Howdy folks! Having a bit of a 'mare with my KR engined Corrado. Every now and then the ECU stops advancing the ignition when the car is revved, you can actually watch it happeneing with a timing strobe. I've swapped the ECU, ignition module, distributor & coil and the problem still persists. The ECU is getting a vacuum signal (I tested it with a boost gauge I had lying around), so I'm thinking there must be a wiring fault somewhere? Are there any other components that the ECU uses to decide how much advance to use? Also, how does the ECU control the ignition timing? Is it through the green wire going to the coil? Any tips would be greatly appreciated!! Edited by: MillSpeed
I'm wondering if this could be down to a fault with one of the three temperature senders on the right-hand side of the head. One of these is used by the ignition control unit. If there's a problem with the temperature signal (which as you'll know is vital because how the control unit behaves depends very much on engine temperature) then maybe the control unit assumes a 'safe mode' and doesn't advance ignition...? As it's an intermittent problem, maybe the movement of the engine when you rev it is causing a poor sensor connection to make and break? There are some very good diagrams floating around the web that show how the K-jetronic ignition control unit works together with all of its sensors etc. Might be worth seeking one of these diagrams out
Cheers buddy, I'm glad you mentioned temp sensors as it's the only thing I haven't checked. I was having a rummage earlier on today and noticed the temp sensor with an actual plug connector on it had a damaged wire. Is that the one that the ECU uses? I'm going to have a massive sesh this weekend with the soldering iron and repair/replace all of the dodgy wires and connections associated with the ECU to see if that helps.
I know that at least one of those sensors goes to the ECU, and a second one is used for the gauge on your dashboard. I think that the third one is used by the ISV (idle valve) control unit but someone will need to confirm that - I could be wrong. What colour is the wire that looks damaged? Someone on here will know what colour the temp sensor wire is from the ECU (or we can dig that information out from somewhere). Anyway, either way you want to get it fixed Edit: Oops, Riley has a point. I was assuming it was one of the three little temperature senders. My mistake Edited by: Trev16v
i think youre on the right tracks trev the rado kr engine will have the 3 small senders,the pic is for the 9a 2.0 16v,it just has the same thermotime switch. like you say on the kr it will be... 1 for gauge. 1 for ecu. 1 for isv. and the thermotime plug type. i had the colours somewhere but cant find them the thermotime is to control the 5th injector/cold start valve iirc. Edited by: riley
Yep, the damaged wire is going to the thermotime switch. Just went for a look now, got a feeling the senor the ECU uses is the one with a blue/white wire going to it, as this wire is bundled together with the wires coming from the hall sensor. The connector is looking decidely ropey, and I've got a bad coolant leak from the plastic flange thing coming from the head, I wonder if that's upsetting things? Edited by: MillSpeed
As a quick check maybe you could disconnect the ECU's temperature sender completely and then see if this causes the fault to be present at all times?
Yes blue/white is ecu, green/red isv and yellow/red is temp guage. The thermotime controls the cold start valve but isn't connected to the ecu in anyway.
You beat me to it Oplaii! Disconnect green/red and the engine dies, disconnecting the blue/white doesn't appear to have any effect at all. Forgot to mention, found out that if the car starts acting up (goes flat, exhaust note changes, pops & farts like a b*stard on the overrun) by dipping the clutch and turning the ignition off and back on quickly the problem clears and she's pulling like a train again. Maybe the ECU is going in to some sort of limp mode and turning off the ignition for a split second resets it? Edited by: MillSpeed
mmmm,im pretty sure you should lose your tickover with the ecu sender unplugged? have you tried cleaning all the earths up m8? rocker cover/gearbox etc?
Nope, made no noticable difference. Just swapped the temp gauge wire with the ECU wire, temp gauge still worked fine so sensors are ok, but the problem still persists. Time to clean all of the earths then! Cheers Riley.
Well, after a weekend of soldering, sweating, swearing and (almost) tears....the problem's still there. Changed the hall sender, completely reworked the ECU loom, stripped out the immobiliser, the list goes on. However, I have just spotted a pattern! If from start up, you don't let the car idle for more than a few seconds (ie. by blipping the throttle), it runs beautifully. However, if you stop at traffic lights for example and let her tick over, when you pull off she's as flat as a pancake again. The problem will persist intermittently until you switch the ignition off and start her up again. So something's happening when she'd left to tick over that's p*ssing the ECU off and perhaps putting into some sort of limp mode. The obvious candidate is the ISV. Can anyone tell me how the idle stabiliser system works? What other components are there other than the closed throttle switch and the ISV itself? Edited by: MillSpeed
Throttle switch, isv, temp sensor, ISV control module behind the centre console and possibly it`s own relay? Don`t think the ECU`s advanced enough to have a limp mode? I think when you remove the red/black coil loop to do the idle setup it stops the ecu advancing (so you can set the timing). From memory the main live power feed to the ecu/ tci module/ hall sender is also red-black.
Ah ok, where does the red/black coil wire go? Perhaps that's shorting somewhere. I know what you mean about the ECU not having a limp mode, but its weird how it keeps refusing to advance the ignition. I'm really clutching at straws now.
