Flat spots running Veg?? read on >>>>

[Mattcheese31]

Just a heads up for those who run veg like myself, been running it for nearly 4 years now . .

anyway we all know the dance, accelerating through the rev range, you get to 3 or 4k or whatever and it feels like you've hit a brick wall, car stops pulling, smoke out the back, it carries on a bit then stops again . . . . .

it's very annoying, now i've always felt that once the engine's warmed up and the veg has recirculated for a good while warming the tank that there's not a massive difference between veg and diesel, (diesel from cold definitely pulls a lot harder) but still it gets lumpy higher up the rev range (veg that is).

anyway i'm going to stop rambling on, i took my Bosch apart on the car the other day and replaced the main seal between top and bottom and also the throttle shaft seal, pump had been weeping veg for a good while, long story short, still on 100% veg and she pulls all the way round to 5k without lumps now.

i guess the crux of the matter is thus, veg is harder to pump than diesel and if you have any air ingress therefore loss of IPP (internal pump pressure) then it's magnified when you use veg . . . . . .

go and sort your pumps out people . . .

peace out x

[Mattcheese31]

now all i need to do is replace Head gasket lol . . . . .

[Piggy]

Lol...not all will be that mind.

I find 5% petrol fixes the flat spots a treat

[Mattcheese31]

Lol...not all will be that mind.

I find 5% petrol fixes the flat spots a treat

i bet you they are, pump, lines, filter or whatever, i mix a little petrol in in the winter, but like i say fella, pulls all the way round now, no perv needed . .

[Mattcheese31]

i should also mention that i've replaced the O ring in the side of the fuel filter housing a while ago, that little bastard is a regular culprit, along with the O ring on the bottom of the filter housing, not forgetting the leak off pipes either

[Piggy]

My first ZX and 306 were bang on, no pump issues, all sealed lines due to know ingress issues.
I always knew when I hadnt put 5% petrol in

---

(Yeah, fuel filter housing seals are more likely an issue for most)

[Mattcheese31]

My first ZX and 306 were bang on, no pump issues, all sealed lines due to know ingress issues.
I always knew when I hadnt put 5% petrol in

well it thins it out Piggy, it's a no brainer really, but i'm talking specifically about those shitty flat spots . .

what i'm saying is if there's air getting in then petrol won't fix the problem . .

[Piggy]

No, true.

Just if peeps are getting flat spots....maybe worth trying 5% petrol before they strip down their bosch pump!

[Tom]

I find 10mm fuel lines make veg run like diesel, cant tell the difference.

[Mattcheese31]

I find 10mm fuel lines make veg run like diesel, cant tell the difference.

all the way from the tank yeah?

[Piggy]

Second that...although an inline filter along with the 10mm lines will make the biggest difference I expect.

[Danny2009]

Best way to avoid lumpy starts and flat spots I found

Use diesel

[Mattcheese31]

Best way to avoid lumpy starts and flat spots I found

Use diesel

where's the challenge in that?

[Piggy]

Well said...


Or the savings

[zx_volcane]

wait what?

if your pump is leaking fix it?

good advice none the less

don't think a slight leak will affect ipp that much tbh, unless its absolutely pissing out. but sucking air through won't help at all

veg in my experience just seems to perish pump seals and make my pipes go baggy (ho ho ho) leak offs anyway - new seal kits should be ok with veg / bio, get some Viton for sure.

also clogs filters surprisingly quickly which can lead to crappy performance and flat spots.

trying to suck it all up through minuscule lines when its on the thick side, not ideal - big lines can't hurt.

[Mattcheese31]

lol at zx... Yes mate i suppose it is a slightly retarded thing to say, i just didn't think it would make quite as much difference as it has

[zx_volcane]

Shaft seal can be a sneaky one too

You may not notice unless you're part of the balls out 'no cam cover crew'

[Mattcheese31]

Shaft seal can be a sneaky one too

You may not notice unless you're part of the balls out 'no cam cover crew'

tbh mate i know how it goes, replace one seal and another gives way shortly after, something to look forward to lol

[Danny2009]

I used to run veg all time but Cba no more

I strapped a big bine and a modified pump to one and ran veg it kills power so went back to derv

On the other had my standard ph1 with Bosch owt that burnt went in the tank

Wouldn't mind using it in the truck but it's site on bio never mind veg it's slow to start with

[Piggy]

I think ZXvolcane has convinced me to stick with it. At 50% veg, with no additives, he managed 237bhp.
So at 40ppl I think I will always chuck in 20litres for every 20 of diesel I put in. Plus some nice cetane booster.

[nominous]

I suggest you check the pressure control valve too. See the recent thread resurrection about that.

Also ditch the tank strainer if there is one and fit one under the bonnet. Ebay.
Get a bigger primer bulb too as it's not 8mm internally.
Loop return and generous addition of heat makes quite a difference too.

[Mattcheese31]

I suggest you check the pressure control valve too. See the recent thread resurrection about that.

Also ditch the tank strainer if there is one and fit one under the bonnet. Ebay.
Get a bigger primer bulb too as it's not 8mm internally.
Loop return and generous addition of heat makes quite a difference too.

where is the pressure control valve? . . .and check what, the seal? . .

[nominous]

http://306oc.co.uk/forum/thread-13232-po...#pid431797

[THE_Liam]

Air leaks make a huge difference, I reckon that's why I never have a problem running soya oil (which people say not to use), and running 100% pure even in winter (which people say isn't possible without starting issues), because I go through the fuel system with a fine-toothed comb before starting to run veg.

[Toby]

Modifying the fuel filter housing to permanently pass coolant heat into the fuel is also makes a big difference once up to temp.

[Mattcheese31]

Modifying the fuel filter housing to permanently pass coolant heat into the fuel is also makes a big difference once up to temp.

yeah i've done that too, very easy mod, you don't have to fcuk around with pennies either, just pull the white stat out the side of the housing, take the shit out of it and re-fit, best to renew the O ring on that too . . . .

[zx_volcane]

careful messing too much with the pressure control valve unless you have some way of measuring ipp, you could be opening yourself up to all sorts issues.

+ I haven't seen a definitive list of what the ipp should actually be

unscrewing it and screwing it back in should be ok to check seals and that its all intact

[Ruan]

Yeah, be mighty careful with the pressure regulator, if you accidentally tap the top of it, it'll completely cock the advance curve - i.e. it'll sound like a transit van at 1400rpm.

TDis will not have this issue since they have a solenoid valve controlling the advance curve, the pressure regulator is knocked in the entire way...

What nominous does describe is the entire problem with running veg oil in the first place, it's massively exacerbated by us using VE pumps that use spring and regulator advance on the timing piston, rather than the TDis solenoid system. Soon as the pump begins to drop internal pressure due to sucking veg, you INSTANTLY drop timing, it's a finely balanced system that if there's any suction going on, it'll instantly retard the pump back to base timing.

As far as I can see, soon as you start running veg - bam you've probably lost 5* of timing midrange, by the time you're past 3800rpm, it's struggling so bad to get fuel, the timing is right back at stock position.

[Mattcheese31]

that's the thing Ruan, if there's any leaks at all when you start caning it you do lose all that advance, hence smoke billowing out the back, seems weird at first, boost leak, or not enough fuel but it's coaling, i'm with you though, the advance just goes tits up and that's why you lose power and engine can't combust properly

[Ruan]

Even if there's no leaks it'll pull timing, because the veg is thick, the pump will struggle to pull it up the lines, lose pressure, bam timing gone... Air makes things even worse!

Thing is, it's got to pull it through the filter, the housing, through the strainer in the tank and all the lines back there, hardly surprising!