Engine going uneven during acceleration 16v from 1988

[Anonymous]

Im restoring my old 16v from 1988, and has had a major work done concerning rust and paint. It now looks new again . However, as the look improved, the performance got worse. The problem occure during acceleration. From about 2500 rpm up to 4500 rpm it is not quite right. the engine coffs and pulls poorly. Above 4500 and up to the red mark (and further) it pulls like in the good old days. Just cruicing around with minimal throttle is also no problem.

I have had it into a garage measuring the HC values which came out to high. I have changed spark plugs, plug cables, rotor, distributor cap, coil, ignition module, air flow meter, the sensor on the clutch housing somehow measuring the revolutions of the engine (dont remember the english word for that) gasoline filter, and air filter. None of these changes had any effect on the problem (I see the new spare parts as an investment...im going to have the car until I die). Some days the engine is especially bad, and other days it could be a bit better. Im running out of ideas, and could use some help from experienced 16valvers. The Citroen garage in my town is not very keen to look at it as they are more interested in new models where they can use "the computer approach".

Hope to hearing from you
All the best
Geir

[Timmo]

generally if its poor below 4.5k then i would have suggested plugs, then distributer cap, which you have done,
so from that i wold say the ignition coil as seems the part that hasnt been changed, mine used to eat plugs like mad the way i drove it (red line most places! ) but after swapping the coil has been spot on,
the engines Do like a good strong spark!

also may be worth a look is that all the earth cables from the battery to chassis, battery to gear box, gearbox to battery tray etc are all in good shape, and that the multi block for the wires that is positioned under the bulkhead side of the battery are all clean (easiest to do when battery is out, unplug, small wire brush to clean with and a light smear of Vasolene - peroleum jelly - on the terminals before reconnecting and then using a cable tie to hold tight), i did all of mine when i had it apart and makes a suprising difference when everything is clean!

i hope that helps in some way!

[Anonymous]

Thanks for that.

Well as I mentioned the ignition coil is already changed, and I forgot to tell that also the two earth leads are renewed. I have inspected the connections under the battery also. Havent done anything with them, but they look really clean and nice. Of course I can try to clean them anyway and see if it does any good.

Got another tip from an experienced Citroën mechanic (professional) that also the connecter to the airflow meter was likely to breake so I will try to change it. (looks a bit tricky for a person unexperienced in car electronics like me...have anyone tried that? It does not look like an ordinary cable).

Then there are some cable connections under the right front wing which also according to him includes some of the ignition circuits. Im going to remove the wing and see what shows up.

Thanks again, Geir

[daaristieweer,wiedurft]

And how's the idling, when hot and cold engine?
Have the same problems here with an "88 16v, with D6c xu9j4 engine.
Think it's also a bad electronic contact somewhere, but haven's sorten it out yet in a few years. going to renew al the electric contacts by new ones, with the original cables, only 2 cm shorter.....
Keep you informed!

[Toddman]

Hi
As mentioned the connection on the AFM is often a problem but just by unplugging it and cleaning the terminals and then tightening them up inside the plug will help a lot.

Because you have changed almost everything I would consider the possibility of an air leak, check all the breather hoses and also the thin vacuum pipe that runs from the manifold up to the pressure regulator on the end of the fuel rail.

Hope that helps

Cheers
Luke

[iain a]

...check your exhaust aswell....

[daaristieweer,wiedurft]

why the exhaust...?
You mean the 2 first pipes in-from the manifold?

It's not the airfuelmeter, it's not the igniion cables, what's it then? Many pages are written with no def answer. I suspect overall bad connections through the electric cables, so that's why i'm changing the conections now.
Also check the wiring through the relais to the ECU, at the right front wing. It has also a connector to bring the electronics in, they can cause the problems.
Motronic uses 5Volt, so any small differance can cause problems.

[Anonymous]

Sorry for the late reply! Was into a very busy period at work lately.

Yesterday I had time to go on with the 16V electrical research project. I took off and cleaned the relays at the front wing and also removed the front wing and cleaned four connections there. Sealed everything in cable hoses. Took a test drive, and guess what. Problem fixed!!!

Im really happy, thanks for the good advises from everybody. The car hasn't been well since last summer, so it feels realy good to finally have it back as it should be. Fast, noisy and charming.

Having a C6 as well. What a different world to go from the BX to the C6...but I love both of them.

Have a good week
Geir

[Timmo]

a C6! very nice!!
noticed the latest C5 has been designed similarly to it now! lovely looking car though the 6!

[Anonymous]

Well, a bit of the topic this C6 talk, but since the problem with the BX 16V is fixt I guess it doesn't matter to much. It really looks great the C6. The new C5 has some similar elements in the design, but the C6 is much more ... should we say facinating. Actually you can mistake the new C5 from an Audi....that would never happen to the C6. And the driving is great. Not a sporty experience, but extremely smooth and quiet. An excellent cruicer, which also goes much better around corners than its ancestors.

Geir

[iain a]

[quote="daaristieweer,wiedurft"]why the exhaust...?
You mean the 2 first pipes in-from the manifold?
quote]

no, i had a problem with my white bx, turned out the front pipe did'nt have the seperator down the middle, so it was quite lumpy and felt as if would stall whilst idling, new exhaust on now and it pulls better than ever

[daaristieweer,wiedurft]

ok then, i look at it....

[Adrian (NZ)]

I have the same symptoms as this car had - misfiring above about 2500 rpm. I've changed ignition module, coil, distributor cap, rotor, spark plugs and leads. The multi-connection blocks behind the battery were all really crappy, and I was hoping the problem would disappear when I cleaned them but no luck.

Geir fixed his problem by "I took off and cleaned the relays at the front wing and also removed the front wing and cleaned four connections there. " Also mentioned is to "check the wiring through the relais to the ECU, at the right front wing".

Could comeone please clarify where these relays are? I've checked the big round connector next to the RH engine mount and that is ok, but I cant see any relays around the right front wing area.

I'm convinced the fault is electrical because the tachometer flutters when the engine misfires, which would indicate a fault in the low tension circuit to the coil.

Any other thoughts would be appreciated.

[Vanny]

If you have the big round connector under bonnet, then chances are the relays are under the drivers seat close to the ECU, one of which is the fuel pump relay.

Have you checked all the obvious things like fuel lines?

[Kitch]

In situations like this it doesn't hurt to spend an afternoon going round all the multi-plug connectors under the bonnet and making sure that the metal contacts inside are nice and tight, so they grip the pin they're supposed to, and that the wire hasn't fractured at the other end where it's crimped into the metal reciever inside the plug. The age these cars are at combined with the patchy quality of the electrical system in general can play hidden havoc!