Technical Revving galore

[dabravokid]

I have a 99 Bravo 100SX and for the most part its a great car. I have a niggling problem with the revs occasionally, every couple of days. Basically it will start to rev higher then 1000 (normal is 800), when the fan cuts in it sometimes goes upto 1500 (doesn't move from 800 normally). It also makes changing gear harder and kangeroos slightly. It has been to fiat (who seem to rely solely on the diagnostic tool) and they say 'we can't find anything wrong' damn technology! You would have thought the builder of this tool could have put a little prompt saying that they should try something else. Anyway the first time in they changed the throttle body (warranty). This didn't really have an effect. Then I did an ECU reset, no effect. I'm starting to think it could be something to do with the Lambada or some other sensor. How hard is it to change the lambada sensor? I'm fairly handy with a spanner and have axel stands. In the meantime fiat are going to replace the temperature sensor because that sometime seems register higher then normal. For info this problem occurs even when the engine is hot. Thanks in advance for help.

 

[Steven]

There is another post by someone with similar symptoms. My Brava 100 HSX idles at 1100 rpm. This is normal which would indicate that your car is idling slower than it should be.

 

[dabravokid]

When you say this is normal, is that the figure in the haynes manual or just what its been reving at since you've owned the car? 1100 sounds a little high to me. I'm trying to find out about the Lambada sensor as well, this doesn't appear to be that well documented.

 

[Steven]

I know quite a few people with 1.6 Bravos and Bravas and they all appear to idle at just over 1000 rpm. Anyone else on here to back that up?

 

[dabravokid]

Well that suggests it could be something else wrong then. I've taken it to Fiat and they have said 800 is normal. I'm going to halfords tonight so I will have a quick look in the haynes, if theres one open

 

[Ozric-Al]

1100 is too high. 800 is the norm.

 

[Steven]

For a 1.6 Bravo/a? I know of at least 4 including mine that rev at just over 1000rpm!

 

[Ozric-Al]

Yep. 1.6 should be 800rpm +/- 50rpm. 1100 is too fast.

 

[Steven]

Must get that checked then!

 

[dabravokid]

The most major cause of this is the idle air control valve, when mine went in they changed the whole throttle body. A quick fix is to remove the valve, give it a good clean with a suitable fluid and put it back on. I still get the problem though so sometimes it something else.

 

[jayfishII]

my wife had a similar problem on her clio, the throttle cable started to fray at the grommet behind the accelerator and got stuck when I was driving it. Fraky experience as i drove about 5 miles of country roads without using my feet until i found a roadsign so we could call the AA.

 

[Steven]

My car is booked in for a timing belt change tomorrow, so I'm going to get it checked. It has always idled at 1100 rpm.

 

[dabravokid]

Thanks for the suggestion, its nothing to do with the throttle cable, I've checked that end to end. When it revving the throttle is fully closed. I'm sure its something to do with a sensor, just not sure which one and where to start looking.

 

[Helz]

I always thought they were meant to idle at 1100 rpm too steve, mine seems much happier at that, it starts juddering at 800rpm. Right now it just seems to pick it's idle speed depending how it feels but this may be due to exhaust problem affecting sensor . I don't know where the lambda sensor is on your model but on my 1.2 it's on the exhaust front pipe. Worth at least pulling out, giving it a wipe and putting back in.

 

[GSEBravo]

i started the other thread on this matter a while back for the hlx. it has been in to the garage and had the ecu wiped, rebooted( or what ever it is) and tweaked abit to run with my exhaust. the guy then said because the computor didnt really come up with much drive it till the end of this month then bring it back in and he will look at it again.
i find if i rag the tits off my car it will never do it but if i obey the 30 limit and waddle round town as soon as i stop it goes mental. it has even been known to rev itself from 2000 to 2500 like i was looking for a race from someone.

 

[polecat]

Idle speed for 1.6 and 1.8 is: 850+-50rpm, the 2.0 is 750+-50rpm.
Not sure about the 1.2 but would expect it to be under 1k rpm.

If you rag the car within 300 miles of having the ECU reset it will remember those settings and expect the car to be permanently driven at high revs. Normal and idle settings will go down the pan.

 

[Steven]

I must reset my ecu and see what happens in that case.

 

[subija]

Dabravokid,

I think the culprit is the coolant temperature sensor.

Reading at 20 deg Cel is 5k ohm & at 60 deg Cel the readding is zero ohm.

The symptom happened to my car once!. When I changed the sensor, problem solved.

 

[dabravokid]

Is it easy to change the sensor? Where abouts in the egine bay does it sit and how do I fit it (i'm not bad with simple mechs after owning a citroen ax gt). Thanks for your help in advance.