348 spark knock?Please help

Hello Forum Romanum,I want to please You for help..My car started to knock....Major service done last month(timimg,injectors etc etc).After cure it was another car-much stronger(timing was bad)better torque,no more problems with hot starts.After 500km on 95 octanes was still everything ok,BUT than on the same day:I filled ca.40L Shell Nitro 100 and drove cca 200km on the Autobahn(180-250kmh) and than I heard (in the city)between 1500-3000/min knocking sound from the engine(not trany,not shaft etc).It is also not rod,not puley,no valve,no water pump...It occurs ONLY under load(also uphills with constant speed).On idle you have to push gas pedal really brutally fast to hear it a little bit.Water/oil temp.normal,oil pressure normal.My exhaust tips are white,not light brown,really white.The car idles a bit high(about 1100-1200/min.cold or warm).I tried to disconnect the battery,but no change.I dont know what happend.I did some research and I think my car is running lean and it seems to be a spark knock.I tried to disconnect the fuel regulators-but also no change.What should I try next???No other symptoms as smoke from exhaus,bad starts,oil pressure drop,oil consumption etc.
My car is one of the very first cars from 1989,pre production TB without cat,with "old seats" and with motronic 2.5,about 57000km.
I thank you very much for every reply,every idea and help..!!!!
Martin

ps-sorry,I have to improve my english...
ps2-I saw thread from 2010 "1991 348ts running rich" but I can't load it

 

Many thanks for Your replies and help!!!I will check all hoses on the intake for air leak.One interesting think-my mechanic told me that there is a large "gap" (some 4-5degrees) between crank and cam puley.But I saw video on Youtube "Ferrari 348 cam belt service" and in part VI at time 4:12 was told "cam puley is not important for timing,just crank" and than in part VII at time I think 6:50 can I see that the crank moves few degrees before the movement comes to the cam puley and cams.My mechanic told me it might be problem...Do You have experiences with this issue????
Thank You!!! Martin

 

You are correct,for timing ist important cams vs. crank.But how it is possible,that you can move with the crank(pistons) to the left or right for 4-5degrees before cam pulley and cams moves?My mechanic did not know,where the correct position is(clockwise to the right???)He did it so as the engine is under load,chain between crank and cam pulley fully extendet)He did the timing correct with cam pulleys off,with TDC and degree wheel,BUT than comes the "gap" crank vs. cam pulley.You can see this in the film "348 cam belt service" in art VII at about 6:50.I am not mechanic,but I thing this is it 4-5degrees is too much.Maybe the outlet valves are opening too early when the temperature in cylinder is too hight and my exhaust coloured to white.
Martin

 

My car is from 1989,pre-production car,VIN beginns with 81xxx,version without cat,with old style seats.I tried other cars,all with cat,but this one was in the best condition and this car was also significantly stronger and faster.
Before major service had I hot starts problem and it was running little rough-the problem was in injectors(now after rebuild ok).The car has X ost exhaust(before Remus) and KN filter.And I have no problems with high speed floating-very strong wind,curves over 200kmh on the Autobahn without problems,as stable as an M5...I absolutely love the 348,no other car makes more fun!!!
What I wanted to describe with my bad english is-when you look at the timing belt:you can move with crank a few degrees to the left or right before the chain moves with the pulley where the timing belt is(this pulley is maybe some cca 15-20cm (some 8inches)above the crank and is with the crank connected with chain).I dont understant how can you set the timing correctly when there is 4-5degrees "gap".You can see this on youtube "348 cam belt service" part VII at time 6:50
Many thanks Martin

 

My car is from 1989,pre-production car,VIN beginns with 81xxx,version without cat,with old style seats.I tried other cars,all with cat,but this one was in the best condition and this car was also significantly stronger and faster.
Before major service had I hot starts problem and it was running little rough-the problem was in injectors(now after rebuild ok).The car has X ost exhaust(before Remus) and KN filter.And I have no problems with high speed floating-very strong wind,curves over 200kmh on the Autobahn without problems,as stable as an M5...I absolutely love the 348,no other car makes more fun!!!
What I wanted to describe with my bad english is-when you look at the timing belt:you can move with crank a few degrees to the left or right before the chain moves with the pulley where the timing belt is(this pulley is maybe some cca 15-20cm (some 8inches)above the crank and is with the crank connected with chain).I dont understant how can you set the timing correctly when there is 4-5degrees "gap".You can see this on youtube "348 cam belt service" part VII at time 6:50
Many thanks Martin

 

The timing was done correctly.Today I will check spark plugs for condition and colour- have new NGK. I can also prove MAFs-they should have about 342 Ohm resistace(for non cat car).And I will check the knocking sound with Stethoscope.Maybe I can also try to use some octane booster.
Many thanks for help,have a nice Weekend!

martin

 

I reseted ecu's(battery for few days off,than idle for 15-20min).The cold idle was much better,but as the temperature rised,the idle was going to be rough and wenn the car is really hot(after 15miles) it sounds like old marine engine.But after ecu reset:there is no more knocking at idle.Just under load on the street.The car feels also weaker,it has lost much torgue between 2000-5000/min.And the car misfires and jerks(most between 2000-3000/min).
I will change crank sensors,ignition modules,coils,temperature sensors ,spark wires and and.....???
I hope it will help!!!
Thanks ,Martin

PS-the injectors are fresh rebuilt

 

Yes.He was not sure,but he did it right:cam wheels were off,because the factory marks are not precise enough.He turned the engine clockwise to get everything to max. extension(chain,belt,pulleys)-to simulate engine under load(as Ernie wrote).Immidiately after service the car runned fantastic,much better than before-stronger,above 2000/min. significantly more torque and above 5000/min it just flied to 7000...
So,I thing,the problem is crank sensor,coils,ign.modele etc...

 

Thank you very much for reply!My car has from factory no cat,it is from 1989,pre-production car.So a have no O2 sensors and many other things...(does anybody know how much 348 were originally without cat????)
I will clean my MAFs and I also bought coils,plug wires and crank sensors(everything from 16th century...
I will post result after changing few things.
Thanks Martin