The RENIX ecu in the 25 V6 Turbo and Alpine GTA V6 Turbo was THE first ECU in the world to have a fully "Mapped" ignition and fuel tables. It was very complex and actually split the ROM data across 2 ROM chips. Even values on 1 chip and Odd values on the 2nd ROM chip. I used to to work remapping these about 20yrs ago and it was very difficult. There is a high chance the Capacitors in the ECU are all dead. I now work on Saabs a lot and its a common problem i see with 80's and 90's cars. Replacing all capacitors in the ECU makes them run like new again. Paul @ The SAAB Clinic.
@@SeasideGarageUsually electrolytic capacitors have a useful life of 10-15 years in average. In any electronic board with age, it is best to replace them all with identical capacity ones. Testing them soldered on the board does not give exact capacity readings due to the other circuit board elements, just change all of them. The burnt board element seems like a power converter or a pwm driver to drive the idle air control valve, as the valve itself is a high power element for the Ecu. If the malfunctions or shorted during service ie replacement of the valve, it can burn the pwm driver. Changing the pwm driver and the electrolytic capacitors can solve your problem
I watched this video while eating breakfast and then on my way to work saw a 1989 Renault 21 in the same colour as yours, gave the driver a big grin and a thumbs and up nd he flashed his lights back at me 😊
My old 1987 RX-7 wouldn't idle - I took the ECU apart and replaced the IAC valve driver transistor with an equivalent I had in my junk box. Worked perfectly and was an easy fix. 1980's was just right.
I love the videos where a mystery is solved. This was a particularly good one! I wouldn't be shy about approaching electronics RUclipsrs if you have any trouble procuring that integrated circuit. If the large metallic tab is soldered, you're going to need a high-powered soldering iron.
Great video and excellent work on diagnosing the issue, Seppo! I hope you manage to solve this eventually - seems like some of your audience is very knowledgeable about these cars.
I had a 4 cylinder Renault 25 that had an annoying high idle. Turned out to be a faulty water temp sensor, so the car thought it was cold all the time.
Sometimes I ponder with these older electronic injection cars that would it be just easier to take off all of those original sensors and simplify the setup with modern custom ECU and throttle body, and then hook it up to intake, exhaust, idle, oil pressure and water temp sensors, instead of fighting with this complicated stuff that has no guarantee that it'll ever work properly.
Bonne question finale. Si l'ordinateur ne présente aucune pièce matérielle ou logicielle défectueuse, le passage en marche arrière de la marche d'un pont élévateur au ralenti pourrait suffire pour franchir la rampe au régime de ralenti, régulé électroniquement et de manière régulière, sans avoir à accélérer ou à freiner. Oui, cela pourrait fonctionner si le frein à main est serré lors du roulage en avant et en arrière sur une ligne droite de telle sorte que la voiture s'arrête immédiatement en moins d'un demi-tour de roue lorsqu'elle débraye. Si ensuite le démarrage avec un embrayage normalement rapide a la même durée que l'arrêt, tant le frein à main est correctement réglé que le papillon des gaz et la régulation automatique du ralenti fonctionnent parfaitement. Good final question. If the computer has no defective hardware or software parts, travelling backwards over the step of a lifting ramp at idle could be enough to drive over the ramp electronically regulated and smoothly at idle speed without having to accelerate or brake. Yes, this could work if the handbrake is applied when rolling forwards and backwards in a straight line so that the car comes to an immediate stop within half a wheel revolution when the clutch is disengaged. If starting off with a normally fast clutch engagement then takes the same time as stopping, both the handbrake is set correctly and the throttle and automatic idle control are working perfectly. Gute Abschlussfrage. Wenn der Computer keine defekten Hardware- oder Softwareteile aufweist, könnte das rückwärtige Überfahren der Stufe einer Hebebühne im Leerlauf ausreichen, um mit der Leerlaufdrehzahl elektronisch reguliert und gleichmäßig über die Rampe zu fahren, ohne Gas geben oder bremsen zu müssen. Ja, das könnte funktionieren, wenn die Handbremse beim Vorwärts- und Rückwärtsrollen auf gerader Strecke so angezogen wird, dass das Auto beim Auskuppeln sofort innerhalb einer halben Radumdrehung zum Stehen kommt. Wenn dann das Anfahren mit normal schnellem Einkuppeln dieselbe Dauer wie das Anhalten hat, ist sowohl die Handbremse richtig eingestellt als auch die Drosselklappe und die automatische Leerlaufregelung funktionieren perfekt.
The RENIX ecu in the 25 V6 Turbo and Alpine GTA V6 Turbo was THE first ECU in the world to have a fully "Mapped" ignition and fuel tables. It was very complex and actually split the ROM data across 2 ROM chips. Even values on 1 chip and Odd values on the 2nd ROM chip. I used to to work remapping these about 20yrs ago and it was very difficult. There is a high chance the Capacitors in the ECU are all dead. I now work on Saabs a lot and its a common problem i see with 80's and 90's cars. Replacing all capacitors in the ECU makes them run like new again. Paul @ The SAAB Clinic.
You AI said he should change it for modern standalone
Is it possible to test capacitors in a ecu? or do you just change them to be sure?
Thanks for this comment!
@@SeasideGarageUsually electrolytic capacitors have a useful life of 10-15 years in average. In any electronic board with age, it is best to replace them all with identical capacity ones. Testing them soldered on the board does not give exact capacity readings due to the other circuit board elements, just change all of them. The burnt board element seems like a power converter or a pwm driver to drive the idle air control valve, as the valve itself is a high power element for the Ecu. If the malfunctions or shorted during service ie replacement of the valve, it can burn the pwm driver. Changing the pwm driver and the electrolytic capacitors can solve your problem
but the ceramic capacitors should be good still? (in theory)
@@SeasideGarage Yes. Its the Electrolytics that would have failed. They are generally dead by about 25yrs old.
I watched this video while eating breakfast and then on my way to work saw a 1989 Renault 21 in the same colour as yours, gave the driver a big grin and a thumbs and up nd he flashed his lights back at me 😊
And the part that let the magic smoke out is a darlington array by SGS: S452-2. There are still some available on the interwebs.
My old 1987 RX-7 wouldn't idle - I took the ECU apart and replaced the IAC valve driver transistor with an equivalent I had in my junk box. Worked perfectly and was an easy fix. 1980's was just right.
It's great that we have a community where people help each other.. (Phil)
It is! The best thing about the internet really...!
I love the videos where a mystery is solved. This was a particularly good one! I wouldn't be shy about approaching electronics RUclipsrs if you have any trouble procuring that integrated circuit. If the large metallic tab is soldered, you're going to need a high-powered soldering iron.
Great find initially with that broken switch
wow and peace be upon you sir from me
Well done Seppo. Really well sussed out!
Great video and excellent work on diagnosing the issue, Seppo!
I hope you manage to solve this eventually - seems like some of your audience is very knowledgeable about these cars.
Does anyone else thinks about the TPS Reports in Office Space every time Seppo says "TPS Switch" or am I the only one? ;)
I had a 4 cylinder Renault 25 that had an annoying high idle.
Turned out to be a faulty water temp sensor, so the car thought it was cold all the time.
8644= week 44 of 1986
Ah yes!
I really wouldn't know where to start with this stuff. I find it very interesting but I'll stick to carbs.
Sometimes I ponder with these older electronic injection cars that would it be just easier to take off all of those original sensors and simplify the setup with modern custom ECU and throttle body, and then hook it up to intake, exhaust, idle, oil pressure and water temp sensors, instead of fighting with this complicated stuff that has no guarantee that it'll ever work properly.
Even the ECU looks retro
I had to replace a burnt power transistor (probably what this is) on my Saeco not too long ago. Same but not the same ;-)
Seeing that cooked part, yep, "well there's ya problem!!!", not sure what it is supposed to be, but it certainly is pretty burned up... :S
Bonne question finale. Si l'ordinateur ne présente aucune pièce matérielle ou logicielle défectueuse, le passage en marche arrière de la marche d'un pont élévateur au ralenti pourrait suffire pour franchir la rampe au régime de ralenti, régulé électroniquement et de manière régulière, sans avoir à accélérer ou à freiner. Oui, cela pourrait fonctionner si le frein à main est serré lors du roulage en avant et en arrière sur une ligne droite de telle sorte que la voiture s'arrête immédiatement en moins d'un demi-tour de roue lorsqu'elle débraye. Si ensuite le démarrage avec un embrayage normalement rapide a la même durée que l'arrêt, tant le frein à main est correctement réglé que le papillon des gaz et la régulation automatique du ralenti fonctionnent parfaitement.
Good final question. If the computer has no defective hardware or software parts, travelling backwards over the step of a lifting ramp at idle could be enough to drive over the ramp electronically regulated and smoothly at idle speed without having to accelerate or brake. Yes, this could work if the handbrake is applied when rolling forwards and backwards in a straight line so that the car comes to an immediate stop within half a wheel revolution when the clutch is disengaged. If starting off with a normally fast clutch engagement then takes the same time as stopping, both the handbrake is set correctly and the throttle and automatic idle control are working perfectly.
Gute Abschlussfrage. Wenn der Computer keine defekten Hardware- oder Softwareteile aufweist, könnte das rückwärtige Überfahren der Stufe einer Hebebühne im Leerlauf ausreichen, um mit der Leerlaufdrehzahl elektronisch reguliert und gleichmäßig über die Rampe zu fahren, ohne Gas geben oder bremsen zu müssen. Ja, das könnte funktionieren, wenn die Handbremse beim Vorwärts- und Rückwärtsrollen auf gerader Strecke so angezogen wird, dass das Auto beim Auskuppeln sofort innerhalb einer halben Radumdrehung zum Stehen kommt. Wenn dann das Anfahren mit normal schnellem Einkuppeln dieselbe Dauer wie das Anhalten hat, ist sowohl die Handbremse richtig eingestellt als auch die Drosselklappe und die automatische Leerlaufregelung funktionieren perfekt.
That's a nice caaaa!
Nice video
I'd change that part myself OR send it to a Good electronic repair guy to have it fully checked.
It look like a SGS Thomson part S452-2,
Great STUFF!
Nice vid, I enjoyed this one. Like and subscribe folks!
has someone actually glued on a huge TURBO badge on the pipe? Please don't say this was done at the factory!
factory casting
If the year is somewhere in the 80s and a turbo is involved, it's common practice to write it as many places as possible!
Rough sounding engine.
hmm Actually sounds pretty nice IRL... but the mic pics up on sounds... The valves are a bit noisy though
Especially mobile phone microphones make even an electric motor to sound like an Opel OHC.
I've always reckoned that Renaults are a pos. Never seen anything to make me change that opinion.