audi a4 2.0 tfsi none stater

[paul fisher]

where do i start lol

car had a slight misfire scanned the car cam sensor so i thought change that which i did know the car wont start so checked the following

changed crank sensor 

checked voltage to crank cam and coil packs

checked chain visually and on vcds its saying bank 1   specific 28 degrees

                                                                             bank 1   actual 28 degrees

                                                                             bank 1  phase 0 degrees 

which i understand is correct   

the car has a spark but looks weak in my opinion

done a compression test 195 psi on all 4 cylinders 

car cranks starts making a chugging noise then dies pulled the plugs out plus bank one o2 sensor and there carboned up straight away there are no fault codes mechanic cant look at the car while next week as anyone any idea where i can look next thanks in advance paul

[Stevey Y]

Hi it would help if you had some codes, not sure on petrol models but on my diesel there is a crank sensor adaptation protocol which has to be re adapted when fitting the new part, it sounds more of a fuel pressure problem but that would throw a code up, only other thing I can think of is try the old crank sensor again as if it starts on that one it may be the new one is defective.

Steve.

[paul fisher]

3 minutes ago, Stevey Y said:

Hi it would help if you had some codes, not sure on petrol models but on my diesel there is a crank sensor adaptation protocol which has to be re adapted when fitting the new part, it sounds more of a fuel pressure problem but that would throw a code up, only other thing I can think of is try the old crank sensor again as if it starts on that one it may be the new one is defective.

Steve.

Ive ordered another crank sensor ive scanned it with delpgi and vcds no codes im going to check the values again and reset the adaptions on the ecu and try again will check the fuel pressure any ideas what it should be stevey in positive its something or nothing thanks again 

[Stevey Y]

Hi Paul, an average lift pump should knock out about 45psi although I have never used a pressure gauge and normally just taken the feed pipe off of the fuel filter out feed and dangled the pipe in an old plastic bottle, then get an assistant to switch the ignition to position 2 and watched if it sprays out like a fire hose you can safely assume the lift pump is working, if this is the case the next thing to try is the regulator solenoid on the end of the fuel rail these as far as I am aware are not monitored by the ECU and can play up and never throw a code up, as I say not to sure with the petrol version but on the diesel  you have to hunt it down as it does cause a misfire of sorts where the solenoid spring becomes weak and won't hold the rail pressure.

Before going off on a tangent try the crank sensor first then if it won't run start looking further afield as it ran before on the old sensor was changed when fitting the new one double check the connector for dodgy pin ports, this is a tough one but please keep this thread updated.

Steve.

[paul fisher]

thanks Steve 

I've disconnected the fuel line to the fuel rail there's fuel there I've took the plugs out and cranked it you can see them firing away if i start the engine with the  plugs in it sounds like its running on two cylinders then cuts out if a disconnect the coil packs it spins over like it should do I've changed the crank sensor for another replacement to see if that des the trick I've  also checked the voltage to crank sensor cam sensor and coil packs I've got a healthy spark its definitely something or nothing will keep you posted got to be timing related 

thanks paul

[paul fisher]

On 7/29/2021 at 5:39 PM, paul fisher said:

Ive put a couple of videos on Steven first one has the coil packs disconnected sound sweet has a nut turning over 

Second video its trying to start but sounds like a can of nits and bolts are in the rocker cover 

 

[Stevey Y]

Hi much as I hate to say this but it sounds from the videos like the timing has slipped, I think from memory these engines have a chain, it sounds as though when the coil packs are connected it is firing back through an open valve which may account for the rapid sooting of the other components down the line it may have gone round one tooth which won't kill it but it won't do it any favours either, how many miles has it done? I know the manufacturers say the chain should last the life of the car but that won't take into account extra wear caused by extended service interval oil degradation.

Steve.

[paul fisher]

Just now, Stevey Y said:

Hi much as I hate to say this but it sounds from the videos like the timing has slipped, I think from memory these engines have a chain, it sounds as though when the coil packs are connected it is firing back through an open valve which may account for the rapid sooting of the other components down the line it may have gone round one tooth which won't kill it but it won't do it any favours either, how many miles has it done? I know the manufacturers say the chain should last the life of the car but that won't take into account extra wear caused by extended service interval oil degradation.

Steve.

130000 thousand miles i take it the one tooth wouldn't kill the valves but would throw  the timing out Steve 

[Stevey Y]

Hi yes indeed I hope I am wrong but the chain guides are made of nylon or some sort of rubber and know for a fact these wear and let the chain become loose thus allowing the possibility of slipping.

Steve.