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Re: Fault code 2221? 5k TQ


Regarding the problem described below, you may want to
disconnect the boost hose from the engine side and plug the
hose and then remove the hose from the ECU and use a hand
vacuum pump to verify that you have no cracks or tears in
the hose going from the intake manifold to the ECU.

Assuming the hose from the manifold to the ECU is ok then
you may have an intermittent connection inside the ECU
between the internal pressure sensor and the Input/Output
(I/O) chip. This is the chip that the microprocessor uses
to measure/look at the voltage signal coming from the   ECU
 pressure sensor. The sensor is an absolute pressure type
which outputs a voltage for different manifold pressures
ranging from vacuum to boost. If the IA stage II mod
includes a resistor divider type mod that divides down the
boost sensor voltage then this might be where the poor
solder connection is at. It could also just be a poor
solder joint due to age.  I suppose the pressure sensor
itself could be going out, especially if it has been
over-stressed with a lot more than 2.0 bar worth of
pressure. If you bought the ECU from Ned, I would imagine
that he would trouble-shoot  and repair it for you. If not,
there are several of us on the list who could take a look
inside and locate the problem. Steve Eiche in CO has a lot
of experience trouble-shooting these computers and may be
closer to you than my location in Portland, OR.

The ECU does not remember fault codes after the engine is
shut off and that would explain why it functions normally
after you restart the engine.

BTW, enjoyed meeting you at  the Pikes Peak event, it was a

Scott M.
Lago-Blue- 89-200-T-Q
Eibach , Tokico, Koni,
TSW Blades w/D40 M2
Overboost to 2 bar

>Chad said:
>I noticed the dreaded orange check engine light
>  come on and the immediate loss of boost back down to 9
psi as indicated on
>  my auxiliary boost guage. Another couple of runs from a
dead stop yielded the 
> same problem with the light staying on at anything over 7
psi boost. BEFORE shutting the 
> engine off, I pulled the codes to reveal a 2221 which
says: Vacuum hose to Pressure 
> Sensor in control unit-Culprit: Vacuum hose disconnected,
leaking or plugged. After 
> searching for anything obvious like a disconnected hose,
I have found nothing. 
> Could the problem be in the ECU itself? Is there a
pressure sensor inside the ECU? 
> BTW, this is an IA stage II box that I've been trying
out. I may put my TAP box back in 
> to see if the problem persists.  Here's a wierd twist
though- After shutting the car down
> and running the car, I get full boost to 15 psi and no
light? HUH? So it's definitely an
> intermitant problem.
>  Chad Clark '87 5k Tq