VR Series 2 Engine conks out when cold

[zukernet]

Hi All,

I have a VR Series 2 engine in my Hilux. Has run reasonable well for a few years with no major issues. Until now.

Cut a long story short, i had my mechanic change both engine mounts and put in a new clutch as they had failed.

After this, within approx 10 minutes of driving the engine just "coughs" or stalls. This only happens within the first 10 minutes of driving so i am guessing its a fault related to engine temperature.

If you are cruising along the tacho goes to zero and the engine coughs and plutters, sometimes misfires and backfires and then it just comes good. Its like its going from open to closed loop.
If you let the engine idle and warm up for about 7-10 minutes there is no problem. For the first 10 minutes of driving it feels like its really held back, almost like the handbrake is on.

Unfortunatly the bright spark that wired it all up didnt wire in a diagnostic light so its a little blind with no fault codes.

It only happens when the engine is dead cold. Once it has warmed up it seems to be fine.

I did find that the Knock Sensor had a wire broken on it so i have replaced the wiring but it didnt fix it. I even installed a customer Stage 3 Memcal and it didnt make a difference (had one in the shed spare). I have also replaced the oil pressure switch and didnt fix it.

The only thing that i have noticed is the mechanic has installed a connector on the O2 sensor wiring. He did comment that there was no way to remove the exhaust unless he cut the wiring to the O2 sensor. There only seems to be 2 wires going to the O2 sensor and there is only 1 O2 sensor. I am only guessing that its going from open to closed loop on the program and when it does this the O2 sensor, if faulty, is giving poor or incorrect readings.

Its hard to say if the fuel consumption has been effected as it has always been thirsty and i really havent taken any notice.

I guess starting with replacing the O2 Sensor might be a start.

Anyone have any other ideas?

Cheers

Danny

[astormsau]

Hi Danny
O2 sensor would be a good start. Does the ECU side of the loom have 4 wires, if so I would suggest replacing with the correctly wired unit would be worthwhile... however the heater unit shouldn't cause your problem as the car will just run open loop for longer until the o2 sensor comes up to temp, you could find that the o2 sensor is never coming to temp if you have an aftermarket exhaust as it runs cooler. Also the o2 sensor could just be shagged due to its age.

The other place to look would be at the IAC valve, I would suggest removing and cleaning the throttle body and IAC valve passages as the IAC is used to control idle and could be sticking / malfunctioning causing the car to stall/idle erratically,etc... there is a tutorial on here which details how to clean the throttle body... will take about 30 mins and cost $12 for a can of throttle body cleaner.

Drew

[zukernet]

Hi Drew, Thanks for the reply.

Will check the O2 Sensor wiring. I am leaning towards it being stuffed and when they removed the exhaust etc it has probably disturbed it. It has always run extremly rich on idle so me thinks that its only a 2 wire sensor with no heater. Makes good sense.

Another interesting fact is after i have put in the Stage 3 memcal, it now wants to rev at 2000rpm all the time. Might have to try a reset of the ECU and see if that fixes it.

Cheers

Danny

[astormsau]

Hi Danny,
Even if the o2 is stuffed, the car will run in open loop mode and although it will run rich it shouldn't cause stalling. I am guessing with the VR that the single o2 sensor controls both banks of the engine... on a vs it has 2 seperate sensors and I expect that when one o2 sensor goes the engine runs rough due to one side running rich and the other running lean causing a bit of an imbalance.

I would highly recommend looking at the throttle body and IAC valve, I think there is a high chance they could be the source of the problem, ie throttle body butterfly sticking open or the IAC getting stuck.

Drew

[Brett_jjj]

02 sensors wont cause stalling.Id be looking elsewhere.If it only just started doing it after the work was done on it,then Id be looking for a wire thats been knocked off or something along them lines.Also as mentioned above,clean the throttle body and the IAC valve itself ,also make sure you get into the IAC passages in the throttle body.

[zukernet]

Thanks for your help guys. I have just done some further testing and it seems that it isnt the O2 sensor. But i have replaced it anyway.

I have also removed the throttle body and cleaned it and clean the IAC. It still does it.

But, it will only do it once. Have its little spak attack or coughing fit and then its fine.

The engine warms up and once it hits it running temp it coughs and splutters and then gets going again.

Very strange indeed! It also could be a coil pack and when it gets to a certain temp it plays up. Think i might go and get some coils.

Just found the wiring diagram for the diagnostic connector so i will be also getting a lamp and a switch for that. Might make life a little easier!

Cheers

Danny

[James39]

Have you checked your leads and plugs? could even be dirty injectors

[zukernet]

Hi All,

Have had a few developments today. Well not really good but anyway. New leads and plugs and replaced coil back and backplane. No different. Maybe the crank angle sensor is the fault???

I have found that a light that comes on whenever the thermo fan comes on, is actually the diagnostics light. Unsure why the light comes on when the thermo fan does, but anyway.

So i then found the connector behind the ECU, the little 6 pin one (strange cause i thought this was a VR motor) anyway i bridge it out and turn on the ignition, the lamp comes on and so does the thermo fan, but they just stay on?

Any ideas?

I as thinking that seeing it is a standard lamp/bulb it may be having an issue, maybe if i wire in a led instead it might be better?

Or, how can i wire in a new lamp for this using the 6 pin connector? is it just pin e (check engine light) to ground?

The plot thickens!

Cheers

Danny

[zukernet]

Also, now that i am concerned that it may actually be a VP motor? is there any easy way just by looking at the engine to tell if its a VR or VP engine?

Cheers

Danny

[Brett_jjj]

The pins to bridge for flashing up ECU error codes on the 6 pin aldl connector is pins A and B.Check out this link to see which one is which..
---http://www.techedge.com.au/vehicle/aldl160/vn_aldl.htm---

[James39]

The pins to bridge for flashing up ECU error codes on the 6 pin aldl connector is pins A and B.Check out this link to see which one is which.---ALDL Information for the VN & VP Holden Commodore---

Not sure that helps if the motor is in a Hilux?

[Brett_jjj]

Not sure that helps if the motor is in a Hilux?

The ECU wiring should still have the diagnostic connector there somewhere near the ECU wiring connectors if the original wiring harness was used.Anyway he said he's already found the 6 pin aldl connector near the ECU,so what are you on about.

[zukernet]

Thanks guys, yeah just confirming that i have found the 6 pin aldl connector. Bridging pins A and B with a paperclip just make the check engine lamp stay on and the thermo fan stay on.

Danny

[delcowizzid]

what sort of tunes in the ecu if its a vr tune in a vn-vp ecu and loom it may not do codes properly

[zukernet]

I really am unsure of what tune is in it. Is there anyway i can tell by looking at the memcal? The ecu has VN Manual written on it?

A mate of mine has one of those code scanners and we will plug that in tomorrow at his workshop and see what shows up.

I wonder of the VN-VP and VR harness is the same where the 6 pin connector is still there along with the other 16 pin connector? Can seem to find the 16 pin connector and i am guessing it would of been removed when the engine was transplanted.

[delcowizzid]

vn only has that one connector vr only has the other connector pull the lid off the memcal and see what code is on the silver sticker on the chip inside

[zukernet]

Ok guys, here is an update.

Finally got the engine check light working. Turns out it actually is a VP commodore engine!

Codes that were present are 42, 21, 22.

42 was easy, was the DFI unit. replaced it and that one went away. seems like it was stuck in "module" mode or limp mode with this one, explains the poor performance.
21/22 TPS sensor. did some wiring checking etc and found that it actually is the sensor that is faulty.

New TPS on order and will let you all know once its in and running.

Thanks to all for your assistance. Will see how it goes when there is no codes. Engine check lamp is on all the time with the fault thats there now.

Cheers

Danny

[zukernet]

ok looks like there is still an issue. even after replaing the DFI it ran ok for a while and now it comes up with the check light and well code 42 again.

i will check the wiring at the ecu and the dfi and see if these pins are loose. i guess if they are i can try and tighten them back in and maybe use a small conductive grease to keep them in contact. then again a good hit with some contact cleaner might fix it, or the dfi may just be a little dodgy!

will be an interesting day