Manifold glowing red

[modcon]

Does anyone know what causes a VN 3.8 to run rough and the exhaust to
glow red after idling for 30 sec at 3000rpm?

[253@7k]

30 seconds at 3000 rpm, thats what makes it glow. That would get very hot with no air flowing over it.

Did the buic 3.8's ever run smooth? Running rough is a broad term, is it missing or just idling like cr*p?

[modcon]

It was running sweet, then I changed the CAS, and the coil pack, then it run rough backfiring ect... so I put the original coil pack back on and still rough.
I have tryed a brand new coil and DFI but still running rough. It probably in the wiring somewhere, I have tryed all the common problem areas

[253@7k]

I would be going with spark plug leads.

[Shortstuff]

I know it sounds pretty obvious, but all the HT leads are on in the right order after changing the coil pack? Very easy mistake if all the leads are off at the same time!

[modcon]

new spark plugs, new leads and the leads are on in the right order, I've checked numerous times, the manifold is glowing in just one part of the join, I'm wondering if there is a leak

[commy92]

ide say more of a blockage. stock manifolds should not glow

[HATER VP]

Burnouts or dyno run

[jules]

ide say more of a blockage. stock manifolds should not glow

at a guess i'd agree. a misfire won't cause the manifold to glow. take your cat off and shake it, if it rattles apparently that's a sign it's history. you can look inside a bit with a torch as well.

[bush_basha]

yes i would 98% say its your cat, i have a V8 and it wasnt reving over 3-4 took it to the mechanics, they noticed the glowing of the and fixed it.

[modcon]

Sorry for my ignorance, but what is the cat short for, and where do I locate it. If you mean the cat converter it doesn't have one, it is running straight pipe with two coby's, the manifold on both sides was taken off when we done the engine change if that is any help

[Patrio7]

the cat is normally located at the bottom of the manifold just after where it joins, even with an upgraded pipe the car should still have a cat

and yes cat = Catalyic Converter

[AirStrike]

Since you have some dodgy pipe going on, by any chance did you put the O2 sensor back on?
AirStrike

[modcon]

The New Zealand VN didn't come out with the O2 sensor

[commy92]

errrr??? hmm

[AirStrike]

Hmmmm I know they dont run a cat, but how can it not run an o2 sensor? Its a crucial part of the efi system.
AirStrike

[modcon]

I discovered about 6 months ago when I brought a chip from blackstar (E bay), I had the fault light come on(code44 O2 lean) then after investagating the O2 sensor I discovered the NZ vn didn't have one it has a different set up, it has a O2 loom system, the NZ VP came out with the O2 sensor... I know Kiwis should just stick to rugby and leave Holdens to the Auzzies. I have just brough a VP so I'm going to take the VN into Holden to get it fixed and then flick it off(after I change the lowering system and mags over of course)

[jules]

i don't see how it cannot have an O2 sensor. as Airstrike said its the fundamental control point of an engine mgt. system. it's like saying it doens't have pistons.

[AirStrike]

i don't see how it cannot have an O2 sensor. as Airstrike said its the fundamental control point of an engine mgt. system. it's like saying it doens't have pistons.

Yep! I still think this is your problem, all EFI vehicles run an O2 sensor.
AirStrike

[modcon]

Trust me - the New Zealand VN didn't come out with an O2 sensor!!! Holden New Zealand has confirmed this, I have had a look at over 20 VN's in the last three months to see if any of them have the sensor, none of them do they all have a bung in the place the sensor should be. I know it's hard for you guys to understand as every Auzzie VN came out with the sensor, do a little research and you will find this information is accurate. As for me iv'e had enough of the VN that's why Iv'e brough a VP

[immortality]

he is correct, the new zealand Vn's were never fitted with o2 sensor/ CAT. mine doesn't have them either. the way it works is that the ecu works in "open loop" mode, just like your VN's, the ecu doesn't use the signal from the o2 sensor until it has reached operating temp whne the ecu is using the signal from the o2 sensor it is considered to be in "closed loop" mode. the ecu uses the signal from the o2 sensor to modify the base fuel map that holden put in your memcal, basically it makes adjustments for the variation in the day to day weather conditons i.e. air temp, humidity, pressure etc. the ecu basically only operates in "closed loop" mode when your cruising and all it's really doing is leaning out the A/F ratio for economy. when you mash the go pedal through the floor it goes back to "open loop" mode to protect the engine i.e. it runs richer to stop detonation etc.

the question i have is, why is it idling at 3000rpm??? is the engine check light on when the engine is running, read some of the other forums on howto check this, did you seperate the coil pack from the DFI module??? if so you may need to check that the connections are correct between the 2 units or otherwise borrow a known good unit from another vehicle (your VP maybe???) clean the throttle body with some carb cleaner especially the IAC valve, check the vacuum hose that runs from the back ofthe TB to the MAP sensor, replace if it looks suspect, i.e. cracking etc

whats the car like to drive, is it guttless, does it idle high when driving??? is it an auto or manual??

[modcon]

The car is not idling at 3000rpm, it idles 1000rpm, I have already tried a coil and dfi from a VP, still the same, I have had the throttle body and sensors changes, I havn't put carb cleaner in though. The hose between the throttle body and map sensor is sweet. I'll try some carb cleaner tommorow and let you know, FYI when I idle the car has an air bubble sound that goes through the exhaust like popping.

[AirStrike]

The car is not idling at 3000rpm, it idles 1000rpm, I have already tried a coil and dfi from a VP, still the same, I have had the throttle body and sensors changes, I havn't put carb cleaner in though. The hose between the throttle body and map sensor is sweet. I'll try some carb cleaner tommorow and let you know, FYI when I idle the car has an air bubble sound that goes through the exhaust like popping.

The noise sounds like a miss. Check the leads and plugs. See if any plugs are fouled.
AirStrike

[modcon]

Dude new spark plugs and leads, I would tend to think this is eletrical

[immortality]

pull all the plugs, does one look different from the others? they should have a light tan look to them. if ones black it indicates that cylinder is fouling, likewise if one is very white it indicates that cylinder is lean( do this when the engine is hot). check all the gaps the same, i've had a rough running engine and found one spark plug gap was considerably smaller then the others, i was being lazy and didn't check 'em when i put them in straight from the shop. one of my mates had a prob with the engine runnign rough, pulled it down, couldn't find anything wrong with it, put it all back, still same prob in the end they found the damper in the fuel line after the fuel pump was stuffed and the fuel pressure was high..... one other thing to try is to check the injectors, when the engine is running, put on some earmuffs, get a long screw driver, put the sharp end against each injector in turn whilst holding the handle to one of the muffs, you should hear a ticking noise as the injector fires.... no ticking = faulty injector. run some injector cleaner through if this test fails to find anything you may just have a clogged injector???? you may need to pull the injectors out and have them cleaned proffesionally