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Technical Punto 1,2 8v rpms hump between 2000-3000

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Technical Punto 1,2 8v rpms hump between 2000-3000

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ticci

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My Punto 1,2 8v 60hp suffers from somekind of missfire between 2000-3000 rpms. First rpms climb up, then after second they drop down to say 1500 rpms. Below and over those rpms engine seems to work right.

Engine suffered also from low idle (500-600rpms), but i tightened the throttle cable and now the idle seems to be ok (yeah i know, thats not how it's supposed to be fixed).

I bought the car with broken engine wich has now been replaced, but i seem to be helpless with this problem. I have not found vacuum leaks and multiecuscan gives me no codes. :( I'll do a compression test some day when I find time but after that I've pretty much out of ideas. So if you have any ideas just give me a shout!
 
ticci said:
My Punto 1,2 8v 60hp suffers from somekind of missfire between 2000-3000 rpms. First rpms climb up, then after second they drop down to say 1500 rpms. Below and over those rpms engine seems to work right.

Engine suffered also from low idle (500-600rpms), but i tightened the throttle cable and now the idle seems to be ok (yeah i know, thats not how it's supposed to be fixed).

I bought the car with broken engine wich has now been replaced, but i seem to be helpless with this problem. I have not found vacuum leaks and multiecuscan gives me no codes. :( I'll do a compression test some day when I find time but after that I've pretty much out of ideas. So if you have any ideas just give me a shout!
Click to expand...
Phlonic wheel relearn required if uve swapped engines
Why? The ecu is working its best from a lifetime with previous engine, its like swappin ur legs, its odd at first

Phlonic relearn makes ecu start a fresh

Also dont rule out timing issues? Tooth out will still run will cause issues
As for coil packs - whats there recharge times like?

Ziggy
 
Ziggy122 said:
Phlonic wheel relearn required if uve swapped engines
Why? The ecu is working its best from a lifetime with previous engine, its like swappin ur legs, its odd at first

Phlonic relearn makes ecu start a fresh

Also dont rule out timing issues? Tooth out will still run will cause issues
As for coil packs - whats there recharge times like?

Ziggy
Click to expand...

Thanks for answering!

Never heard of phonic wheel relearn, but will definetly try it! I'll also check the coil packs some day.

I've checked timing 3-4 times, and I suspect that if it's out of timing still I just haven't got the talent needed to get it right.:D
 
ticci said:
Thanks for answering!

Never heard of phonic wheel relearn, but will definetly try it! I'll also check the coil packs some day.

I've checked timing 3-4 times, and I suspect that if it's out of timing still I just haven't got the talent needed to get it right.:D
Click to expand...
If the 2 riming marks line up after 2 full revolutions then uts good to go and timing isnt the issue

Ziggy
 
Had some problems with multiecuscan but got it going finally. I'm not an expert, but somehow the lambdas seem to keep giving odd numbers altough theres no codes and program tells me they're ok. Evry now and then they give me "open loop".

Did a short log with rpm's and lambda volts, and I honestly don't know what to think about this. 16000 rpms, 42 volts at best? Am I reading this right or doing something wrong? :D Shows at least well the "humping".

Haven't bothered with the compression test yet, but thinking of doing it also today.
 

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If you've got access to an oscilloscope, I'd make a readout on the signal of the crank sensor. Those blips in engine speed and lambda definitely shouldn't be there. Also check the teeth on the crank pulley, where the sensor reads - maybe one is broken or cracked.
 
Just finished the compression test, 1,3 and 4 were somewhere between healthy 210-220 psi and 2 was bit higher 230-240 psi. Maybe I turned the engine little longer, I wasn't counting. But it seems that the "hardware" is ok.

Can't get hold of an oscilloscope, but those crank sensor seem to be quite cheap so maybe I just order one. I checked the phonic wheel and it seemed to be fine. Thanks for advice!
 
Repeat that lamba voltagr test again but with just the2 sensors
That graph isnt sensitive enough on the current scale to see how there doing

Also ensure the engine js warm before doing the test as the system needs to be in closed loop
Not open which it is for the first few mins till the engine warms up

The pre sensor so be going up and down very frequently
If not that can cause fueling issues and flat power

Ziggy
 
First of all thanks for evrybody of answers and sorry for me being off for a month.

Took the time to do lambda runs separately. I can clearly tell that something is not right in the graph, wish I knew what causes it.:bang: I think both of lambdas give very low readings (they seem not to give reading at all from time to time), fueling can't be that rich can it?

Is this some sort of wiring issue? Pre-cat lambda is brand new and exactly same model as the old one I took off.
 

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All of the graphs have simulation run data is not real at bottom!
 
Sitrep. I'm starting to feel really desperate with this. I've run the engine with the cam advanced and reduced (?what's the word?) by one teeth in cam pulley, no difference.

I've changed the cam and crank sensors and coil packs (with cheapo ones mind you) with no results. Engine may run a bit friskier now but the problem is still there.

Once I unplugged the first lambda no error lights occurred in the dash. What symptons would a broken ecu cause? Would it show multiple error codes?
 
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