Technical Seicento SPI with P75 conversion

[TheAutopsy]

Hi guys. I have a seicento SPI and I have done the P 75 half conversion.
I used the bottom end of the 1242, the head from the spi, the 866 cam and the pulleys and water pump from the SPI.
My "problem" is that the car doesn't like to run above 4k rpm. And I only recently found out a thread that said that this half conversion does this?
I did not tune the car, so standard ECU and did not increase fuel pressure on the regulator.
My question is why does the car does this? Is it something that I did wrong? Or this formula does not work?
Also I haven´t fitted the 38mm TB with the SPI injector, but I am going to put it in. Do you have to increase the pressure on the fuel pressure regulator or the SPI ECU has the ability to increase the amount of fuel that the bigger engine and TB send?
Also important to mention that I did the conversion 30k km ago, and the car runs really smoth, just doesn't like to go above 4k rpm.
I searched alot of threads about this and could not find a solution for my case.

 

[bugsymike]

Hi guys. I have a seicento SPI and I have done the P 75 half conversion.
I used the bottom end of the 1242, the head from the spi, the 866 cam and the pulleys and water pump from the SPI.
My "problem" is that the car doesn't like to run above 4k rpm. And I only recently found out a thread that said that this half conversion does this?
I did not tune the car, so standard ECU and did not increase fuel pressure on the regulator.
My question is why does the car does this? Is it something that I did wrong? Or this formula does not work?
Also I haven´t fitted the 38mm TB with the SPI injector, but I am going to put it in. Do you have to increase the pressure on the fuel pressure regulator or the SPI ECU has the ability to increase the amount of fuel that the bigger engine and TB send?
Also important to mention that I did the conversion 30k km ago, and the car runs really smoth, just doesn't like to go above 4k rpm.
I searched alot of threads about this and could not find a solution for my case.

Sounds an interesting conversion.
Can you use a diagnostic tool to point you in a direction, fuel pressure not keeping up, mixture wrong,is the ignition timing advancing as it should or something else to guide you.
What do the spark plugs look like , are they running weak or rich etc.
Where you read someone else had a problem can you find out further what they did about it?

 

[TheAutopsy]

I found it here https://www.fiatforum.com/threads/punto-75-engine-in-seicento.265318/
But he talks about a seicento MPI but is exactly what mine does.
And they don't talk about a fix for it

hi

ok i have just fitted a 75 engine in a 2001 sei mpi and its not easy and its a pain to sort the ecu out as the 75 ecu is totally different to the sei mk2 so if you are really looking into doing a 1242 swap into your sei do a 16v swap as it is actually easier in the mk2 due to ecu

the problem stems from the electic power steering which is run from the sei mk2 ecu but the engine map (for the 1108) doesn't run the 75 engine very well plus due to the way the sei mk2 inlet is wired up it all needs lenghening to fit the 75 inlet and tb, you could get around this by fitting the 1108 inlet to the 75 head but they dont mate up very well and causes running issues so then you will end up fitting the 1108 head to the 75 block and then running it of the sei ecu but it will then pull really badly over 4k rpm at which point you will be sick of it and pull it out and fit a 16v

save yourself the time and expense and just fit a 16v to start with and fit a mk2 punto ecu or get the sei ecu re-mapped

so you know i have spent the last 6 months trying to get a 75 engine to work in a sei mk2 mpi and we have finally given up and are now going to fit a 16v lol

I don't know about doing a diagnostic on it, its a 99 with the 3 pin port. I don't have an adapter not a program to read it. Could try and get my hands on one though.
Fuel pressure as came to my mind. The car is 26 years old. I think that it could still have the original pump. If I wanted to test the fuel pressure where would I conect the fuel pressure tester? before the inlet for the TB or on the return?
Im going to take a look at the timing and the spark plugs to see if I find something wrong.

 

[bugsymike]

I found it here https://www.fiatforum.com/threads/punto-75-engine-in-seicento.265318/
But he talks about a seicento MPI but is exactly what mine does.
And they don't talk about a fix for it


I don't know about doing a diagnostic on it, its a 99 with the 3 pin port. I don't have an adapter not a program to read it. Could try and get my hands on one though.
Fuel pressure as came to my mind. The car is 26 years old. I think that it could still have the original pump. If I wanted to test the fuel pressure where would I conect the fuel pressure tester? before the inlet for the TB or on the return?
Im going to take a look at the timing and the spark plugs to see if I find something wrong.

I see there is some talk about a cam sensor?
If you go on Gendan website they can advise re cables etc.

 

[TheAutopsy]

I see there is some talk about a cam sensor?
If you go on Gendan website they can advise re cables etc.

Yhea but mine does not have a cam sensor. I thought that mine would been easier because it has less sensors.

 

[bugsymike]

Yhea but mine does not have a cam sensor. I thought that mine would been easier because it has less sensors.

Was there a cam sensor on the previous engine that the ECU needs to give advance?
Apart from that any chance the cam timing is a fraction out?
Re the error code reading go on Gendans website and it will tell you what leads you need and what details it can give you.
Many on Forum use MES MultEcuScan on their laptops etc.
Re fuel pressure you would need to test before throttle body and with vacuum off.
Is any of this data relevant?

 

[TheAutopsy]

No. The 1.2 engine that I used for the swap was from the punto 75 and it does not have a cam sensor also.
I built the engine myself, so there is a possibility that I did not get the timing 100% correct. Will check tough.
The car does not give any errors.
What do you mean test the pressure with vaccum off? Disconect the vaccum line that goes to the intake?
The valve clearence for the inlet and exhaust are different to what I used.
I saw on autodata that it was for the inlet 0.25 - 0.35 and the exhaust was 0.35 - 0.45. I belive that I used this values.
And should I have used the clearences for the 866 camshaft because that is the cam that I used? If you have the specs for the Punto 1.2 8v 75 engine on that book it would be awsome.

 

[bugsymike]

No. The 1.2 engine that I used for the swap was from the punto 75 and it does not have a cam sensor also.
I built the engine myself, so there is a possibility that I did not get the timing 100% correct. Will check tough.
The car does not give any errors.
What do you mean test the pressure with vaccum off? Disconect the vaccum line that goes to the intake?
The valve clearence for the inlet and exhaust are different to what I used.
I saw on autodata that it was for the inlet 0.25 - 0.35 and the exhaust was 0.35 - 0.45. I belive that I used this values.
And should I have used the clearences for the 866 camshaft because that is the cam that I used? If you have the specs for the Punto 1.2 8v 75 engine on that book it would be awsome.

It mentions in the Auto data "vacuum off" so presume pump pressure regulated by vacuum.
Any of this relevant? Check Engine Series details.

 

[MazCinq]

I found it here https://www.fiatforum.com/threads/punto-75-engine-in-seicento.265318/
But he talks about a seicento MPI but is exactly what mine does.
And they don't talk about a fix for it


I don't know about doing a diagnostic on it, its a 99 with the 3 pin port. I don't have an adapter not a program to read it. Could try and get my hands on one though.
Fuel pressure as came to my mind. The car is 26 years old. I think that it could still have the original pump. If I wanted to test the fuel pressure where would I conect the fuel pressure tester? before the inlet for the TB or on the return?
Im going to take a look at the timing and the spark plugs to see if I find something wrong.

Hi, just an FYI about why I didn't post a fix, there isn't one, we gave up and fitted a 1.4 16v instead which went in a piece of cake compared.

 

[bugsymike]

Hi, just an FYI about why I didn't post a fix, there isn't one, we gave up and fitted a 1.4 16v instead which went in a piece of cake compared.

At least back on the road again.