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Ciocoflenderu
PostPosted: Wed Dec 19, 2018 9:40 pm 
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Hello guys, I really could use some help. I have a very annoying problem with my 1994 323F BA 1.5 for quite some time.

The problem was present since i got the car (i got it for free from a friend) - After the engine would heat up, the revs would drop randomly from 800 RPM to around 600 RPM, then it would rev up to 1000, then drop again to 600 RPM and so on. When i added consumers ( especially lights and vents), the problem would get even worse and the car would eventually stop with all consumers on.

Since then got a "new" ( second -hand) MAF Sensor, replaced the radiator, replaced the lambda sensors, cleaned the IAC valve, changed the spark plugs and even searched the car's circuitry for short-circuit. The rev drop problem has improved significantly, now i can turn two conusmers on. But during winter, when i must turn almost all consumers on, the problem comes back again . :( :(

I don't know if there is a link between them, but when i turn the lights on, sometimes the radio starts turning on and off and so does the interior lights. It is very annoying. Also, from time to time the speakers would sometimes stop working all of a sudden, especially when i brake hard. My guess would be that there is a short circuit somewhere but i have no idea where else to look. I used to think that it is kind of acceptable for this kind of things to happen since the car is 24 years old.

Any opinion would be very appreciated. Thanks!


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maZZda
PostPosted: Thu Dec 20, 2018 9:46 am 
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First get the engine warm to work T,
Bridge TEN and FEN conectors(as it is running) so the car goes to service mode,
Watch the rpms, if they go down this could be from wrong positioned brass screw wich allows air to go arround the throtlle butterfly, adjust it higher than 750rpms(just for
comparison, mine is at 1100)
After that remobe the bridge wire and dribe the car for 5-10km to check if it is better.Load the engine with consumers and try to see if the drop persist.
The other thing wich you should check first i AIR LEAKS.
If they are present, you should remobe them first and the problems could go away from itself after that, without making any corrections.
The fading off lights,radio and others consumers occurs when the rpms drops right?
If so, this is because the load of the consumers is bigger that the produced electricity from the alternator by that time(rpms).
If they occurs randomly independant from rpms the problem is electrical and need attention.
Hope you've clear it, because i know how annoyng and dangerous is to have near dead engine when braking at winther condition.


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Ciocoflenderu
PostPosted: Thu Dec 20, 2018 11:41 am 
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Thanks very much for the tip. I will try to bridge TEN and FEN as you said and give it a try.

Quick question - do you always keep the brass screw at 1100 RPM? If so, why?


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maZZda
PostPosted: Thu Dec 20, 2018 1:02 pm 
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If you look at my car tread you will notice there aren't many stock parts under the hood.That's why i keep it there.


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Ciocoflenderu
PostPosted: Thu Dec 20, 2018 5:21 pm 
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After bridging TEN and FEN the revs still drop, but there seems to be a slight improvement. If i set the RPMs to 1100 the RPMs still drop to 400 with all the consumers on. I do not understand why the revs donot stay up...


Last edited by Ciocoflenderu on Thu Dec 20, 2018 5:32 pm, edited 1 time in total.

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Ciocoflenderu
PostPosted: Thu Dec 20, 2018 5:22 pm 
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I still cannot turn all the consumers on without the engine stalling :(


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maZZda
PostPosted: Thu Dec 20, 2018 6:39 pm 
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Did you searched for air leaks?
Did you checked for error codes?


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brucey76
PostPosted: Thu Dec 20, 2018 8:55 pm 
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Sounds like a failing battery to me, get battery and alternator checked. battery is not just there for when engine not running or to start the car. it's there to power stuff all of the time. The alternator is there to charge the battery when engine running, so a bad battery won't provide enough power for everything like a good battery would. Think of it like a mobile phone, it will work when battery charged but flatten the battery plug in the charger and it wont work until there is around 5% battery


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Ciocoflenderu
PostPosted: Fri Dec 21, 2018 8:03 am 
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The battery and alternator were changed one year ago.

I don’t know how to check error codes.


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pitrack_1
PostPosted: Sat Dec 22, 2018 3:00 pm 
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Some suggestions:

1) Remove, clean and refit the battery terminals and see if that makes a difference. Check them carefully for damage- I had something similar occur (lights flicking on and off plus surging during driving) due to a battery terminal strap tearing and causing an intermittent connection.

2) Change the battery and see if that makes a difference (borrow one from another vehicle)

3) Measure the voltages at two points whilst you progressively 'load up' the system by turning on the 'consumers' one at a time: at the battery (multimeter) AND on the ignition-switched part e.g. though a cigarette lighter volt monitor (cheap online).

- You should get around 12.6V with the engine stopped. If it's less than that either the battery's discharged or has a problem.

- You should get 13.8 - 14.1V with the engine running.- If it's less than 13V at the battery, the alternator's not charging properly (at least at idle) or the battery was flat.

- Load up with the engine running and note how the voltages change.

- If there's more than 0.1 or 0.2V discrepancy between the battery voltage and the cigarette lighter voltage, there's a wiring issue.

- If the voltages remain around 13.8V or so as you load the system up, then we'll have to dig a little deeper.

4) Oh, one other thing to check: check all the grounding cables are connected properly. Apart from the battery earth strap to ground, there should be one from the engine to chassis, plus probably some under the dash in various spot (don't know where). It could be a bad ground is causing the loads to try to ground through the wrong spot (e.g. the electronics) or changing the potentials leading to misreading and bad running.

5) One more thing to do is to pull all the fuses for the ancillaries and then start adding them back in one-by-one to try to isolate the fault.

Patrick


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Ciocoflenderu
PostPosted: Sat Dec 22, 2018 7:29 pm 
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Thanks for reply Patrick, i will try to do the measurings tomorrow and let you guys know how everything is going.


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maZZda
PostPosted: Sat Dec 22, 2018 8:57 pm 
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Checking codes is easy, you just bridge GND and TEN in the diagnostic box under the hood, put an LED with a resistor to FEN and B+.
Then turn ignition on and watch the flashes of the LED.They represent codes wich will guide you to the problems the car is suffering.
Here's a picture:

Image

If you don't know how to translqte the blinks to numbers just use the search in the forum and you will find alot of info.
Good luck!
Edit:If you have removed the battery the codes may not be present, but surely they will apear again soon.


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Ciocoflenderu
PostPosted: Wed Dec 26, 2018 2:19 pm 
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Stupid question - i am beginner in all this and not quite good with phylsics...
1. When you bridge TEN and FEN to adjust idle speed, is it safe to bridge with a small metal wire with no isolation and to do it with bare hands?

2. You must adjust idle speed while you bridge TEN and FEN ? And if so, why? How does it work??

I am a beginner and i would appreciate if someone would explain to me just how it works. Maybe i was doing theese the wrong way, and that is why i don't get any improvements.


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maZZda
PostPosted: Wed Dec 26, 2018 3:01 pm 
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Hi, i mislead you, it's not Ten and Fen but Ground(GND) and TEN.
Sorry about that, i seached and found the picture to correct my self.
TEN stays for Engine Troubleshoot.
My bad, sorry!
For the bridge, it's not that important whar kind of wire strip or paper clip you will use.Just make sure you make the jump solid and intermitment free when you make the adjust.


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pitrack_1
PostPosted: Thu Dec 27, 2018 12:53 pm 
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Hi,

1) bridge (connect) TEN to ground (GND).
2) You may use a simple piece of wire like a paper clip, however be careful not to let it touch anything else esp. other wires or connectors.
3) I think "TEN" stands for "Test ENgine."
4) When you set the engine is this mode I think you are effectively telling the car to go to the default values for running the engine and stay there so you can make appropriate changes without the car trying to compensate for you. So you can adjust the idle speed without the car perhaps trying to 'fight' you. The car will then (hopefully) accept your new settings and any associated readings from its sensors as the new 'defaults' to use. Basically you're telling the Engine Control Unit (ECU) "I'm recalibrating you". This helps accomodate any wear, tear, change and drift in the engine's components. It will also read out any fault codes that are stored for diagnosis.

Patrick


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Ciocoflenderu
PostPosted: Tue Jan 01, 2019 10:55 am 
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Ok, tried to make a diagnosis, i used a led instead of the light bulb, but i didn't light at all... I am probably terrible at this... the car is 24 years old, it cannot have any error codes...

As for the problem, since i played around a bit with the idle, the problem with the idle speed seems to have resolved itself but i will drive it more and keep you posted. Thanks for all the answers so far! :D


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maZZda
PostPosted: Tue Jan 01, 2019 2:49 pm 
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The LED works only in one direction, did you try to put it backwards?(switch pins) it does not flash if the + is not on the right leg of the LED!


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Ciocoflenderu
PostPosted: Wed Jan 02, 2019 8:20 pm 
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Good point. Will try it out tomorrow.


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Ciocoflenderu
PostPosted: Mon Jan 14, 2019 9:54 am 
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Update: I tried all i could to diagnose the car but to no avail... it just wouldn't work. I switced the polarities of the led, tried another buld, but with no success... I would love if there would be some sort of video tutorial on how to do it and what equipment to use (what amperage, voltage, resistance the light bulb, etc).

The thing is, in the meantime, the idle problem has got worse... the rpms drop by themselves sometimes at around 500 RPM, other times car revs itself at around 1500-1250 rpms. Rightnow my idle is set to 850 RPM. Moreover, there is marked hesitation when accelerating (in the rpm range 1500-2500) that just wasn't present before.

I invested lots of money until now (around 1500 euros) trying to fix this problem, but there is noone in my town able to solve my problem. To recap:

- the MAF is changed (second-hand)
-the IAC valve is clean as a whistle;
-new spark plugs;
-Cleaned throttle body etc.
-New battery;
-new radiator;
-new lambda sensors;
- new alternator;
- the car was searched by a professional for short circuits (my main fuse blew a while ago with no obvious reason)


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brucey76
PostPosted: Wed Jan 16, 2019 10:32 am 
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Just a thought but could help, warm car up so that its displaying the fluctuating idle and clip a jump lead on the battery negative and the engine lifting point just to give it a better earth to see if it improves. Given these cars ages now even the copper wires will deteriorate.


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