Could the battery be to blame for no start even if it cranks

[Mawrick 0]

Not realy a Corrado question but as the engine is the same, and I'm hopefully a corrado owner myselfe in not a such distant future I'd thought I could ask in here:

 

I'm quite lost on this problem, my VR6 won't start now, it had some problems earlier with bad wiring ending with regular cutouts etc, but got that fixed, and the engine seemed to work ok. One night I fired it up to defrost it, it had been standing for couple of weeks then.

 

Went inside, forgot about the car, about 1 hour later I went back out and the car had stopped. After this I haven't been able to get it started, It doesn't seem to give me sparks, pretty much all the ignition parts have been replaced, besides the distrubutor (the cap and rotor have been), I'v measured the coil according to the bentley manual, and it seem to be ok (AFAIK the resistance number in the bentley is a bit low when measuring pin 4 and 15, I'v measured 2 coils and they have same results).

 

The car seem to crank ok, but won't fire, I'm starting to think of the ECM but not sure, the voltage in on the coil seem a *bit* lower then on the battery but it's not much.

 

Could it be that the battery is somewhat wrecked if it can crank the engine, but not fire it?, I'v tried with a new ignition switch as well...

 

thanks in advance.

 

One last thing: Do the part-number of the ECM have to match 100% to work?, mine have BOSCH: 0261 200 469, VW: 021 906 258 (I'v found others for sale with same VW Number but with added leters after it, f.ex the letter C), anyone got any tips on this? It is a OBD-1 engine with distributor.

[RW1 0]

Voltage while cranking the engine should be above 9.5 volts or the electronics don't like it and stop working.

 

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[Mawrick 0]

Hmm, ok, I'l check that out. Thnx.

 

Any other ideas of what to check for would also be greatly appreciated.

 

btw will a faulty LMM also cause the engine not to start?

[Bobert healetty 0]

Voltage while cranking the engine should be above 9.5 volts or the electronics don't like it and stop working.

 

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i thought it was 9.6

 

 

anyways why dont you bring the battery to a shop and have them do a heavy load test...to see if your battery is good..what is the static voltage with the car off and the ignition off?

[CorradoVR6-Turbo 0]

Voltage while cranking the engine should be above 9.5 volts or the electronics don't like it and stop working.

 

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i thought it was 9.6

 

 

Lol :lol:

[Bobert healetty 0]

also check for parasitic drain...make sure when you turn the car off and leave it sitting for the night...make sure EVERYTHING turns off because even if the trunk light stays on over time it will just completely drain your battery and can cause hard starting..

 

a good way to check for parisitic current drain is to take off the negative battery terminal hook up a jumperwire from the post to the terminal then turn the ignition to the on position for 15 seconds then hook up your ammeter parallel to the jumperwire and disonnect the jumper wire...then read your amps it should be between 0 milliamps-100milliamps if its anything more then you have parisitic current drain and you should go and find whats causing it

 

but first and foremost check the batterys static voltage it should be between 12.45volts(75% charged) and 12.68(fullycharged)

[RW1 0]

i thought it was 9.6

 

Jeeezzzzzzzz we have a scientist amongst us......... :lol:

 

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[Bobert healetty 0]

i thought it was 9.6

 

Jeeezzzzzzzz we have a scientist amongst us......... :lol:

 

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sorry i wasnt sure if it was 9.6 or 9.5

[H8RRA 0]

i thought it was 9.587? 8)

 

ow quickly does the mtor crank? - if its slow, the first port of call is to get it checked as suggested above.

[dinkus 10]

As Bobert healetty says - the boot/trunk light is the usual culprit for parasitic drain - the microswitch in the boot latch breaks and so the light stays on all the time...

[Pickard1 0]

Went inside, forgot about the car, about 1 hour later I went back out and the car had stopped.

How much petrol was in it? :lol:

[Mawrick 0]

hehe, I guess it was newly refilled, so I guess about 70litres.....should be plenty for 1 hour...;)

[Mawrick 0]

btw, any of you have any ideas about the ECU numbers, do they have to match 100% ? f.ex same vw number, but ending with some letter combinations, what is the differences?

 

thnx again

[RW1 0]

021 906 258

 

All Corrado VR6 are this number but the suffix counts as there are minor wiring loom differences plus the last in the series (CP) is an immobilised version. The range is B, BF, CC, AG & CP. First three are 6 way distributor, last two are coil pack versions.

 

 

"Have had quite a few problems with this VR6, it's a 1991 model passat vr6."

 

Is the engine a 2.8 or 2.9 ltr engine? Passat engines will have another set of suffices.

 

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[Mawrick 0]

On the Passat's ecu it have these numbers:

BOSCH: 0261 200 469

VW: 021 906 258

 

seem to be the same, but it doesn't have any suffix, it's a early model ie distributor (1991/92 model).

 

Does this mean I can use other ecu's if the number match and it got any suffixes, eventualy will the connection harness of the ecu differ too?

[RW1 0]

021 906 258

 

Seems 258AC, 258CB & 258AF will possibly work. What won't are the later coil pack types as the wiring is significantly different.

 

A 021 906 258 brand new was on FleeBay about Christmas time and I seem to remember it didn't sell at £50. Pity...........

 

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[Mawrick 0]

Ok, thnx m8, just got hold of a ecu from a friend hoping to hook it up tonight to check it out.

 

btw, any idea about the "C" Suffix, same number but ends with C, as that seem to be quite common on ebay.

 

Also how does one disconnect the wiring-harness (the round connector) close to the distributor?, eventuelly is it common to have bad connections in that area?

[Mawrick 0]

Problem solved.............well almost.

 

Put the ecu I borrowed into the car today, it fired up right away, so guess that's sorted, now I gotta get my hans on one of these.

 

btw, anyone ever took one apart, I was thinking of just opening it and see if it's something "obviously" wrong with it like bad soldering etc, we'l see.

 

Thanks again for the respons...:)