[urq] hesitation at higher RPM & boost

[Pasqualoni, James E]

5kcstq injector fan switch is the 85 deg C one. 

-----Original Message-----
From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On
Behalf Of Ben Swann
Sent: Wednesday, July 26, 2006 2:01 PM
To: tlum at flash.net
Cc: urq at audifans.com; 'Ben Swann'
Subject: Re: [urq] hesitation at higher RPM & boost

See *** comments&questions ***

From: tlum at flash.net [mailto:tlum at flash.net]
Sent: Wednesday, July 26, 2006 12:57 PM
To: benswann at comcast.net
Subject: Re: [urq] hesitation at higher RPM & boost

Boost up to around 2 Bar - I can do more, but silly until I get this
resolved.
++++++++++++++++++++++++++++++++
I'm assuming 1 bar over normal 1 bar atmo or 14.5 PSI boost right?
***CORRECT***
++++++++++++++++++++++++++++++++

F/TCU has a TAP chip - don't know much about it, just happened upon the
ECU one day.
++++++++++++++++++++++++++++++++
I have the same chip in my MAC02.  I dyno'd it on the ATP Turbo 4wd dyno
at 152WHP, 13.3 AF at 15 psi indicated on my VDO boost gauge with no
seeming stumble.  To be a bit more conservative, I adjusted the WG to
limit boost to
12 psi.
*** I would doubt I have overboost problems.  The compression ratio is
so low, I normally run on 87 octane. I plan to install a Schrapnel Knob
and possibly P.T, resistor to purposely advance timing - already cranked
on the WG - that got the 2 bar ***
++++++++++++++++++++++++++++++++

Injector cooling fan works, but I should probably put in a switch or
after-run system, as it only kick on when extremely hot.
++++++++++++++++++++++++++++++++
I changed my switch to run at 85C instead of 95C to run fan almost after
every run.
*** OK - good idea.  Where do you get this switch? ***
++++++++++++++++++++++++++++++++


I doubt I get any CS inj. For hot start - been tempted to put in a
manual trigger.  Sometimes I need to introduce fuel when having hot
start issue.  I did not have the problem with the CPR mod - enriches
based on airflow - using venturi effect from port at turbocharger -
works a little too well, but indicates there is enough fuel to be had if
need be.
++++++++++++++++++++++++++++++++
Hot starts are sometimes a little tricky after say 20 minutes and I have
to listen carefully to hear the engine catch.
++++++++++++++++++++++++++++++++

++++++++++++++++++++++++++++++++
I'm going to switch to 034efi and a MC2 engine soon.  Nothing wrong with
the WX except for a marshmellowy takeoff even with a K24 turbo making
boost at 1900 rpm.  Jeff Lewis's MC1 034efi starts in under 2 revs and
has tremendous power and yet excellent fuel economy.
++++++++++++++++++++++++++++++++
*** I plan to keep this one nearly stock as everything CIS has been
reworked or new - it runs to good to replace, but I'd like to get it
perfect.  I have at least three other engines to do EFI - 034 or MS on
and two are going into UrQ's.  ***

++++++++++++++++++++++++++++++++I'd double check the intake temp sensor
leads.
That sensor is so low resistance, anything marginal might cause the
timing to back off. ++++++++++++++++++++++++++++++++
*** BTDT several times - even replaced the temp sensor ***

Have fun,  *** I plan to!  BEN ***

Tony

-----Original Message-----
From: tlum at flash.net [mailto:tlum at flash.net]
Sent: Wednesday, July 26, 2006 10:23 AM
To: benswann at comcast.net
Subject: Re: [urq] hesitation at higher RPM & boost

Ben, how much boost are you running?  Is your F/TCU chipped?  Make sure
your injector cooling fan is working.  Hot starts can be a little
problematic, but not severe.  Supposedly there's a hot start relay
involving a pulsing cold start valve, but my car doesn't have it.

Tony
'83 urquattro #302

= = = Original message = = =

'83 Ur Quattro  - new injectors, vac lines, ignition, fuel pump, filters
and fairly well sorted over and over.  The car passed emissions with
flying colors
- CO reading 1/10 of allowable standard and 0% HC which is amazing.  The
car still has a little bit of a hard start problem particularly when
warm after sitting, and usually starts right up when cool.

After installing the JCW  air/fuel ratio guage, I note good mixture and
operation during normal acceleration and cruising.  Still there is this
strange hesitation at full accel - over 4000 RPM usually and boost
at/over 1.8 bar.  The air fuel ratio guage indicates more of a rich
condition than the lean condition I expected at full throttle - this
tells me there should be more power on tap, or am I running out of air?
If there is any air leak under boost, I don't know where it could be.
The guage hits one light below max rich usually.

I have the fuel pump jumpered on with ignition, so no fuel cutout.  I
have a means to enrich or enlean CPR if need be, but does not seem to
make any difference, except that I had boost controlling the CPR to
enrich which is now undone.  Still AF on rich side at full throttle. 

I notice that if backing off of full throttle a little, there is
somewhat of a momentary power surge.  I set the full throttle switch
cut-on a little higher and seemed to help, but not much, except what I
perceive was XS rich was less pronounced.  Should I be in the 12:1 fuel
air range at full throttle?

I installed a Jacobs ignition which definitely helped, but still seems
to be a bit of hesitation - like there is more power on tap, but maybe
ignition is being retarded. I fell the power coming on then dropping out
- inconsistent.
Sometimes she feels like it has a 1.8 bar MC engine and other times the
power just isn't there.  The power increase I noticed after adding the
Jacobs ignition boost was dramatic when  relatively cold, but after
warmup, seems to drop off, although still better than before I added the
ignition booster.

After having been over this engine over and over, I'm wondering what
else it can be.  The problem is minor, but enough that it will effect
acceleration in autocrossing situation or passing. 

Oh I also installed a Bypass valve which helps smooth out shifts, but
made no difference with this "problem".

Is this a timing retard due to the intake air sensor indicating to hot
intake air temp?  and if so, how do I override or compensate?  - short
of adding a larger intercooler, etc.

Ben

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