VN 3.8 Engine Misfire

[TimmyVn]

Hey all.

Just recently i got a new second hand replacement DFI/Coil pack for my '89 VN, because the last one died. The car worked fine for a few weeks or so, then sudenly it was slightly hard to start and misfiring when lightly accelerating and going past 70k's or so. I was told to replace the DFI/Coil pack again, but someone said that the Fuel pressure regulator would cause that... im not sure.. does anyone know of this problem or know anything else that could cause this?

Cheers Tim

[Not_An_Abba_Fan]

How are your leads?

[sawychri06]

yea mate i would get a cheep multimeter first so u can eliminate that

[nathanVY]

my VR V6 is missing too, just replaced plugs and leads today. bought a new coil pack and tested it in each slot, missed everytime.

what could it be?

[TimmyVn]

Hey thanks for you replies, my leads seem to be in good condition, high performance ones were put it before i bought it. Im not sure about them

[TimmyVn]

yea mate i would get a cheep multimeter first so u can eliminate that

Yeah, i bought one the other day, but i.ve only used it to read the Tach, how do i go checkin them?

[TimmyVn]

my VR V6 is missing too, just replaced plugs and leads today. bought a new coil pack and tested it in each slot, missed everytime.

what could it be?

Weird ayy... My uncles a mechanic, he asked me the other day if its a rough start, and sometimes misfires... at that point it was running rough but no misfiring.. he then told me to buy a replacement Fuel pressure regulator, cuz sometimes if it wears out it doesnt regulate the pressure properly, on start up, and/or acceleration underload... i didnt really take much notice and havent spoken to him since but im thinking it the regulator... but ive got no idea about it... i probs give him another call, ill let you know if it changes anything.

[sawychri06]

Yeah, i bought one the other day, but i.ve only used it to read the Tach, how do i go checkin them?

take 1 lead at a time off and put the red and black points in either end. u should get a reading of between 3.?? on the shorter leads and anything upto 8.?? or 9.?? on the longer leads. with mine i tested it after i had a missfire and found leads 3 and 6 where dead i knew that because the lead tested ... on the multimeter meaning its effed. but i just went and bought a new pack of leads fixed the prob. i cant remember what reading it was on i think it might have been 200,000 or 20,000 on the multimeter setting
hope that helps

[nathanVY]

Weird ayy... My uncles a mechanic, he asked me the other day if its a rough start, and sometimes misfires... at that point it was running rough but no misfiring.. he then told me to buy a replacement Fuel pressure regulator, cuz sometimes if it wears out it doesnt regulate the pressure properly, on start up, and/or acceleration underload... i didnt really take much notice and havent spoken to him since but im thinking it the regulator... but ive got no idea about it... i probs give him another call, ill let you know if it changes anything.

yer sounds alright, ive got no idea what/where that is lol, let me know.

[TimmyVn]

No luck, the regulator, wont cause the problem... im going to replace the plugs and the leads and see what happens... thanks for all your help.

[sic308]

i have a vg ute and it runs rough as guts and missis alot under load dose that soound like your problem? iv replace all plugs and leads put a new fuel pump in and injectors. new head gaskets and vally but still dose it. any ideas?

[delcowizzid]

my vn did the same thing was the cas on the way out would drive ok untill really sinking the boot in and it would cough and fart i replaced dfi coils and numerous parts i had on hand bought a cheap new ebay cas and shes away going better than ever

[aussieghostrider]

wow what can I say but the fricken dreaded misfire of the vn ..

I have replaced coilpack/dfi , spark plugs , leads , cleaned throttle body , new fuel filter and nulon injector cleaner etc ...

it helped alot replacing all those items ...

coil pack died couple months later ... was 2nd hand <----

bought a BRAND NEW coilpack/dfi and miss is slightly there ... put bottle injector cleaner again but at full bottle to 1/4 tank premium and go on the freeway at high revs/speed ..

all good now .... if you still have a miss then it's inlet manifold leak or ya injectors are really stuffed or the computer has dry solder joints.. or worse head gaskets gone .....

try replacing or reconditioning injectors first then if miss still there inlet manifold ... and thenif still there headgasket ... <-- if you have done a headgasket then just get a 2nd hanf engine be cheaper ...unless your engines worked and you want to keep it.

[Vlad01]

I got a vn with a conrod hanging out the side, starts first time and runs spot on. Well except the loud banging of the half conrod swinging around inside. I can't ever say I experienced rough idle on a buick before.