My car has had a rough idle for quiet some time, when u promote a jumpy idle eg. slight revving of car to 1300RPM while reversing, when back to neutral and idling car will bump around from 600-990RPM. Doesnt happen all the time though, once car is driven continously and driven a bit harder it steadys perfect.
I've only recently joined the club so don'tknowmy way round these cars yet - however, similar "hunting" on my Integrale has occured in the past and has been down to the idle control valve needing a clean with carb cleaner or equivalent, I presume there is a similar device on this beast - perhaps a good place to look initially?
Yes
Vacuum hoses or Maf.
Do a search on both topics.
Also 8000 rpm limit etc etc..
I temper my advice on this based on the huge range of variables a a tuned eprom engine
with other modifications brings to the fault elimination procedure.
Whilst doing a search, I would recommend looking at the consequences of fitting an oiled filter
to this type of vehicle with its hot wire mass metering unit.
Cheers
Farrell
Last edited by farrell; 2nd January 2008 at 20:14.
Skip the K&N filter crap as they ruin Mafs. The original setut is very good
Also an 8000 rpm limit can have serious consequences for your engine such as resonance etc. I would recommend you return to the original limit as several cars that I have followed in Sweden have suffered serious engine failures due to this.
The hunting of idle is there even with standard chip in and when i got it from Japan, with 80 000Kms on it; it still did the same stock standard. Just not as bad.
I have got the chip in there only for the sake of the power gain in the higher revs but still gear shift @7000-7300RPM as I no that bottom end damage can be caused eventually.
Although we have chipped many E34 M5 3.6L and have used them on race and rally circuits for a good solid 2-3years and never had problems, however have had major problems with the 3.8L.
The Knn filter is in the stock airbox setup , just with a knn panle filter insert to replace the stock panel filter insert.
I have changed the MAF, TPS, Computer and found one air leak which was fixed in one vacumm line. However have not looked for more since.
I might have another look over the lines again and see if i can get anything.
Did this vehicle come to you as std with an idle & maybe other air / spark / fuel issues as std ?
Was it then chipped with existing condition ?
Were the MAF, TPS & DME diagnosed as faulty ?
You mention that you have been changing eproms on vehicles other than this.
Are you using Carsoft or Autologic diagnostics to interrogate the DME ?
This would rationalise diagnosis in conjunction measuring output
voltage etc at the relevant sensor plug.
K&N panel filter will kill & MAF just as quick as a cone but without the
thermodynamic issues of intake heat soak affecting the K&N cone filters.
Is the vehicle still running closed loop Lambda.
Whats th AFR on part throttle & WOT ?
What make of Eprom is fitted ?
Does it allow / inhibit the DME's ability to flash the self learning aspect of the driving
characteristics if you disconnect the battery or the DME from the power for longer than
30 mins ?
Farrell
Last edited by farrell; 3rd January 2008 at 01:57.
Linear Mode
