Technical Uno 999 FIRE ie erratic idle on warm up (Bosch SPI)

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Technical Uno 999 FIRE ie erratic idle on warm up (Bosch SPI)

darren_hill

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I have looked at several similar threads to my car's problem.

It is a K reg Uno Hobby 999cc with SPi. From cold it starts perfectly and initially sounds great. It starts to get rougher the warmer it gets. I have replaced plugs, leads, dizzy cap, vacuum to no avail although the vacuum did cause some improvement. Short journeys are fine but once temperature has raised car is a nightmare in traffic. It will stall unless I keep pedal down. If I do get heavy on the pedal, it kangaroos a bit afterwards.

I have also noticed that peformance at higher speeds (motorway) is way down and I struggle to get above 70mph. There is a bit of a tappety noise but only when I floor the pedal.

I have had timing checked and that is spot on after recent cam belt and tensioner replacement.

After nosing through my trusty Haynes I have come to the following possibilities:

Dodgy sensor
ECU is packing up
Throttle position switch

I'm leaning towards the last one as the spring clip was missing off the plug when I started to tackle the problem. I think the previous owner may have had a dabble.

I assume that only a FIAT dealer will have the correct kit to check the sensors or ECU.

I live in the Worcester area if you can recommend any specialists

Cheers

Darren
 
Re: Uno 999 FIRE ie erratic idle on warm up

Hi Darren,

(y) Welcome to the forum! There are a lot of threads about Bosch SPI Idol issues.

One or two questions for you with quotes that I’ve found really helpful!

___________________________________________________

Whats the air filter like?

Did you check the Vacuum Advance pipe for splits / leaks?[/QUOTE] Substitutes Throttle Body for carburettor lol
alexGS said:
...Don't forget to check the vacuum pipe all the way to the carburettor - it's easy for this to crack near the carb.-Alex

Which plugs did you fit? (hopefully NOT Champions) NKG are better - sorry I can't find the sauce at Mo - you deserve rep too.
Louie Bee said:
...I forgot to tell you the car ran rubbish with a 0.95 MM gap and ECU reset :( .

:mad: Next day the plugs were black with soot!

I gently cleaned it off, changed gap to 0.85MM –and did another full ECU reset – Wh HAAAAAAAAyyyyyy :nutter: !

:confused: Could the soot on plugs be caused by the long idol required for full ECU reset? (Please be just that lol)...


Have you checked the idol plunger, accelerator cable adjustment, cleaned throttle body (and inspected/wiggled the ECU cables in engine bay to hear changes in Idol speed) and reset the ECU?
Morty Mort said:
Look on the rear of the njection module (SPi). On the rear left where the accelerator cable "thing" is, there should be a little plunger supposed to be depressed when you put your foot of the gas. If it isn´t depressed, the engine will get too much fuel (twice amount) when idling. This can be caused by a too tight accelerator cable. If your is, loosen it, to make it hit the plunger....
...And the ECU is reset by disconnecting the battery which you have done for some time. Then reconnect, start the engine and let it idle until fan cuts in. Shut off engine. ECU is now reset.

Morten.
Morty Mort said:
Check the little plunger at the left back of the throttle body. Is it depressed when idling? Check by using your finger at it. If it isn't loosen the throttle cable a bit. This solved the idle problem on my 1.1 i.e.S. Clean the injection module / throttle body at the same time. Morten.....


I hope this helps!

Let us know how you get on!


:woot:New Moderator,
 
Hi Louie Bee.

Thanks for swift response.

Air cleaner is brand new.

Plugs are brand new and NGK (although condition of old NGK plugs were fine)

Will check vacuum pipe tomorrow. I'll also have a look at this "plunger" and check the ECU cables. I am warming to the idea of the accelerator cable needing adjustment as when I floor the pedal when the car is in neutral it drops then picks up. I'm still quite suss as to why the "plug" that fits into the side of the SPi, under the accelerator cable, had the clip missing.

I am reluctant to take it to my local Fiat dealer (Hylton of Worcester) as they buggered up a previous Uno of mine. I need the internal rad matrix replacing after a stereo theft. They filled it full of sillicon which knackered and blocked the controls. They also dropped the ignition barrel, some bits went missing, so they taped it up and hoped for the best. The police pulled me over because my lights were flickering on and off!

Just out of interest, my Fiat connection is as follows:

"Y" reg mirafiori 131 - my Dad's but I learnt to drive in it.
"V" reg 127 - my brother's but I knackered it.
"C" reg 1106 Uno
"C" reg 999 fire Uno
"L" reg 999 fire Uno SPi
"K" reg 999 fire Uno SPi
"H" reg 999 fire Uno
"T" reg 900cc seicento (girlfriend's car)

Anyway - cheers for the advice so far.

Darren
 
hey sorry to say but ECU is packing up any fiat dealer if you take youe ECU into them they can send it away to a company called fair exchange who will check the ecu!

this will cost £40 (approx) if your ecu has to be replaced the £40 will be knocked off the price of new ECU.

this is a common fault with BOSH SPI and will not show up under examiner interrigation

info from fiat uk tech :)

sy :)
 
That’s a few Unos Darren! LOL.

Sorry to sound negative (EDIT; about FIAT Garages) , but personally I’d never take my Uno to a FIAT garage for work – Ever. They’re way too expensive. And as above they don’t all know what they are doing!

Labour charge isn’t worth it for a 1.0 Uno. Our sponsors will sell you the same part at a fraction of the price and get them to you (normally) next working day. There are plenty in breakers yards too.

I wouldn’t like to make a snap decision about faulty ECU and send it off. At there youngest UK Unos are 10 years old so there will be many underlying problems to work through like built up oil, sensors and interconnecting wires!

Say for example the ECU’s external earth strap had corroded, you send it off, pay £40 – get it back with the all clear. You then refit it and have the same problem. You wasted £40.

If I suspected faulty ECU, I’d go to the scrap yard and borrow/buy one to see if any batter. and pocket the 30ish quid lol.

Darren, let us all know how you get on.
 
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Hi folks. Time for an update:

I have checked the vacuum hose and it is fine. I have given the SPi unit a good clean where I can get to it. I have adjusted the accelerator cable as per Haynes manual. I'm not quite sure which bit by the accelerator cable is the "plunger" that was referred to?

Are you on about the thing with the spring on underneath the cable that is covered with protective rubber? Anybody got a picture??

I did get a FIAT mechanic to have a quick nose and he said it was the "stepper motor". He was pointing to the accelerator cable side of the SPi unit. I'm not sure what he meant but he said it wasn't working properly and I should get another from a scrappy. I can't see how to remove it. There is the black plastic case with the BOSCH logo on but it seems to be held on with two bolts with those nasty allen key type heads. I can't get anything in there to undo them.

I have also managed to locate a SPi ECU for £20 as a last resort.

Adjusting the accelerator cable has prevented any stalling so far. The car still sounds rough idling and the loss of power when trying to overtake or on the motorway is worse than ever.

Thanks for the advice so far. Any further suggestions are welcome.

Darren
 
Darren,

If you floor the pedal at 70mph and get a 'tappety' sound, it could well be something called 'pinking' (pre-ignition). If this is the case, it is almost certain that you have an ignition fault somewhere.

Even though you've already checked the timing, you should check again to be sure. Did you do the timing with the distributer vacuum pipe disconnected?

Other than that it could be an ECU problem, but you'll need to take the advice of other Uno owners regarding this as I only know about the carburetor Unos!

Hope you get it fixed.

Chas
 
Thanks for this.

Could the "pinking" be cause by a mixture problem due to the SPi and it's ECU having a problem?

I have a second hand ECU on its way from an N reg Uno.

I will check the timing again. Is it worth having a look at the distributor? When I replace the cap about a month ago, two of the four pins were really worn down. How can I check if the ignition ECU is working?

I was having a look on shop4parts. What does the distributor pick-up sensor do and what effect would there be if this was knackered?

Thanks again for all of the advice, I'll keep soldiering on.

Darren
 
Hope to help you

Hello!
I'm quite familiar with BOSCH mono jetronic fuel injection: I have a Uno 1.1 i.e. and I checked it from all sides and points of view in order to solve an idle problem.
However, I' try to describe to you some checks you can develop on your car in order understand something about your problem!!!
I'm going to describe some procedures for cheching your throttle position sensor (a linear variable resistor), your idle switch (a simple switch, the "plunger"), your engine temperature sensor and your lambda sensor.
All this is not so easy but neither difficult.

First of all: when engine is cold, ECU increases throttle aperture (in order to increase idle speed and let it run correctly).
So you can do the following thing:

1) With engine completely cold (for the first start in the morning after all the night, and BEFORE you turn on ignition key, watch the throttle pulley (it's the pulley that moves as you push accelerator; it is under the left side of air filter, if someone pushes accelerator, you can clearly see it to move and rotate).
You watch it and then let some friend to turn on ignition key and electricals (with or without start engine).
If idle switch and step motor (it is the motor which controls idle speed by changing throttle aperture) are good, you have to see the throttle pulley to turn automatically when your friend turns on the key. Infact ECU opens throttle a bit in order to permit to the engine to start and run properly at cold. This is a very simple and preliminar check. If nothing turns, probably you have a fault with one of that parts.

2) Then you can check your temp sensor: you have to identify your "intake mainfold"... Probably I can't translate it correctly in English, but it is an "one part" 4 tubes metal object which connects air/fuel/mixture intake to the head of the engine. So, see at your engine from the right side (opposite to throttle pulley) and point attenction to the distributor. Under the distributor there is that collector (you can see only a part of it because it's covered by air filter and other stuff). On the right side of this You will see also a "plunger" with a black cable which exit and goes out of hte engine zone: that is the engine temperature sensor with its wire connection. With engine cold and not running but ignition turned ON, you have to disconnect the cable (it's easy to do: you have to push the little metal object which locks the connection, then you have to pull the cable...here I have another translation problem because I can't explain and describe this procedure better). As soon as you disconnect, you have to see your throttle which closes air intake (in other words, you have to see throttle pulley to rotate and which returns in the position it was before you turned ON the ignition key during step 1).
Reconnect the cable and see the pulley to turn, opening air collector another time.

You also can start engine and try to connect/disconnect with engine cold and warm:
When engine cold, it have to work normally with the cable connect, and not to work correct with cable disconnect (because ECU have not the information of "engine cold" if you disconnect the sensor.
When engine warm, cable is not longer important (sensor is only to note that engine is cold; if engine is hot, ecu doesn't need any information about temperature) and engine have to work with or without its connection. IF engine runs better WITHOUT that connection, then you have the sensor faulty and probably you have solved your problem. But I think this is not your problem.

3) Lambda check.
This is a little more complicated because you need a tester (at least). Tester is not the best you can use: I have a little electronical circuit which permits to test lambda (ald also all the fuel injection system) very precisely. It's an easy circuit (only a chip which produces all you need all by itself, and a series of 8 led in order to see the output). I can describe it if you have some confident with electronical stuff.
However, if you have a tester you can roughly check your lambda.
Let me know if you are able and interested in this measure and I'll try to explain it!!!

Very very sorry for my English, but I'm Italian and I studied English only at school... then I have a lot of difficulties to understand what you wrote and also I'm not used to write...
I hope to be helpful! Let me know for all you need and I'll try to help you.
That are basic test you can perform on your fuel injection system.
If you perform that checks in this way, you will not cause problem to your electronicals or at your engine, don't worry!!!
 
Re: Yes Please

-Where can i find explanation for making that little electronical circuit which permits to test lambda? Did you opened a new thread ? Thanks in advance !
 
Hi.From personal experience I think that you are heading in the right direction when you mention the distributor, and particularly the pick up sensor.
My Uno was showing the same symptoms as yours until it finally came to a halt.
Inside my distributor the wire to the pick up sensor was broken and the bearing was worn out.
I ordered a new pick up sensor from Italy, put it on and the car ran beautifully.
Hope this helps
 
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