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Won't start!!

Started by chrismsullivan, 03 September 2011, 11:10 PM

oscar

How did you get on Chris? 

I've been away so just reading this now, I agree with WGB thinking this is a case of an AAV/idle screw balancing act .  It can be fiddly to get a happy medium for setting hot versus cold idle particularly now that we see in that other thread on AAVs just how a cut down AAV looks like and how the wax decomposes.  It seems there's really no point expecting miracles from old AAVs.

Anyhow, that hunting issue you mention, it's purely that d-jet characteristic we've mentioned before about the engine getting too much air whilst at idle, the ECU cuts out the injectors until revs drop, then they jump back in again and it keeps going up and down till the engine warms more and either the AAV closes a little and/or other sensors plus ecu come into play.  Something like that. No real issue.

There's two other things I want to mention relating to stalls I've had whilst driving;
1. After washing the car and engine bay years ago I've got water into somewhere.  I don't know where and there was no indication of any probs initially.  It took about 3-5km of driving before the engine started to splutter and then wouldn't restart.  This has happened twice, clearly I didn't learn my lesson the first time and the second time was worse.  I pulled all sorts of EFI cables, took out dizzy, spark plugs. Air hosed everything, left the bonnet open for days (late spring early summer) and it took a week or more before the car would fire back to life.  I've no idea where water went, I didn't drown the engine by any means but that's what happened.  In the end all but two cylinders came to life and that issue was due to two injectors not firing and recitfied by relubing the cam shaft in the dizzy for the trigger points.  The mention of "white smoke"  made me think of white steam instead, thinking that the car wash you gave it might have inadvertently put water in places that shouldn't have been wet, ie like spraying through the grill and some water getting into the intake somehow.
2. A simple one but a combination of dodgy battery and alternator has seen me stall twice without warning too.  Well, in hindshight maybe lights dimmed a little and performance was becoming sluggish but there was not enough juice to run d-jet.  Yet it could be restarted after a bit and continue running.

And one more thing, the Sensor 2 that Nutz talks about is the Thermotime Switch.  If that's disconected the engine simply wont start and if there is some continuity issue with it's wiring I suppose it could cause stalls perhaps, though I've never disconnected one on a running engine.  Can't remember,  but like everything else, check it's connection for contact and water ingress.  It's located in the sensor box RHS of cam box above exhaust manifolds and numbered 4 as below.  I think it's got a bakelite kind of fitting for the plugged connection tha can be brittle and has a delicate clip so it wont just pull straight off.  Take a close look at the plug first to see how it's locked on.  If the clip/s break it's not too big a drama but there should be some physical drag as the plug is connected/disconnected to ensure some kind of good contact.







1973 350SE, my first & fave

chrismsullivan

Hey Oscar, thanks for the reply mate.

No joy I'm afraid. I've actually not had any time to play with the car further since my last post, so it's still got a problem. I'm not so sure that it's a problem with the air mixture, given that it will start fine, run for a few minutes, cut out without warning and then cannot be started again until cold.

The hunting issue was a one off, I must have had something disconnected to cause this.

Thanks for the info about the dizzy and the thermotime switch.

I'm kind of at a loss as to what could be causing all of this. I will be checking the thermotime switch, dizzy and all other electrical connections soon. I have to go and fill up the Jerry can first as all starting/stopping/running rich has taken it's toll on the petrol tank!
I might also get a new fuel filter for good measure and dump the oil as it's bound to be pretty ordinary by now.

I'll let you know if I make any headway, but at the moment I'm feeling quite dejected about the lack of cooperation and am almost inclined to just let it sit there until I've saved up a few extra pennies to drag it to a workshop for an engine overhaul.

chrismsullivan

Another add on.

After mowing the lawn today, I thought I'd have another tinker with the car. I've checked the thermotime switched, traced the wiriing to the ECU and it all looks to be OK.

I put it all together, connected the battery and now it will not even start. It turns over just fine, there's fuel pressure and I can hear the pump priming. I'm thinking there's something wrong with any of the following the Dizzy, the coil, the leads, (the plugs are new, but fouled), the thermotime switch (although this shouldn't allow the car to just cut out while it was running would it?). I'm going to have to get the missus to crank the car to see if there's spark coming from the coil firstly.

I'm starting to get frustrated with this thing now!  :o

oscar

Quote from: chrismsullivan on 18 September 2011, 09:47 PM
thermotime switch (although this shouldn't allow the car to just cut out while it was running would it?).

I'm a tool. I just pulled my thermotime switch and the car started fine.  Even when the car's idling and I pulled it it seemed to have little effect on the idle quality. Sry bout that.  ::)  However, the coolant sensor (number 1 equivalent in that photo above).  I pulled that and the car was very hard to start and chugged and stalled.  I connected the plug, started it, then pulled the plug again and it chugged to a stall in no time.  So it's the coolant sensor (1) that has a serious effect on idle/starting, not the thermotimeswitch (4) in the way I was describing.

So that's one thing to look at though you probably have already.  Not sure what's going on but I'll be sure to jump on again with another misinformed brainwave if I have one ;)

1973 350SE, my first & fave

chrismsullivan

Hahaha.... No worries Oscar. At this stage, any information is good information.

OK, after a little more electrical diagnosis, I've noticed the following:

referring to the picture below; I pulled the cloil lead from the top of the distributor that leads back to the coil (as highlighted by the left circle, stuck a screwdriver in there, had the missus crank the engine and there was no spark.
I then went over to the coil (at least I'm pretty sure it's called the coil, highlighted by the bigger circle on the right) and placed my multimeter on the "+" and "-" ends (highlighted by the two smaller circles) while the engine was being cranked. It read zero volts.

Thoughts?


jjb-w116-hu

Is your coil ok? i occasionally have an issue with my coil and no spark , usually under strain or as a 'heat' issue. i have to wait for the car to cool a bit, give that lead into the coil a wiggle and it resolves. most annoying when helping female friends move house with a trailer ;)
any change you could show the look of your connection of the lead that goes into the coil? im sure mine has lost a connection or is buggy... cheers James

chrismsullivan

Hi James... No idea if the coil is OK mate. I'm suspecting it's not. I'm waitin guntil dark to check properly for spark, but I think it might be cactus.

Here's a pic or two of the HT lead that goes into the top of the coil for you. My leads are relatively new, but I'm thinking that I might replace the coil (if I see no spark at night) and the leads as an inexpensive option. Here's hoping the ignition module hasn't decided to die.






jjb-w116-hu

great, cheers for that - i'll have a look at mine tomorrow morning - or later today when i get home ,thanks  :)
oh does anyone know how to post images into posts? i can never seem to find my way there -

chrismsullivan

Quote from: jjb-w116-hu on 19 September 2011, 01:41 AM
great, cheers for that - i'll have a look at mine tomorrow morning - or later today when i get home ,thanks  :)
oh does anyone know how to post images into posts? i can never seem to find my way there -

I use photobucket.com
Sign up for an account there, then upload the photo you would like to appear into photobucket. From there, you will be able to copy the image code of the photo you uploaded and then paste that code into your forum post. The forum will then read the image code and translate that into a photo.

Nutz

#24
If the circular plug is bulged out on top of the the coil, replace.
If not, check the primary resistance between terminal #1 and #15

with starter resistance, 0.33 - 0.46 ohms
without starter resistance, 0.5 - 0.9 ohms

Secondary resistance terminals #1 and #4

with starter resistance, 7 - 12 K ohms
without starter resistance, 6 - 16 K ohms


















chrismsullivan

Thanks so much Nutz.

I think that the answer will be in amongst the information you've posted above.

The good news is, that I've tested the coil to be firing spark and that the HT lead has the ability to send the spark through to the distributor.
I hope I explain the fololwing parts correctly, I'll post some pics tomorrow if it helps.
I pulled the dizzy apart this afternoon and took the trigger point?? out, it was pretty dirty... So I cleaned it up and put it back in, unadjusted, but roughly back where it was.

I then tested it by manually moving the part and received a strong spark from the coil and HT lead when the contact was broken. Next I cranked the ignition and it started right up, but was running rough... maybe due to me not adjusting that part in the dizzy correctly?
It ran well for a few minutes (although rough) and revved freely. Then again, it stopped without warning.

One random observation... I noticed that one of the resistors under the capacitor was very, very hot. Like burn your skin off hot. If you look at my previous pictures, it's the resitor shown with the blue metal band around it. Surely it's not normal for them to get so hot that it can burn skin or make liquid sizzle?

Anyway, there's been some minor progress in isolating it to the dizzy area.

Now, if the coil or the resistors are playing up and arcing out, or something like that, when warmed up, I could have a double problem on my hands... right?

Cheers,
Chris

Bandolero

I'm wondering if the ignition module is suspect as I had one just completely fail.
Worked one minute, switched off, then nothing.
I now always carry a spare module in the boot. (Along with spare coil and ballast resistors.) ☺
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]

oscar

I don't know much about ignition but when the modules go that's it isn't it?  No warning, no intermitent running, just kaput, no more ignition?

Anyhow, I've never touched the resistors before so I've just gone out to see if they get hot.  I started the car then felt them, they were cool.  I let the car idle up to 80degC and both blue and silver resistors were lukewarmish.  In no way were they too hot to touch.  Whatever's going on Chris it seems your onto something here.  Whether it's a case of a dodgy ballast resistor or it's getting hot due to the coil or module I don't know.  It might be worth taking the resistors out and checking for cracks. 
1973 350SE, my first & fave

chrismsullivan

The ignition module, coil, resistors are all on the suspects list at the moment!  ;)

OK, that info about your resistors is interesting. Mine become hot within seconds of starting the car. I think it would be well worth the effort replacing the coil, resistors first (cheaper option) before looking that the ignition module.

Nutz

What kind of plugs you have in there?