuelling" section .

But , one of the best tools to use for diagnosing faults is the "elanscan" program but you need a laptop and cable to plug into the Socket under the glove box.

I use a home made lead which is explained on this forum and an ancient laptop running windows 7. There is a gentleman on this forum who was selling made up leads

I can tell you that the 1 and 4 plugs are from one coil and the 2 and 3 plugs from the other coil. The ignition system does use the waste spark system whereby 1 & 4 spark together and 2 & 3 do.

I dont know if you have timing strobe light but if you have try aiming it at the cam cover and clip onto each plug lead individually to see if your suggested two cylinder are actually missing a spark.

Also be aware that if you wish to check the timing, you need to trigger the service mode , if you dont your engine management system (The ECU) will alter the timing to its calculated requirement so you will be wasting your time . For my elanscan lead i found a suggestion on this forum by "dapinky" to insert a toggle switch that you can use to select service mode. You then have the advantage of viewing live data whilst doing adjustments .
It will show you figues in an understanable format. It will show you the manifold pressure (vacuum) , Idle air control valve setting, O2 or CO sensor readings, throttle position . All of these things are vital to view if tampering yourself.
I currentley have just found my throttle position sensor reading 0 volts intermitently whereas the idling setting is with the throttle closed but reading 0.4 volts. this 0 volt reading means other parameters are not met.

If you havent already done this, you should download the Lotus manuals from this site and especially the engine management section. it describes fault finding and explains really well most functions.

I also had trouble getting my head round the engine control unit and im still baffled by it at times .

Chas

[FunElan]

The injectors fire in pairs also. At this point with how old these cars are, injectors and coils are just wear items. I know some will disagree with that statement, but it's peace of mind, which is priceless.

[Geordie]

Hi
Cheers for reply ,I’m almost certain it’s an injector problem ? Any ideas where I can purchase new ,as they have done 85000mls so I think they could do with more than just a clean
Cheers in advance

[FunElan]

Hi
Cheers for reply ,I’m almost certain it’s an injector problem ? Any ideas where I can purchase new ,as they have done 85000mls so I think they could do with more than just a clean
Cheers in advance

Call Mike at Southwest Lotus Centre

[Chas54]

Have you tried swapping the 1& 3 injector to the 2 & 4 under positions?.

I ask this as looking at the injector wiring diagram , 3&1 have a common supply from the C15 pin on the engine control module behind the glove box. And 2& 4 have a common supply from the D15 terminal

The ECM pulses the pairs once every crankshaft revolution . ie. Half the required fuel dose each time.

It is possible to witness this by removing the fuel rail and resting it on top of the engine in a shallow cooking tray. With the injectors in position and the loom attached.
It can be extracted without removing the inlet Plennum . You have to grope about behind the engine to remove the inlet and outlet fuel flexibles.
Of course spraying petrol all over the place is ill advised. But with engine cold and the spark plugs hidden under their cover and doing one injector at a time electronically , it can appear manageable.

I've done this to observe injector dripage after having a set cleaned. One still dripped.

Chas

[Geordie]

Cheers for your reply
I’ve removed the injectors and they are away for testing ? Depending on results will dictate my next step ?
Geordie

[mattdovey]

I wouldnt put to much faith in the testing of the injectors. We had a set cleaned and tested by reputable company. Pasted the test but 2 off the 4 injectors failed once fitted back on the car. Also bear in mind if you have one injector that is faulty. There is a good chance it will bring its partner injector down with it. Easy way to find out if you have a faulty injector is to disconnect each injector one at a time. If you have one bad injector, when the bad injector is disconnected its paired injector will start to work and you will start to run on 3. You will know then which injector is U/S. Another easy test is to measure the resistance of the injectors. They should all have the same resistance approx. 2 ohms (dependant on type of injectors fitted. You might see 2.2 ohms). If you have one say 1.5 ohms then that's the culprit. I pissed about buying injectors off ebay, utter rubbish. Ended up buying a set off South West Lotus. Good luck.

[Geordie]

Hi folks
Injectors have been tested and No1 is u/s. All others reasonable (what do you expect nearly 30yrs old) so I’ve ordered new set of Delphi
Should be here in next couple of weeks ,then we will see how we have done once fitted
Many thanks to those who have sent me ideas ,but I have to say rather a few on the ground ,but not to worry I think I’m getting there
Geordie