Sebastian
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| posted on 14/3/09 at 06:54 PM |
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Problems with ECU, HELP.
Hi,
I have an older Dunnell system on my 2.0 Silvertop engine, i purchased this system from a guy who also used it on a 2.0 Zetec but now i have the
following problem.
When i start the car the engine runs perfect i can rev the engine with no problems but when i want to drive it i don't get any power it just
stalls and all the dials that are connected to the ECU stop working.
The engine also blows out of the exhaust.
Dunnell has been very helpfull but since this is an older system they can't give a lot of advise anymore.
What do you guys think the problem is?
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Paul TigerB6
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| posted on 14/3/09 at 06:56 PM |
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Do you have a throttle position sensor and if so is it wired up the correct way around??
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Sebastian
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| posted on 14/3/09 at 07:02 PM |
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I do have a TPS sensor and i was a little bit in the dark with the wiring since the plug was taken of, the guy used it on his supercharger system, so
this could be a point.
I never realised that his would have such an impact espacially since it does rev ok in neutral.
What happens with the TPS when reving in neutral and under load?
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David Jenkins
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| posted on 14/3/09 at 07:12 PM |
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The TPS sensor tells the ECU how far to advance the ignition timing. If it's not right it may leave the timing too far retarded - it will be
fine at idle, but may not give much power when the revs rise.
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Paul TigerB6
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| posted on 14/3/09 at 07:14 PM |
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Well the TPS is basically a potentiometer and the ECU takes the signal and alters the ignition timing to suit the engine speed and throttle position
based on the map that is loaded into it (assuming its a 3D system rather than 2D). If the wires are the wrong way around then it could be working in
reverse (I think - so basically giving you lots of ignition advance at closed throttle) and less as you open it, or not at all.
Try unplugging the TPS and see if this improves matters. If so then you know its wired wrong
[Edited on 14/3/09 by Paul TigerB6]
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Sebastian
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| posted on 14/3/09 at 07:45 PM |
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OK i will try this, so i can just unplug the TPS and try driving?
O is this a better option:
I have a diagram of the 3 wires which shows that the brown wire is always in the middle so this would mean that i had the diagram upside down 
Is it than better than to just switch the wires and try again?
[Edited on 14/3/09 by Sebastian]
[Edited on 14/3/09 by Sebastian]
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Paul TigerB6
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| posted on 14/3/09 at 07:51 PM |
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Yeah - switch the two and see what happens.
I thought the ECU would require the TPS to be calibrated myself (so it knows what is closed throttle and wide open throttle, and can work out
everything inbetween. Did this on my old Zetec car's Omex system, and also on the MegaJolt system i fitted to a Pinto car i built recently. I
know Dunnel ECU's dont have the option to alter the map yourself but how is the TPS calibrated? Anyone??
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big_wasa
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| posted on 15/3/09 at 09:31 AM |
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The dunnel clubmans ecu had the Tps as an upgrade and wasnt part of the bassic system unless you speced the 3d upgrade.
I have the instuction manual with wiring diagrams if you need any help.
1) Battery ignition switched 12v in
2) 5 volt output for sensors- spec. tps
3) Throttle position sensor (Tps) - wiper
4) Engine coolant temp sensor Ect
5) Air charge temp sensor ACT
6) Crank position sensor positive
7) Battery negative
8) switch 1 (pull down)
9) RXD (rs232)
10) TXD (rs232)
11) Fuel pump relay (low side)
12) Tachometer output
13) Coil 0 (lowside)
14) GND (rs232)
15) Tps signal return
16) ECT signal return
17) ACT signal return
18) Crankshaft position sensor negative
19) N/A
20) Switch 0 . Max
21) switch 2 . Log
22) Battery Negative
23) Battery negative
24) Shift Up/Down (low side)
25) Coil 1 (low side)
So pins for Tps are
2) 5v to tps
3) Sensor
15) signal earth
so on the webcon tps pins on tps to pins on ecu are.
3-2
1-3
2-15
to set the new tps the instructions are
Ground ext-switch 1 (pin 8) for 1 sec then depress and relese the throttle atleast twice so that the tps traverses its full range.
What temp sensor are you using ? It should be the large top one in the zetec thermostat housing.
Hope thats of some help ?
cheers 
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Sebastian
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| posted on 15/3/09 at 11:51 AM |
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OK thanks so far, i will first try to switch the wires if that doesn't work i will try and reset the TPS.
I will keep you posted.
@ Big-Wasa: thanks for the offer if i need the wiring diagram i will let you know, and i do have the tempsensor in the Zetec thermostathousing and
this is the one supplied with the Dunnell kit so this should be OK.
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NS Dev
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| posted on 15/3/09 at 01:19 PM |
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as far as I know the dunnel ecu is DTA, so could be worth giving them a call, but it sounds like a tps issue to me
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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big_wasa
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| posted on 15/3/09 at 04:11 PM |
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^^^^^
They claim its there own but I think its actually made by a firm in Os called Aee or AAE or somthing like that. I used to have a link for them but ive
now lost it.
I dont understand what you mean by the clocks loosing power as they should have a seperate suply. Its only the Tacho signal that goes to the
clocks.
Have you wired the fuel pump via a relay ? The ecu earths the relay as it cant handle the power of the pump. It would cook it or trip the ecu out
depending on how its designed.
How have you wired the coil ? as that should also have its own suply.
The ecu has three seperate earths and should be earthe seperate from each other and not bunched into one.
A couple of years ago they took mine back reprogramed it and reset the hour meter for a fresh engine.
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