I would use the stock Ecu and injectors to start with.
Technical Seicento MPI Swap (8V -> 8V)
- Thread starter thunderfox5
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Technical Seicento MPI Swap (8V -> 8V)
Check for spark.
OP
OP
Solved. Turns out it was due to damaged/fouled spark plugs and lack of fuel after all! 4 liters of fuel and new spark plugs let it roar for the first time 
Cheers guys!
Cheers guys!
OP
OP
Well, car ran today for the first time! It goes like hell!
However there's still one problem that I haven't managed to fix or diagnose successfully. When I turn on the car, the idle is way too fast (2000-2500 RPM maybe?) and then the car just starts repeatedly cutting off and accelerating on it's own...
It goes like this:
Car accellerates to around 2.5k RPM
There a repeated "puffing" sound like the car is cutting off
Engine dies back to 800RPM
Then it accelerates again
This repeats itself like, every two seconds or so. It's like the idle valve can't keep up or there's a massive vaccuum leak somewhere. I think the car is accelerating, then cutting off as overrun because it sees the throttle closed, then gets back on the gas and accelerates again.
I've seen something like this happen before actually... On my swapped Punto it happens every once in a while. Also on a friend's Seicento if he presses the throttle and leaves it all of a sudden, it starts doing something like this. And finally, I've seen it happen on 16V MK2 Puntos when the drive-by-wire system is damaged.
I'm betting the P75 head won't seal properly against the Sei's MPI manifold
However there's still one problem that I haven't managed to fix or diagnose successfully. When I turn on the car, the idle is way too fast (2000-2500 RPM maybe?) and then the car just starts repeatedly cutting off and accelerating on it's own...
It goes like this:
Car accellerates to around 2.5k RPM
There a repeated "puffing" sound like the car is cutting off
Engine dies back to 800RPM
Then it accelerates again
This repeats itself like, every two seconds or so. It's like the idle valve can't keep up or there's a massive vaccuum leak somewhere. I think the car is accelerating, then cutting off as overrun because it sees the throttle closed, then gets back on the gas and accelerates again.
I've seen something like this happen before actually... On my swapped Punto it happens every once in a while. Also on a friend's Seicento if he presses the throttle and leaves it all of a sudden, it starts doing something like this. And finally, I've seen it happen on 16V MK2 Puntos when the drive-by-wire system is damaged.
I'm betting the P75 head won't seal properly against the Sei's MPI manifold
Well, car ran today for the first time! It goes like hell!
However there's still one problem that I haven't managed to fix or diagnose successfully. When I turn on the car, the idle is way too fast (2000-2500 RPM maybe?) and then the car just starts repeatedly cutting off and accelerating on it's own...
It goes like this:
Car accellerates to around 2.5k RPM
There a repeated "puffing" sound like the car is cutting off
Engine dies back to 800RPM
Then it accelerates again
This repeats itself like, every two seconds or so. It's like the idle valve can't keep up or there's a massive vaccuum leak somewhere. I think the car is accelerating, then cutting off as overrun because it sees the throttle closed, then gets back on the gas and accelerates again.
I've seen something like this happen before actually... On my swapped Punto it happens every once in a while. Also on a friend's Seicento if he presses the throttle and leaves it all of a sudden, it starts doing something like this. And finally, I've seen it happen on 16V MK2 Puntos when the drive-by-wire system is damaged.
I'm betting the P75 head won't seal properly against the Sei's MPI manifold
I'd think an Idle Air Control issue. You could check for a leak at the manifold/head with length of windscreen washer hose or soap bubbles. If there is a leak, you might try a polyurethane as sealant.
OP
OP
Going to check. If all else fails, I'll revert back to the 8V injectors and stock ECU and check again.
This sounds more like a fueling issue, IIRC this happens when the engine is seriously under fueled. The flactuation is the ECUs inability to decide whether it should keep idle or not, when revs are high enough it gives up, goes into engine braking mode, rpms drop, and then it tries again to maintain idle, but can't because of wrong fueling. But without hooking up diagnostics and/or wideband I would not be able to tell anything more.
Well, car ran today for the first time! It goes like hell!
It goes like this:
Car accellerates to around 2.5k RPM
There a repeated "puffing" sound like the car is cutting off
Engine dies back to 800RPM
Then it accelerates again
This repeats itself like, every two seconds or so. It's like the idle valve can't keep up or there's a massive vaccuum leak somewhere. I think the car is accelerating, then cutting off as overrun because it sees the throttle closed, then gets back on the gas and accelerates again.
I'm betting the P75 head won't seal properly against the Sei's MPI manifold
Mine did a similar thing, if you block the TB with your hand and it stalls this isn't your problem, if not with a P75 head and sei inlet you have these options:
- Use sealant, this proved to be messy and we couldn't get it to seal anyway.
- Remove the metal inserts in the inlet and bolt it on as low as possible. This is how I'm running mine now and it sealed perfectly but of course the ports won't be lined up exactly.
- Use a P75 inlet gasket and bolt it on as normal which I'm told works just fine and the inlet will be at the right height. I will be doing this on my next engine since I can't be bothered to faff about taking it off again.
It will run just fine once it seals. I'm running on standard injectors and ecu which appear to be ok for at least 100bhp or so. Although I'm tempted to fit some bigger ones to see what happens. However as I understand it single stream ones are the best for 8v but they're basically non existant from what I can see.
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OP
OP
Thanks for the input woj! That was my first thought, and although I didn't hook up the wideband to it, I did run diagnostics to test what was happening. The car is actually running pretty rich at idle (when it's not cutting off) and pretty nicely tuned througout the rev range, although it still needs some fine tuning on the higher RPMs when I see consistently rich figures through the lambda feedback.
So, this being out of the table, leaves me with the possibility of a vacuum leak, and I'm pretty certain it is, since if you let it coast down in a high gear, when it gets back on the fuelling, it actually finds enough strength to pull the car forward, even in fifth gear at like 30km/h.
Also it is pretty noticeable that there's a huge "jump" when going onto the throttle, from a decel cutoff state, which tells me that there is enough air inside the manifold so that when the car gets back on throttle it will pull forward as if it opened suddenly. Not sure I've made myself clear explaining this.
Which leaves me...
... with this! Been searching all day for a P75 gasket hoping that it would provide a good sealing surface (my theory is that the leak is on the upper part of the ports, near the injector stream, where the P75 ports are a lot shorter and the plastic MPI manifold seal is a lot taller). However, to no avail. FIAT is closed for the holidays here.
The 85 injectors are split stream IIRC. They seem to work fine though. As opposed to that, my Punto is running the 16V with single streams from the P60 engine, and it passed MOT emissions just perfectly (runs on LPG on a daily basis).
OP
OP
All the problems solved. There were four vacuum leaks on top of the manifold ports as expected... Fuel was also leaking at WOT, there was evidence of "washing" on top of the ports. P75 gasket solved it.
As promised, since the thing is finally done, I took all I learned from it and from you guys, and turned it into a guide here:
https://www.fiatforum.com/cinquecen...1-how-mpi-8v-c526-gearbox-swap.html?p=3522827
I hope this helps people doing the same stuff on their Centos.
Cheers for all the help!
As promised, since the thing is finally done, I took all I learned from it and from you guys, and turned it into a guide here:
https://www.fiatforum.com/cinquecen...1-how-mpi-8v-c526-gearbox-swap.html?p=3522827
I hope this helps people doing the same stuff on their Centos.
Cheers for all the help!
I’ve got an 03 cento, with the 1.2 block and 1.1 head I’m pretty sure it’s using the 1.1 pulleys and tensioners, had some trouble recently have an engine light on and it’s running really rough. Checked the timing and it was out about 4-5 teeth checked it after retiming and it still ran rough, timing has slipped again and awaiting new belts etc but doesn’t explain why when the timing is correct it’s still over fueling and coming up with the p0170 fault code chances the lambda etc, plugs, packs and leads. Pretty sure the fuel pump is alright but I need to check it again as I couldn’t keep the external pump pipe to stay on my fuel line to run the test. I’ve had diagnostics on the car and all the sensors seem to be working fine I just can’t figure out what is causing the overfueling with is making it misfire and run lumpy, and lose so much power a bud could overtake me at this point. If anyone has had this issue with the swap and knows what it is it would be much appreciatedHi guys!
There doesn't seem to be much information regarding this kind of swap. Most of what I've seen is either people fitting 16V engines, or P75 engines to SPI cars.
I reckon that, from what I've seen in my car and the donor parts I have, it should be pretty straight forward. However, I've got a few questions about a few bits and bobs, that were raised when I looked up some of the swaps here in the forum, as well as that great guide for the 1.4 swap
So, first of all, here's what I have. The car is a Seicento S, but it's an MPI version, so a 1.1. It has the older (uno-style, I believe) gearbox with the long driveshafts and inner cups. No power steering, AC, electric windows or any other "extra" stuff in this car.
The donor parts are a huge mix of things I collected in my garage throughout the years. For the engine block, I have a PMK2 60 engine block to go in, it still has the original head in it, albeit cracked, would still work for a cento. I also have a spare P75 head laying around with no anciliaries, and in much better condition, so this will be used. A donor gearbox off a Seicento Sporting, and driveshafts off an SPI Seicento Sporting as well.
The main idea here is, for now, to swap the engine with OE anciliaries, and replace the gearbox with the better one from the Sporting. Then build it up from there, with the engine already running and in the car. But a few questions arise, mostly due to the fact that my Sei is not a Sporting to start with.
1. Do the Sporting driveshafts fit the hubs on a standard Sei?
2. Does the standard Sei gearbox lower mount also fit the Sporting gearbox, or should I be looking out to buy a new one?
3. Will the Punto MK2 exhaust manifold fit between the engine and radiator? The catalytic converter is MASSIVE! I reckon this will be needed due to the fact that the Sei manifold is shorter in height (10mm) and should not clear near the sump. It's also a bit more restrictive. A plus is that I want to use aftermarket punto exhaust manifold at a later point in time, so I can have the exhaust system made to order meanwhile.
4. Will the Punto clutch/flywheel fit OK? I reckon it's the same size as the cento, however the part number is different. Maybe the flywheel changes as well?
5. Will the alternator from the Sei fit the 1.2 as a straight swap? I know this is an issue with the 1.4 swap on SPI centos, from the guide, but since the 1.2 8V engine is different... I remember it was even an issue when I swapped my Punto, the 8V alternator had to be spaced out to fit by a couple milimeters.
6. Last but not least, will the harmonic damper from the Punto work? Or if I fit the Sei harmonic damper, will it be a straight swap (i.e. align with the camshaft VR sensor properly)? Not looking forward for oil pump swaps...
7. Bonus question: Is the Grande Punto 1.4 8V MLS headgasket a good swap for the 1.2? From what I've seen, it should fit, measurements look to be about the same, but I don't see anyone talking about it, so maybe it doesn't?
If you guys know the answer to any of these questions, I'd be greatly appreciated. Considering making a guide for this kind of swap afterwards, so people will not have to ask the same questions I did
