Hive

I've finished for the most part a heads/cam swap on a 1993 a4 lt1. The tune was done by Solomon (lt1pcmtuning).

Other mods that may be of relevence:
1.All new spark plugs (NGK TR55IX iridium, stock 0.059" gap - seems huge, the emissions sticker says gap them to 0.050 but iridium plugs say not to do this)
2. Long tube headers by pacemaker, dual cats and exhaust aftermarket.
3. Standard single wire unheated O2's (Heard that unheated sensors + long tubes is a bad idea as they dont heat up enough)
4. 1.6RR Comp cams, all comp cams valvetrain, 1/2 turn past lash preload.
5. 23 year old opti (Yeah sue me)
6. 6 month old 98 octane petrol in it (93RON in USA). Tune was built for Australian 98 / 93RON US petrol. Probably an issue
7. Firing order has been checked, but might do this again.
8. FIC 30lb/hr injectors
9. Lloyd elliot LE2 heads, Lloyd elliot 218/224 111LSA cam
10. EGR Deleted and blocked off, blocked off vacuum line for it. Air fittings removed but air pump is still in the car. 93 are electric pumps.
11. Engines only done 42,000 miles.

after about 2-3 minutes of it running from cold, the left bank will start backfiring or popping out of the exhaust every 10-30 seconds, not extremely loud but noticeable, it definitely gets worse once warmed up. I've ordered new heated O2's and a conversion kit but could the o2's not getting hot enough be feeding the PCM bad information which leans/richens the mixture and causes this? I noticed that when i put the foot on gas and got RPM's up it would enter closed loop, but after 5-10 seconds of going back on idle it goes back into open and immediately seems to improve idle quality.

before i had it tuned i was running it (Albeit extremely rich, fouled plugs up!) it never backfired once but the tune has changed since then, this suggests the tune has introduced something or made a fault more obvious. when it's idling and i'm datalogging, i can see the MAP vacuum go up and down, but that's probably just the cam in it. When out of idle it doesn't backfire at all.

After about 10 minutes of running i took a plug out and it didnt seem overly rich or lean, it did have the FAINTEST smell of gas on it, very very faint but not much if any carbon. Funnily enough as well, i let it run for 15 seconds from cold, felt all the header pipes, 5 was only slightly warm whereas the rest were hot enough to boil water, this probably means jack ****, but Solomon did hint at a 5/7 lead cross, i will double check again later as checking the leads on the opti is a painful process

I'm learning as i go

SJW

Sounds as though you have unburned fuel that's lighting off in the exhaust. The cool primary on one cylinder is a major clue. Start there looking for a mis-fire.

Live well,

SJW

Hive

Knew it would be something simple... #1 cable was loose, after fixing that and giving it a few belts of the throttle, it seemed to stop completely at idle.

Let it heat up to running temps, at idle it drops out of closed loop no matter what. Hit the throttle a few times and it goes into closed, before returning to open and staying there until the throttle picks up, so this almost completely confirms those unheated o2's are useless? Additionally, there is a split BLM.

Also found some leaks, i did the AN conversion for the rear steam line, both have green around the ARP thread sealant, it's not really a drip but the white ARP paste shouldn't be turning green antifreeze colour, is that paste pretty much useless in this situation? I did tap the threads before putting the AN fittings in.