AX 1.0 to 1.6 jp4 - Saxperience

spruce · 6th June 2021, 17:44

Hello all, I'm converting a 1997 1.0 AX Flash to 1.6 16v. So far I've swapped the suspension and brakes from a saxo vts donor and I have a jp4 ready to go in.

Is it possible to use the existing ECU for ignition only? It's a Bosch monopoint ECU from what I can tell. Can I just swap the sensors, coil and fly wheel over from the 1.0? Don't need fueling just ignition. Thanks in Advance!

spruce · 8th June 2021, 18:56

Looks like the TU flywheels are the same in terms of number of teeth for the crank sensor.
The JP4 also has the correct mounting holes for the crank sensor.

The question is, will the ignition timing be correct for 1.6 engine with the 1.0 ECU?

VeiRoN · 8th June 2021, 19:02

No it will not,you need 16v ECU.

spruce · 8th June 2021, 23:35

Just the ECU or the loom too?
Again I only need ignition and only temporarily- for the car to move and drive decently, not looking for performance.

Chipwizards · 9th June 2021, 18:20

The ignition would probably 'work' but the timing will be miles off because of the difference between the engines and there's a good chance that det will damage the pistons.

spruce · 11th June 2021, 09:56

I counted the teeth on the flywheel between the missing ones and the point where the engine reaches TDC on cylinder 1. Roughly 20 teeth +/- 1 tooth on both engines.
When I swap them over next week I'll measure more accurately, if needed I can fab a bracket to change the crank sensor's position and fine tune the timing.
This is all assuming the spark won't be out of phase between the JP4 and the 1.0...Shouldn't be- isn't the crank more or less the same (I know the main bearings are the same between TU engines). Obviously, the stroke is 20mm more in the JP4..

Its going to be a pain finding a working 16v ECU in my part of the world..

That being said, I'm really happy with the VTS suspension (although it sits a bit high a the front) and brakes, feels very solid but pathetically underpowered for now..

spruce · 16th June 2021, 16:20

Well the swap is complete and the ignition works well. I can't notice any detonation or misfiring across the rev range. In fact, it looks like I'll use the bosch ecu permanently for spark control. I guess the tu ecus are interchangeable for ignition.
The power feels 3 times better than the 1.0l.

Chipwizards · 17th June 2021, 21:52

Quote:

Originally Posted by spruce

Well the swap is complete and the ignition works well. I can't notice any detonation or misfiring across the rev range. In fact, it looks like I'll use the bosch ecu permanently for spark control. I guess the tu ecus are interchangeable for ignition.
The power feels 3 times better than the 1.0l.

Thank Bosch for knock control, I guess.

spruce · 18th June 2021, 21:02

I'm not seeing a knock sensor on this unit.

I put a long screwdriver in the 1.0 and 1.6 engines' cylinder #1. I then measured the missing teeth's position during TDC. It was the same for both. Lucky I guess.

Chipwizards · 21st June 2021, 20:07

Quote:

Originally Posted by spruce

I'm not seeing a knock sensor on this unit.

I put a long screwdriver in the 1.0 and 1.6 engines' cylinder #1. I then measured the missing teeth's position during TDC. It was the same for both. Lucky I guess.

The missing teeth being in the same place doesn't mean that the timing is the same, it just means that the crank reference index position is the same. The actual ignition timing is mapped in the ECU and is VERY different for the two engines.

The 16V engine typically wants around 24 degrees of advance at full load once the revs are up a bit. The 8V engine typically wants around 34 degrees in the same load and speed range; and much more of the ECU thinks that the engine is at part load because the load signal isn't there any more.

spruce · 21st June 2021, 20:30

Fair enough, makes sense. If I can trust my seat-of-pants dyno the engine pulls healthily throughout the whole rev range. I listened for knock or ping while accelerating with open windows next to a concrete wall and couldn't hear any (i'm aware it can be inaudible for the human ear).
I just did a 200km trip with the car.
I'll check the timing with a timing light to see where we're at.

Chipwizards · 23rd June 2021, 07:46

Quote:

Originally Posted by spruce

I'll check the timing with a timing light to see where we're at.

You need it under load for it to be relevant.

Better to watch live data on a dyno, or get someone else to drive it whilst you watch live data so you don't crash or kill someone.

MartinObviously · 24th June 2021, 16:00

Quote:

Originally Posted by spruce

Fair enough, makes sense. If I can trust my seat-of-pants dyno the engine pulls healthily throughout the whole rev range. I listened for knock or ping while accelerating with open windows next to a concrete wall and couldn't hear any (i'm aware it can be inaudible for the human ear).
I just did a 200km trip with the car.
I'll check the timing with a timing light to see where we're at.

Make some knock ears using a cheap microphone, a croc clip and some good headphones.

Clip the croc onto something solid near the base of the head or better still directly onto the block.

As Chipwizards has already said, it needs to be under hard load. So listen to the engines natural sound under light load, that way you won't mistake any knock for natural engine sounds. If it sounds similar and you don't hear a light ticking develop then you're in the clear.

It still doesn't mean the timing is correct though

just means it's not advanced enough to cause knocking.

The trigger point isn't really relevant. I think all the petrol TU engines are 60-2 trigger and the sensor is at 114 BTDC.

The only TU which isn't, is the 1.5D which is simply 2 pulses per rpm, and the ECU on them advances timing by rising rate.

spruce · 20th July 2021, 19:00

I ended up dropping a phone in between the spark plug wires, did several runs, played it back, couldn't hear any clicking other than valvetrain, which was present at any rpm, regardless of load. I'm driving the car daily, everything seems normal, but I haven't pushed it hard yet since I don't have a tachometer (the ax only has a quartz clock) and this brings me to the next question;
Does this ECU have a rev limiter and if so, does it cut ignition or fuel (or both)?

MartinObviously · 20th July 2021, 22:31

Quote:

Originally Posted by spruce

I ended up dropping a phone in between the spark plug wires, did several runs, played it back, couldn't hear any clicking other than valvetrain, which was present at any rpm, regardless of load. I'm driving the car daily, everything seems normal, but I haven't pushed it hard yet since I don't have a tachometer (the ax only has a quartz clock) and this brings me to the next question;
Does this ECU have a rev limiter and if so, does it cut ignition or fuel (or both)?

Yes, the 1.0 ECU has a rev limiter. I think it is about 6750rpm. I think it will just cut the spark gradually as it approaches the limit?

spruce · 21st July 2021, 08:28

Quote:

Originally Posted by MartinObviously

Yes, the 1.0 ECU has a rev limiter. I think it is about 6750rpm. I think it will just cut the spark gradually as it approaches the limit?

Good to know, thank you. And lastly, do you think the Bosch ECU will tolerate in the long term not having the TPS and monopoint attached? The tps is plugged in but not attached, so the ECU thinks its always at 0% throttle. I've unplugged the mono completely, and I've left the idle motor plugged in to minimize errors.
Still with the check engine light almost constantly on, I'm hoping the ECU won't "burn out" at some point and leave me stranded. According to the Haynes, the 1.0 Bosch ecu controls timing separately via static timing, so should be a different circuit?

MartinObviously · 21st July 2021, 10:13

Quote:

Originally Posted by spruce

Good to know, thank you. And lastly, do you think the Bosch ECU will tolerate in the long term not having the TPS and monopoint attached? The tps is plugged in but not attached, so the ECU thinks its always at 0% throttle. I've unplugged the mono completely, and I've left the idle motor plugged in to minimize errors.
Still with the check engine light almost constantly on, I'm hoping the ECU won't "burn out" at some point and leave me stranded. According to the Haynes, the 1.0 Bosch ecu controls timing separately via static timing, so should be a different circuit?

Don't worry, it's not going to burn out.

the ECU can't calculate the advance, so I suspect if it's seeing high rpm and an idle condition from the TPS it's going to have the timing very retarded. It may be advancing it slightly seeing the MAP readings.

Out of interest, what country are you from?