Minimum engine RPM for ignition
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- Posts: 12
- Joined: Thu Jun 27, 2013 10:48 am
- ECU Model: S40 Pro
Minimum engine RPM for ignition
Hello everybody!
I am new in DTA. Short intro: My name is Toni from Köln (or Cologne), Germany. I build a S40 Pro in my US '77 VW T2 and made the flywheel a 24 - 1 incriment flywheel. The DTA shall work as a substitude for the original controler. Now i am having a problem with the ignition. With the sparking plugs mounted off i get a RPM of around 230 - even if I jumpstart it. I am not sure if this is a normal cranking RPM. But with the sparking plugs mounted it even drops further to probably just below 200. I am not sure because the map shows 0. even if i just put in one sparking plug. The flywheel spins a little slower and no more output of rpm. It looks like the sensor or the ECU can't sense rpm's below 200. Or is this a configuration problem? And because the rpm shows zero there is no ignition. No ignition - no running engine - problem...
I know there are a lot of you having DTA's installed in older cars? Anybody had the same or similar problems? Thanks for any support!
Greetings from Köln
Toni
I am new in DTA. Short intro: My name is Toni from Köln (or Cologne), Germany. I build a S40 Pro in my US '77 VW T2 and made the flywheel a 24 - 1 incriment flywheel. The DTA shall work as a substitude for the original controler. Now i am having a problem with the ignition. With the sparking plugs mounted off i get a RPM of around 230 - even if I jumpstart it. I am not sure if this is a normal cranking RPM. But with the sparking plugs mounted it even drops further to probably just below 200. I am not sure because the map shows 0. even if i just put in one sparking plug. The flywheel spins a little slower and no more output of rpm. It looks like the sensor or the ECU can't sense rpm's below 200. Or is this a configuration problem? And because the rpm shows zero there is no ignition. No ignition - no running engine - problem...
I know there are a lot of you having DTA's installed in older cars? Anybody had the same or similar problems? Thanks for any support!
Greetings from Köln
Toni
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- Posts: 318
- Joined: Tue Aug 09, 2011 2:54 pm
- ECU Model: S80 Pro
- Distributor: Roverdose
- Location: Stevenage
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Re: Minimum engine RPM for ignition
so you see rpm in the dta software with the plugs out, but not with the plugs in?
sensor/wiring problem for me. possibly getting interference?
Drew
sensor/wiring problem for me. possibly getting interference?
Drew
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Re: Minimum engine RPM for ignition
Havent most problems like this before been a lack of battery supply when cranking ?
Post a scope trace of the signal when cranking, with plugs in and out. And also monitor voltage at the ecu when cranking.
Post a scope trace of the signal when cranking, with plugs in and out. And also monitor voltage at the ecu when cranking.
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- Posts: 12
- Joined: Thu Jun 27, 2013 10:48 am
- ECU Model: S40 Pro
Re: Minimum engine RPM for ignition
Thanks for the quick answers!
@Steve
I already dealed with that problem. When cranking the voltage of the Ecu drops to around 11V, wich is okay I think. Nevertheless I tried two thinks to even be sure that this is definetly not the problem. I jumpstarted the bus with another car and had over 13V all the time. And I hooked another batterie at the Ecu so it has is very own power supply. I will still try to do scope trace.
@Drew
Thanks
Toni
@Steve
I already dealed with that problem. When cranking the voltage of the Ecu drops to around 11V, wich is okay I think. Nevertheless I tried two thinks to even be sure that this is definetly not the problem. I jumpstarted the bus with another car and had over 13V all the time. And I hooked another batterie at the Ecu so it has is very own power supply. I will still try to do scope trace.
@Drew
That is excactly the problem. I thought it might be a lower than 200 rpm that is not shown by the DTA software. But I tried it only with cylinder 1 plug in or out and the wiring for the sensor runs nearby the cylnder 1. I will try to just put the plug fpr cylinder 4 in and see what happens then. Maybe it is interference... I will gibe it a try.so you see rpm in the dta software with the plugs out, but not with the plugs in?
Thanks
Toni
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- Posts: 318
- Joined: Tue Aug 09, 2011 2:54 pm
- ECU Model: S80 Pro
- Distributor: Roverdose
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Re: Minimum engine RPM for ignition
mine cranks at 150 when cold, just over 200 hot, so its not that it cant be seen by the software. mine also drops into 10v range on crank.
as steve said the S series has a crank scope feature, might be worth running that with no plugs then all plugs to see if it can see the crank sensor properly.
Drew
as steve said the S series has a crank scope feature, might be worth running that with no plugs then all plugs to see if it can see the crank sensor properly.
Drew
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- Joined: Tue Aug 02, 2011 12:08 pm
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Re: Minimum engine RPM for ignition
11v is plenty.
Scope trace would tell a lot. A 2 wire VR sensor generates it's own voltage, so if for example the air gap was too large, the the voltage generated would be much smaller and the ecu may not see this until a higher rpm.
So something like that may be a potential issue. The height of the yellow trace indicates voltage seen
Either way, 200rpm is plenty fast to start an engine. I think mine cranks around 180rpm or so most of the time.
Scope trace would tell a lot. A 2 wire VR sensor generates it's own voltage, so if for example the air gap was too large, the the voltage generated would be much smaller and the ecu may not see this until a higher rpm.
So something like that may be a potential issue. The height of the yellow trace indicates voltage seen
Either way, 200rpm is plenty fast to start an engine. I think mine cranks around 180rpm or so most of the time.
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- Posts: 12
- Joined: Thu Jun 27, 2013 10:48 am
- ECU Model: S40 Pro
Re: Minimum engine RPM for ignition
Hi everybody,
today I found the time to go to my garage and do a scope while cranking. The scope without plugs still looks good to me. But it looks quite strange with the plugs in and especially with only one or two plugs in. So it really looks like an interference problem to me... what do you think? Thanks a lot!
today I found the time to go to my garage and do a scope while cranking. The scope without plugs still looks good to me. But it looks quite strange with the plugs in and especially with only one or two plugs in. So it really looks like an interference problem to me... what do you think? Thanks a lot!
- Attachments
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- without plugs
- without.png (10.57 KiB) Viewed 8218 times
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- with all plugs in
- withall.png (11.56 KiB) Viewed 8218 times
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- Posts: 12
- Joined: Thu Jun 27, 2013 10:48 am
- ECU Model: S40 Pro
Re: Minimum engine RPM for ignition
Here are the scopes for plug in #3 cylinder in, with #3 and #2 in and for #3,#2 and #1 in...
- Attachments
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- only #3 in
- with3.png (10.21 KiB) Viewed 8218 times
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- #3 and #2 in
- with3and2.png (8.16 KiB) Viewed 8218 times
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- #3,#2 and #1 in
- with3and2and1.png (9.08 KiB) Viewed 8218 times
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- Distributor: None-Coil On Plug :)
Re: Minimum engine RPM for ignition
Don't get hung up on cranking rpm, remember that the ecu does not use the ignition map until the 'transition from cranking' speed is exceeded. Up to this point it just relies on firing tooth on start up.
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- Joined: Tue Aug 09, 2011 2:54 pm
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Re: Minimum engine RPM for ignition
looks fine to me, can you post a pic of the general engine settings page?
Drew
Drew