Unstable idle

Yea, thanks for advice.

The problem is that the engine was re-built (there are 2 mechanics, one is building hardware only but mapping is done by other guy, it had previous map by this same guy but the engine lost compression etc (not by his fault, engine was weak long before it), valve was damaged and sparks were terrible etc.

So I got new valve, piston rings, ported head, lightened flywheel and lightened crank pulley, etc. And then got mapped by this same guy I used to go to, and that was all awesome.

Then there was engine light and idle was shit and I had that problem while filling tank. Missfire again. Changed Ignition coils, issue was there. Changed sparks, issue still there. Changed throttle body, issue there. Changed MAP sensor, issue there. The only difference that I can say for now is that I don't see engine light flashing anymore. But I didn't drive car that much anyway, maybe 3 times last 3 days so who would know, maybe engine light will come back.

Regarding the tank / venting valve / etc was not altered from what I know. So now it is either that or the map somehow. My mechanic for hardware is now away for holidays for next 20 days (the one which rebuilt the engine), and I the mapper is coming back from holiday soon and as soon as he is back we will check out the map.

Currently I don't know what else I can do. I just show these messages you guys tell me, all the suggestions, I send them to mechanic to take a look. Until then, map will be checked.

There will be 3 upcoming track days next week. I will skip them all... don't want to push the car while I have this problem.

Do you think something can get seriously damaged even if I just drive it around town slowly?
 
FishFart said:
Yea, thanks for advice.

The problem is that the engine was re-built (there are 2 mechanics, one is building hardware only but mapping is done by other guy, it had previous map by this same guy but the engine lost compression etc (not by his fault, engine was weak long before it), valve was damaged and sparks were terrible etc.

So I got new valve, piston rings, ported head, lightened flywheel and lightened crank pulley, etc. And then got mapped by this same guy I used to go to, and that was all awesome.

Then there was engine light and idle was shit and I had that problem while filling tank. Missfire again. Changed Ignition coils, issue was there. Changed sparks, issue still there. Changed throttle body, issue there. Changed MAP sensor, issue there. The only difference that I can say for now is that I don't see engine light flashing anymore. But I didn't drive car that much anyway, maybe 3 times last 3 days so who would know, maybe engine light will come back.

Regarding the tank / venting valve / etc was not altered from what I know. So now it is either that or the map somehow. My mechanic for hardware is now away for holidays for next 20 days (the one which rebuilt the engine), and I the mapper is coming back from holiday soon and as soon as he is back we will check out the map.

Currently I don't know what else I can do. I just show these messages you guys tell me, all the suggestions, I send them to mechanic to take a look. Until then, map will be checked.

There will be 3 upcoming track days next week. I will skip them all... don't want to push the car while I have this problem.

Do you think something can get seriously damaged even if I just drive it around town slowly?
Click to expand...
If it’s not running right it’s very possible something may be damaged... your asking for a crystal ball prediction bud, can’t really say yes or no to that one
 
Alright so from speaking with tuner he suspects that the crank sensor is damaged and needs to be checked/replaced.
There were a few cases that describe my problems in past from his experience, and if this would be solution I would be more than happy :smile:

Will do that early/asap next week.

That's all I got for now. Let me know your thoughts!
 
Try one, a crank sensor often doesn’t throw codes as it reads and doesn’t as it doesn’t have anything to compare to, why no manufacturer has never fitted two next to each other like the two tracks on a throttle pot I’ll never know...
 
New crank sensor will arrive tomorrow or day after, and will replace it ASAP.

Meanwhile I had AC on, and what happens is that while standing in place or even driving, if the AC is set to 2nd level or higher (it is manual AC) when RPM is dropping it chokes the car and it turns off.

So in this case I tried to rev a little bit (engine warm or cold, all the same, in this case it was warm), and on AC level 2 it chokes really bad and sometimes the car turns off.
But on Level 3 or 4, if I rev up to 2000-2500 rpm and let go of gas pedal, the rpm drop down so much that it kills the car:




This can also be related to a sensor (In this case will first try with crank sensor)... do you have any thoughts?

Thx!
 
That could be something as simple as incorrect learning of the throttle and it’s position for idle, wide open throttle and shut off
 
Yeah but the throttle body is new oem unit replaced like 2 months ago and maybe 1000km driving.

Could the error be related to gas pedal and overall TB control, and not the tb itself??
 
Yes that’s what I mean, when you fit a new throttle body you have to run through a sequence of learning with a diagnostic pc or a set of instructions to learn the throttle body and it’s basic positions, if it lost this and that was the issue a simple re learn of it’s various limits may well have sorted its issue...

We used to get it with stepper motors on Peugeot’s, a re learn would sort them and they would do similar

Or on the later ones it took about an hr with the bmw mini and had to be completed from stone cold, the ecu learnt the ignition coils characteristics and the cam positions and various other bits and bobs as well, oddly they don’t actually use the throttle body for normal day to day running, instead they vary lift on the valves via a massively strong spring and a wiper motor (it really is!) to effectively use vtec with a third cam which acts on the followers, more cam = more lift and more throttle, they oddly do have a throttle body, but it’s only used in emergency if the wiper motor etc fails, strange but true!!
 
While I admire your efforts, you also have to sometimes bite the bullet and let someone who can properly diagnose the car have a look as currently you are guessing, I can’t imagine a throttle body was cheap, nor everything else you’ve done, it’s ok looking at it as you want to fix it yourself, but you and I are guessing as I can’t actually see what and how your engine is doing what it’s doing via parameters from a diagnostic pc...

As an aside... I used to love it when people came in work and...

a, told us what was wrong with there car, we did as they instructed and then got pissy when it didn’t fix it... erm... you told us what was wrong with it, don’t blame us if you got the wrong bit and it didn’t fix your issue

Or

b, they dropped the car off and we then said it would need a diagnostic at 42 quid and then we would let them know roughly what our first steps would be... and then they insisted on knowing what’s the most it would cost... erm, my psychic link with your car has failed today, so I’m not sure without looking at it... we had more than one customer take his car back because we said beyond 42 quid we weren’t able to say...
 
Yup i understand! Will take this info and fowrard to mechanic.

The thing is, I am not trying to fix anytging myself, the problem is that my mechanic had plugged in diagnosis device 3 times alrdy and it says it is all good.

The other day i went to other mechanic/mapoer, he did the same.

Device shows nothing is wrong with the car.

Both mechanics are now away for holiday.

The car is still nit working properly and i am desperate so i statrted guessing and asking around for opinions, so maybe somebody would be able ti tell ne a bit more closely. Currently all i got is crank sensor.

I would love for some mechanic to just tell me what is wrong so i can pay and fix. But nobody knows. Everyone gussing and the diagnosis devices show that everything is 100% good when obviously it isn’t which pisses me off for quite some time now.

Thx for all the time you invested @Dumdum
 
Mapper is not very good if he can’t work out what’s up with it...

Diagnostic devices can’t show all problems! Don’t get mad! Somethings will never show up, that’s when you need a good mechanic who knows the vehicle, but it being mapped will not help as that will potentially throw set values off and make them not read within tolerance, but, if you can show a mechanic they then need to start looking at things that don’t throw faults like crank sensor for example
 
Yep i get you, thx.

It is obviously mechanical fault, i will be going around mechanics until somebody finds out.

I can’t do anything else. I myself only add whiper cleaner liquid and pour petrol...

Meanwhile I got kw clubsport added as well as TL031 gearbox with quaife LSD, hoping that at same time errors would be found and fixed.

But now i missed 4 trackdays alrdy and i am at home rottening with car being parked in garage 99% of time.
F*** me, right? XD
 
Ok so I have the crank sensor replaced with new one, still all the problems are there. Got the car's electrics check out at professional mechanic for car electrics, and it all seems fine.

Tomorrow I will go to check further stuff, I got some input that there might be problem with cam sensor or vvt pulley, since tomorrow people come back from holiday and now I can continue with attempts to see what is wrong with the car.

I also got input that the problems I have with AC and idle/RPM drop to death, is actually caused by lightened flywheel. I also have lightened crank pulley. But this I doubt is the problem since a lot of folks have these mods for ages on cars an none of them have issues like I do. One friend even has these mods and his car was never even remapped (he also has akrapovic evolution and v6 airbox etc), and has no problems at all.

Will write here when I get some new input.
 
New cam sensor was placed today, the problem remains
-Crank sensor re-check / cleaned all related parts
-Compression check, all good
-Wiring / electrics all checked
-Engine timing/cams re-checked, all perfect
-All pressures good
-vvt solenoid good
-vvt pulley good
-And from before: new sparks in, new coils, new throttle body, map sensor new, new belts, water pump, filters all good, airbox clean

Next step is to check if the flywheel is faulty and giving the crank sensor fails.

One thing there is: sparks are wet and black, gas smells. Too much fuel in there obviously.
Given the above, could it be ECU / map?

From mechanical / electrical standpoint, we ran out of ideas.

Any thoughts?
 
if you have done all that then its the mapping (assuming its been mapped)....have they mapped it to chuck fuel in to get round the flat spot perhaps
 
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