'94 S2 misfire. (info needed before fri lunch)

[s@.]

looking at an s2 tomorrow for mate, audi didnt find anything wrong when it went in there, no codes etc logged, they think its the crank sensor.. but i dont as that should bring a code yes??, 94 i think, dizzyless with seperate coil dooberys(yes that is the technical term ).

Misfiring started under heavy load, now seems to be all thru the range sometimes, and intermittent. like running on 4.

but injector leads were pulled one at a time, and no noticable difference between the 5, so can't pinpoint to any one cylinder. didnt do that myself, will retry in the morning. Safe to drive the car like that or only test at idle?

Will test the resistance of the "plug leads".. and also check the fuel filter to see if recently changed/clean flow etc..

Anything else to check? I can't see anything using the search. I'm familiar with turbo basics but just not audi at all.. Definately sounds like ignition prob to me... Any way to test the coil packs with basic multimeter etc?? can you check their resistance etc anyway? doesnt appear you can from searches etc.. but i'd have thought you'd be able to..

Cheers,
S

[Henka]

Fuel pump. Feels as if it's running on 4 cyls. Hard to check though. A fault code that says lean running conditions could be a sign though. VAG-COm is alwasy handy in these situations!

[s@.]

Unfortunately no codes are logged
I will check all the connections etc and try a quick flow test if possible... tbh I don't even know where the pump is yet lol... hopefully not a pesky in tank thing.

keep um coming, I'm off out now untill lunch, then i'll be back to check for more messages before going to have a look at it.

[karlblues2]

Sounds like coil packs to me. Budget on around GBP400 for the lot. I had the same symptoms. As for checking, I had mine tested through a coil driver, which basically fed a spark across a gap. Bank on them being shot as a lot have tended to fail on the forum over the last few months. It's an age thing. Use it as bartering power.
HTH
Cheers
Karl
Oz

[dan_b]

This does sound like coil packs as well - this was the symptom that Honahon had on his and we went through the whole shooting match of possible faults: Audi tried to sell him a new MAF, it wasn't that - did the WGFV and all those things, checked for boost leaks, you name it. Ultimately it was a dodgy coilpack.

[s@.]

OK i'm home for lunch now, then off to pickup the car..
The problem on idle is very rare, its mainly on boost apparently now.. i've heard a slightly different story from everyone who's driven the car lol.. i'll pick it up in half hour or so..

Can someone tell me then, is it safe to disconnect the injectors one at a time and to drive the car on boost?? pulling them one by one did nothing on idle, so i need to press it a bit harder to see if i can then tell which cylinder is faulty... as theres no fuel it shouldnt be running lean or anything so it should be fine imo.. but i'd rather hear someone back that theory up... I think this has to be the way forward.. once the pot has been esablished i can swap the 2 power dooberys over (i assume it has them like later ones??) to double check it is the coil pack not one of those.

[s@.]

I'm off now to pickup the car, won't be able to get to internet in the meantime.
So if anyone has any more ideas. and most importantly whether its safe or not to stress the car with an injector disconneted please could you drop a short email to me which i'll be able to collect on my phone. Many thanks
Stupink @ thunderisgod . freeserve.co.uk (you have to take the spaces out obviously, i didnt want it taken by bots etc_

cheers for all your help.
Stuart.

[s@.]

UPdate. problem still unfound.

When i drove it, It drove fine off boost. when you went WOT and it boosted 3k+ it started missing.. it seemed very frequent and imo seems as tho it was on all cylinders.. certainly more than one.. but then i've never driven a 5pot before, im used to 4 cylinders.

So anyway, first thoughts were then that it was a fuel rather than ignition issue, so i pulled the filter off, emptied it out and while it did have some bits and dirt, and the last petrol came out dark grey it didnt seem an exeedingly large ammount for what is rather a large filter... not enough to block it??? So i put a pressure gauge on the fuel pump outlet there where i took the filter off, cranked it for a few seconds and it went up to 5bar and probably still rising, seeing as i found the pressure regulator was 4bar i thought not a lot of point going anymore, it is obviously creating enough pressure, didnt flow test it, but it was coming out "quickly" but not gushing out, sound right?

So i think its not fueling, however audi were rubbish and can't get a new filter untill tuesday.. booooo... so i coudlnt run it up to test anything live to definately rule the filter out etc. didnt want to run it without one.

So i made use of the time to measure the "plug leads" they were all about the same.. and 4-5 dooberys on the multimeter which is right i believe. removed all the plugs. and they're all clean? no sooting or oil or anything on them what so ever... again suggesting perhaps that there is no one cylinder causing any problems?? surely if one was missing it would show on the plug??

So i'm at a loss
All i can do now is try it with the new filter, then again try it with the injectors removed, can someone please confirm this is OK to drive under stress with one removed(electric plug), the car was tested like this before in neutral stood still and no difference was noticed.. but im wondering if it might show up something while driving... I'm fresh out of ideas now and would like to hear anyone elses thoughts or things to test, the filter is coming next tuesday, so plenty of time to reply so get typing.. heheh.. otherwise the car is booked into audi again on the wednesday morning, and they're just going to do the whole swapping sensors left right and centre trick charging a fortune for them all no doubt

Thanks for all the help so far.. would be great to get it solved tho after all this
cheers
stuart.

[djavant]

94 s2 misfire

hi have you tried putting new rubber boot things on there the rubber thing between the coil pack and the spark plug .kingos2 had the same problem with no fault codes ,they where 26 euro each hope this helps

[s@.]

no they're old, and quite cooked in appearence as are the coils themselfs.. but I put my multimeter on them on the 2000k range and they all showed 4-5 which i believe is right? so I'm assuming its not them?

it would be great to solve it, but i need to locate the problem for sure before any parts are bought rather than just change things because they might be the problem else it goes to audi.. its not my car but a friends.

[newsh]

Misfire above 3500 could be air temp sender? But if oc should show a fault..

Or multifunction sender on water manifold, try disconnecting this and driving the car, tricky to get to.

[s@.]

Is that the sender at the back of the head under where the wires for the coil packs go into the camcover, facing the bulkhead? I can certainly try that
There are no fault codes though for certain, nothing showing on the dash, and already been tested at audi before i got hold of the car.

If it was mine, i think i'd replace all the coil packs, they've seen better days whether they're the problem or not. but its not my call.

[shadquattro]

i think the thing you are talking about is an ignition amplifier , i had to replace one of those and it was a big misfire all through the range when it went ,the whole car shook

[s@.]

well a fuel filter has arrived, so i'm going down there in a half hour to fit that, have a double check over for airleaks after the afm etc.. the car is de-catted so it can't be that.

The car doesnt really shake, its kinda fairly smooth still, and still pulls.. its a shame there isnt a boost gauge installed, but i'd be fairly confident to say its not allowing the car to boost fully because of the problem...

If it was because of the fuel pump, or the filter etc causing it to run lean, and its so bad its noticable like that, shouldnt the lambda pick it up and bring up an ecu code?

It has to be one or more of these power output stages, or an ignition coil really.. just doesnt feel like its missing on one.. feels like a poor ignition on all cylinders... its like what i get with my turbo car if i have big plug gaps and the spark blows out. fine off boost, fine low boost, as the boost kicks in each cylinder misses... however the plugs are renewed and made no odds.. afaik they're the right type, and the gap is only 0.7mm which ought to be fine? platinum plugs if i recall..

thanks for all your help, but looks like we've failed on this one, the car is now booked back in for tomorrow morning, and i cant see me sorting it out today at all.. not really made any progress towards the fault, only ruled out a few things

[s@.]

Today has been another waste of a day.
new fuel filter in, problem not changed.

Pulled the injectors one at a time idle, all made it drop the same and recover, tried driving one at a time, all made the car misfire in the same way, a lot worse than the actual problematic misfire too. but a similar frequency.

Tried blocking the air intake to the air box... the pipes to the intake started to collapse etc on revving, so if there is a leak anywhere its not big.

Checked over all the boost control valve wiring, all seems ok. no other hoses etc etc have come off anywhere or anything..

hopefully audi will find something tomorrow without too much time/expense.

The problem is very specific now i've driven the car a bit... if you are driving light throttle it will run thru the rev range fine.. if you boot it WOT its fine untill 2.5k where the turbo comes in presumably.. if you go 3/4throttle(or more.. simply not the last 5mm or so) then the car picks up boost wonderfully and boosts well thru the rev range.. put the last 5mm down... misfire... bring it up those 5mm misfire goes...

RAAAAh...

Still feel therefore that its ignition prob.. probably one of the stupid coils, but just can't isolate it at all..

Any more ideas that are fairly easy to check before 9am GMT monday would be appreceated.. otherwise its over to audi..

It's been "fun" for me anywya to learn a bit about these engines, my own car is the only turbo engine iv'e really got into at all, and didnt know squat about them untill i got that.. so its nice to see how similar some things are etc..

cheers again... i'll put up the resolution if/when its found so you all know..
stuart.