VR V6 in VNs1, teething troubles

[savage1987]

Got an issue in my VN.. just put a VR V6 in it, fresh rebuild.. it idles fine, lovely even, but stutters under load. Seems to be dropping 1cyl under the slightest load.

All the ignition gear was used on the previous engine, same coil and DFI, same leads and plugs even..

I have tried 2 sets of plugs, an NGK 13 and an NGK 15, but no change.


Motor is stock apart from bolt ons.

Any ideas welcome, want this thing driving asap.

No fault codes

[Tocchi]

faulty injector?

[TJ]

CAS?

[Alt_F4]

If it was an RB id say it was an AFM issue(not plugged in or shagged), or coil amp not earthed properly.
Not sure if it applies in your case.

What about old shit fuel? or blocked fuel filter?

[yeahlow34]

Yeah I'd check the coil, and coil connections.

[stumps.]

you may need to get a tune, could be an issue with the old key matching up with the new engines computer. Harmonic balancer? Loose lead as mentioned above.

If it was a sensor or an injector there would be a fault code?

[joshg123]

Have you tried some new leads? And coilpacks. Grab a bank of coilpacks and swap em to test

These have problems where they will test ok (leads), and will break down under load.

Also coilpacks are common, covs sell them on their own, bout 53 each for genuine.

[joshg123]

you may need to get a tune, could be an issue with the old key matching up with the new engines computer. Harmonic balancer? Loose lead as mentioned above.

If it was a sensor or an injector there would be a fault code?

It wont crank if theft deterrant doesnt register a signal, harmonic balancer would throw crank angle sensor code

[savage1987]

faulty injector?
Hope not :s

CAS?
Don't think so, runs fine at any RPM when stationary. Smooth as anything, until it's in gear and some load is put on, then stutters from idle onwards

If it was an RB id say it was an AFM issue(not plugged in or shagged), or coil amp not earthed properly.
Not sure if it applies in your case.
What about old shit fuel? or blocked fuel filter?Got no AFM, MAP connections are fine.. Coil, leads and plugs ran fine on the VN engine 3 weeks ago, same ignition system exactly. Fuel filter is new enough, fuel only been sitting for 3wks.

check the coil, and coil connections.
Checked the earthing and tidied up all earth points for the DFI and coil packs, no change. Beginning to suspect damaged lead.

may need to get a tune, could be an issue with the old key matching up with the new engines computer. Harmonic balancer?
If it was a sensor or an injector there would be a fault code?
Tune is fine, running the VNs1 computer and memcal so no security shit, my tuner tells me it will work fine on the VR motor and he knows these engines backwards (greenfoam). The engine runs smooth as anything so don't think it's a problem with the HB.
No fault codes present, I think there would be if there was an injector problem.. any sensor will throw a fault. No codes for ignition problems on these engines so that's where my suspicions lie.

Grab a bank of coilpacks and swap em to test
These have problems where they will test ok (leads), and will break down under load.
Will grab a new set of plugs, leads and see if that changes anything.. otherwise yes I'll test another coil pack. Running a slightly higher plug gap last night for a while may have been enough to burn a coil... unlikely, but possible I guess.

[Alt_F4]

Ah one more to try, check your normal battery earths ie battery to chassis, chassis/battery to engine block etc.

[savage1987]

Cheers will do

ps this forum is awesome. SC has had 0 responses in the same time, and JC has had a few but not this variety of ideas

[savage1987]

have changed over entire ignition system. coil packs and DFI replaced, plugs and leads replaced with new

also changed the MAP for good measure

still splutters

worse now, does it free revving too

[bulkos]

fuel ..... are both ur fuel pumps ok?, shite in the filter?,
I had dramas with my old vn 5.0, fine at idle but stuttered under load, after going through ignition which ended up all ok got a new pump, all good. Cant remember if i replaced the lifter pump but..

[savage1987]

That would be an annoying problem... V6 only has 1 fpump. I don't know the condition but ran fine 3wks ago, filter not old at all

I will replace the TPS as unplugging it seemed to enhance the problem that I have, so if that doesn't fix it I will start looking at fuel

[Bazelinez]

something to with the auto?

as you say its fine stationary, ie neutral or park.


Are VNs electronic autos like the VR?

[savage1987]

I had that thought also.. it's not fine stationary any more. Can't hold 1500 in neutral/park without stuttering

fyi VN autos are cable controlled, moved to electronically controlled in VR

[stumps.]

i still think its a computer - engine compatibility issue. For the person that said it wouldnt start i know with an ls1 at least that it will run but wont drive if there is a computer compatibility issue.

Also your computer could be trying to learn the new engine so do a cpu reset. DIsconnect the batery for half an hour then start it up fan and aircon on full then shift it through the gears. i think there is a mopre exact method somewhere.

[Butcher]

Ive got another engine+ all accessory's you can buy cheap cheap if that one goes to hell

[vnformula]

give justin at BYE performance he will be able to sort it, plenty of experiance with v6 conversions 0438944648

All the vacuum lines hooked up correctly? MAP hooked up properly? could be a fuel issue, check filter and maybe try different pump.

[savage1987]

hahaha this one is a fresh rebuild, it had better not go to hell

stumps, I think the reset on a VN is 3000rpm for 15sec after battery disconnected

we did that before.

The VN computer and loom are used here - all electronics and wiring are from VN. Just the engine hardware itself is from a VRs2. People have run this setup before with no compatibility issues. **jealous**

[RRob]

It's not something like different size injectors?

[savage1987]

stock VR injectors.

[Bakerboy]

i would say sounds like a fuel problem of some kind

[savage1987]

post disproved

[savage1987]

It was the fuel pressure reg

Problem solved, mine was bent
replacing tomorrow

[Bakerboy]

told u it was a fuel problem

[savage1987]

Indeed you did.. my reg was bent and jammed. prick of a thing.