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Who Wants To Play Detective

sanger

By sanger,
in Engines & Forced Induction

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sanger Community Regular

sanger

Posted
Posted

OK for all you budding or wannabe mechanics see if you have any ideas on this one..... even if they seem obvious im open to any suggestions!!!!

My car doesn’t idle properly

It hunts when stationary and sometimes goes close to or actually does stall when you lift off the throttle. The faster you lift off and the slower you are going the worse this is.

Its running rich

At the moment it is going through a full tank in 200km as apposed to the usual but not much better 350ish. This seems to be only intermittent though as sometimes you cant see any black smoke and other times there is heaps. By heaps I mean more than the usual skyline running rich on boost from factory.

It is not boosting up properly

It usually has positive boost by about 2500rpm but at the moment its not getting positive boost till more like 3000rpm to 3500rpm. It sounds like the turbo wastegate is opening early and bleeding off boost to early as you can hear the turbo spool up but nothing happens until later in the rev range.

It is down on power all through the rev range

Im sure this is quite obviously linked to the turbo problems.

I have reset the ecu but this had no effect on any of the above problems.

I have also had the air flow meter cleaned,the compression checked and im sure a few other things checked that i forget.

As far as mods go it has a turbo back exhaust, pod filter, front mount although still running standard boost as the next step was to wind the wick up a little but that seeems kinda stupid at the moment given the way its running. factory computer, no boost controller.

Any help would be much appreciated ;)

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R33GOD Grand Master

R33GOD

Posted
Posted (edited)
OK for all you budding or wannabe mechanics see if you have any ideas on this one..... even if they seem obvious im open to any suggestions!!!!

My car doesn’t idle properly

It hunts when stationary and sometimes goes close to or actually does stall when you lift off the throttle. The faster you lift off and the slower you are going the worse this is.

Its running rich

At the moment it is going through a full tank in 200km as apposed to the usual but not much better 350ish. This seems to be only intermittent though as sometimes you cant see any black smoke and other times there is heaps. By heaps I mean more than the usual skyline running rich on boost from factory.

It is not boosting up properly

It usually has positive boost by about 2500rpm but at the moment its not getting positive boost till more like 3000rpm to 3500rpm. It sounds like the turbo wastegate is opening early and bleeding off boost to early as you can hear the turbo spool up but nothing happens until later in the rev range.

It is down on power all through the rev range

Im sure this is quite obviously linked to the turbo problems.

I have reset the ecu but this had no effect on any of the above problems.

I have also had the air flow meter cleaned,the compression checked and im sure a few other things checked that i forget.

As far as mods go it has a turbo back exhaust, pod filter, front mount although still running standard boost as the next step was to wind the wick up a little but that seeems kinda stupid at the moment given the way its running. factory computer, no boost controller.

Any help would be much appreciated ;)

check/ change the air flow meter first oops didnt see that u typed it but it could be

Edited by R33GOD
paulr33 Grand Master

paulr33

Posted
Posted

intercooler pipework leak

causing some pressure in the manifold to be lost to the atmosphere, gives it a bit of a laggy feeling. its stalling or struggling as some pressure and air is leaking out, so its over rich.

the bad economy could be the same problem or it could be your 02 sensor is shagged. the die and only last about 50,000 k's so chances are you have never changed it, so do that and it should fix your economy.

sanger Community Regular

sanger

Posted
  • Author
Posted

Thanks for the heads up guys im open to more suggestions as this one's got me stumped. We did clean the air flow meter. but haven't checked the 02 sensor.... Excuse my ignorance but were abouts is this? do you mean the one in the exhaust???? or is there another in the manifold or something???

sanger Community Regular

sanger

Posted
  • Author
Posted
yeah the 02 sensor is in the exhaust dump pipe

3 wire sensor

its used for fuel economy and correcting rich mixture

Yeah thats one of the on the list of things to try that we havent got to yet!!!

Thanks paul

Anyone else got any ideas?????

Try swapping computers maybe???? By this i mean to another stock one.

sanger Community Regular

sanger

Posted
  • Author
Posted
Check your IC pipes again - thats your problem.

Thanks for your 2cents... will check em again tomorrow but we did go over all the joins with soapy water to get some bubbles showing to no avail...... Its starting to s%#t me though so ill try anything!!!!

sanger Community Regular

sanger

Posted
  • Author
Posted
it wont be the ecu

it doesnt wear out or forget

Yeah just heard a few stories of older cars getting electrical gremlins!!! After all the old 89 r32's aint spring chickens no more!!!!

Thought i would be a waste of time im just trying to think of everything. Funnyly enough me not being a mechanic means the most logical explinations dont always come to my mind first!!!!

thanks again for the input guys!

BH_SLO32 Proficient

BH_SLO32

Posted
Posted
Yeah just heard a few stories of older cars getting electrical gremlins!!! After all the old 89 r32's aint spring chickens no more!!!!

Thought i would be a waste of time im just trying to think of everything. Funnyly enough me not being a mechanic means the most logical explinations dont always come to my mind first!!!!

thanks again for the input guys!

A classic sign of a faulty O2 sensor is hunting when the car is idling. Judging by your poor fuel economy this would also support a faulty sensor. To test if it is the O2 sensor, simply disconnect the O2 sensor next time the car hunts and see if the idle stabilises.

Hope this helps

sanger Community Regular

sanger

Posted
  • Author
Posted
A classic sign of a faulty O2 sensor is hunting when the car is idling. Judging by your poor fuel economy this would also support a faulty sensor. To test if it is the O2 sensor, simply disconnect the O2 sensor next time the car hunts and see if the idle stabilises.

Hope this helps

Thanks again guys!

Will be checking all these options tomorrow hopefully. Ill post if anyone wins with their diagnosis.....

keep anymore ideas coming though however stupid!!!!

sanger Community Regular

sanger

Posted
  • Author
Posted
My money is on a leaking BOV. I bet you have an ATMO bov and it is leaking :happy:

Ha ha... good thought but i dare not partake in such foolishness when the factory one is more than capable and one less thing to get deffected for, also they make enough noise standard i and my car is loud enough as it is!!!

There could be a problem with the the temp sensor f%^ked and then the ecu thinks that it needs to go on to cold start enrichment!!!

It will kill the fuel econ and when hot it will be to rich and be flooding!!

Just a nother place to look.

Thanks again for the idea but i think we can rule that one out as it seems to run the cold start up mode ok and it idles fine in this mode, all be it at about 1100rpm. Then settles down to its hunting on idle shennanigans after the car has warmed up so i think the cold start must be off after that..... Good idea though and one i'll investigate further if the others come up with no results!!!!

:wub:

blind_elk Grand Master

blind_elk

Posted
Posted
Thanks again for the idea but i think we can rule that one out as it seems to run the cold start up mode ok and it idles fine in this mode, all be it at about 1100rpm. Then settles down to its hunting on idle shennanigans after the car has warmed up so i think the cold start must be off after that..... Good idea though and one i'll investigate further if the others come up with no results!!!!

:happy:

Engine will start and run fine from cold because that is what the sensor is telling the ECU. However, if the sensor is shagged, it continues to tell the ECU that the engine is cold, despite the fact that the engine is actually up to temperature. When the engine is hot, it doesn't run so well when the ECU is dumping sufficient fuel to keep a cold engine running.

It's certainly worthy of consideration in your quest for a resolution to the problem.

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