Another Bogging down issue

[completelyrevlimited]

No fuel and/or no spark on an m20 can be as simple as the CPS and cylinder ID wires crossed.

Yeah, checked those, is it definite that it works from the OHM range in the book?

Edit: Though that wouldn't explain why my old one doesn't work in the vehicle as well.

[ForcedFirebird]

No fuel and/or no spark on an m20 can be as simple as the CPS and cylinder ID wires crossed.

[completelyrevlimited]

Easiest way to see if the injectors are firing, is remove the valve cover, pull the rail, point them at a piece of cardboard, turn the key to start, and take note of the spray patterns. Many times I have seen them all "spraying", but one or two will have a weird pattern, or dribble out.

If you swapped your chip and it didn't start, make sure it's installed in the correct direction. There's a notch on the socket and a notch on the chip - they have to match.

1222 is o2 circuit. Can either mean the o2 relay isn't kicking off, or the sensor is dead. While diagnosing, just unplug it (the o2 plug) so they ECU will just ignore the feedback and run a basic map. If the sensor is giving back wonky reading, the ECU might compensate for it, so best to have a dead signal than a wrong one.

Pull the boots off c109 and inspect the pins on the other side of the connector. That pic appears that the copper female pins are quite corroded, don't be surprised if the crimps are all green.

Yeah I've verified pretty much everything, so just waiting on the a new ECU. Replaced parts with old parts that were working, just old. So in theory that should rule out sensors. I'm at a no start situation, no fuel, but spark is present.

[ForcedFirebird]

Easiest way to see if the injectors are firing, is remove the valve cover, pull the rail, point them at a piece of cardboard, turn the key to start, and take note of the spray patterns. Many times I have seen them all "spraying", but one or two will have a weird pattern, or dribble out.

If you swapped your chip and it didn't start, make sure it's installed in the correct direction. There's a notch on the socket and a notch on the chip - they have to match.

1222 is o2 circuit. Can either mean the o2 relay isn't kicking off, or the sensor is dead. While diagnosing, just unplug it (the o2 plug) so they ECU will just ignore the feedback and run a basic map. If the sensor is giving back wonky reading, the ECU might compensate for it, so best to have a dead signal than a wrong one.

Pull the boots off c109 and inspect the pins on the other side of the connector. That pic appears that the copper female pins are quite corroded, don't be surprised if the crimps are all green.

[ForcedFirebird]

Jim used to copy/paste often (RIP). This guide will help any m20 issues, used it many times throughout the years.

For the engine to run the following conditions must be met:

Power on DME pins:
27 Start Input
18 Un-switched Power input
37 Power Input from Main Relay

Ground on DME pins 2, 14, 19, 24

Timing data from the CPS on DME pins 47 & 48 from a rotating engine

To have spark power must be present at the coil positive and ground pulses
from the DME's pin 1 must reach the coil negative. Power to the coil is
controlled by the ignition switch via C101. When checking for spark, use the
output lead from the coil to eliminate the distributor, rotor and plug wires.

To have injector firing power must be present at each injector and ground
pulses from the DME's pin 16 (Bank1) and pin 17 (Bank2) must reach the
respective injector bank. Note that the injectors are wired as two banks of
three. With cylinder 1,3,5 being bank 1 and 2,4,6 being bank 2. Power to the
injectors is controlled by the main relay. Injector firing is best checked
with a noid light.

The fuel pump relay must have power on pin 86 (relay coil) from the main relay
output (pin 87) and power on pin 30. The DME will ground pin 85 to turn on the
relay and power the pump(s) via pin 87. Of the above, only the fuel pump power
is fused. So if the there's power at pin 87, but not at the pump, check fuse
11.

The main relay and DME pin 18 receive power from the smaller of the two wires
that connect to the battery's positive terminal. That wire incorporates an
in-line fuse. When the DME is presented with a start signal, it grounds the
main relay pin 85 and furnishes power to the fuel pump relay, injectors, and
DME.

Troubleshooting:

Disconnect the battery and the DME cable. Then:

1) Disconnect the coil negative and check continuity from that connector to
DME pin 1. Also verify that from DME pin 1 to ground is an open circuit.

2) Check the resistance across DME 47 & 48, which should be 500-560 ohms. If
the CPS is dismounted, the resistance can be seen to change from about 500 to
540-560 ohms when a ferrous object is brought to the face of the
sensor. Neither pin should be grounded.

3) Check for continuity from DME 36 to main relay 85 and from DME 3 to fuel
pump relay 85.

Reconnect the coil, remount the CPS (air gap should be 1mm), plug the
relays back in, reconnect the DME, and connect the battery. Then do the
following checks:

1) With the key off, verify that power is present at DME pin 18 and main relay
86 & 30.

2) With the key on, verify that power is present at DME pin 27 and pin
18. Power to pin 18 is from the main relay and there should be power to the
injectors and fuel pump relay.

3) With the key on, verify that no voltage is present at the DME grounds (2,
14, 19, 24).

4) Verify that power is present at the coil positive and at fuel pump relay
pin 30. Those get switched power from the ignition switch via C101.

The engine will start and run (if poorly) with only those connections to the
DME in place. The other signals from Cylinder ID, AFM, temp sensor, etc., are
necessary for proper operation. But they won't prevent the engine from firing.

IMPORTANT:

A power check means seeing a voltage within about a tenth of a volt of what
you measure across the battery terminals, which should be at least 12.6v on a
charged battery.

A continuity check means seeing less that 1 ohm of resistance.

An open circuit means seeing a resistance of at least 100k ohms.

A good quality auto-ranging digital multimeter will make these tests much
easier.

[completelyrevlimited]

I put a set of eBay injectors in chasing my misfire from the bad intake rocker as the spark plug was fuel fouled at that time. Not that that rules the injectors out. No visible corrosion on the injector wiring, the engine ground is looking a little green but adding an extra ground from the valve cover to ground point on the right strut tower did not make a difference. I need to hook a fuel pressure gauge back up too see if pressure is dropping when the issue happens.

If you go to your harness and Ground pins 36 and 2 together, (2 is ground, 36 is main relay, should hear a click), then ground 16 to ground, you should be able to hear them click, there will be only 3 that fire, to fire the other 3 injectors, ground 17 to ground. Also check continuity on the injectors themselves, I believe it goes if you have continuity it'll be in the closed state (the injector).

You said the plugs were looking lean, are they in that state now? You also said one was fuel fouled, was that before? Im still running diagnostics on my setup, so far its seeming like the ECU, I'll post any update once I get a hold of another ECU, should be on the 26th.

[Tom Galloway]

Don't laugh - A few years ago I had a similar problem and (eventually) I put a penny behind the ICV, jacked up the mixture and idle , and been running great ever since.

[Caperix]

No occiloscope at home, that would help on an issue like this though, any advise on an affordable one that is also accurate? Something is changing at temp, the coolant temp signal has been monitored & stays at 87 to 89 degree celcius.

[digger]

Time to pull out the scope and check your triggers and control signals

[Caperix]

I put a set of eBay injectors in chasing my misfire from the bad intake rocker as the spark plug was fuel fouled at that time. Not that that rules the injectors out. No visible corrosion on the injector wiring, the engine ground is looking a little green but adding an extra ground from the valve cover to ground point on the right strut tower did not make a difference. I need to hook a fuel pressure gauge back up too see if pressure is dropping when the issue happens.

[Caperix]

I put a set of eBay injectors in chasing my misfire from the bad intake rocker as the spark plug was fuel fouled at that time. Not that that rules the injectors out. No visible corrosion on the injector wiring, the engine ground is looking a little green but adding an extra ground from the valve cover to ground point on the right strut tower did not make a difference. I need to hook a fuel pressure gauge back up too see if pressure is dropping when the issue happens.

[Caperix]

I put a set of eBay injectors in chasing my misfire from the bad intake rocker as the spark plug was fuel fouled at that time. Not that that rules the injectors out. No visible corrosion on the injector wiring, the engine ground is looking a little green but adding an extra ground from the valve cover to ground point on the right strut tower did not make a difference. I need to hook a fuel pressure gauge back up too see if pressure is dropping when the issue happens.

[Caperix]

I put a set of eBay injectors in chasing my misfire from the bad intake rocker as the spark plug was fuel fouled at that time. Not that that rules the injectors out. No visible corrosion on the injector wiring, the engine ground is looking a little green but adding an extra ground from the valve cover to ground point on the right strut tower did not make a difference. I need to hook a fuel pressure gauge back up too see if pressure is dropping when the issue happens.

[Caperix]

I put a set of eBay injectors in chasing my misfire from the bad intake rocker as the spark plug was fuel fouled at that time. Not that that rules the injectors out. No visible corrosion on the injector wiring, the engine ground is looking a little green but adding an extra ground from the valve cover to ground point on the right strut tower did not make a difference. I need to hook a fuel pressure gauge back up too see if pressure is dropping when the issue happens.

[completelyrevlimited]

I thought I made some progress on mine. My cat had a bit of a rattle to it so I disconnected the exhaust at the manifolds & the misfire seemed to stop. So I thought that bad rocker arm had melted the cat. So today I cut the cat off the car so I could run with the o2 sensor connected. The cat was hallow, so the cat had melted but had been pushed out the exhaust. Unfortunately once the engine warmed up the misfire was still present. So either the o2 sensor was damaged or I did not let it run long enough with the exhaust disconnected for the issue to occur.

How are your injectors, have you done the necessary continuity tests? Checked c191 for corrosion, etc? I believe I've narrowed my problem down, but waiting for parts now.