2.7i problems

[hurttech]

I just completed my swap and have a weird spark issue. Whenever the car is in "run," the coil puts out a constant spark. Car won't start. Am I missing a sensor that would cause this? The pulse sensor is installed correctly.

Thank You

Alex

[jlevie]

That has to be a bad DME. When timing data from the CPS is present from a rotating engine the DME momentarily grounds the coil to produce a spark. If the coil is sparking just with the ignition on, there's a fault in the DME.

[hurttech]

I have tried 173 with a WAR chip and stock chip. And a 380 with stock chip, both do do the same thing. You can hear it trying to start, almost like a timing issue.

EDIT: I swapped in the 173 and theres no spark at all

[jlevie]

Maybe I misunderstood what you were trying to say, sorry. I interpreted your post as saying that spark was present when the ignition was on but the engine not being cranked over. Now I think you mean that you have spark when cranking the engine but it doesn't fire.

In that case you need to look to the fuel system to see if the rail pressure is correct and to see if the injectors are firing. You also need to make sure that you don't have any intake leaks.

[hurttech]

When the 380 DME is connected, with the ignition on run and start there is a constant spark from the coil (i connected a spark plug to the coil to distributor wire), but not from any of the spark plug wires. With the 173 there isn't any spark.

Also what is this connector for? It comes off the engine harness into the cabin.

[SpecM]

with the ignition on run and start there is a constant spark from the coil (i connected a spark plug to the coil to distributor wire), but not from any of the spark plug wires.

has to be an issue with the cap/rotor if that is the case. Inspect them closely.

and that plug is for idle control if I'm not mistaken. Late models didn't need it

[jlevie]

When the 380 DME is connected, with the ignition on run and start there is a constant spark from the coil (i connected a spark plug to the coil to distributor wire), but not from any of the spark plug wires. With the 173 there isn't any spark.

Is that only when you are cranking over the engine? If so, double check the cam timing. If it is okay check the rotor & distributor.

[hurttech]

Is that only when you are cranking over the engine? If so, double check the cam timing. If it is okay check the rotor & distributor.

It's during run and cranking with the 380 DME, I got nothing with the 173. Gonna see if I can test it with another 173. Should the 380 work though?

[bataangpinoy]

yes it should. its an i ecu after all...

[hurttech]

How come the write ups say a 173 is needed?

[jlevie]

Because that is what the author of the write up used. Any M20B25 DME will work

[hurttech]

An '89 engine harness put into an '85 body would not cause any problems as long as the engine to body plug is correctly wired, right?

[jlevie]

I think that should work. A trouble shooting guide for an M20B25 engine management system is below. Work through it step by step.

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.

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 to 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 540-540 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 0.040"), 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 batter 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.

[TS87325IS]

that plug is for auto tranny , it just sits there if you dont have an auto , 380 ecu is also a 1.3 motronic so it should work fine ,

[hotballs]

85 eta has the 3 pin connector. There is a green wire out of the three that is essential to making the car run. 87 i harness' had the other end of that plug by the DME so it was easy just to plug them together. I'm not sure what the process is if you have a 87+ i harness. You need to get power to that green wire.

Terrible explanation I know, but there are threads about it, and I'm not sure if you've already got that covered.