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Discussion Starter #1 (Edited)
hello , could any one possibly shed any light as to what my problem may be , after 2 yrs trouble free motoring in my " r " reg alfa 145 cloverleaf , in march this year whenever i went over a bump the engine management light came on . the car ran fine but this problem persisted for a few weeks . then one day the revs started to blip intermittently and engine jerked hard with sudden power losses with the engine management light flashing whenever this happened . the car then ran fine . this happened 3 to 4 times . i had the car plugged into a diagnostic machine the next day and was told it was o2 sensor on the exhaust and i believe he also said the throttle variation sensor which was at back of engine bay was at fault . he told me it wasnt a break down problem but i needed to replace the o2 sensor as this was a mot issue . he reset the fault codes and i had the 02 sensor replaced a fortnight later . the car has ran fine for 9 months but the same problem has occurred with engine management light flashing whenever i go over a bump for a few weeks then all of a sudden sudden power losses / and rev blips with management light flashing but the car then drives normally as if nothing has happened. is this the throttle sensor as previously advised . i was told by mechanic i had done well to have a car that is 13 yrs old and has not has throttle sensor replaced . any help would be greatly appreciated ....thanks in advance
 

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Almost certainly a problem with the fuses and relays located around the battery (aka BBoB). Being under the bonnet they are exposed to the elements and due to this the connections to them come loose / corrode / oxidise over time. Going over bumps is going to shake these connections exacerbating any dodgy connection issues. One of the relays is the main power relay that supplies all the engine sensors and ECU with power and another is for the fuel pump power so if you get a momentary connection issue on either of these you are going to get the sort of symptoms you describe and the injector light will also come on.

You need to clean / tighten all the connectors and connection points really well or completely rewire with new connectors.
 

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Discussion Starter #3
thank you very much my good man ! - i will investigate when i take it to my mechanic friend - its been a fab car so far . owned it for 3 years now - had 77 k on when i bought it and ive put 30 k on since and the only problem ive had was the earlier sensor problem i mentioned which was easy fix so for a 13 yr old car i cant complain really .............
 

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Mine has started putting the management light on when cold and on the overrun after a hard acceleration so I reckon my BBoB connectors are moving about too. Had the odd spin over but not start instantly moment too when cold.
I thought it was all still good after 15 years and 66k............maybe not !
 

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Discussion Starter #5
been new to all of this ive just had to google " bbob " -- oh i see , been a mechanical iliterate im taking it to my friends garage to investigate - since i posted yesterdays post its ran fine for 40 or so miles but i know its an intermittent wont go away till fixed problem so ill take the advice and investigate the bbob!
 

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Discussion Starter #7
Hello again , connections and relays were checked and according to my mechanic friend there was only one that had any rust that needed cleaning up. all the others were fine and there were no loose connections - which is a shame because ive still got the same problem , the light still comes on when i go over a bump and also comes on intermittently , i had one quick power drop whilst driving to work today for a split second , so it looks like im going to having to connect it to a diagnostic machine ........
 

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If you have the lid off, check the coils and their connections with the HT leads (i.e. pull the leads out of the coils and inspect the ends). If they're the OE leads, the connectors will be a little corroded by now and the metal brittle. It could cause and on/off contact as the car gets rattled about.

Ralf S.
 

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Discussion Starter #9
thanks ralf we will do that - after reading a number of threads on here ive seen that there is a number of reasons once the bbob is removed from equation , 1) ignition coil/plugs 2) oil/water in plugs 3) ignition timing ( belts jumped ) and 4) crank sensor or 5) maf problem - i guess its just a process of elimination as several threads say diagnostic machine may not show what problem is -
 

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If it only misfires over a bump, it's not a valve timing issue.. that would be a problem all the time.

To look in the plug wells to see if they have oil in them you need to lift the coils off anyway (they sit directly on one plug and have an HT lead to a second plug on another cylinder) so by checking the coil-plug and coil-HT lead connections you can also check the wells at the same time.. :)

Also I don't think it's the MAF .. that makes the car run nice but if it's disconnected it runs in "failure mode".. the car would still run, just not at peak efficiency. It's more likely to be a relay, or an intermittent cut-out to the fuel or ignition circuit (obviously TDC sensor is involved in that) .. including fuel pump and safety-shut-off switch under the seat..


Ralf S.
 

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Discussion Starter #11
yes to clarify , and my apologies for any confusion , the engine management light comes on when i go over a bump but the car does not misfire at that point - every time the car goes over a bump the engine management light flashes - it has been for a few weeks now , the power drop occurs intermittently at any time , this can happen two or three times on a journey then the car can run fine for a few days , though the light still flashes every time i go over a bump - thanks for all the help so far
 

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ps - tdc sensor ? what is that - is that throttle positioning sensor ?
It's the Crankshaft Sensor or Crankshaft Position Sensor, however people prefer to call it.
 

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Discussion Starter #14
update - now every time i go over a bad bump the engine management light comes on for a few seconds now instead of just flashing on and the power drops albeit very briefly - this contradicts my previous post i know but it has only just started to do that today - i have booked the car into garage next week , question am i right in thinking as prev posted by several of you guys this must be a loose relay / connection somewhere as the problem is exasperated by car rattling about ? I know you mechanically minded guys would just check / fix this yourself but i admit i know nothing about fixing cars and even knowing what im looking at - so would this be a matter of checking all relays sensors ? another thing , i had same symptoms of flashing engine management light problem in february this year ( 2011 ) every time i went over a bump then i had intermittent power drops and that was fixed when i replaced the 02 sensor on the exhaust in march 2011 ( i believe this is also called lamba sensor ) - i thought this latest problem must be something else with only just replacing this part but is there a possibility the lamba sensor has failed again ... is it known they could pack in after 8 or 9 months ? is there a way to check if it is lamba sensor again ?
 

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Hi Linfy
Reading your thread, I can't help myself but wonder - are we really 100% sure it's not the BBoB? I know you wrote above that your friend checked it and that only one connection had any rust at all and all the rest was fine - but to be honest, to me this seems almost too good to be true of any BBoB. Couldn't your friend have misunderstood and check the fuse box inside the car under the steering wheel, instead of the BBoB, which is under the bonnet right in front of the battery?
I suggest that you do a quick check yourself - just pull up the bonnet, and you will immediately see a black plastic cover right in front of the battery. Take the cover off (it's held by clippers) and under that you will see a couple of fuses and relays. Just pull any of them out and see how the connection looks. It's really simple and you don't need any mechanical expertise for that.

Jan
 

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Also, some people believe they've cleaned the BBoB up properly when all they've done is a half-hearted effort. We had a couple of members who took 2 or 3 attempts before they did a proper job and solved their problems.

You need to properly strip down the connectors and use scotchbrite or wire wool to get rid of ALL corrosion and oxidation on the connectors inside the blocks and the connectors on the fuses/relays. Then tighten the connectors in the blocks by squeezing them closed with pliers so they get a really good grip on the fuses/relays. Also use a liberal amount of electrical contact grease or vaseline on all the connectors.
 

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Discussion Starter #17
hi diyjan and gialloevo - thankyou for your comments and suggestions i do appreciate them , to answer the question yes he did check those by the battery , though how well he did this i accept both your points that others have said they have done this right , only to find they didnt actually resolve the matter the first time and had to revisit that area - i do understand as per prev posts why the bbob would cause the symptoms that i am experiencing , especially the management light flickering on when i go over a bump or any rough road surface and intermittet power losses which can happen any time which can then be followed by 50 miles symptom free , it does make sense ... i hope i can sort it because ive had a great time with this car it has been cheap to run so far in 3 years ive owned it , it has only cost me a new lambda sensor .... on a personal note these last two winters where i live, the snowfall was horrendous and temperatures stopped a lot of old cars in there tracks - i got home from work last winter driving through 5 inch of snow travelled 25 miles and passed dozens of cars abandoned and persons stranded because there cars failed or got stuck , that experience along with many others is why i would love to get this problem fixed ... i dont mind even if it cost a few hundred to fix id be happy to do that , it makes sense to do that , my worst fear at moment however is what some have experienced where the garage keeps trying replacing various parts ie sensors etc and the problem still remaining because they have been stabbing in dark ......
 

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They shouldn't go changing sensors.. since sensors generally help the car run more efficiently but they seldom make the engine management light flicker on and off, even if they failed completely.

The bump followed by the light coming on and the hesitation is at least consistent.. so the BBoB is the place to start, since even one corroded connector would do it, depending which it is).

My old Fiat 128 3P had a similar problem that affected dip/main beam... the friendly auto-leccy man completely re-connectored (new insulated spade connectors and then shrink-wrapped) the connectors to the relay... the problem was where the copper wire joined the connector, not where the connector connected to the relay... so that's why you need to take each connector off and have a good look at it.

It's interesting you had the same symptoms with the lambada.. The lambo' should last for years unless you feed the car leaded petrol, or dropped it on the floor while fitting it.

What kind of lambo' did you fit? Does it have an integral block connector (£100) or does it have just bare wires which had to be spliced into the existing wiring .. i.e using the old block connector and upper wiring (£30)? In my experience these wires can also become detached, since the joint is made via an insulated crimped metal sleeve... and the wire tends to bend at this sleeve... and the wire can eventually break, since the insulation was cut away and some of the wire probably already had a score mark in it....

So. it may be you have a de-activating lambda.. though this would be an unusual one for sure.. :)

Anyway... it's more likely to need an auto-electrician to sort than a grease-monkey.. but doesn't sound like you have a major component problem.. touch wood.. you just need to find out what's loose.

Ralf S.
 

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Discussion Starter #19
HI Ralf , sorry for late reply , with regards to lambda sensor it was the hundred pounds one i had fitted - old one had to be cut off last march with welder because it was so corroded which is why it probabley had gone in first place , i had a mobile diagnostics guy come to my house on thursday , his computer pointed to throttle sensor and whilst he was certain this was the fault and recommended i replace it , he admitted there could be number of relays / connectors loose that could also do this , he also noticed that the cable that led to the sensor appeared too tight or short with no play and the voltage wasnt right when he checked it with multimeter - he had to open terminals on connector so that the voltage issue was corrected , he then reset the ecu and asked me to drive round for two days then he actually gave me a free reading on saturday to see if the fault showed again , there has been no fault since and warning light has not reappeared , and no further fault showed on computer , though i have only covered approx 100 miles - he has said if it reoccurs to replace sensor and if that doesnt work to ask a auto engineer to investigate further to see where the loose connection is , though i agree with you and if this problem reoccurs to further investigate bbob first and if this is not source of the fault to contact an auto electrician .... i just want to take the opportunity to say thanks to everyone who has posted a reply so far , i do appreciate all the help and assistance thanks ......
 
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