What should the voltage generally be when cranking over a car?

Battery is 12.6v from cold
When cranking it's going down to anything between 9.8v - 10.8v

Is this normal or is the starter drawing to much current?

 

SOunds about right to me fella

 

Bang on target.
tabetha

 

Bugger.......

The starting issues on my Zetec running Weber Alpha throttle bodies and management has been getting worse and worse recently......
I just wouldn't fire up today even after fitting a new battery and trying with jump leads on it as well.

Backfires from the exhaust and induction plus a starter motor that keeps sticking (and sounding a bit slow now) is all I'm getting. Cold starting is a nightmare (and now impossible!). Hot starting was also very tricky yesterday too....

My theory was that maybe the starter was drawing too much current and dropping the voltage lower than the ECU could cope with.... but I guess that can't be right.

 

Ecu's will typically work down to around 6/7 volts perfectly for this very reason.
Have you had a set up, what you are describing sounds like ignition is way too far advanced, this will cause a slow starter and spitting in exhaust, will even try to kick back if bad enough.
The webber/alpha is ok but a bit tricky to get into, there are better ecu's though, most ecu's will work on these tb's.
It will/should be ok once set up, gon onto live settings if it has them(I don't know) and tweak the timing down a touch to see the difference.
tabetha

 

Haven't had it set up as it's an 'out the box' kit with an ECU ready mapped for a Silvertop 2.0 & the supplied TBs. Weber insist that it should run 'out the box' too.

 

Well you've had it running so they are not lying, but here comes the difference between what you call decent running and what they do.
What sort of software did you get with it ?, it clearly isn't running right, and I wouldn't expect it to, there is no way it will be 100% on each car.
To get the best it will need adjusting/setting up, quickest easiest way is RR.
tabetha

 

You get sod all software with it! ......as they expect it to work 100% with every car.

I'm thinking maybe the map is a bit off and several months of the starter being used for ten times the duration it should on every cold start has finally taken it's toll.
The faulty starter is now dropping the voltage so much that the ECU doesn't want to play ball?



It does runs amazingly when it actually starts though....

 

There's nothing wrong with starting voltage, starting is part of the programming, and the hardest bit to get right.
You need to visit someone who has thge software to tweak start up and decay settings etc, or get a software disc and diy.
I know it's hassle but the only cure, do you want me to get the software disc ?
tabetha

 

Does sound a pain, but has to be done I guess!

That would be ace if you have it/can get it.... just let me know

 

Having spoken to someone who does the alpha stuff, it seesm they are unwilling to supply a software disc, and say "the ecu has been mapped for each car to run perfectly straight out of the box".
Never in a million years will this happen, even 10 standard engines will each benefit from a slight tweak here and there.
The cold starting is actually a very hard part to get right, mostly as the tuner only has one stab, then it's no longer cold.
Your best and cheapest bet is a visit to a webber alpha dealer for some RR work, a lot of people don't like webber alpha for this very reason, I've seen a direct test on a supplied kit for the exact engine it was on compared with a alternative ecu fully mapped, a new loom/patch lead had to be made to suit the different ecu, the difference must have been noticebale, the owner asked if anyone wanted to buy a webber alpha kit, as he took away the new ecu fully mapped.
It's not the webber alpha is a bad kit by any means but it's ridiculous to suggest it's right for all right out of the box, you will benefit from mapping.
tabetha

 

Bugger!
Ahh well, cheers anyway.... Hmm, visiting a tuner for a re-map may be tricky, as it won't start anymore...

Need to investigate who can deal with these I guess, gotta get the car back up and running! Any suggestions are welcome....

 

There are many but the only one I have experience of who does the webber alpha is Northampton Motorsport, who I found very good, but a bit of a trek!!
tabetha
If you contact webber 01932 788805 they will be able to tell you, if not speak to Andy Gray there.
tabetha

 

Cheers for trying!

Someone else suggested today (a Honda tuner!) that the initial problem may have been down to the wrong crank sensor being used. He's got experience of similar symptoms when fitting DTA management, which uses a Ford crank sensor!