Auto v6 misses when 75%+ throttle is applied or high revs in neutral PLEASE HELP!! :)

[shmickmik]

Hey thanks for reading :P BTW its a VN S1 Auto

Ok whats happening is that when i rev the car in neutral to redline (the only reason i do that is to check wether or not the car is going to play up or not.) it will stop at around 4000rpm and start to miss.

When in drive if i give it anymore then 75% throttle it will act as if i were to put my foot on the clutch in a manual, and the car wont let any power to the wheels.

I have brand new sparkplugs, leads, set of coil/dfi of a vy commodore, memcal swap. Aall of this was swapped AFTER i experienced the problems so all of this is not to blame.

Could it be the CAS? The only other issue i have with the car (besides the RATTLES!!!!!! lol) is that when its hot its hard to start. Where as in the mornings starts first go. I am pretty sure that is a CAS related issue, but could that also be whats causing my WOT- high revving miss issue??

Thanks guys/gals

PS! - I should also mention that i have ALWAYS received a code 13.. or 14 i cant remember now.. the one regarding O2 sensor low voltage for 30secs.. Tried 3 different memcals and 3 difference 02 sensors and it still pops up!

[immortality]

check the O2 sensor wiring. might have got burnt against the exhaust at some time.

what plug gap have you set? have you checked the fuel system? fuel filter/fuel pressure?

[shmickmik]

what had happened was somebody had poured caustic soda into my fuel tank right.. which destroyed the fuel filter and clogged up the injectors. I brought a new fuel pump, new filter, replaced injectors and fuel regulator after that. AS far as i could tell she was ok, but seeing as i hardly ever put my foot to the floor i wouldnt be able to tell you if this missing was happening then aswell.

One thing i have noticed is that ever since then, whenever i pull of a fuel line, or the fuel reg i no longer get sprayed with fuel lol As in there is no fuel pressure built up in the lines to spray any fuel directly into my eyeballs when i disconnect the fuel line somewhere.

Oh in regards to the 02 sensor wiring, the wiring is fine near the exhaust i was hoping thats all it was aswell lol And with the plugs they are the cheapo supercheap items installed straight from the packet. I had no feeler gauges on me that wernt rusted so i just whacked them straight in. I read somewhere that somebody else had used the same plugs without gapping and seemed to be fine.. i should double check them i guess.. its only going to cost me time, not money.

[immortality]

for starters you definitly have a fuel pressure problem of some sort. and need to fix it before you can really get any further.

you need to get hold of a fuel pressure guage of some sort and tap it into the line before fuel rail and see what the pressure is with the engine running. then remove vac line from regulator and see what the fuel pressure does. thne shut engine down and see how fast pressure drops. then turn ingition on and fuel pump should (prime)for a few seconds and bring the fuel pressure up (if necessary cycle the ignition afew times to get presure up to normal working pressure), then as soon as pump stops pinch the fuel line after the regulator and see if pressure still drops, then perform same test but pinch line before presure gauge and see if pressure still drops. doing this will tell you if your loosing pressure through the regulator or back through the fuel pump. if pressure drops both ways then do test again and pinch both fuel feed and fuel return lines and see if pressure drops (injectors leaking). then fix what ever is wrong.

that tests pressure but we still need to check flow if further problems persist. out of curiosity, see what the fuel pressure does when you rev it an and it starts to miss.

plug gaps should be 1.5mm +0/-.1mm feeler gauge should be firm in the gap but oyu shouldn't need to force the gap open to get the feeler gauge in. they probably supplied you 1.3mm as the NGK catalogue states for the VN s1

[centy]

yes fuel issue are what i would look at but sounds like your cas is on its way to.
if you had caustic in your tank you will need to replace it if you plan to keep the car.
.steel fuel tanks are painted inside to protect them from rusting with condesation.
if the caustic has damaged that film then your tank will rust

[shmickmik]

Thanks for the replies fellas :P

I will definitely be replacing the CAS sometime this week.. just need to scavenge $70 for one.. damn christmas :P

Thats annoying in regards to the tank.. i was hoping all that drama was over by now. Ok what i will do now is go through everything you have suggested immortality. Was just wondering if maybe you knew, or anyone knew exactly what i should buy.. as in which fuel psi tester.

I will have a look on ebay for a cheap one.. and post the links up just to get confirmation that i am buying the correct one :P

I have an adjustable malpassi with a gauge that i can connect AFTER the stock fuel reg.. will that do for any testing purposes?? I have no issues installing that, however i agree that i would be better off with a proper fuel psi gauge so read in the car and see whats happenign at different revs, starting, etc..

Thanks for the replies guys

[shmickmik]

i was thinking, would i be able to run a long ass fuel hose from the stock S1 regulator, into the cabin with the malpassi + gauge? It SOUNDS unsafe haha but ill make sure a **** load of sealant and hoseclamps oare on the reg before it goes anywhere near the cabin of the vehicle.

The only thing could cause a problem that i can see is the length of the hose affecting pressure? And having the adjustable maplassi hooked up after the stock regulator...

what do you guys think??

[immortality]

you don't specifically need an automotive fuel presure gauge. you could just get any fluid type pressure gauge as used in the hydraulic industry and then just plumb it into the fuel line using some brass fitings. only needs to be a tempory fit whilst you diagnose your problem.

edit: damn 4000 posts. i need to get a life

[greenfoam]

I don't think caustic soda will do anything apart from block stuff when mixed with fuel? it really wants to be in water (or on watery humans) to start melting stuff and even then it takes along time to hurt paint which is really just plastic and plastic doenst care about caustic soda (gets pretty agro on alluminium tho:S)

[shmickmik]

Hey all well i have today off so i thought i would muck around with the fuel system and see if i cannot at least find out what the problem is.. thats what annoys me the most.. not knowing! grrr I was using my adjustable malpassi with its own gauge to measure the fuel psi. I made sure it was open allll the way so it would not interfere with the readings.

you need to get hold of a fuel pressure guage of some sort and tap it into the line before fuel rail and see what the pressure is with the engine running.

Ok so i grabbed my trusty malpassi reg with gauge before the fuel lineand i am getting 38-/+ 2psi fuel psi. (the gauge is pretty hard to get an EXACT reading but its a smudgeon below 40)

then remove vac line from regulator and see what the fuel pressure does.

If i take the vacuum hose of the reg it jumps up to about 45psi.. once again give or take 2 or so psi..

thne shut engine down and see how fast pressure drops.

It will drop down to 20psi then straight down to about 2psi or 0psi. all within 1.5 seconds of turning the car off.

then turn ingition on and fuel pump should (prime)for a few seconds and bring the fuel pressure up (if necessary cycle the ignition afew times to get presure up to normal working pressure),

Ok here is where it gets a bit tricky.. when you turn the reds on to prime the pump, it will get to 40 psi without any fuss, but as soon as you hear the 'click' sound come from the fusebox area the pressure plummets back to the 0psi area??

Then as im trying to start the car while watching the gauge, i notice that the psi is slowly creeping up from 0psi the longer i let the car crank.. as soon as it gets near the 35psi area it starts to stutter. Usually when this happens i know to stop cranking the engine, and the next time i turn the key it will start..

then as soon as pump stops pinch the fuel line after the regulator and see if pressure still drops,

Yup psi still drops

then perform same test but pinch line before presure gauge and see if pressure still drops. doing this will tell you if your loosing pressure through the regulator or back through the fuel pump.

Since i was by myself and only had two hands lol i had to grab to pliers and pinch both lines while in the engine bay. Since i couldnt prime the pump then pinch the lines, i just pinched them while the car running, which raised the psi and would allow the engine to stall. Once the engine stalled and pinching the hoses with all my might the psi dropped as it would during any of the other tests.

if pressure drops both ways then do test again and pinch both fuel feed and fuel return lines and see if pressure drops (injectors leaking). then fix what ever is wrong.

Soooooooo hopefully if i have done all these little helpful tests right, the logical explanation would be the injectors leaking????? :O:O:O

[voxbox]

I'd say your fuel pressure regulator is totally hosed.

[shmickmik]

I was really hoping that was all it was aswell.. i tried swapping it with another one but nothing changed whatsoever. sighh.

I mean i never go that far in the rev range its just annoying knowing something is wrong. I just want to fix it before it gets any worse, and one day ill be in whoop whoop and the thing wont start at all.

[immortality]

as i read through the test results it seems that the regulator is working, 38psi and the 45psi with no vac sounds ok. should be 43psi from memory with no vac. the fact that you loose all pressure in a matter of seconds points to the pump, if it was loosing all that fuel through leaking injectors i'd say the cylinder(s) would be flooded and extremly hard to start.

if possible try and get someone to help with the test. pinching the line after the regulator should see a large rise in pressure if the engine/pump is running.

pinching both lines and presure still dropping would suggest leaking injectors, however i wouldn't think it would loose all pressure in a couple of seconds.

try giving the engine a rev and see wht the fuel pressure does as it starts to missfire

[shmickmik]

as i read through the test results it seems that the regulator is working, 38psi and the 45psi with no vac sounds ok. should be 43psi from memory with no vac. the fact that you loose all pressure in a matter of seconds points to the pump, if it was loosing all that fuel through leaking injectors i'd say the cylinder(s) would be flooded and extremly hard to start.

Hmm it might not be them then.. if i turn the car off and try to start it right away it kicks over after the first crank. It has trouble starting when u leave it for about 15mins, then it takes awhile to get it fired up.

if possible try and get someone to help with the test. pinching the line after the regulator should see a large rise in pressure if the engine/pump is running.

pinching both lines and presure still dropping would suggest leaking injectors, however i wouldn't think it would loose all pressure in a couple of seconds.

Im pretty sure that when i did this it was around the 80 mark.. i just noticed that it sky rocketed when i pinched the line either before or after the regulator..

I should point out aswell, i pulled out the tank to clean out anything that was inside it, and when putting it back in pretty much all of the breather hoses were so brittle they all snapped. I have plugged them all up as well as the charcoal cannister, also tried unplugging them but nothing changes.

See after replacing the pump with an oem replacemnt (or so it said on the box from parts plus) within 2 days the car started acting up when it got near 1/4 of a tank.. it would surge as if out of petrol. Then one day with about half a tank of fuel i stopped off at the servo, then whent to start the car and no priming . I had to push the car to the side of the road out of anyones site (as i was embarressed lol) and pulled out the fuel pump to see what was going on.

I noticed the filter sock was missing first off. After cleaning the connections on the pump (thinking the caustic soda corroded the wires or somethign like that) and giving it a bit of a tap on the ground it start whizzing away again.. ever since then it has never died but getting that high rev, hard to start issues.

try giving the engine a rev and see wht the fuel pressure does as it starts to missfire

I will go give that a try now :P brb

[PaRaDoX]

i think its the flux capacitor? you may as well change that too considering i told you to...

A) unless you can prove the CAS is faulty, dont replace it or atleast get another to test with
B) fuel pressure helps
C) check your grounding strap on the coil packs.. if its loose it will miss like a mother****er under load,

on the fuel pressure issue get a bucket of fuel, pull the pump out, wire the pump to a battery and run the pump directly off the fuel line in the engine bay, how are you checking fuel pressure? just pulling the line and going hrmmm wheres my fuel? or using a gauge, imo go buy a guage, they're $20

id start with the known problems first then worry about the mythical ones

[shmickmik]

Ok NOW its running fine When it hits the rev limiter there is a slight drop in psi although it would be expected at high rpm i would imagine.

I had noticed that since atm it is running how it should, when priming it will goto 40ish psi right away then drop straight back down. However it will start right away. However when left for 15mins it will prime to about 20psi.. then while ur cranking away u an se the psi gradually rise to 35ish psi untill it splutters. Thats when you know the next time u crank it will splutter into life.

I am not sure if i mentioned this.. but in the morning it will 100% of the time start after 3 or so cranks. It has never not started first go in the morning.. its alway when warm. However i have never tried revving the guts out of it when its cold for obvious reasons :P

I am thinking that my idea of using the fuel reg might not be all that good if the fuel psi drops so suddenly. I had always thought that there was a check valve of some sort in the fuel pumps that kept the fuel psi in the fuel rails?? Is that right? Maybe the pumps fine, but that valve was faulty to begin with.. I should try putting in the old fuel pump (the caustic one) and see how i go.

[shmickmik]

think its the flux capacitor? you may as well change that too considering i told you to...

No offence mate but who are you? I have never spoken to you so i have no idea how u told me to change the 'flux capacitor'.. which never gets old btw

how are you checking fuel pressure? just pulling the line and going hrmmm wheres my fuel? or using a gauge, imo go buy a guage, they're $20

thanks for the helpful advice, but yeah as stated in the above posts i have a gauge.. dodgy gauge but it works :P.

[immortality]

the non-return valve is part of the pump unfortunatly. it sounds like your entire fuel system is ****ed the regulator you just fitted, is it a know good unit or you have no idea?

[shmickmik]

It sounds like it hey.. i was going to go through and buy all replacement items:

injectors
pump
filter
regulator

The pump and filter are brand new, however the injectors and regulator are not and from the local wreckers.

When the fuel gets a little lower i am going to whack the older pump back in and see how that goes.. IF THAT works, im going to buy another pump from another source, reco injectors, another filter just to be sure.

It would have to be the pump wouldn't it? I mean if there was a leak somewhere (besides the injectors which would flood the cylinders and would show black smoke once it started) shouldn't there be fuel leaking out of that same spot?

My mechanical experience goes as far as swapping a few engines in my backyard so im no mechanic lol but a faulty check valve in the fuel pump sounds about right.. If im not mistaken the valve is to stop the fuel travelling in the opposite direction back into the tank, so if that is stuck open for instance, as soon as the pump stops working the fuel is pushed back into the tank. Which is what the gauge said was happening when the pump stopped running.

maybe haha just trying to figure it out hmm

[voxbox]

Change the pump, see if that fixes it. If it does, get a reco pump. If other stuff plays up down the line, change it then. No point changing injectors if there's nothing wrong with them. If an injector was stuck open, it would fiill the cylinder with fuel and the engine would hydraulic-lock - it wouldnt be able to compress that amount of petrol and the engine would lock solid(previous experience ).

[shmickmik]

If it fixes it ill be ****ed. I paid $75 for that one not long ago!

Just a question..

Would having the charcoal canister line and the small hoses from the top of the tank plugged up have any serious issues later on? One of the lines ontop of the tank was blocked compeltely.. the air compressor couldn't clean it out at all. While the whole mess of hoses on the filler neck have all withered away.

It seems EVERY commo was like that at the wreckers though.. there is a guide on SC but i am more worried about this psi issure first.

Just wanted to make sure that these hoses wouldnt be having an effect at all?

[immortality]

don't worry about the charcoal cansiter lines, thats only to recycle petrol fumes to reduce pollution

[shmickmik]

I dont want to be too hasty in saying that it is FIXED but..... its fixed
She now starts within 1-2 cranks of turning the key, just like the good ol days and NO machine gun fire revving in the high revs.

Can anyone take a WILD guess and tell me what the problem was??? :

Thanks SO much to immortality for the list of trial and error suggestions that led me to the correct conclusion which was the BRAND NEW Delphi fuel pump all along The original pump is a bit noisey but keeps 38psi in the fuel line for a good 20mins and within 1 hr was down to about 10psi according to the dodgy hard to read gauge

Thanks to everyone who took time to help me out

On a side note.. the pump that is in there now that is working 100% is a:
Carter 944 or 994 one of them... i cant find info on these anywhere?? Are these the stock pumps at all?

[immortality]

thats good news mate how old is that brand new pump? it should have some sort of warranty on it. maybe try and get your money back