it seems that quite a lot of people think on older cars you dont need to use mothern diagnostic skills. Well yes that is true to the extent that you can swapatron your selfs thru the few components a older car has. Fact is these old cars use the same comanding input and outputs as a 2015 vehicle only you cant go swapatroning on these modern cars because it would cost a huge fortune by the amount of wrong components you would guess to be faulty.
Now back to the old ones like a classic the bullet proof 95 toyota corolla , I just repaired it with 0 new parts for a stall problem. Right step one what would a swaptron guess it to be ? frankly i am not sure as i am no swaptron and never was I have had a suspicion what it most likely is as i turn the aircon on and it almost died and the fact that when i start it there is no engine flear up that its most likely the idle air controller.
i went and sit down to study how the ecu runs the engine by marking out the cuircuits important to me like the idle air controller Y99 is the idle air controller and wire 1 goes to the ecu this tells me the ecu is commanding the idle air controller. So nect step is i take out my cheap scope and hook it to the ecu comand wire and see its squar wave pwm comand signal. then i turn on the aircon as that should rais the rpm by the ecm number A35 and yes it does do this so i check power and ground on number 3 and 2 of the idle air controller Y99 and see its all working fine .
i used a can of throttle body cleaner to clean it all out . but you can see the air bypass hole thats where the air goes down to the idle air controller . i did this cleaning and turning ac on and off so the iac could work again with no real sucess. So i dismenteled it and figured out it is a round slever and the electromagnetic field commands the thing in either direction so i carfully started moveing the component while keept spraying cleaner in to the air bypass. every now and then i fired the car up again to burn off the cleaner and not possible hydraulic the engine even do the cleaner seems to evaporate over time. After a while i had it fully free moveing so that i was confident the electromagnetism from the iac would be able to move it to its desired position again.
intrade,
Feb 19, 8:20pm
and yes it did its now raising the idle when i turn on the aircon with sucess . 0 parts required just diagnostic thinking and step by step eliminating all possible causes . and a can of throttle body cleaner and applying the liquid correctly. Also i dont want to sound smart or superior to anyone on here , i just would like to point out that you can learn on old cars and you wont fix no new cars with swapatron thinking .
intrade,
Feb 19, 8:24pm
also i did not use my 3500$pico automotive scope i just used my handheld Velleman HSP140i and some probes from hickleys to backprobe the iac wiring for simple stuff like this any scope will do
intrade,
Feb 19, 8:40pm
i will take 2 pictures of the scope with the pwm signal aircon off and aircon on you can see a differenc in the on time on the scope this means the wiring is fine to the component it self
this is aircon off on the scope what you do is look for change only as you wont know what you will see on the scope http://iforce.co.nz/i/wezdxk1i.xe3.jpg
intrade,
Feb 19, 8:44pm
this is with aircon on you can see the difference 50% on time and 50% off time about when aircon is on and the idle air comad signal to the scope from wire 1 that i found on the wiring diagram above http://iforce.co.nz/i/3o01vsss.alg.jpg clcik both immages and put em side by side to see what i mean.
intrade,
Feb 19, 8:52pm
conclusion you need to learn well i sure have to its why i practice these things on a old car even. Could i have just guessed it was the idle air controller yes. could i have gone to pickapart and got me a secoundhand one yes would it have fixed my problem ? yes unless it was also conterminated . could i have gone and purchased a brand new componetn to fix the problem yes 100% would it fix my problem however did i need any components ? NO i dont .
rsr72,
Feb 19, 8:59pm
There should be more like you about.
supernova2,
Feb 19, 9:00pm
I just 10 mins ago solved a similar problem in a 2006 car. In this case high idle. Only tools I used was a 10mm spanner and a air gun.
Unpluged IAC - no change. Undo 2 10mm bolts and there ya go rusted shut. Soak in WD40 and blast of air and as new.
Refitted - fixed.
Total time 15mins.
bjmh,
Feb 19, 9:06pm
yes but you scanned it with your built in optical analyser,then your inhouse computer directed the repair. so you also are very superior and its nearly beer o'clock.
intrade,
Feb 19, 9:12pm
the thing is anyone can do this if they are not ignorant and learn. who knows some of you might even be faster learners then i am . i had the problem i had to figure out where to learn from my self there is a lot of missinformation on the net.
elect70,
Feb 19, 9:18pm
Iknow a father & son garage old man good at old school mechs & son did his time with a euro dealer & up with the mod stuff .
differentthings,
Feb 19, 10:15pm
I must be old. When you said older car, I was thinking the early 80's or older. A 95 car is modem to me. lol.
muzz67,
Feb 19, 10:23pm
Agree! Wish my cars were '95 or newer!
intrade,
Feb 19, 10:30pm
differentthings these are old cars its 20 years old in europe a 30 year old car is a classic car and you will be surprised that contact set - the points are still the same thing its just enbeded inside a electronic module and its called a transistor , its doing the exact same thing it interrupts the current flow to collaps the magnetic field just like the contact set points did.
just they can do it more precise then the points could. I diagnosed a faulty spark plug on a v8 stingray with my pico scope thet car was 1977 or so and i have a recording of a wave form on a lets see i think 1934 motosacoche the spark is exactly the same thing as it is on a 2010 car same stuff you can read out of the wave form. Like burntime of spark on this old as you can on the brand new cars. this is pritty mutch what my recording looked from the motascoche motorbike http://www.picoauto.com/waveform/Ignition/Primary/wave2.html
bigfatmat1,
Feb 19, 10:45pm
Well I fixed a 92 civic that stalled today and hard starting. I checked fault codes. Ckp sensor and ckp sensor out Of range. Checked resistance of all 3 sensors in distributor all OK 370 ohms. Pulled cap off of dizzy checked wiring colour For crank sensor. Rechecked at resistance at ecu. That was OK. Removed ecu, pulled cover off a two leaked capacitors corrosion on board. New capacitors and some cleaning of circuit board with some circuit board repair spray and 1 hr later car runs sweet as. Tools needed $10 multimeter, 8 &10mm tube socket short extension ratchet Phillips screwdriver soldering iron, pick and some magic spray
bigfatmat1,
Feb 19, 10:47pm
I did however use a $10k scan tool. Could of been done with a paper clip.
thejazzpianoma,
Feb 19, 10:51pm
Nice write up intrade! Also, great repair bigfatmat1, so nice to see someone not scared to pull the cover and replace cheap components instead of just immediately ordering a new ECU at great cost. I always enjoy reading these sorts of writeup's, especially when they are so well done with pic's and links. There is almost always something to learn, even if it's just a new website or some such. Tech's and enthusiasts of all levels read these boards, so be it something simple or something tricky it's always great to share.
extrayda,
Feb 19, 11:07pm
- Yup, same here. ECU to me = new cars ! (I haven't yet owned any Euro).
Old = Mechanical Fuel Pump, Distributor with points, Carby, 8 HT leads and just the one coil, if you are lucky it had a temperature sensor for the gauge in the car, and maybe an oil light. If you go crazy wild you could add a tachometer and an oil pressure sender / gauge.
I work with computers for a living, but find the amount of computers and sensors in modern cars crazy. Also can't figure out why they are often so expensive when a reasonable quality car stereo / dvd player / touch screen is relatively cheap? Yes, they are more efficient and powerful than older cars, but so much more complicated. If you buy an older new car (you know what I mean) and something goes wrong, it can cost a lot.
Intrade, I agree 100% with working out what is wrong, but if you end up paying a dealership to do this the costs mount up quickly. Sometimes if you are doing a home job it's quicker to swap out parts from pick a part (always the risk the 'new' part is broken, but it's worked ok for me over the year). Yup, I'm a bit of a swapatron ! But also resort to the #8 wire approach at times to keep stuff going.
mechnificent,
Feb 19, 11:07pm
As long as the information being shared is accurate.
mechnificent,
Feb 19, 11:16pm
It could be said that everything prior to CAN systems is old and relatively easy to diagnose using common tools.
It's all relative.
gammelvind,
Feb 19, 11:42pm
Haha I'm much flasher than you, mines a 98!
Since the public registrations are closed, you must have an invite from a current member to be able to register and post in this thread.
Have an account? Login here.