idle control ecu

[cam.in.head]

hi. as many of us on here who have done the 2.2 conversion (and owners of carltons and senators of the same jetronic system)  we will have come across the faulty ecu that controls the idle air valve. i certainly have experienced it a fair few times over the years and have just had issues this week with one of mine, the car starts and revs up quite high on its own for a few seconds and then settles itself down and the valve does its thing. this is the usual failure mode in my experience and isnt usually the  valve itself. although they can become gummed up and cause similar issues. mine are clean and swappable between cars to prove condition.

so its something in the control ecu. (swapping it resolves thefault)

SO as parts supply gets harder..

my question is. ..... after opening these up and finding no water damage,no bulging caps( tried changing electrolytics also),no bad solder joints or traces . what on earth is the failure point on these ? certainly nothing immediately obvious thats for sure.has anyone solved ,repaired their own ? 

[Jonathan Pounsett]

I’ve had similar issues with the iacv on my V8 but I’m sure these valves all work in a similar way. 
 

I don’t know why it would happen, but the motor would cause the plunger to travel too far and beyond it’s normal range of travel so even when the computer tried to pull back a few steps to maintain the correct idle it was stuck and couldn’t retract. The only solution was to remove it, setup somewhere mid range and reinstall it. Next time the engine is fired up the ecu resets the valve and it works as it should. 
 

I don’t know the cause but I suspect several things conspire to muck it up;

carbon build up 

other foreign matter 

weak spring

poor air flow

worn plunger end that allows too much travel

low quality or dirty petrol

dodgy map sensor sending dubious info to the ecu

I also noticed that when tested out of the car it would only extend, (closing/reducing) air flow - the engine had to run for the ecu to get enough information to retract.

 

[cam.in.head]

thanks for that . the type you have is a plunger with a conical end thatopens or closes an air channel i beleive. we had a similar one on a range rover clasic v8 that was very temperemental.

mine is a rotary valve type that are usually pretty reliable. its an issue within the ecu that seems to happen.

a shame realy cos once i find the exact faulty part ive thrown many an ecu away over the years as being scrap whereas now they are very hard to find except for silly money .

[Jessopia74]

Open one up and take a picture 

However, The driver circuit to the valve is probably not the failure mode, but more than likely the input signal side that should be from the Tach pulse? When they fail do they always fail in a particular way? Any clicking from the motor when it happens?

[Jonathan Pounsett]

13 hours ago, cam.in.head said:

thanks for that . the type you have is a plunger with a conical end thatopens or closes an air channel i beleive. we had a similar one on a range rover clasic v8 that was very temperemental.

mine is a rotary valve type that are usually pretty reliable. its an issue within the ecu that seems to happen.

a shame realy cos once i find the exact faulty part ive thrown many an ecu away over the years as being scrap whereas now they are very hard to find except for silly money .

That’s interesting you say that. The current one, that is doing a great job so far, is from a classic. I had to use an older sloped plenum to give enough clearance to close the bonnet.

[cam.in.head]

20 hours ago, Jessopia74 said:

Open one up and take a picture 

However, The driver circuit to the valve is probably not the failure mode, but more than likely the input signal side that should be from the Tach pulse? When they fail do they always fail in a particular way? Any clicking from the motor when it happens?

yes thats true. they get a tacho signal to monitor speed and a temp signal too for increasing idle a bit when cold. ive resoldered a few joints and replaced some caps for the hell of it and refitted to try. will see what happens. failing that il make a manual system for now to adjust idle and use one of the gte type air vslves to give a fast cold idle.

[Jessopia74]

4 hours ago, cam.in.head said:

yes thats true. they get a tacho signal to monitor speed and a temp signal too for increasing idle a bit when cold. ive resoldered a few joints and replaced some caps for the hell of it and refitted to try. will see what happens. failing that il make a manual system for now to adjust idle and use one of the gte type air vslves to give a fast cold idle.

Is it the same controller used on the KE system ?

[cam.in.head]

its the same unit used on carlton 2.2 84-86 (rekord)and similar age senator and monza (albeit different tacho speed references due to being 6cyl) and slight differences again depending on manual / auto.

mine behaved itself yesterday for most of the time and just held the idle at 1200 once. i rechecked all the connectors in the plug for tightness/ springiness ! and confirmed good continuity on tacho ,neg and pos feeds.and replaced the temp sender for good measure.  im pretty sure its something that intermittently fails on the pcb but works again as normal. as you would expect from a bad connection or dry joint .but nothing obvious.

i need to compare what the differences are physically between engine sizes and transmission to see what is different in relation to the adjusted rpm.  mr google doesnt help this time !

and ive not had any dealings with ke  jetronic ? so cannot say .

[cam.in.head]

ive messaged a couple of places that do ecu repairs but no one has replied with any definitive answer. some not even offering advice but claiming they can repair them if i send them ? .

ive thrown away so many of these over the years after faults (replacing them cured the fault every time)

now they are thin on the ground i need to talk to someone who  knows about these and the issues and differences between different models that make them specific to a certain rpm / cylinder count .

i am also wondering if other cars will use anything similar. othercars use jetronic and the idle valves so there must be some swappability ? 

[2400man]

20 hours ago, cam.in.head said:

ive messaged a couple of places that do ecu repairs but no one has replied with any definitive answer. some not even offering advice but claiming they can repair them if i send them ? .

ive thrown away so many of these over the years after faults (replacing them cured the fault every time)

now they are thin on the ground i need to talk to someone who  knows about these and the issues and differences between different models that make them specific to a certain rpm / cylinder count .

i am also wondering if other cars will use anything similar. othercars use jetronic and the idle valves so there must be some swappability ? 

Just thinking out loud, would it be worth talking to the Autobahn stormers, being as you mentioned similar idle control systems were fitted to Senators and Monzas? Btw I have a spare 2.2 idle control unit, if any use as well as 2.2 manual LE jetronic ECU. Never got them to work with my 2.4......

[cam.in.head]

hi there. thanks for reply.

the ecu is the same manual or auto and ive got a few of them already but imight be interested in the idle control ecu .mines an auto but a manual  will still be ok as a spare ( it just holds a slightly higher idle)

send me a message regarding price and the bosch part number please. much appreciated.thanks.

 

i used to be a member of the autobahnstormers but not now so cannot send them a message or post but if anyone on here is a member it would be fantastic if you could ask for me !

Edited November 3, 2023 by cam.in.head

[Sutty2006]

You know I had issues with mine right? 
 

Well I resolved it on a temporary permanent basis. 
 

 

And stuffed it in

 

 

first hole was 4mm which wasn’t enough. A bit of fine tuning with a 5mm bit sorted that right out. 
 

Total cost? About 2p

 

Runs fine now. 
 

I do have a 6 cylinder ecu, that I don’t need. It’s untested but if anyone wants it for a donation to the running costs of my Carlton that fine. 
 

[cam.in.head]

yes i remember you had some issues and its probably the ecu thats faulty on yours as well. i have tried my last ecu on it and everything is now fine so i know that theres something in the old one thats faulty .but what ?

the method you have used will work fine to maintain a lower idle and a non changing one but it wont have any compensation for alternator load (or coldstart increase like the 2 litres have with the aux air valve.)

its annoying me that theres something faulty in there that i cant mend (YET) !

[2400man]

On 03/11/2023 at 18:20, cam.in.head said:

hi there. thanks for reply.

the ecu is the same manual or auto and ive got a few of them already but imight be interested in the idle control ecu .mines an auto but a manual  will still be ok as a spare ( it just holds a slightly higher idle)

send me a message regarding price and the bosch part number please. much appreciated.thanks.

 

i used to be a member of the autobahnstormers but not now so cannot send them a message or post but if anyone on here is a member it would be fantastic if you could ask for me !

No worries. It might take me a while to dig out the idle ecu from the man cave but will have a look next time I'm over there. No idea on price what the going rate is.......

I'm not a member of the autobahnstormers atm either but I see they are admitting Manta owners now and could be a useful source of help on Motronic remapping for the 2.4 so will let you know if/when I join. Need to start sussing out the whole remapping thing over the winter.

[cam.in.head]

 to mr sutty above.if your interested ?

if you wanted a more permanent solution to the faulty ecu on yours ( suspected)

you could add a aux air valve in the hose like a gte uses instead of the electric valve wired to be on when ign is on and then adjust the throttle bypass screw under the throttle to give the required hot idle speed.around 650 on an auto.

the aux valve will be open when cold giving an increased idle when cold as is needed. this will then work 95% of the intended original system just missing the idle auto fine tuning depending on alternator load drawing idle speed down, it worked fine on cars before the electric valve was used so shouldnt be an issue realy.

this is what i may end up doing on mine if the last ecu gives up !

[Jessopia74]

Dump the Motronic and go aftermarket for sure 

[cam.in.head]

hi jess thanks for input.

2.2 is jetronic anyway but wouldnt want to bin the entire system to change to something unknown/aftermarket.especially when the system is working well anyway. only issue as i mentioned is an occasional non regulating idle speed.

mine is working fine in all respects. 

the ecu i had on has an intermittent fault which i was hoping someone who had had the same issue would come on and say "its resistor 33 or chip ic5 that causes this for example.i did start tracing anything related to the tach input as you suggested but all appears to test and look visualy ok on the board .

the jetronic in general used on mantas,carltons etc is quite basic but reliable.and i dont beleive in swapping to non oem stuff anyway. aftermarket replacement 'service parts' are one thing that we have to accept but i dont beleive in stuff like putting non gm engines into gm cars ,as an extreme example. each to their own. 

i will just keep swapping components willy nilly until the offending one is found ,the bugger is in there somewhere !

[Jessopia74]

10 hours ago, cam.in.head said:

hi jess thanks for input.

2.2 is jetronic anyway but wouldnt want to bin the entire system to change to something unknown/aftermarket.especially when the system is working well anyway. only issue as i mentioned is an occasional non regulating idle speed.

mine is working fine in all respects. 

the ecu i had on has an intermittent fault which i was hoping someone who had had the same issue would come on and say "its resistor 33 or chip ic5 that causes this for example.i did start tracing anything related to the tach input as you suggested but all appears to test and look visualy ok on the board .

the jetronic in general used on mantas,carltons etc is quite basic but reliable.and i dont beleive in swapping to non oem stuff anyway. aftermarket replacement 'service parts' are one thing that we have to accept but i dont beleive in stuff like putting non gm engines into gm cars ,as an extreme example. each to their own. 

i will just keep swapping components willy nilly until the offending one is found ,the bugger is in there somewhere !

No that was mainly for 2400man mate as the Motronic will hold back his tweaked engine for sure.

I know what you mean about the component fail, it would be great for those that do want to keep OEM setups if we can identify what’s failing. If you tried caps ( agree usual suspects) then it is most likely a MC chip, but I have never seen the PCB of these idle controllers , so we would be just guessing anyway. 
keep at it, sure you will get some obscure info at some point that will help. After all, the Bosch setups was used on a lot of EURO cars for item fitment, so the info must be out there 👍

[Sutty2006]

How many suspected broken ones do you have? Can you send me one? I have a source that might be able to take it apart and test the solders/resistors etc etc. he’s fixed a few relays for me in the past. Even wired up the Ford blower motor with a new variable resistor 👍

[cam.in.head]

this is the problem .in the past ive had many spare ones so just threw them away and fitted a spare. i have 2 cars now with the 2.2 engine and only 2 idle control ecu's . fault swaps car to car. both cars are driveable and the fault shows up intermittently as a 1200 rpm idle that then settles on its own accord.

im an engineer by trade anyway which is why this one is realy annoying me. i should be able to sort it but every part i test (caps,resistors and diodes all test ok and close examination doesnt show any solder issues although ive resoldered anything i can think of.

cannot test the chips as such so if id had more spare units i could swap chips to see when the fault swaps over ! 

someone on here has a 6 cylinder ecu for sale  that should be usable providing i can identify the component that differenciates 4 cyl to 6cyl idle speed/ ignition pulses .

 

the one on yours is suspect i beleive ? ? 

1 hour ago, Jessopia74 said:

No that was mainly for 2400man mate as the Motronic will hold back his tweaked engine for sure.

I know what you mean about the component fail, it would be great for those that do want to keep OEM setups if we can identify what’s failing. If you tried caps ( agree usual suspects) then it is most likely a MC chip, but I have never seen the PCB of these idle controllers , so we would be just guessing anyway. 
keep at it, sure you will get some obscure info at some point that will help. After all, the Bosch setups was used on a lot of EURO cars for item fitment, so the info must be out there 👍

ah yes i see that now !.

the pcb's in these appear very well made. all the components are named brands and the soldering looks good and has a varnish laquer over it .its hard to work out the failing bit !

Edited November 6, 2023 by cam.in.head

[2400man]

1 hour ago, Jessopia74 said:

No that was mainly for 2400man mate as the Motronic will hold back his tweaked engine for sure.

I know what you mean about the component fail, it would be great for those that do want to keep OEM setups if we can identify what’s failing. If you tried caps ( agree usual suspects) then it is most likely a MC chip, but I have never seen the PCB of these idle controllers , so we would be just guessing anyway. 
keep at it, sure you will get some obscure info at some point that will help. After all, the Bosch setups was used on a lot of EURO cars for item fitment, so the info must be out there 👍

You're not the first person Jess to not be keen on Motronic lol! What I want to know is what is the difference between remapping a Motronic system and an aftermarket set up. Is it the fact you can do stuff like run a wide band lambda sensor, add a knock sensor and such like? I'm certainly not intending to run the stock Motronic maps. They will need to be modified extensively to take account of the gas flowed head, bigger throttle body, high flow injectors (probably), higher flow inlet manifold etc etc

[Jessopia74]

1 minute ago, 2400man said:

You're not the first person Jess to not be keen on Motronic lol! What I want to know is what is the difference between remapping a Motronic system and an aftermarket set up. Is it the fact you can do stuff like run a wide band lambda sensor, add a knock sensor and such like? I'm certainly not intending to run the stock Motronic maps. They will need to be modified extensively to take account of the gas flowed head, bigger throttle body, high flow injectors (probably), higher flow inlet manifold etc etc

Virtually an analog system from 1990s versus a fully mapped sequential setup that polls faster and has far higher resolution of control. 

[2400man]

2 minutes ago, Jessopia74 said:

Virtually an analog system from 1990s versus a fully mapped sequential setup that polls faster and has far higher resolution of control. 

Ah so more sophisticated basically. Which one would you recommend? I know some of them can be very pricey. I checked out Motec after seeing the Tolman resto mod 205 GTI but baulked at the cost 😳

[Sutty2006]

[cam.in.head]

ah yes i knew id seen one somewhere lol !

obviously being the wrong one it depends on how much you want for it but might be worth playing with.

you said you also have a mate thats good with electronics. has he had a nosy at yours ?  possibly faulty too ?

its turning into a long post this one for what might just be a simple component issue. annoying especially after the numerous ones ive binned over the years that didnt matter at the time cos every scrapyard had a few !