Year of Manufacture *: 1994
Engine Size and Code *: 2.8 v6
( Optional ) Scanner Used: Snap on modis
Any help or input into my issue
1994 Audi A6 2.8 v6 petrol
179000miles on clock
Engine code ABC
presented to us after being to a lot of different places having lots of money spent complaint rough running and lack of power sometimes cutting out.
So list of parts fitted prior to us looking
Genuine coil, leads and plugs
Injectors sent for testing and cleaning
Several sets of O2 sensors (aftermarket and genuine)
Service items (ie oil fuel air)
Head removed and valves re-seated (only 1 side right hand side when looking bank 456)
Tests we have carried out.
Code read using snap on modis on heritage software.
smoke test revealed small leak on bottom inlet manifold
So we replaced that genuine parts.
Had several faults for lambda sensors and map
Found faulty map sensor.(built into ecu) sent to actronics who repaired
We've now got a fault- 00554 lambda sensor control lower stop value.
Can't get any live data so this is a downside
Scope shows the fixed lean 100mv on 456 bank
Will occasionally react if revved hard enough.
Sensor reacts to brake cleaner so it can read.
Tail pipe emissions are
Removed lambda sensor on Each bank inserted probe and got the following readings
Bank 123 idle
Bank 456 (side that has previously had head removed)
Vac gauge into inlet get a steady needle and reading of 16inhg
fuel pressure = 3.6 bar spec is 3.3-3.7 bar
current flow for pump and appears ok.
I'm having some user error with transducer in inlet manifold as just get a flat line of the vacuum reading.
Timing appears ok (from what i can see of in cylinder waveforms could be wrong?)
In cylinder readings I can see the bank with issue has a lower running compression roughly 60psi compared
To roughly 75 psi on other bank
Cranking compression is all pretty much even 190psi
havent got a cylinder leakage tester so used smoke machine on offending bank setting each cylinder to TDC compression and no smoke coming out. I understand that smoke machine may not be enough pressure, but have had success in past.
But I'm still at a bit of loss tbh.
Swapped injectors and spark plugs over bank to bank no change.
hope the link works but heres google drive with in cylinder and spark wave forms ive captured with LSM file for shop stream connect.
would be really grateful if someone could take a look and let me know where im going wrong.
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