is my engine on its way out? or is it the computer?

[Jezza]

Problem 1: my car is running rough first thing in the morning (sounds lumpy when reving it a bit) but it will be cured by reving it upto 5k rpm which i dont want to do every morning

Problem 2: now im filling the car up with BP Ultimate and have been doing so since it was registered on the road 5 weeks ago and im only getting 200kms in 1 tank and this weeks tank is looking like only 130kms from full

Problem 3: i have recently bought a 2.5 inch catback and its now as black as hell on the inside and the back of my car has black spots appearing on it

now i have no idea where to start and what could be wrong being my first car but after i told my mechanic he made a adjustment on the fuel air mixture but that hasnt worked so im asking here if anyone has an idea if maybe the enigne is on its way out (only done 180,000kms on the dash) or if the computer needs replacing

[VL Berlina 5speed]

ruff at the start,
when was the plugs last changed? might be a little gummed up and when first starting it you notice it as they havnt burnt any crap off


excessive fuel try the afm first

1. Air flow meter: check the connections including rubber boot, clean with contact cleaner if necessary. remove the airflow meter (undo the clamp behind it and remove the top of the airbox and air flow meter together) and clean using contact cleaner or some other cleaner thats safe on electrical components. clean out the airbox and replace the air filter if necessary ($10 for a cheap one, $100 for K&N) reinstall everything

if the car is stalling after starting or seems to be choking still after this, check AAC valve, air regulator, make sure there's no air leaks, then replace the air flow meter ($20-$60 from wreckers, approx $150 reconditioned, about $400-$600 new)

TO CHECK AND ADJUST MIXTURE:
1. start and run the engine until its at operating temperature
2. set idle speed and timing to specified values
3. take off the passenger kick panel to view the LED's on the ECU
4. start and run the motor at 2000rpm for 2 mins
5. check the flashes from the LED's on the ecu while at 2000rpm, they should both flash together more than 5 times every 10 seconds. if they don't you have ecu or oxygen sensor issues (refer to the picture at the bottom explaining the interpretation of flashes other than what are stated)
6. if there are more than 5 flashes per 10 secs, stop the engine, disconnect the wiring connector from the AAC valve and the throttle switch
7. start and run the engine at 2000rpm for 2 mins
8. let the engine idle
9. the leds should now flash simultaneously
10. if the green light is flashing more the mixture is lean, if the red is flashing more the mixture is richer than it should be.
10. if the LED's do not flash together remove the plug next to the Air flow meter connector and adjust the screw until they flash together (clockwise raises the resistance and leans the mixture, anti clockwise lowers the resistance and richens the mixture)
11. replace the plug, replace the AAC and throttle switch connectors and return to instruction 4. do the test again to check that the mixture is now right
12. if the mixture cannot be adjusted so that the leds flash together, its time to test the AFM

TO TEST AFM:
pull back the rubber boot on the AFM connector revealing the wires. grab your multimeter and stick the probes on wire 4 (white) and 2 (1 being the closest to the airbox) with the multimeter on DC voltage. turn the ignition on and the voltage reading should be between 1.26V (lean) and 1.32V (rich). this is the base setting and if it is out then the AFM wont be able to be adjusted to a satisfactory mixture (meaning you need a new one)

and just for interests sake you can test the mixture by putting the probes on wire 1 and 3 with the key on and measuring the voltage. 3.6V is the factory setting which is lean, with 2.0V being rich. the mixture should be in the vacinity of 2.0-4.0i couldn't get the LED's to flash and therefore couldn't set it using the computer so i did it this way and set it to 3.5V (AFM resistance of 375 ohms) and then checked it using the computer and it was right, LED's flashing together.

[harry3]

if the engine is a 6, you need to turn ign on and wait for the fuelpump whine to stop, then with foot off the accelerator, a short run of the starter motor should start it

the engine runs rough for a while if you dont wait as the injection doesnt have enough fuel pressure

[Jezza]

the spark plugs where replaced when we gave it a service after i got it but i will do that test when i have some time on tuesday

[Jezza]

well ive found that problem 1 was me forgetting to let the fuel pump whine stop before i started the car and im going to get the other problems fixed tomorrow hopefully

[Goon]

ask ur mechanic if he did the timing too, thats another issue u might want to look at.. just a thought!!!

[Jezza]

cool thanks for the help and hopefully i will have a better running vl soon

[jatsvl]

well ive found that problem 1 was me forgetting to let the fuel pump whine stop before i started the car and im going to get the other problems fixed tomorrow hopefully

getting in the car and starting it straight a way is not the problem, there is no reason for you to wait for the fuel pump to prime unless there are other underlying issues, the vl should start on cold without pause no worries it has a pressurised fuel system.
you should never rev a cold engine past 2k when starting, and you should not have to touch the accelerator until the car is in gear and you are ready to drive away.
a workshop manual will tell you how to test the fuel and engine management system to find your problem e.g. oxygen sensor, air flow meter, fuel pressure regulator, idle air controller etc.....

[Jezza]

Well we have adjusted the setting and we did this test (below) and the voltage was 3.4 so it was running VERY RICH so we have now adjusted it to 1.29 and we also changed the computer do the spare one it came with which was a genuine vl computer and the pictures below are the one we pulled out and i suspect it was from a R31

TO TEST AFM:
pull back the rubber boot on the AFM connector revealing the wires. grab your multimeter and stick the probes on wire 4 (white) and 2 (1 being the closest to the airbox) with the multimeter on DC voltage. turn the ignition on and the voltage reading should be between 1.26V (lean) and 1.32V (rich). this is the base setting and if it is out then the AFM wont be able to be adjusted to a satisfactory mixture (meaning you need a new one)

[HoldenOnn]

Many many things that it can be. You have to narrow it down. Sounds like the CTS (coolant temp sensor). If your mechanic has been around a while, he will have seen many vls and he will know all the things to check for when you drop the car off. Many items it could be and any long time mechanic should have seen a few vls by now.

[detox_nath83]

as well as O2 sensor can cause car to run rich meaning more fuel consumption, AFM settings like 5Speed has stated and CTS 3 majors to check. Have you checked for any moisture along your fuel lines etc. leaking/loose hose clamps... pin hole in steel lines from tank and return line.
Goodluck
keep us informed

[Goon]

lol looks like a skyline ecu??? i never seen that label on vl ecu's.. maybe the ecu is giving u problems???..

[Jezza]

yeah as i said in my post we have changed the ecu to a one that came (previous owner couldnt get the car to start and replaced alot of things including the ecu and the one in the picture is the original one he found in it) with one that he bought for it but it wasnt needed which is the correct one but it was also the mixture setting which instead of running between 1.26 and 1.32 volts it was running at 3. something which is over double

[Goon]

Fair enough mate, aslong as u got both lights flashing togthere on the ecu, everythings sweet!!

[Tasmaniak]

Another thing to throw into the mix is the Fuel Pressure regulator...sounds strangely like this also...

[Jezza]

well i think ive sorted the problem because i was told that the car uses more petrol till it warms up and my work is only about 10 minutes away so i get to work just as the car has warmed up

[LiamVK]

i only get about 250km from a tank. just went and checked my AFM and got the reading of 10 volts on wires 4 and 2 and 0.01 on wires 3 and 1. i also have alot of black on my bumper and get a regular smell of fuel. will be getting a new afm tomorrow. i have replaced the coolant tempt sensor also. any ideas of what is wrong or anything to help me get better economy.
sorry to hijack the thread a bit.
thanks

[Tasmaniak]

do people actually check their o2 sensor anymore for issues? Thats the best way to see if your running rich or lean.

[nasty1]

well i think ive sorted the problem because i was told that the car uses more petrol till it warms up and my work is only about 10 minutes away so i get to work just as the car has warmed up

i highly doubt thats gona be causing your exsesive fuel consumption

[seans VL Calais]

yeah that def isnt it mate, my work is about 5 mins away and i drive there everyday with car cold and i get 400ks to a tank. and yeah the car does use more fuel when cold but not enough that you are going to notice it that much.

[Jezza]

well after reading through this good info on VL not posted here for quite a while i think it is the oxy sensor so im buying one today from motor traders and will install it tomorrow and hopefully notice a difference in the fuel consumption

[Tasmaniak]

by the socket to go with it and plenty of penetrating spray.

Have you actually measured the o2 sensor?

[Tasmaniak]

and look that may not be the problem either! If then engine is not going into closed loop mode that will use excess fuel.

[detox_nath83]

but the o2 sensor also tells the motor/ecu to go into close loop mode etc etc...and vise versa by measuring oxygen/heat/gasses/ yada yada.. :P

[Tasmaniak]

actually it doesn't. all it tells the computer in that regard is if the o2 sensor is hot enough to operate efficiently enough for the vehicle to go into closed loop mode. What tells the computer to gointo closed loop or not is the ECT and the TPS.

First things first...stop pumping in hi octane fuel...it ain't helping you. it's only hurting your pocket. Here is my suggestion mate... Before dropping the bills on an o2 sensor. Go and buy yourself a cheap multimeter. Switch ito Volt DC and have it on a setting somewhere be 2Volts and 20Volts. Now, put the black probe onto the negative of the body and force the red one deep into the middle pin of the plug coming out of the o2 Sensor (where it connects ot the main loom.) Now, start the car...this wire will be reading somewhere .0 and point .2 of a volt. within 60 seconds but maybe as long as 5 minutes dependant upon sensor you will see that voltage go up...then it's going to go down...then back up....then back down... catch my drift? It should go upto about .7 and back down to around about .3 and it will go each way about on every two seconds dependant upon sensor. Now if it goes to a certain voltage and really doesn't change at all then we now know the engine is in open loop mode. It shouldn't be there while it's idling...or while it's cruising. It should be in open loop under heavy acceleration and warm up...thats about it.

A breif run down on the voltages...

The o2 sensor works like a small battery in that it is unpowered...it creates and sends out it's own electricity. It operates between 0 volt and 1volt. Well actually not quite but pretty damn close so we won[t go into it.

A reading of over .8 indicates a rich mixture
A reading of under .2 indicates a lean mixture.
.45 is stoichiometric

Closed loop mode is when the voltage fluctuates between .3 and .7 volts. You WANT the car in CLosed loop. Open loop is great for wawrming up the car and getting more power out of the engine during heavy acceleration as it creates a rich mixture condition. Do that and let us know how it goes. we can further diagnos the issue from there....just somehow I don't think it's the o2 sensor. It would be interesting to see where the Long Term Fuel Trim has set itself to on your car mate.