Idle problems.. Getting to the end and no solution in sight(full story)
07-26-2015, 12:30 PM
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Idle problems.. Getting to the end and no solution in sight(full story)
So, I've already on the forum for a while now
But i'll give a detailed discription on how i got to the point where i am now.
I'm a 24 old guy and live in Belgium.
About a year ago i was driving a 2008 BMW 530D wich was a manual.
After modify it to the point it made 320 HP and 650 NM of torqeu. the gearbox gave me the royal finger and so did the clutch after a few thousend KM.
also yearly inspection was coming up and smog test was a no drainer that it would fail. So a enthusiast bought it of me and i started looking for an atleast 25 year old V8(they are nearly free to run when they hit the age of 25 here in belgium). looked for some bmw 840i some 560SEC and some 928.
The porche seemed the best choise because:
1 Porche
2 It was the only multi valve whit a propper injection
3 i rather liked the idea of a "small" v8 coupe
So 928 it was! bought one whit 275k miles on it, the guy who sold it had not the slightest idea about cars. and i came to find out later niether did his mechannic. He was the second owner of the car, had it about 2 years.
The first owner did pretty much everything porche official.
it drove like ****. The engine heat was coming inside it shifted badly it over revved when planking it had some corrosion some rust at the doors, but ellectrical everything was working and not overheating so had that going for it..
Bought it for 4000 euro wich is cheap (its a 1988 928s4 Autogearbox).
So the money butchering began!
Timing belt, other belts, spark plugs and cables, rotors and caps, coils, every seal in the engine, 2knock sensors, hal sensor, TDC sensor, O2 sensor, temp 2, water pump, remade the vacum, new feul pressure regulator, the 2 feul dempers in the back of the engine, injectors cleaned, new brakes and pads, engine mounts and tranny mounts, a few no brainers such as oil oil filter etc.. Same for the gearbox. Proberly there is still stuff i changed that arent on this list.
I also did powder coat the intake and valve covers... What ended up bieng terminal.
after putting all back together and driving home whit it (10 km)
The damage done to the engine by this short distance made it have no compression left to start... It turns out the very inner parts of the manifold was falling to bits deu to bieng baked to warm and came lose and flew into the engine...
I really couldnt be arsed anymore about it after spending nearly 6000 euros just in parts and 5 months of work...
But in the end i found a wrecked car whit good millage(79k) on it so... old engine out new one prepared, coating done the right way and back in!
it drove much much better the the old one and i was pleased but the idle problem wich still haunts me was there. did clean the isv wich was better but mixturae was still much to rich at this point. So MAF rebuild done the week.
now my car runs at 1100 RPM and it runs to LEAN wich make absolutly no sence to me. It run on 1.045 ich and it should be 1.000 (on cleu how this unit is called sorry). Just today i tested my LH in my dads S4 and it drove just fine at a steady 650 ich rpm.
Sumary of the problem:
High idle 800 ich cold steady 1100 when hot.
I changed pretty much everything.
Mixtare is to LEAN.
I found one with the same problems that the idle stop screw kept the throttle a little bit open, i cheked for that and nothing changed.
No vacum leaks.
So i have no idea whats left for me to do, so i came to ask perhaps anyone knows more!
Thanks alot,
Andy
But i'll give a detailed discription on how i got to the point where i am now.
I'm a 24 old guy and live in Belgium.
About a year ago i was driving a 2008 BMW 530D wich was a manual.
After modify it to the point it made 320 HP and 650 NM of torqeu. the gearbox gave me the royal finger and so did the clutch after a few thousend KM.
also yearly inspection was coming up and smog test was a no drainer that it would fail. So a enthusiast bought it of me and i started looking for an atleast 25 year old V8(they are nearly free to run when they hit the age of 25 here in belgium). looked for some bmw 840i some 560SEC and some 928.
The porche seemed the best choise because:
1 Porche
2 It was the only multi valve whit a propper injection
3 i rather liked the idea of a "small" v8 coupe
So 928 it was! bought one whit 275k miles on it, the guy who sold it had not the slightest idea about cars. and i came to find out later niether did his mechannic. He was the second owner of the car, had it about 2 years.
The first owner did pretty much everything porche official.
it drove like ****. The engine heat was coming inside it shifted badly it over revved when planking it had some corrosion some rust at the doors, but ellectrical everything was working and not overheating so had that going for it..
Bought it for 4000 euro wich is cheap (its a 1988 928s4 Autogearbox).
So the money butchering began!
Timing belt, other belts, spark plugs and cables, rotors and caps, coils, every seal in the engine, 2knock sensors, hal sensor, TDC sensor, O2 sensor, temp 2, water pump, remade the vacum, new feul pressure regulator, the 2 feul dempers in the back of the engine, injectors cleaned, new brakes and pads, engine mounts and tranny mounts, a few no brainers such as oil oil filter etc.. Same for the gearbox. Proberly there is still stuff i changed that arent on this list.
I also did powder coat the intake and valve covers... What ended up bieng terminal.
after putting all back together and driving home whit it (10 km)
The damage done to the engine by this short distance made it have no compression left to start... It turns out the very inner parts of the manifold was falling to bits deu to bieng baked to warm and came lose and flew into the engine...
I really couldnt be arsed anymore about it after spending nearly 6000 euros just in parts and 5 months of work...
But in the end i found a wrecked car whit good millage(79k) on it so... old engine out new one prepared, coating done the right way and back in!
it drove much much better the the old one and i was pleased but the idle problem wich still haunts me was there. did clean the isv wich was better but mixturae was still much to rich at this point. So MAF rebuild done the week.
now my car runs at 1100 RPM and it runs to LEAN wich make absolutly no sence to me. It run on 1.045 ich and it should be 1.000 (on cleu how this unit is called sorry). Just today i tested my LH in my dads S4 and it drove just fine at a steady 650 ich rpm.
Sumary of the problem:
High idle 800 ich cold steady 1100 when hot.
I changed pretty much everything.
Mixtare is to LEAN.
I found one with the same problems that the idle stop screw kept the throttle a little bit open, i cheked for that and nothing changed.
No vacum leaks.
So i have no idea whats left for me to do, so i came to ask perhaps anyone knows more!
Thanks alot,
Andy
07-26-2015, 01:09 PM
#2
Rennlist Member
Andy,
A perfect example of why cheap 928's are cheap! Nothing at all unusual about what you experienced and the problem with the inlet manifold sadly demonstrates why one needs to ensure that those who carry out the work know exactly what they are doing.
Regarding your current problem I would say it is normal for a cold engine to idle at around 800 rpm but not 1100 when warm of course. Good starting point with idle/starting issues is to check is the resistance values of the temp 2 sensor at various temperatures irrespective of anything else but I suspect your problem is more likely to be a leak in the induction system such as the shaft seal on the throttle butterfly leaking air. you also have the various hoses under the inlet manifold that may be leaking/cracked if they have not been replaced. I do not have the temp 2 resistance values to hand but you should be able to find such within the Rennlist search engine.
Rgds
Fred
A perfect example of why cheap 928's are cheap! Nothing at all unusual about what you experienced and the problem with the inlet manifold sadly demonstrates why one needs to ensure that those who carry out the work know exactly what they are doing.
Regarding your current problem I would say it is normal for a cold engine to idle at around 800 rpm but not 1100 when warm of course. Good starting point with idle/starting issues is to check is the resistance values of the temp 2 sensor at various temperatures irrespective of anything else but I suspect your problem is more likely to be a leak in the induction system such as the shaft seal on the throttle butterfly leaking air. you also have the various hoses under the inlet manifold that may be leaking/cracked if they have not been replaced. I do not have the temp 2 resistance values to hand but you should be able to find such within the Rennlist search engine.
Rgds
Fred
07-26-2015, 01:35 PM
#3
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Join Date: Jan 2015
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Andy,
A perfect example of why cheap 928's are cheap! Nothing at all unusual about what you experienced and the problem with the inlet manifold sadly demonstrates why one needs to ensure that those who carry out the work know exactly what they are doing.
Regarding your current problem I would say it is normal for a cold engine to idle at around 800 rpm but not 1100 when warm of course. Good starting point with idle/starting issues is to check is the resistance values of the temp 2 sensor at various temperatures irrespective of anything else but I suspect your problem is more likely to be a leak in the induction system such as the shaft seal on the throttle butterfly leaking air. you also have the various hoses under the inlet manifold that may be leaking/cracked if they have not been replaced. I do not have the temp 2 resistance values to hand but you should be able to find such within the Rennlist search engine.
Rgds
Fred
A perfect example of why cheap 928's are cheap! Nothing at all unusual about what you experienced and the problem with the inlet manifold sadly demonstrates why one needs to ensure that those who carry out the work know exactly what they are doing.
Regarding your current problem I would say it is normal for a cold engine to idle at around 800 rpm but not 1100 when warm of course. Good starting point with idle/starting issues is to check is the resistance values of the temp 2 sensor at various temperatures irrespective of anything else but I suspect your problem is more likely to be a leak in the induction system such as the shaft seal on the throttle butterfly leaking air. you also have the various hoses under the inlet manifold that may be leaking/cracked if they have not been replaced. I do not have the temp 2 resistance values to hand but you should be able to find such within the Rennlist search engine.
Rgds
Fred
Havent even considert that there is a seal on the butterfly is it replacable?
And indeed the hoses are already orderd.
TA,
Andy
07-26-2015, 01:49 PM
#4
Rennlist Member
Andy,
If the temp2 is new chances are it will be fine but you might check the resistance values with temperature just as a quality check.
Suggest you read Mike Steiner's thread-"vibration at 3000 rpm-cracked flexplate". He did some great work with the inlet manifold system to find and eliminate leaks- you may find it helpful- he found a substantial leak on the shaft seals and replaced them- he too has been through quite a lot in a matter of months and is heading for a great result I believe.
Rgds
Fred