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Re: 1jz gte and injectors

2004-10-13 09:32:00

>What is interesting, that on dyno runs with my JZA70 with boost at 15 psi, my
>AFR was 10.
>You would expect that the injector duty is therefore completely maxed out,
but
>it was not leaning out, only by adjusting the FCD could I bring the afr to
11.

>Stuart how have you verified your meter accurate?

With an oscilloscope attached directly on the injectors.

It is only reaching 95% at redline and max boost, you will have more headroom
at lower rpm. Remember that higher boost is a rapidly loosing battle which
does not increase the available air that much (certainly on the stock
turbos).

Also, how are those AFRs bring calculated - oxy sensor? unless they are from a
3-gas analyser they are 'approximate' at best.

The 1jz does run damn rich so there is some headroom, and injector outputs do
increase significantly as they hit 100'% (as there is no closing/opening
delay and interruption to their flow), but my point is that they are getting
close to their limit stock.

Regards,
Stuart.

Re: Re:1jz gte and injectors

2004-10-13 09:53:00

excuse my lack of knowledge on the subject, your setup is running everything
stock right? so this would include the fuel line pressure? your measuring
the opening and closing of the injector, is it possible to increase the line
pressure, so that even with the injectors running out of duty cycle, there
can still be more fuel added, as there will be more fuel added per cycle by
the pressure being higher?

hope that made sence.

john R

----- Original Message -----
From: "Stuart" <stuartw@kcbbs.gen.nz>
To: "Supra Club of NZ Mailing List" <sconz@list.supras.org.nz>
Sent: Wednesday, October 13, 2004 9:32 AM
Subject: Re:[sconz] 1jz gte and injectors

> >What is interesting, that on dyno runs with my JZA70 with boost at 15
> >psi, my
>>AFR was 10.
>>You would expect that the injector duty is therefore completely maxed out,
> but
>>it was not leaning out, only by adjusting the FCD could I bring the afr to
> 11.
>
>>Stuart how have you verified your meter accurate?
>
> With an oscilloscope attached directly on the injectors.
>
> It is only reaching 95% at redline and max boost, you will have more
> headroom
> at lower rpm. Remember that higher boost is a rapidly loosing battle which
> does not increase the available air that much (certainly on the stock
> turbos).
>
> Also, how are those AFRs bring calculated - oxy sensor? unless they are
> from a
> 3-gas analyser they are 'approximate' at best.
>
> The 1jz does run damn rich so there is some headroom, and injector outputs
> do
> increase significantly as they hit 100'% (as there is no closing/opening
> delay and interruption to their flow), but my point is that they are
> getting
> close to their limit stock.
>
> Regards,
> Stuart.
>
> ---
> Supra Club of New Zealand - http://www.supras.org.nz/
> Website sponsored by Alltech Diesel & Turbocharger http://www.turbo.co.nz

Re:1jz gte and injectors

2004-10-13 13:27:00

The reason for the question was that from what I understand, 85% Duty is max
recommended for these type of injectors and I cant understand why Toyota would
program their ECU's to drive past manufacturer's tolerances.

> >Stuart how have you verified your meter accurate?
>
> With an oscilloscope attached directly on the injectors.
>
> It is only reaching 95% at redline and max boost, you will have more
> headroom
> at lower rpm. Remember that higher boost is a rapidly loosing battle
> which
> does not increase the available air that much (certainly on the stock
> turbos).
>
> Also, how are those AFRs bring calculated - oxy sensor? unless they are
> from a
> 3-gas analyser they are 'approximate' at best.
>
> The 1jz does run damn rich so there is some headroom, and injector
> outputs do
> increase significantly as they hit 100'% (as there is no closing/opening
>
> delay and interruption to their flow), but my point is that they are
> getting
> close to their limit stock.
>
> Regards,
> Stuart.
>
> ---
> Supra Club of New Zealand - http://www.supras.org.nz/
> Website sponsored by Alltech Diesel & Turbocharger
> http://www.turbo.co.nz
>

Re: Re:1jz gte and injectors

2004-10-13 13:32:00

----- Original Message -----
From: "Marc Archbold" <marc.a@paradise.net.nz>
Subject: Re:[sconz] 1jz gte and injectors

> The reason for the question was that from what I understand, 85% Duty is
> max
> recommended for these type of injectors and I cant understand why Toyota
> would
> program their ECU's to drive past manufacturer's tolerances.

Isn't the issue with duty cycle only one of accuracy at high percentages?
i.e. as you approach 100% the proportion of time used for pintle movement
relative to the available duty becomes greater, making the likelihood of
error greater... In which case if the ECU is already overfuelling the
engine, then injector accuracy becomes less of an issue, yes?

Or are you referring to the heat issues with the coil being live for
excessive periods?

Cully

Re: Re:1jz gte and injectors

2004-10-13 14:10:00

>
> Isn't the issue with duty cycle only one of accuracy at high
> percentages?
> i.e. as you approach 100% the proportion of time used for pintle
> movement
> relative to the available duty becomes greater, making the likelihood of
>
> error greater... In which case if the ECU is already overfuelling the
> engine, then injector accuracy becomes less of an issue, yes?
>
> Or are you referring to the heat issues with the coil being live for
> excessive periods?

Quite right on both counts, my point being injector failure with excessive
duty rates/on time. Ive have not heard of a JZ injector failing.
As you have suggested, the ecu overfuels, and accuracy is less of an issue -
that would explain the wild afr's seen on the dyno. I agree with Stuart that
the typical wideband sensors are no gas analysers and especially less accurate
with Turbo applications.

Perhaps the Walbro Fuel pump has 'helped' in my situation, and possibly the
factory FPR is 'wild' at boost pressures greater than Stock.

I'd love to sort this out properly....

>
> Cully
>
>
> ---
> Supra Club of New Zealand - http://www.supras.org.nz/
> Website sponsored by Alltech Diesel & Turbocharger
> http://www.turbo.co.nz
>

Re: Re:1jz gte and injectors

2004-10-13 14:16:00

----- Original Message -----
From: "Marc Archbold" <marc.a@paradise.net.nz>
Subject: Re: Re:[sconz] 1jz gte and injectors

> Quite right on both counts, my point being injector failure with excessive
> duty rates/on time. Ive have not heard of a JZ injector failing.

Using the accurate seat-of-the-pants method, I'd say that for the majority
of the injectors that come through here for servicing, by far the most
common reason for failure involves the state of the injector resulting from
the petrol going through it (eg damaged pintles). It seems to be quite rare
that an injector plain stops working for any reason relating to the
electrical side of it.

It amused me quite a lot to learn that Alltech has no dot punches in
existence anywhere in the workshop. Instead there is a very healthy supply
of old diesel injector needles that work even better! @#%@! they're hard
stuff!

Cully

Re: Re:1jz gte and injectors

2004-10-13 14:31:00

> It amused me quite a lot to learn that Alltech has no dot punches in > existence anywhere in the workshop. Instead there is a very healthy > supply > of old diesel injector needles that work even better! @#%@! they're hard > > stuff! > > Cully > What would you recommend as a serice period, and how are they tested?

Re: Re:1jz gte and injectors

2004-10-13 14:51:00

----- Original Message -----
From: "Marc Archbold" <marc.a@paradise.net.nz>
Subject: Re: Re:[sconz] 1jz gte and injectors

>> It amused me quite a lot to learn that Alltech has no dot punches in
>> existence anywhere in the workshop. Instead there is a very healthy
>> supply
>> of old diesel injector needles that work even better! @#%@! they're hard
>>
>> stuff!

> What would you recommend as a serice period, and how are they tested?

Petrol injectors? Well, that's an interesting subject...

Petrol injectors seem in all respects to have a really good lifespan. It's
not very common to find them completely wrecked. Most injectors straight
out of a car will be within about 5% of their nominal capacity, and if
anything are just suffering from bad spray patterns. I would guesstimate
that 50,000kms is a reasonably conservative service period.

The service for injectors goes like this:
- The filter basket and o-rings are removed.
- The injectors are bolted into the flow tester and the pressure run up to
2.5bar without the injectors open to check that they don't leak.
- The injectors are run through a series of different duty cycles to check
the spray patterns are good.
- The injectors are run at a standard 2.5bar/50% duty/30 second cycle to get
a reading of what volume they are delivering.
- If required the injectors are run through the ultra-sonic cleaner to
remove carbon deposits and other fuel-born crap, then re-flow tested to
check their output.
- New filter baskets and o-rings.

Diesel injectors are a different matter, as they mostly operate by hydraulic
actuation rather than electrical, and the service involves stripping them
and working on/replacing various internal components, checking clearances
etc. That's all quite a specialist area, and not one I have much to do
with.

Cully

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