Thats it... I am pissed off with the car. Any hints or if someone has had the same problem - let me know what you did to get it fixed. Car is an 88 Calais Turbo. Has an intercooler and exhaust, and thats about the limit of performace mods. Problem: Car will drive fine - not a problem in the world... and then all of a sudden will start running rough as though its missing slightly. The miss is not constant (ie, not 1 cyl all the time missing). When it runs rough, the car will put out black smoke. When its running rough - the miss is very small and car still drives ok-ish on idle, very low load (less than 10% throttle and not going up a hill). If you try any more than a little throttle, or put a little load on the motor (ie, going up a hill or accel more than 10%), it will start missing alot more and a HEAP of black smoke comes out the back. Interestingly enough the car will make boost (5 psi plus) at even 1500 rpm while its missing and being rough. This makes me think its overfuelling something cronic, or spark is cutting out. If you keep the boot in (100% throttle) and ignore the intense bucking/missing (yes, i know its probably not good - but when you get the ****s in the middle of traffic...) the car will eventually get up to about 3000ish rpm and then start going ok... i suppose by then its gotten to a point where the intake of air is somewhat matching the intake of fuel to start going ok. This problem is giving me the ****s because its intermittant. The problem will arrise and stay around for a day or a week, and then it will go for a day or a few months. This makes the problem very hard to see if what i've done has fixed it. Lately its really giving me the ****s cause it seems to have set in a little more permanently then previously, and be even more rough than usual. When the problem started, It "seemed" that it happened whenever the fuel went below 1/4 tank left and about 10 minutes after filling it up it would fix itself - however this doesn't fit in with whats now happening - any amount of fuel in the tank - same deal. What have I tried to fix this? replaced spark plugs and leads with brand new items. replaced Ext Fuel Pump with known working unit. replaced Fuel Filter with brand new item. replaced AFM with known working unit. replaced coil with known working unit. replaced Dizzy with known working unit. replaced Oxy Sensor (did have some bare wires that could have shorted on heatshield) with known working unit. checked ECU Error codes - none come up that are of interest. checked leads in the dark to see if theres any arcing (even on a bit of load) and cannot see any arcing. Any suggestions as to what could be wrong??? I'm starting to pull my hair out over this. Things I have considered, but don't know how to test this on my own - or dont have the tools to check this - or even if they could cause the above problems? - Water in the fuel tank? - In tank fuel pump? - Fuel Pressure Regulator? (anyone got a fuel pressure guage they want to come over and use??) - ECU itself? (anyone got a spare Turbo ECU to test??) - Lack of Compression? (anyone got a compression tester????) What else could it be? Anyone keen enough to come over and give me a hand sometime?

hey, ive had a similar problem where it will run heaps rough and heaps rich in fuel. my car is only a N/A but i found when i was having the same problems as you, the plug on the Air flow meter would come loose and having a poor connection. the air flow meter itself is fine, it could be just the plug, make sure its on nice and tight and the wires themselves are making connection with the Air flow meter.

yeh the AFM plug corroded or lose

Gotta be an AFM problem.

AFM with a touch of O2 I reckon. Get that wiring fixed sport.

Quote: Originally Posted by Munro- AFM with a touch of O2 I reckon. Get that wiring fixed sport. And a pinch of CAS too perhaps? Gotta be an AFM related issue. Some original photos have not been recovered yet.

well the O2 can cause a lot of what he is saying with the overfueling. Cas would stop working when it was hot.... So no not the CAS.

The O2 sensor was suspect at one stage as the wires had rubbed through on the heat shield and was possibly shorting or giving wierd signals. However - I replaced the O2 sensor (including the rubbed through wiring) and modified the heat shield to give enough clearance to not happen again. The car seemed to be ok for about 10 kms, then went back to its usual tricks. The O2 Sensor wiring looks to be ok now. If it was the 02 Sensor, it wouldn't go to crap if the car was cold, on full throttle, or above 2000 rpm (out of Closed Loop Mode). I then changed the dizzy over with another unit, and the car ran fine... this time only for about 500 meters, then started back to its old tricks. I will check over the AFM wiring when I get home and see if I can see anything wrong with it (corrosion, loose connectors, rubbed wiring, etc).

Hey insane, i think i might be having the same problem as you. With the Berlina, i'm also having overfueling probs. Do you also find that she runs hotter than usual?? Cheers

yer if you have already solved that issue. I would check all the wiring from the AFM all the way back. It sounds like you have some shot wire on that side that when you fix something you rub it, but vibrates it loose as your driving along.

Yeah... beggining to think that. When i fixed up the Oxy sensor, I had to pull the heatshield out - which is right where the wires go through the firewall. Couple that with the fact I moved the fusebox to the glovebox quite a while ago - some of the wires were a bit tight/stretched coming through that grommet in the firewall. That'll be my first place to check out tonight when I get home from work. Oh - and no, my car still runs the same temp... but kind of hard to drive it any decent distance with it acting up like it is.

i vote TPS Some original photos have not been recovered yet.

TPS is not giving an error code though - and it still runs a bit rough and overfuelling on idle. Its a very intermittant miss. I'm not sure how the TPS would affect the idle and fuelling like that.

my car did the same thing and it turned out to be the cas or dizzy, i just swapped the whole thing and the problem went away. its probly not the o2 sensor, i drove my old car without one for months Some original photos have not been recovered yet.

Ok. i think dodgey wiring might be the cause. My roommate just called me to say that the car alarm is beeping every now and again. This would support the theory that theres some wires being rubbed away somewhere or shorting out.

I'm thinking fuel pressure reg or water in fuel, both will give you the miss in low range on random cylinders. If the fuel pressure reg is stuffed and stuck on high then it will over fuel until top end or if its leaking through the diaphragm then fuel is going straight into you're plenum under vacuum. Also check to see if you're leads have any burn marks on them you can't always see them arcing and it may be arcing into another lead if they're close together which may give you a spark on an exhaust stroke which would explain the early boost. Once you have sorted it get you're cat checked (if you have one ) because the unburnt fuel going straight into a hot cat is going to burn the core out. Also that beeping could be a low battery warning feature of you're alarm. Hope this helps. Some original photos have not been recovered yet.

sounds afm related to run that rich all of a sudden. does it rev over 2000rpm when it plays up? also dont be afraid to check the coolant temp sensor as well, its it dodgy and going open circuit the ecu defaults to open loop mode and cold start conditions (which means to much fuel when its hot already) in saying that i still think afm though...

ok.. the AFM wiring looks all ok... I have tried 2 AFM's on it, and now it makes no difference if its plugged in or not (either of them). However - its worse now than it was before. Before, if i unplugged the AFM, it then ran rougher. argh... this is getting bloody stupid. Anyone know good mechanics/auto sparkies on the Nth side of Brissy that wont charge me Eleventy Billion dollars to find its something stupid????

my car jsut recently had a similar problem.. same mods as far as performance side goes.. try your fuel pump, mine would run fine for like 5 mins.. then it would miss until i rev'd it.. Jason

Fuel pump has been changed.