Miatapower List Archive

This read-only message was archived from a public mail list.
Mail From: Brian Van Lieu <(email redacted)>

I am banging my head against the wall here.

In an effort to up fuel pressure/deliver for
safety, etc....I seem to have either found
a second problem, or made things worse.

Under WOT boost, target 180kpa, my car will
stumble and 'burp' from 4000-5500. If I
push on to readline (3rd gear pulls) it usually
stablizes.

I am at 12 PSI, and the car will pulse, boost gauge
blips up to 13, falls down to 10, then comes back
to 12. Car bucks. Its not as abrupt as when
you exceed boost limit with the Link (BTDT), but
its noticable. I think I hear a bit of a burble/burp
from my tailpipe, which makes me wonder about
excess fuel, or missed ignition cycle.

- I am not hitting boost cut. Logs show
I am not coming close to 194kpa cut off

- If this was ignition related, i.e. plug
gap, etc...I would presume I would be getting
a break up all the way to redline. Is
that incorrect?

- Could very rich settings cause this? I have
confirmed my new Walbro GSS250 is mounted tightly
in the fuel tank (R&R'd that the other day). I
run a Jim B rail, and have pulled some fuel in row 4/5
over FM defaults.

- Would something wrong with the factory FPR
cause this?

My plugs and plug wires each have abotu 12K miles
on them...its possible I suppose that this
is the case, but I am not big into coincidences, and
since I have been mucking with fuel delivery in
the past 4 weeks, I am suspicious. After installing
the GSS250, I showed low 50PSI fuel under boost (only
ran 7psi at the time) to redline, which seemed
fine and steady. On mechanical boost, I don't
get this nearly as badly, though I can feel it
a bit.

I just don't know what else to do, and feel
like a bad parent for my poor miata :(

cheers,

- b

This read-only message was archived from a public mail list.
Mail From: Bill Cardell <(email redacted)>

Start with plugs. The cutout could go away as you go up in rpm because cyl
pressures are highest at torque peak, most likely to blow out spark in 4-5k
range.

Bill Cardell (TurboDog's Dad)
Flyin' Miata
www.flyinmiata.com
www.fmprotege.com
970-242-3800



-----Original Message-----
From: Brian Van Lieu [mailto:(email redacted)]
Sent: Friday, April 04, 2003 7:12 AM
To: (email redacted)
Subject: What else would make a boosted car surge & cut out


I am banging my head against the wall here.

In an effort to up fuel pressure/deliver for
safety, etc....I seem to have either found
a second problem, or made things worse.

Under WOT boost, target 180kpa, my car will
stumble and 'burp' from 4000-5500. If I
push on to readline (3rd gear pulls) it usually
stablizes.

I am at 12 PSI, and the car will pulse, boost gauge
blips up to 13, falls down to 10, then comes back
to 12. Car bucks. Its not as abrupt as when
you exceed boost limit with the Link (BTDT), but
its noticable. I think I hear a bit of a burble/burp
from my tailpipe, which makes me wonder about
excess fuel, or missed ignition cycle.

- I am not hitting boost cut. Logs show
I am not coming close to 194kpa cut off

- If this was ignition related, i.e. plug
gap, etc...I would presume I would be getting
a break up all the way to redline. Is
that incorrect?

- Could very rich settings cause this? I have
confirmed my new Walbro GSS250 is mounted tightly
in the fuel tank (R&R'd that the other day). I
run a Jim B rail, and have pulled some fuel in row 4/5
over FM defaults.

- Would something wrong with the factory FPR
cause this?

My plugs and plug wires each have abotu 12K miles
on them...its possible I suppose that this
is the case, but I am not big into coincidences, and
since I have been mucking with fuel delivery in
the past 4 weeks, I am suspicious. After installing
the GSS250, I showed low 50PSI fuel under boost (only
ran 7psi at the time) to redline, which seemed
fine and steady. On mechanical boost, I don't
get this nearly as badly, though I can feel it
a bit.

I just don't know what else to do, and feel
like a bad parent for my poor miata :(

cheers,

- b

This read-only message was archived from a public mail list.
Mail From: "JessMX5" <(email redacted)>

Sounds like you are rich. Put in the wideband? I am leaving for France
today, but I will try to get a look at your logs soon.

Jess
----- Original Message -----
From: "Brian Van Lieu" <(email redacted)>
To: <(email redacted)>
Sent: Friday, April 04, 2003 7:11 AM
Subject: What else would make a boosted car surge & cut out


> I am banging my head against the wall here.
>
> In an effort to up fuel pressure/deliver for
> safety, etc....I seem to have either found
> a second problem, or made things worse.
>
> Under WOT boost, target 180kpa, my car will
> stumble and 'burp' from 4000-5500. If I
> push on to readline (3rd gear pulls) it usually
> stablizes.
>
> I am at 12 PSI, and the car will pulse, boost gauge
> blips up to 13, falls down to 10, then comes back
> to 12. Car bucks. Its not as abrupt as when
> you exceed boost limit with the Link (BTDT), but
> its noticable. I think I hear a bit of a burble/burp
> from my tailpipe, which makes me wonder about
> excess fuel, or missed ignition cycle.
>
> - I am not hitting boost cut. Logs show
> I am not coming close to 194kpa cut off
>
> - If this was ignition related, i.e. plug
> gap, etc...I would presume I would be getting
> a break up all the way to redline. Is
> that incorrect?
>
> - Could very rich settings cause this? I have
> confirmed my new Walbro GSS250 is mounted tightly
> in the fuel tank (R&R'd that the other day). I
> run a Jim B rail, and have pulled some fuel in row 4/5
> over FM defaults.
>
> - Would something wrong with the factory FPR
> cause this?
>
> My plugs and plug wires each have abotu 12K miles
> on them...its possible I suppose that this
> is the case, but I am not big into coincidences, and
> since I have been mucking with fuel delivery in
> the past 4 weeks, I am suspicious. After installing
> the GSS250, I showed low 50PSI fuel under boost (only
> ran 7psi at the time) to redline, which seemed
> fine and steady. On mechanical boost, I don't
> get this nearly as badly, though I can feel it
> a bit.
>
> I just don't know what else to do, and feel
> like a bad parent for my poor miata :(
>
> cheers,
>
> - b
>
>
>
>

This read-only message was archived from a public mail list.
Mail From: Brian Van Lieu <(email redacted)>

Bill Cardell wrote:

>Start with plugs. The cutout could go away as you go up in rpm because cyl
>pressures are highest at torque peak, most likely to blow out spark in 4-5k
>range.
>[/i]
>
Makes sense Bill...and it appears I am learning from this list as I was
wondering about peat torque, etc...

I re-gapped in the parking lot of work (I carry some tools
with me, and some gauges) and voila...no more stumble.

However, looking at the plugs was very revealing. I
think my car is trying to tell me something. Gonna
start another topic.

Thanks folks. For now, I am feeling better about
overall fuel delivery/pressure.

- b