Technical Mk1 1.6 injector problem

[bebel]

This is my first post here so hello to everyone!

I bought an old Punto 1.6 a few months ago, it was cheap so I was bound to have a lot of problems with it. One of them is that the injectors are not delivering the same amount of fuel. I've spent an awful lot of money on servicing (I could've almost bought an other car from it...) and some problems were fixed but since there's no new injector on the market for this car, the basic problem remained unsolved. Two injectors out of four are OK, they deliver 170cc/min.

I bought two used injectors, also expensive but they also don't deliver the same amount so the engine is not smooth, the injector light is constantly on and eats a lot of fuel, about 15-20 litres/100km.

I also bought 4 used injectors not made for this car but they all deliver the same 212cc/min, I was hoping the o2 sensor feedback would make them deliver less but that doesn't work. It was even worse than with the originals, someone said the spray pattern might be different.

On ebay I've found new injectors delivering 175cc/min but they're too expensive for an experiment that might not turn out good. I can replace injectors in about 15 minutes now with my eyes closed I can also test injectors with a battery and a syringe but this is not useful for anything really.

I'm really at my wit's end so I came here, someone might be able to help me.

Thank you!

 

[fingers99]

I'm not clear why/how you came to the conclusion that two injectors are not delivering the right/same amount of fuel.

This is the most important part of the story because:

a. It's a pretty rare issue
b. How they're tested can have a big impact on the result
c. There can be other issues which lead to similar results.

You can't test injectors with a battery and a syringe.
The lambda can't compensate for overly large injectors on anything but the most sophisticated ECU.

 

[bebel]

All the measurements were made on professional equipment of course. But I can see that with the syringe too, that they're don't open or close fully at all times, etc. I was told it's a fairly common problem if these parts were not cleaned regurarly during their lifetime. Now we've cleaned them with an ultrasound machine but to no avail.

I had other injectors on loan for a while, they were doing 230cc/min, the injector signal was of course on, but the spray pattern (and/or something) must have been good because the engine ran very smoothly. But I had to clean the spark plugs every 200km probably because the rich mixture.

thanks!

 

[fingers99]

Emerald can probably supply them -- I think they're £40 or so a pop. Beware of Chinese copies!

To work OK the injector needs:

the same delivery rate (and at the same test pressure)
the same impedence
the same spray pattern (especially on bifurcated inlet ports, which I think the 1.6 16v has).

There will be plenty in scrap yards over here -- maybe £30 to £40 a set? Try eBay UK. Eventually you'll find 4 good ones.

But what were the symptoms initially? I've yet to come across it, but, then, only yesterday did I find an MR2 turbo that did infinite mpg (fuel gauge sender had stuck!).

 

[bebel]

Emerald who? Could you give a url please?

I regularly check ebay but they're not that cheap so as to buy them blindly. Currently there's a set for £110 incl. postage, then I'd have to clean and test them locally to find out. There are a few at local dealers as well but they also don't give any guarantees. Who knows how many I'd have to buy? I'd prefer new/refurb even if it's a bit more expensive but don't know where to look for. Local shops couldn't get any.

The symptoms originally were as with the "new" injectors. Uneven engine, lot of fuel, but it was also high CO because the o2 sensor was faulty. The latter was replaced which also wasn't cheap...

thanks!

 

[fingers99]

Just a thought -- stuck open (or missing) thermostat? Fubar engine temp sensor?

They're fired on the negative side, so any breakdown on insulation to earth also tends to monumental over-fuelling.

Emerald -- and the ever helpful Dave Walker are here.

 

[Elxpunto90]

Does the injector light come on after about 10 mins of driving or if you put foot on throttle to about 2000rpm and then it comes on whist stationery is there any difference in engine behaviour like revving high or giving more throttle response when pulling off and sounding more noisy in air filter roaring

 

[bebel]

Thanks I'll check all of these things you've both mentioned and then report back.

 

[Elxpunto90]

I'm having these problems at moment and have replaced virtually everything going to order a air temp sensor it's the only thing that is left to replace I
Did thermostat the other day flushed system and new coolant still no
Luck

 

[Elxpunto90]

Changed the air temp sensor today and still no luck will be replacing inlet and exhaust gaskets to see if that cures problems will let you know the out come

 

[bebel]

I've found a place where there were several used injectors of this type. We've swapped and cleaned and measured them until we've found two good ones which go well together with my originals. The delivery rate differs only with about 5%. Now the injector light comes on rarely, the engine is strong and relatively smooth. It won't get better than this with used injectors but it's okay. Fuel consumption on the weekend was about 10L/100km but I was really driving like mad to test the stuff so it's actually lower.

Whereas before, the light has turned on after a few minutes of driving and stayed on during the whole drive. But I didn't experience the strange throttle responses you've mentioned.

 

[fingers99]

Now the injector light comes on rarely

Hang on, it's not the injector warning light but the ECU warning light. Get the codes read. It should never come on (except on start up as a bulb test).

 

[bebel]

hm that's strange, it looks like an injector symbol. It certainly was constantly red before and now it lights up only occasionally.

 

[Elxpunto90]

It's really doing my head in now this light problem every sensor been changed and still no luck start car up and it runs fine then once it warms up that's when the problem starts light comes on just after sensors kick in the car idles but has a slight rough idle every few seconds and when driving and slow down it tends to run at 1300 rpm when comes to a stop but is ok when started from cold it runs at 900 rpm really don't know what it is
I've replaced
Head gasket
Water pump
Plugs
Ht leads
Coil pack
Air temp sensor
Mass air flow sensor
Cam belt
Thermostat
All sensor on intake
Egr valve
Lamba sensor
Fuel pump
Fuel filter
Crankshaft sensor
Vacuum lines
Coolant sensor
Antifreeze
Water pump
Exhaust

Any ideas guys
Will take injectors of and give them a clean
And going to replace gasket on inlet and manifold to see if there is a leak

 

[blu73]

i know you have had huge issues with connecting to the ecu to read codes but really you need to sort this out to get to the bottom of this.

I'm pretty sure the ecu used in the 90 is same as what is used in GM Corsas and Astras of similar age. And from a quick read they can be blink tested just like a GT can. So really it stands to reason you should be able to blink test the 90. But the diagnostics ports are clearly different. From memory you have tried a blink test procedure for a GT and that didn't work, so on that front i can only suggest you try again and make sure you earthed the correct wire to start the test.
Failing that i suggest getting the fiat 3 pin to OBD adaptor and vagcom cable and then having a search to see what program can be used on a corsa/astra of the same age and downloading that and trying with that.

As you say, you have basically changed everything on the engine now - and a leaking gasket is not going to throw an EML, it would cause erratic or high idle so if you got that then by all means change the gasket but it will not solve the eml issue. So figuring out why you get an eml is your best bet.

Have you opened the ecu and had a look for damp inside and/or water damage? And removed all the earth's on the car and cleaned and put back?

 

[flisko]

maybe it has something to do with this?

https://www.fiatforum.com/punto/328971-if-my-car-revs-past-3000-rpm-dies.html

 

[bebel]

I don't think injectors are your problem but if you take them out make sure you measure them as well besides cleaning. They have to perform the same.

 

[Elxpunto90]

What do you mean by measuring them they are the originals to the car never been changed I will give them a clean I was just wandering if it could be fuel pump because when car mucked about was when old fuel pump went up the creak and since replacing pump had problems could be a possible ?

 

[bebel]

No matter if they are originals or not. If they're old, they can get stuck closed/open/half open and sometimes even ultrasound doesn't help. Usually who cleans them also measures them too so they can tell you if one them needs replacement.

 

[Elxpunto90]

Oh right it started when pump give up and also found the fuel filter the wrong way around when I was checking for probs and put it back the right way wondered if that caused the blockage on injector the car runs okay but you can hear a very slight misfire on idle or 2000rpm and splits a little out exhaust aswell light comes on when cars at temp sensor kicked in