Technical Question about SPI to Carburetor 899cc

Currently reading:
Technical Question about SPI to Carburetor 899cc

JohnDodge

New member
Joined
Dec 5, 2022
Messages
8
Points
2
Location
Lom
Hi guys! I found this forum very helpful in the past, so finally i registered.

I have a 1991 ciquecento 899 spi car.
I love older cars and carburated ones in particular, so when the SPI started acting up (the car currently refuses to hold idle when cold, and cuts of when i slow down to change gear or stop at a traffic light), so i decided to mount a carburator on my car.

I have one WEBER 32 ICEV from a Yugo 45 (which has the same engine as the 899). The problem i'm facing is that there is no distributer and as far as i understand the ECU is combining the ignition timing, and fuel management.

My question is, if i disconnect everything but the crank position sensor, and replace the throttle body with a carburetor, will the ignition timing be still correct or will the ECU constantly try to find info from the remaining sensors, to correct itself?

Thanks in advance for your replys!
PS The car is runig a basic LPG system which is close to the carburetor setup, it doesent have a computer nor does it use the current one.
 
Hi guys! I found this forum very helpful in the past, so finally i registered.

I have a 1991 ciquecento 899 spi car.
I love older cars and carburated ones in particular, so when the SPI started acting up (the car currently refuses to hold idle when cold, and cuts of when i slow down to change gear or stop at a traffic light), so i decided to mount a carburator on my car.

I have one WEBER 32 ICEV from a Yugo 45 (which has the same engine as the 899). The problem i'm facing is that there is no distributer and as far as i understand the ECU is combining the ignition timing, and fuel management.

My question is, if i disconnect everything but the crank position sensor, and replace the throttle body with a carburetor, will the ignition timing be still correct or will the ECU constantly try to find info from the remaining sensors, to correct itself?

Thanks in advance for your replys!
PS The car is runig a basic LPG system which is close to the carburetor setup, it doesent have a computer nor does it use the current one.
I don't know the answer , but some early Ford Fiestas and similar age vehicles had a simple sort of ECU I think it was an EEV which had a vacuum advance tapping on it and I think a Weber type carb. with no distributor just a timing sensor.
 
I don't know the answer , but some early Ford Fiestas and similar age vehicles had a simple sort of ECU I think it was an EEV which had a vacuum advance tapping on it and I think a Weber type carb. with no distributor just a timing sensor.
Hi! And thank you for the reply! That is a interesting idea, worth of checking it out!
 
Hi! And thank you for the reply! That is a interesting idea, worth of checking it out!
This isn't exactly the one I was thinking about but does seem to be available . Other than that there are some simple ECUs late 1980 to mid 1990s with their pin outs details in the Haynes Engine Management Pin Tables 3558 and 3578 though mostly early injection, but fairly simple layout
1670433978442.png

1670433927669.png
 
Thank you again for the valuable info!

My only concern now is if the fiat crank sensor will work with that type of brains, if not, will the ford crank sensor work with the fiat pulley, and is the firing order same for the fiat and ford (but that can be adjusted with the leads). Hm i'm going to dig into that this weekend.

In the meantime, i am thinking of just disconnecting every sensor on my car (except the crank sensor), and try to run it of the LPG installation (it will be a simulation of a carb). Then i will know if i'm going the ford root or sticking with minimal changes and the fiat electronics (i like to be able to reverse to stock everything i do to the car)
 
Thank you again for the valuable info!

My only concern now is if the fiat crank sensor will work with that type of brains, if not, will the ford crank sensor work with the fiat pulley, and is the firing order same for the fiat and ford (but that can be adjusted with the leads). Hm i'm going to dig into that this weekend.

In the meantime, i am thinking of just disconnecting every sensor on my car (except the crank sensor), and try to run it of the LPG installation (it will be a simulation of a carb). Then i will know if i'm going the ford root or sticking with minimal changes and the fiat electronics (i like to be able to reverse to stock everything i do to the car)
That sounds like a good starting point. From memory earlier Fords ran 1243 firing order. But that ESP1 looked like a "wasted spark" setup
It doesn't have to a Ford, just whatever is available around your area that age, providing there is enough information available.
I have never got involved with LPG.
 
HI John

The Fiat Panda Fire 999cc has a distributor fitted to the end of the cam shaft. Could you source one of these and truly dump the ecu?

The ignition immobiliser might be upset though, even though the immobiliser ecu under the dash is separate I think it talks to the main ECU.

Then the electronic fuel pump would have to be replaced with a mechanical one or a pump designed for carb pressure?

Is your car currently flooding due to faulty temp sensor or something? I have never had any issues with the FIAT computers but ive not had an 899.
 
HI John

The Fiat Panda Fire 999cc has a distributor fitted to the end of the cam shaft. Could you source one of these and truly dump the ecu?

The ignition immobiliser might be upset though, even though the immobiliser ecu under the dash is separate I think it talks to the main ECU.

Then the electronic fuel pump would have to be replaced with a mechanical one or a pump designed for carb pressure?

Is your car currently flooding due to faulty temp sensor or something? I have never had any issues with the FIAT computers but ive not had an 899.

Hi Purf! And thanks for the reply! My car has the 899cc (series 100) pre FIRE engine. This type of engine with different displacement is used in the fiat 600, the zastava 750, the fiat 850 and many more fiat cars, from the period. On the early engines and some cinquecentos, for the polish market, there was distributor and a carburetor. The distributor was mounted on the head facing upwards facing the bonnet. On all SPI cinqecentos, pandas and any other fiat the hole for the distributor is plugged on the head and the carburetor is replaced with throttle body and injector (and sensors). My car is early SPI and it doesn't have an immobilizer.

The pump will be an electrical one, for carburetor use.

Where i live there is no one capable to diagnose the problem, and i'm not to happy spending loads of money replacing unnecessary parts. I've owned cars with carburetors before and i'm happy with the performance and setting them up.
 

Attachments

  • 0000027845_001.jpg
    0000027845_001.jpg
    269.1 KB · Views: 47
There isn't an immobiliser on a 1991 Cinq.
You are right! I'm getting rusty!

Of course the panda is a different engine, but the concept of getting an early 899 carb setup is what I was thinking :p

I presume the car doenst have a catalytic converter either?
 
You are right! I'm getting rusty!

Of course the panda is a different engine, but the concept of getting an early 899 carb setup is what I was thinking :p

I presume the car doenst have a catalytic converter either?
The factory put one in, the previous owner removed it...
 
You are right! I'm getting rusty!

Of course the panda is a different engine, but the concept of getting an early 899 carb setup is what I was thinking :p

I presume the car doenst have a catalytic converter either?
at the moment i'm running and LPG system, which basically is a aluminum plate with a hole, put between the two sections of the throttle body, and when i turn it on, it cuts the power supply to the injector and lies the ECU that the injector is working fine, then it just releases the correct amount of LPG next to the throttle flap, and the car runs perfectly.
i'm only concerned at this point if the timing will be affected by the absence of the throttle position sensor. Thinking about it the other ones, are more to do with the correct time and amount of gasoline to be injected thru the injector, than with the timing.
 
at the moment i'm running and LPG system, which basically is a aluminum plate with a hole, put between the two sections of the throttle body, and when i turn it on, it cuts the power supply to the injector and lies the ECU that the injector is working fine, then it just releases the correct amount of LPG next to the throttle flap, and the car runs perfectly.
i'm only concerned at this point if the timing will be affected by the absence of the throttle position sensor. Thinking about it the other ones, are more to do with the correct time and amount of gasoline to be injected thru the injector, than with the timing.
A faulty lambda sensor can cause stalling by overfueling, or if it detects excess oxygen from a manifold or upstream exhaust leak? Then it will stall unless full throttle. If theres a manifold leak they can flood completely.

I think the earlier ECUs relied more on throttle position sensor than later ones. I have a 1993/4 tempra spi engine which is extremely sensitive to TPS. The contact tracks on the sensor wear out and it's a real problem to set it up/calibrate it. But as long as you have fuel provided by other means then it should be ok?
 
Back
Top