Engine misfires like mad when under load, usually at about 2,500 revs. Now its getting worse with the colder mornings, misfiring on idle till it warms up. Pulling off each HT lead in turn makes matters worse, I thought maybe a lead was breaking down. First started about 6 weeks ago after battery was changed. Have tried resetting ECU by disconnecting battery over-night. Local Fiat mechanic put computer on to ECU but didn't really show anything concrete. He suspects the MAP sensor is duff. Coil pack replaced 6 months ago for not firing on no. 3 cylinder.
MAP sensor Bosch part number is 0 261 230 035. Any comments on the diagnosis and where's the cheapest place to order a sensor. BreakersWeb.com want £42.50 ex delivery for a used one.

TIA

Ian

its impossible to say really, i wouldnt go buying new sensors unless you're sure. scrapyard sensors dont cost much (£10) or they're free if you have a pocket . did the mechanic use a fiat examiner smart machine to do the diagnostic?

The computer he had wasn't the Fiat Examiner, I think it was made by Snap-on. He said it did the same things as the Examiner and from what I saw it did all the diagnostic things I would expect, eg it picked up the MAP sensor as being duff when it was disconnected and on a couple of occasions it picked up the MAP sensor as being duff after the engine was run. However it also picked up the Lambda sensor but he didn;t think the symptoms I was getting pointed to the Lambda sensor, more to the MAP. Anyway I bought a second hand MAP sensor through ThePartsGateway.co.uk to the tune of £42 incl delivery and f..k me its still the same.

When the engine is cold it idles very rough and is virtually un-drivable at low revs until it warms up to normal (1/2 a dot below the middle temp range). Once its warmed up it is ok so long as I don't put too much load on the engine, then it misfires like mad. The fault has been there for about a month, but the rough ideling and misfiring at cold has only started since the cold weather. Would a Lambda sensor give this sort of fault? I can see a trip to a garage soon.

i want to cry for you

archer-ian said:

The computer he had wasn't the Fiat Examiner, I think it was made by Snap-on. He said it did the same things as the Examiner and from what I saw it did all the diagnostic things I would expect, .

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yes they always claim a third party machine is just as good. but it isnt ever as accurate. (not that the examiner is exactly 'accurate' in many situations)

archer-ian said:

eg it picked up the MAP sensor as being duff when it was disconnected and on a couple of occasions it picked up the MAP sensor as being duff after the engine was run. However it also picked up the Lambda sensor but he didn;t think the symptoms I was getting pointed to the Lambda sensor, more to the MAP. .

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well you changed the MAP and it made no difference so i guess we can assume the diagnostic was in fact wrong.

archer-ian said:

Anyway I bought a second hand MAP sensor through ThePartsGateway.co.uk to the tune of £42 incl delivery and f..k me its still the same..

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i did try to tell you this could happen, i see it all the time. a £10 scrapyard MAP would have been just as useless, but much cheaper. guess you could try to sell the MAP on ebay and make a small loss. fingers crossed

archer-ian said:

When the engine is cold it idles very rough and is virtually un-drivable at low revs until it warms up to normal (1/2 a dot below the middle temp range). Once its warmed up it is ok so long as I don't put too much load on the engine, then it misfires like mad. The fault has been there for about a month, but the rough ideling and misfiring at cold has only started since the cold weather. Would a Lambda sensor give this sort of fault? I can see a trip to a garage soon.

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a lambda sensor makes no difference what so ever when the engine is cold. a faulty lambda sensor will usually waste petrol and make warm starting difficult, and can also cause the injection system fault light to come on. your problem does not sound at all like lambda sensor problems. it might be worthwhile disconnecting the lambda just to see what happens.


save yourself some time and money, take it to fiat.
on the 1.2 the throttle position sensor often causes problems when the battery is changed. my money is on that, and the only way to fix it is to use an examiner to teach the ecu the TPS range. tell a fiat tech that its the 1.2 model and you changed the battery when the problem occured and im sure they'd think TPS too, without even looking at it.

the good news is that teaching the ecu the TPS range should not cost any more than the diagnostic check, as it is done using the same equipment and can be done at the same time. maybe there will be a small charge for the extra time it takes (they are dealers after all)

good luck

Hi Jug:

My mechanic works on Fiats all the time and recons that the ECU self-learns the TPS, so there is no need for the Fiat Examiner. I hate this, when 2 experienced people come up with opposing views.

Ian

Man, this happens all the time with 1.2 engines... Search in the forum and you'll believe me.
Trust Jug on this one...hell trust Jug on everything !!! He's very experienced in these things.

unfortunately the 1.2 16v is the exception to the rule (dont ask me why), but on other models the ecu will learn the TPS range automatically.

if you're unsure, ask a fiat dealer.

Jug:

My fiat mechanic thought that there was a way of getting the ECU to learn the TPS range by going through a procedure like, ignition on for 60 secs, off for 15, on again, throttle pedal to the flooor and back off again. He couldn't remember the exact procedure though. Ever heard of anything like that ??

Ian

no i know for a fact the examiner is needed on the 1.2 because i have the procedure here in front of me, if you gave me an examiner i could do it for you.

in case you're curious, to do it you simply

to zero:
-switch ignition off
-connect switch MPX97 to the examiner and move handle to position 3
-connect the examiner
-set examiner to "control unit test" mode
-turn ignition on
-set examiner to "active test" mode, then select "reset self-adaptive parameters" and "idle actuator"
-confirm reset and wait for "executed" message
-turn ignition off and wait 30 secs

self learning:
-turn ignition on and wait 30 secs
-re-establish examiner comms with ecu
-set examiner to "parameters" mode and select "idle identification test - executed" and "idle identification signals - synchronised" from the "selection" menu
-turn ignition off for 30 secs
-start engine and do not operate accelerator
-wait for cooling fan to operate
-disconnect examiner
-drive baby drive

according to the fiat manual this MUST be done every time the TPS is disconnected, however the same problem often occurs is the battery is left flat for some time (because ecu loses all parameters if it is reset)

Jug:

OK, seems clear to me. I'll get it booked into a Fiat Dealer and report back.

Ian

Ciao Folks! I own a fiat Brava 1.2 16 v with 106.000 miles and I had same issue ! I took today my car to Fiat in Glasgow but cannot find anything wrong! they used a Examiner utit to test my car but its seems everything fine for them! but the car occasionaly seems have a loose of power , and revs sometimes tend to be erratic but just for a second or so...

BAD NEWS! : THEY CHARGED ME TODAY £ 70 FOR NOTHING!!!!!! IAM SO FRUSTATED! IVE CHANGED THE SPARK PLUGS 6000 MILES AGO..AND TO BE SURE TOMORROW I WILL REPLACE THEM...

QUESTION ; WHY ARE THEY SO UNPROFESSIONAL? NOW AT BOTTOM LINE I HAVE £ 70 LESS IN MY POCKET AND MY CAR WITH SAME ISSUE.

HELP MEEEE

CIAO E GRAZIE

CLAUD:bang: IO

this often happens when a fault is intermittent. the ecu will not have any fault codes stored for an occasional problem, and if it wasnt happening during the diagnostic it will be impossible to find the fault. if the fault occurs more often and for longer periods there is a better chance it will be logged in the ecu. you could try another diagnostic when the problem is worse. i know thats not much help but this does sometimes happen and there's nothing anyone can do

Well the waiting is over. One ECU and a set of HT leads later and it runs as sweet as a nut, however my wallet is lighter to the tune of £553 !!!!!!!!!!!!! I tried to trade it in against a Fiesta and according to Glass's guide its only worth £900 trade in.

Anybody want a 1.2 Brava 93K on the clock with new ECU & HT leads ??

Seriously though, what is the best way to sell a Brava these days, part ex or private. Its got a score down the rear nearside door, apart from normal wear & tear bodywork spots its fine (I think)

Thanks Jug for your help. TTFN. Ian

oh no! thats bad luck. ecu failures are very rare.

private sale is always better for every car. a 1.2 will fetch £1000+ in average condition. its an easy model to sell because its cheap to run so the kiddies can afford it.