Classic Alfa Forums

Hi guys
.please bare with me on this one, i may ramble on abit, As shrew and alex will know (i've picked there brains on the phone alot this week) my 33 16v is idleing and running very rough. i'll start from the start, over christmas/jan the car started getting a roaming idle but drove ok really, just really drove you mad at a stand still, i changed the idle valve and it did nothing. i spoke to alex and he said he remembered someone has the same problem in the past and it was gunk or grit not allowing one of the throttle body butterflys to close, so i stripped it all down and checked them and they were fine, at the same time i checked the throttle linkage adjusters and made sure they were opening together in sync, i also checked everything to do with the idle valve was air tight. this could just be my mind but the car seemed to drive smoother on the way home. the next day i went to start the car and it would start but it sounded like it wouldn't spark (the only time i've heard a noise like that before was when i got the firing patten wrong on the dizzy cap while doing the restro) and it wouldn't rev above 2000 revs, i held the throttle and the revs rose and it coughed and spluttered and then began to run normal but very rich and if you let it idle the idle speed would drop very low, alot of the time to the point of cutting out. when warm however it ran almost normal, alittle rich and stuttered every now and then. the idle when warm was quite stable but still roamed alittle bit. so the past two days i've swapped the air flow meter, that did very little, spark plugs (the old ones were black!!) and ecu, still now change.
i know this is abit of a long chain of events, but I was wondering if anyone could offer any advice or things you have experienced with the 16v engine.
i found this today
http://www.opel-scanner.com/files/Opel_ ... cML4.1.pdf
and i'm going to check all the the voltage readings tomorrow. any advice is welcome no matter how small, its driving me crazy and i can't remember the last time it ran sweetly
cheers
Dave

coolant temp sensor?

Hi
Have you tryed adjusting the afm ? From memory if you wind the screw out it leans it out . mite be one of your problems plus with your linkages one side needs to open very slightly before the other , the throttle switch side! God its been to long time away from my 16v
Hope that helps a bit !

hi guys, there both frist on the list. im feeling its the temp sender after reading the bit about the cts sensor. the thing is i changed it late on last year, but i was speaking to alex and he said he had one that didn't work as there was some crap on it, so worth a check

Good luck with it!

aahhh miss read the throttle linkage bit. that might be one of the problems as there both in sync now!

Morning
The throttle switch side only needs to open just before the other side! Mine is out abit , it's like a flat spot ,If you slowly rev the engine, it will shake at about 1500 plus revs then smooth out.this only happens on slow revving which I never did
I take it your cars got a cat? The lambda mite be nackered too which I'm guessing would cause it to run rich! If it is dead . Chop the cat open weld a pipe through the middle and buy one of my non cat ecu's

If yours has got a cat a faulty lambda would cause your problem it's best to fit a new lambda changing ecu a bit of a backward fix as a closed loop system containstly adjust fueling as you drive , you could still remove cat for better flow , a blocked cat could also be your problem

its a non cat model 1990, so i knows its not that. i'm off to tinker now so i'll let you know what i find

I would try temp sensor

Good luck chap

I'm back! i changed the temp sensor, and made sure i got a bosch one, that made it run abit better, but couldn't really tell as the engine was still pretty warm, i got the multi meter and checked the co pot voltage on the air flow meter and that was running at 3.5 volts on idle, so i dropped it to the 2.5 the bosch manual said it should be, then fettled with the throttle linkage as i knew it must be out, and after 15 mins trying got it right, the car now runs like a dream!!! no flat spot low down and no over fueling! the only little thing is the idle still roams a tad but not a massive amount. i'll give it a week see if it calms down at all, as i bet the engine must be coked up abit after running rich for a few months.
MASSIVE thankyou for you input can't tell you how nice the drive home was!

Hi dave (thanks for the text too!)

Glad you sorted it mate, those multimeter readings are all important when it comes to these early, and quite primitive injection systems eh.

Don't forget, they say that these early Motronics have a pretty slow self learning process within the ecu, so driver her around a bit, as you normally do (like you stole it!), and it should self learn to suit the new adjustments.


Cost you a bit in fuel mate, but it should behve now hopefully eh?


Well done, and ill bet you're glad you've learnt a thing or two about the JerrtyJection system anyway!

Happy days
Glad you sorted it, just go for a proper drive! That will clean it out
I downloaded that link you put up. Will be handy for the future

hahahaha the thing is with no flat spot i can dive her normally now! i am glad i know more though mate it does give you a better understanding of the engine. alex told me if you take off both battery terminals and hold them together for a min or two it drains the ecu capacitors as its like its starting a fresh, might try that if it doesn't sort its self out

Always helps to work on your own stuff, then you get to know it. Plus when you fix broken bits it makes you feel epic
With the idle you say your cleaned the throttle bodies ? What about the main inlet manafold ? Plus the idle control valve on there too. Mite have some gunk in there?

the manifold is spotless mate, i blocked off the oil breather along time ago as it was throwing crap in there. i have a spare idle valve so im going to swap them if it continues. if not maybe a few squirts of carb cleaner?

Good you got it sorted.

Mine runs a bit shite before the auto choke cuts out and thought that CO Pot measurement sounded interesting.....then I read the link and it doesn't apply to cat cars.....dammit. Still, There's a lot of info in that link which should come in helpful, cheers.

yeah its some really good info, helped me understand how it works so it must be good hahaha. just went out and tested a cold start and smooth as butter, yay!

Cold start, smooth as butter!


running too well that is Dave!



we always knew when a race engine was going to Blow Up! cos it felt fan flippin tastic just moments before!!!!



only kiddin Degster, lets hope it stays that way

well butters abit far but it felt alot better than before! me too mate me too.

Shrew
That's like a two stroke just before it lets go lol
Deggy glad you sorted your boxer

Johnboy wrote:Shrew
That's like a two stroke just before it lets go lol

thats the one mate


one mo there singing like birds, all of a sudden, you think you hear it revving to another octave, pulling like a rhino!

then (rolling R's!) RRRRRRRRRRRRRRRRRattleNipSieze - Implode!



and it never ran better! or the same since, no matter what you do! ha ha!!

reminds me of me old AR50 lol

My mtx 50 with big kit always heat seizing or my rd350 nipped up solid at 110 mph after overtaking a line of cars and a bus then I had the shame of them all over taking me at the side of the road

Lol
I remember a mates two stroke jetski letting go! The thing was flying then bang! Cost him £1500 to sort it