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Chris T

Sanity check, how is this possible???

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As a few here know I'm having endless trouble with a 3.4 conversion. Too little space here but suffice to it's been a bugger for over a year and it's persistent misfire is getting worse.

Sanity check; On Tuesday it ran like a bag of stuff (as normal) with either the after-market Canems ECU attached OR the original. On Wednesday I went to replace the battery (I've changed everything else) to see if my gremlins (high/low spikes voltage) were coming from there. Connected a 2nd battery Via jump leads, turned but not quick enough to start. So, I added a fast charger in 'start' mode, turned but still no start. So, I put back in the original battery and it turned just fine but not a hint of firing on the Canems nor the original ECU. Worse the fuel pump runs as normal as you turn the key with the Canems but NOT the original ECU!!! 

Today I checked the pins on the 35 way ECU plug, checked and re checked everything and same symptoms.

How can it run the fuel pump with one ECU not with the other and totally fail to start after just a battery swop??

Anybody? It's driving, no has driven me mad.

Thanks, Chris.

 

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So you've definitely got spark yes?

Have you tried hot wiring the fuel pump so it runs constantly to check if it starts & runs?

Just because the pump runs when you first crank it over if the crank sensor is dead it will cut out. 

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Not really up to speed with this but I assume it's the '84 in which case the original ECU would need a DIME and I assume the Canems wouldn't? If that's the case the difference could just be the DME not working. Probably doesn't solve your problem but may help trouble shooting

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Thanks guys. Alex I haven't yet checked for a spark only one of me so it's hard. Roy, both ECUs use the DME relay, and yes I have changed it. My point really was how can it change from both ECUs running the fuel pump, car runs on both to overnight not running on either ECU and fuel pump running on and not the other. Literally, ALL I did was change the battery!!! 

Chris. 

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Not too familiar with the modern electricery ECU versions in the P, but .... is there an equivalent to lifting the paddle in the earlier (SC et al) versions, to keep the fuel pump running ?.  If so, I'd start by hot wiring the fuel pump to make sure it hasn't inconveniently failed mid-playing.  Then assuming all OK, then I'd get the fuel pump running with whichever ECU will work, then start wiggling the all the wires looking for a duff joint/connection or a wire with continuity issues.

 

Roll on the end of lockdown - I need a drive out and a play 🙂

Peter

 

PS - how's my pre-'73 H/Exs 

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Thanks Peter. I have indeed already hot wired the fuel pump, it runs and builds pressure fine, but no-go, so I suspect sparks. I've checked, re-checked and checked again any wire I went near during battery change, all as it should be. A mate is planning on coming over later to help check for sparks. The >2m distance between the ignition key and the plug leads are the reason I've not confirmed no spark syndrome myself! 

Your pre-'74 H/Es are fine, well and have a new MOT. Sadly they are still on the car as the other one has been marooned on the lift for weeks and weeks, has consumed all my car-time and much more than all of my car-patience. When it's going I'll swap them over and remove H/Es Unless (post-lockdown) you wanna come and assist and take them away (heavy discounts applied!)?

Chris.

 

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I can’t really help with that problem but to remotely check spark I use my inductive strobe - easy to position so you can see it through the rear window. 

Cheers

David 

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If its spinning up but refusing to fire, gotta be a spark/fuel issue? Daft question but you've checked all your fuses? Do you have an updated blade type fuse board? I used to get fuel pump failure just because of the old style bullet fuses on my SC. The fuel pump fuse used to get hot and lose contact. Changed to one of Jonny's boards and all the hassles went away. 

Gotta get systematic I guess. Fuses, Spark, Fuel. bring the mrs in to crank it over while you check. 

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3 hours ago, Chris T said:

Your pre-'74 H/Es are fine, well and have a new MOT. Sadly they are still on the car as the other one has been marooned on the lift for weeks and weeks, has consumed all my car-time and much more than all of my car-patience. When it's going I'll swap them over and remove H/Es Unless (post-lockdown) you wanna come and assist and take them away (heavy discounts applied!)?

Chris.

 

Love a trip out once we’re ‘unlocked’

 

As you know, I’m not near needing them just yet.  Progress on the targa has been good, but slow 🙈

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2 hours ago, Busybee said:

If its spinning up but refusing to fire, gotta be a spark/fuel issue? Daft question but you've checked all your fuses? Do you have an updated blade type fuse board? I used to get fuel pump failure just because of the old style bullet fuses on my SC. The fuel pump fuse used to get hot and lose contact. Changed to one of Jonny's boards and all the hassles went away. 

Gotta get systematic I guess. Fuses, Spark, Fuel. bring the mrs in to crank it over while you check. 

I have tried all the usual obvious stuff, and yes I have one of Jonny's excellent fuse boards. My question was and still is how can this change with just a battery swap?

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2 minutes ago, Chris T said:

I have tried all the usual obvious stuff, and yes I have one of Jonny's excellent fuse boards. My question was and still is how can this change with just a battery swap?

Could it be a voltage difference between the two battery's and your Canems thinks there's a fault? Is there a reset procedure on those? Clutching at straws to help ya. 

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It's a thought, I've been clutching at straws for a long time now, all thoughts are welcome! 

 

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Chris, what is driving your spark? Do you have a dizzy or a coil pack?

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Hi Phil, Canems ECU drives standard 3.2 coil and 1/2 of a 964 twin dizzy. 2nd Canems output drives another 3.2 coil and 2nd 1/2 of the same distributor which then fires lower set of plugs.

Update; A mate helped to prove sparks top and bottom set are working, fuel pump runs and delivers fuel to fuel rail, injectors can be felt clicking when cranking, all the time not a tiny glimmer of firing. I will send my ECU back to Canems for testing, 'maybe' I somehow blew it up changing battery...? Unlikely but with fuel and sparks both happening, distributor timing hasn't moved so ECU gone pop may be the answer....?

Chris.

 

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Very annoying and frustrating, I hope you get it sorted soon. It will be a great engine when it is done though, so don't get too down.

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Thanks Phil, all positive thoughts welcome at this time..... I started this 2 years ago, one rebuild due to popped gudgeon 'C' clip later, a super-expensive rolling road session and subsequent endless poor running issues have used up all of my patience and more, all available funds and more and it's still mis-behaving. Now I'm taking 2 steps forward, 3 back as it now doesn't run at all!! 

Beer O'clock.

Chris.

 

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The canems solution doesn’t use the 964 dizzy setup; what does this give you over the crankfire?

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Sorry Shrish, I don't understand the question.... Canems ECU can use pencil coils or regular coils and a 964 dizzy or a modified 3.2 dizzy with a 12 way cap. I went 964 as was the easiest at the time. 

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With a set of coil packs and a crank sensor and toothed wheel setup, you can delete the dissie with many ECUs

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27 minutes ago, PeterK said:

With a set of coil packs and a crank sensor and toothed wheel setup, you can delete the dissie with many ECUs

You are quite right Peter but before spending more cash and not knowing what the current issue is it might be not be wise to change more things just yet as It could make the mystery even more difficult to solve. It may well just be the ECU playing up. 

In fact Chris your misfire could have been the ECU all along and now it has finally given up altogether?

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Yes, I think Canems can do that too. I THINK it cannot do twin plug like that, I really can't remember, but I guess I chose a 964 twin dizzy for a reason..... Seems a long time ago now!

Phill, I hope you are right! David at Canems has been studying the logs I've sent him and has said he suspects the sharp voltage spikes 12v-16v but really spikey. Let's hope it was the ECU easy fix but almost a year wasted.....

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1 hour ago, Chris T said:

Sorry Shrish, I don't understand the question.... Canems ECU can use pencil coils or regular coils and a 964 dizzy or a modified 3.2 dizzy with a 12 way cap. I went 964 as was the easiest at the time. 

I meant why did you go with using dizzys and not the crankfire solution, which I thought was part of the standard Canems offering.
No worries, I see you responded above.

 

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27 minutes ago, Phill said:

You are quite right Peter but before spending more cash and not knowing what the current issue is it might be not be wise to change more things just yet as It could make the mystery even more difficult to solve. It may well just be the ECU playing up. 

In fact Chris your misfire could have been the ECU all along and now it has finally given up altogether?

No suggesting anything new be bought, just commenting when Chris questioned Shirish's comment.

 

Without knowing exactly what Chris has tried, my logical approach would be to put the standard ECU back in for now, give it plenty batteries and start again. Next I'd check whether one or more pins in the ECU connector have got bent or connection s loose.  If all OK, but it isn't firing despite having fuel and spark, then I'd be checking that the spark and fuel are happening at the right time and that the fuel is at the right pressure.

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Quick thought - you say you have fuel (pump running) and spark, but are the injectors pulsing ?.  Do you have any node lamps to check the injector pulse ?  Do the injectors have a separate fused live supply ? (I'm assuming that the ECU triggers to earth)

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Have you connected your laptop to the Canems to see if it's showing you anything. If you're getting a response then I would doubt the ECU has gone? You may, however, have lost a connection (possibly sensor) and my understanding is that Canems is good at identifying that.

Good luck!

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