HELP! Car won't stay running! Hard to diagnose!

TTalon95 · Nov 1, 2003

Here's the deal: 90 GST

( 8 months ago)
The ECU caps leaked and damaged it. When this happened I also heard a ticking noise around the intake manifold area (while the car was OFF mind you).

(This week)
- Turbo replaced
- Swapped ECU's
- I have a big exhaust leak between the o2 housing and the DP (nut rust welded on)
- My K&N doesn't seal perfectly

Symptoms: [Idle] -9 mmHg vacuum @ like 450 RPM
30 (fuel guage)
VERY lumpy idle (entire car shakes)
Can't rev past 3k RPM's in neutral
Turning BISS screw Doesn't change idle
C.E. light sometimes comes on (other lights may also flicker)

Here's the weird part: Sometimes the dummy lights will glicker and the car will die. One time I touched the brake pedal and the car regulated itself (900 RPM and 18 mmHG at vacuum). As soon as the car "fixes" itself it will instantly die. After the "fixing" the car won't start for like an hour. Right before the car dies, theres a click behind the dash (I have yet to listen to see if it is the ECU or MPI relay.

So whatcha think!??

Fuel vs. Electric?
I just changed the plugs and the wires only have about 1k miles on them. The car sat for about 7 or so months also.

The one thing that puzzles me is that theres a clicking noise at the intake manny area after the car dies and it continues until I remove the key??

Thanks for your time.

ICGerms · Nov 4, 2003

TTalon95 said:
Symptoms: [Idle] -9 mmHg vacuum @ like 450 RPM
30 (fuel guage)
VERY lumpy idle (entire car shakes)
Can't rev past 3k RPM's in neutral
Turning BISS screw Doesn't change idle
C.E. light sometimes comes on (other lights may also flicker)

These symptoms are similar to mine when the exhaust cam had jumped a tooth. Maybe check to make sure that, @ TDC (the crank) the cam gears are lined up correctly.

TTalon95 · Nov 4, 2003

Thanks, I will check that out. The thing is I still think it is electrical because today I went to start the car and it stayed on until I eas revving it a little. Right after I heard 2-3 clicks coming from the ECU/ MPI relay location.

That means 1 of 3 things:

1) The ECU I bought is also defective
2) The MPI relay is shot
3) Theres a problem somewhere else that causes of these 2 to start to click and the car instantly dies and won't restart for some time after?

I am getting closer to the problem. As for your suggestion about the exhaust cam being a tooth off, the car sometimes reguates itself out of nowhere but then instantly dies.

Any other suggestions ?
(Will check cam centering this week)

Thanks!

Boostin'X' · Nov 4, 2003

Sounds like when you replaced the turbo you either forgot to tighten a coupling or tore one. I think that will only solve one problem though. You may want to check your new ecu.
Check for leaks first.

Shawn300z (TSI) · Oct 17, 2006

I have the same problem with it clicking from the intake manifold area..

?????

anyone?

lackingawd17 · Oct 17, 2006

i'd check the relay, and swap it with a known good one, and get a meter and check out some basic engine control circuits and make sure the ecm is working properly, is it a stock ecm replacement, or from a different year or something?

Shawn300z (TSI) · Oct 17, 2006

for me, its a stock OEM replacement

TALONLVR · Oct 17, 2006

MPI relay is in that little box attatched to the battery close to the instake mani so thats probably whats ticking. Its labeled so find it and put your ear up to it to locate it. As for the idle it sounds like you need to fix all your intake leaks and also pressure test it. The reason it regulated when you hit the brakes is because the brake booster uses some intake pressure off the manifold and that use of pressure regulated it. You can check relays by swapping it or a Haynes manual and a circuit tester/meter.

Shawn300z (TSI) · Oct 17, 2006

Aren't you talking about the MPI fuse?

I thought the MPI relay was near the ECU, in the center console.

TALONLVR · Oct 17, 2006

Oh you may be right. I just knew I had pulled it for doing compression tests so Im not spraying fuel at the same time. Come to think of it it may have just been a fuse. Hard to remember. Anyone know for sure and care to enlighten us? Thanks

4G2NV · Oct 17, 2006

Some Things to Check First:

-Cam Timing
-Cam Pos Sensor Timing
-MPI Relay
(Does your fuel pump prime when the key is on before start?)
-Fouled Plugs?
-Compression?
-Hot Spark?
(Consistent Spark on ALL Cylinders?)
-Blocked Air Pipe?
-Blocked Filter?
-Vacuum Leak?
-Firing Order
(Just in case... From front to back on the coil pack firing order is 4123)

Try to check all of those one by one, this should fix your problem, unless it is inside the ECU, but I doubt it.

4G2NV · Oct 17, 2006

Shawn300z (TSI) said:
Aren't you talking about the MPI fuse?

I thought the MPI relay was near the ECU, in the center console.

The MPI Relay is behind the radio, near the ECU, but the fuse for it is mounted on the Positive Battery Terminal.

4G2NV · Oct 17, 2006

Also an easy way to check that relay is to manually ground the relay and turn the key on.. If the fuel pump primes, then that side is fine.

Shawn300z (TSI) · Oct 17, 2006

how do I know which is the ground?

HELP! Car won't stay running! Hard to diagnose!

TTalon95

ICGerms

TTalon95

Boostin'X'

Shawn300z (TSI)

lackingawd17

Shawn300z (TSI)

TALONLVR

Shawn300z (TSI)

TALONLVR

4G2NV

4G2NV

4G2NV

Shawn300z (TSI)

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