Do i have to increase my fuel perssure

[PH430]

Do i have to increase the fuel persure to 3 bar when i switch over to the Vectra injectors to match the Mark Adams chip.

I have fit a 20AM AFM with the MA chip. After switching to the Vectra injectors the long term fuel trim is +100% on both sites on Rover Gauge.

Thanks for al your answers

[phazed]

I did.

It was adjusted on a rolling road.

It will be impossible to adjust the pressure correctly without any indication of what is happening without this.

If you adjust the pressure blindly, you will never know what the mixture is.

[blitzracing]

IS the MA chip calibrated for both the 20AM and the Vauxhall injectors?. Messing around with fuel pressure is a very crude way of doing things- the map can be altered quite easily for increased overall injector flow. You could try speaking to Joolz at Kits and classics- he may have one of his maps to suit your set up, or you will need to go back to MA to get him to alter his map.

Edited by blitzracing on Sunday 2nd August 09:48

[ChimpOnGas]

PH430 said:

Do i have to increase the fuel persure to 3 bar when i switch over to the Vectra injectors to match the Mark Adams chip.

I have fit a 20AM AFM with the MA chip. After switching to the Vectra injectors the long term fuel trim is +100% on both sites on Rover Gauge.

Thanks for al your answers

Do yourself a massive favor and fit a wide band lambda kit.

Your narrow band lambda sensors just swing rich/lean and Rover Gauge tells you very little about the true AFR at a multitude of load sights.

I have the AEM X-Wifi system, this broadcasts the true AFR over a wireless adhoc network which can be read on your iPhone, iPod Touch or PC.

With this system fitted you can pop the car on the rolling road, whip out your iPhone, log into the X-Wifi and start tweaking the pressure while watching the true effects in real time on the screen as you increase & decrease the fuel pressure.

https://www.youtube.com/watch?v=0dJ3p7_qMTU





I also have exhaust gas temperature feedback on both banks which is another very useful tuning aid.

You could tune your fuel pressure on the road but you'd need to keep stopping at the side of the road to tweak the FPR then driving again watching the AFR to assess the effects of each change in pressure. This could prove extremely time consuming & frustrating, it would also be completely impossible to repeat the exact same load condition on your next drive meaning what you see on your AFR gauge is meaningless and you'll only ever end up chasing your tail.

That's where a rolling road comes in, you can accurately hold the engine at a set load site while tweaking the pressure and observing the changes in AFR all at the same time, and in compete safety.

A rolling road makes the job so much easier, faster, safer, repeatable & so infinitely more accurate. While never cheap, inevitably the time on a rolling road will prove to be a no-brainer.

Rolling road or no rolling road what you absolutely must do first is fit that proper wide band system or you'll be working more or less blind, and TBH tweaking the fuel pressure while you're still on the 14CUX is a very crude way of tuning your TVR.

Ultimately you'll be fighting the 14CUX anyway as it tries to lurch the lean/rich fueling towards the target 14.7:1 (most of the time). Rather than messing about with fuel pressures the proper way to get your fueling right throughout the range of all driving conditions on the 14CUX would be to burn a revised map on a new Eprom chip, but this will require some specialist help.

Your other option is to bite the bullet of logic and move on from the old 14CUX and put the control back into your hands by fitting an aftermarket engine management system which will immediately give you total & complete control over your fueling (and ignition).

What's revealing here is.... with such systems you typically leave the fuel pressure right where it is and tune by altering the injector durations, because unlike feking about with fuel pressure that's the proper way to tune.

Ultimately whatever engine management system you run dicking with fuel pressure is a fast track path to messing up your fueling somewhere in the very wide range of driving conditions a road car is expected to operate at.

The best you'll probably ever achieve with fuel pressure tuning is either too rich or too lean in a number of different load sites which will equate to either poor drivability, terrible fuel economy, dangerously lean conditions... or very likely all of the above.

MegaSquirt, Omex, Emeral or Canems all offer the perfect solution

[ChimpOnGas]

PH430 said:

Do i have to increase the fuel persure to 3 bar when i switch over to the Vectra injectors to match the Mark Adams chip.

I have fit a 20AM AFM with the MA chip. After switching to the Vectra injectors the long term fuel trim is +100% on both sites on Rover Gauge.

Thanks for al your answers

As an addition to my "Don't tune on fuel pressure" response above, I can also give you some real world feedback on running Vectra injectors while still on the 14CUX as I ran this setup for a while before moving to the Canems system.

In the end I finally admitted to myself what I always knew anyway, that is that the whole 14CUX thing was always going to be somewhat of a blind ally.

Anyway all that aside I did the Vectra injector mod some four years ago and like I say the car was still on the 14CUX but did also have the benefit of the miracle Mark Adams chip .

The important bit here is when I fitted those Vectra injectors I made no changes to fuel pressure whatsoever!

I didn't have a proper AFR gauge at the time but what I can tell you is the spark plugs came out a nice tan brown, the economy remained respectable, and the car drove as well as any TVR running the 14CUX/distributor could be expected to.

My advice once more is...

"Leave your fuel pressure well alone, but do get yourself a wide band lambda system that shows you your true real time AFRs"

It's the only way to tell you what's really going on while you drive, if you then find an issue go back to MA and ask him to sort it by burning you a new chip.

With my AEM X-Wifi you can download a little piece of software to your laptop, plug the AEM X_Wifi USB cable into it, go for a drive, and run an AFR log.

Send the free AEM software and your log to MA and see if he can burn you a chip that solves any undesirable fueling anomalies. You'll need to help him by explaining how you were driving (engine load, RPM, throttle position ect from Rover Gauge) when the AFRs go too lean or rich as there's no load or RPM info on the AEM log.

The above exercise will be a good test for MA and his mapping abilities, not to mention his after sales customer support. After all you paid a substantial sum of money for his magic chip , so to my mind the very least MA should do is make sure that very expensive chip of his is genuinely delivering better fueling than what TVR gave us.

To be fair to Mark just sending him a log is not giving him much chance as there are many other things that can effect the fueling like ignition, mechanical issues, induction leaks ect ect, so you're probably better off going for one of his £700 rolling road sessions where he can properly assess the car in person and as a whole.

No offense to the great man himself but personally I'd call a halt to all the MA spending right here & now, simply put the £700 towards an aftermarket engine management system and have done with the whole dinosaur 14CUX & distributor circus once and for all.

It'll be cheaper & better in the long run

And remember.... cheaper + better = best value...

[blitzracing]

Was it a best guess map?

[davelittlewood]

COG,

So if I put in the Vectra injectors without doing anything else (I'm currently running a stock motor) is there any point (other than maybe replacing a dribbling injector)?

I've always said that as soon as any part of the fuel injection or ignition system dies then the whole lot is coming out and I'm putting an MBE system in.

[ChimpOnGas]

davelittlewood said:

COG, So if I put in the Vectra injectors without doing anything else (I'm currently running a stock motor) is there any point (other than maybe replacing a dribbling injector)?

Well if you are looking at getting your Lucas disc type injectors reconditioned you'll find you can buy a set of reconditioned Vectra injectors for roughly the same money.

They aren't going to give you any more power or massively improve your fuel economy, but they are a more modern pintle type injector and do offer a better spry pattern, they also allow safer fueling if you're planning on going over 300hp.

Like I say, if you're considering getting your Lucas disc type injectors reconditioned in my opinion you may as well switch to the Vectra injectors.

They are after all a proven "plug n play" 14CUX compatible choice, no mapping or fuel pressure changes needed, just fit them and drive.

[davelittlewood]

I was thinking of changing them in an attempt to help sort my hunting problem (long term offset on one side is a lot different to the other - thought it could be a dribbling injector) and I'm starting to look for power increase without going forcing induction.

Thought I'd get a matched set (if nothing else it rules out the injectors and gives me more room for future power increase).

[ChimpOnGas]

davelittlewood said:

I was thinking of changing them in an attempt to help sort my hunting problem (long term offset on one side is a lot different to the other - thought it could be a dribbling injector) and I'm starting to look for power increase without going forcing induction.

Thought I'd get a matched set (if nothing else it rules out the injectors and gives me more room for future power increase).

If hunting is your problem I can recommend deleting the cats, worked for me

[davelittlewood]

Pre-cats are already out.

The hunting as recently got a lot better, almost gone, sorted the vacuum advance.

[ChimpOnGas]

davelittlewood said:

Pre-cats are already out.


The hunting as recently got a lot better, almost gone, sorted the vacuum advance.

I've seen your other post, please don't confuse hunting with shunting.

Hunting is a ragged uneven idle condition and is an industry accepted term that's been used for decades.

Shunting is not really a word an experienced mechanic would be familiar with, it is an amateur term that seems to have been adopted by the TVR community to describe a violent lurching effect at small throttle openings that Chimaeras & Griffiths often suffer from.

The two conditions are very different things, in the case of my last few posts here I am referring to hunting not shunting.

Going back to the hunting (ragged idle) on my Chimaera I removed the pre-cats first which did give a very small improvement.

But it was when I deleted the big main cat that the hunting fully disappeared, throttle response improved, the idle was so much smoother and the engine also felt like it gained 10hp.

If your engine is hunting at idle simply get shot of that big main cat and you'll immediately hear & feel the benefits.

It's also well worth getting shot of those dreadful original spec shrouded electrode plugs (NGK B7ECS) with their excessively cold 7 heat rating, replace them with the much more suitable extended electrode hotter NGK BPR6ES.

http://www.pistonheads.com/gassing/topic.asp?h=1&a...

Change the plugs for NGK BPR6ES and delete all the cats and the engine will idle much much smoother

[davelittlewood]

COG,

Cheers for the advice, in that case it's been suffering from shunting, not hunting.

The idle has always been really stable. From cold and with no throttle input it will slowly drop to ~900 rpm and sits there quite happily.

The shunting was worse after a recent service but now pulling the cap retard cap off seems to have made a big difference.

I'm just waiting for the ECU, coil or dizzy to pack in, and despite my attempts (dropped the ECU) it still keeps going. I guess that although nothing has packed up, none of it is working 100% anymore so the car is not what it was or could be.

[PH430]

blitzracing said:

Was it a best guess map?

Normaly the map is for standard. Injection, so i e-mailed Mark. He said that the 14cux will do the rest for matching the vectra injectors.

I think the vectra injectors have a Total different spray. At idle they have less than the standard injectors an at high revs they have more.

[blitzracing]

Umm- so we are saying the injectors have the same flow rate as the Lucas ones then?? I thought the whole point with the Vauxhall units was to allow more fuel for less injector time at 300 bhp+, so they must have a greater flow rate?? If this is the case its a bit much asking the lambda trim to sort it out as the whole map would need rescaling, plus the ECU stops any trim at 3400 rpm anyway.

[PH430]

With the vectra injectors in place and 2,5bar fuel perssure, rovergauge reads +100% long trem trim on both sides.

On 3bar the vectra injectors do 250ml, and what at 2,5 bar?

[TV8]

Hi OP, not sure why you are putting all of these new bits on the car?

the 20am needs to have a different scaling on the map to the 5am. Has that been factored into what is on the car?

[PH430]

TV8 said:

Hi OP, not sure why you are putting all of these new bits on the car?

the 20am needs to have a different scaling on the map to the 5am. Has that been factored into what is on the car?

The chip from MA is mapped for the 20am to my 430, only for standard Injection.

[TV8]

PH430 said:

The chip from MA is mapped for the 20am to my 430, only for standard Injection.

Ok. The other question to help sort your problem is what has changed to require the larger injectors?