i'm getting codes for multiple misfires, and #5 #6 misfire. also now found a code for exhaust gas temp sensor1. if thats on bank 1 why is bank 2 misfiring? can someone help please. could this also happen from putting the wrong octane (too low) and whats the best and cheapest way to fix this?

 

What model and engine????

How old is your timming belt and tensioners????
Check your timing belt first it may have jumped. No sense of doing anything else till you know that's OK.

If just 5 and 6 misfire that is cause for the ecm to set a multiple misfire.

I would think timing related , start with Combustion and ignition. Check compression, coil pack wiring or ICM

 

it's an 01 a6 2.7t and i just got the car. the misfire is intermintent. it doesnt happen all the time. and it has all kinda of power till the code sets in again. and the first time it misfired it was just #5 so i swapped coils with #4 and it decided to misfire on 5 and 6. then it gained the EGT code. i already swapped the ICM to see if it would switch banks and that has failed to change anything. and before all of this the transmission was in limp mode. cleared that and gained other codes.

 

Coils are under recall-free replacement. CEL has to be on for dealers to consider replacement.
EGT's wear down. Even the code is intermittent one - eventual replacement is coming.
ECSTuning have a pair for $300 (half of the dealers price). Even one could buy single EGT - sold in pairs by the dealers.

Have you swapped the spark plugs? How old are they?

You stated you swapped the ICM - it's known to fail on 2.8 l - on 2.7 is a rare failure.

 

for the coils looked that up and found the 2.7 didn't have the recall cause they are the newer individual coil packs. like i said i just got the car so i have yet to pull any plugs. but another question is why didn't is misfire while the transmission was in limp mode? and could this be from a vacume leak? cause i did change the valve cover gasket on the drivers side.

 

Unplug your maf and see if things improve. You've already ruled out the coil packs, it can't be the plugs (they don't fail in pairs, but it'd be worth replacing them if you havent in a while), and not likely to be a bad head gasket. The only other thing to suspect is your maf (even if you don't have a maf specific fault) or somebody pissed in your gas tank. The octane shouldn't matter. Thats what knock sensors are for.

You'd have to have a huge vac leak to cause misfires. If it was a bad enough vac leak to cause misses, it'd be stumbling or gasping at idle.

 

ok i'll give that a try.

 

once you drop over o certain count of misfires it will put the car into limp. have someone read misfire counts on a diagnosic reader and see if you have mutiple or one hole counting off misfires. if none then i would look into the egt probes next i think they r like 70 bucks each. or just yank it all and have someone reflash your ecu to take it out. they dont do shiot anyways

 

well with the misfires it started as #5 then later #6 came up. then it threw multiple misfire code. and then the EGT#1 came up. but after disconnecting the MAF the car has a bit more power and is a bit smoother. but when putting into drive it goes in kinda hard. also the traction and ABS light are on after disconnecting. so it looks like the MAF? i need to drive it a few more times to see if it will misfire though. it's rare that it will miss the first time you drive it in a day.

 

those 2 lights come on in limp...mine does the same when a coil is turd...im not talking a code reader i mean a diagnostic tool that reads off misfires on each cylinder as they happen like a snapon diagnostic tool. not a code reader...well it does that too. and more

take it to a local shop and ask them if they can read the miss fire with thier snapon tool. most shops use them for inspections