Misfire and over fueling

[Jon_d_h]

I have an issue with my recently fitted 2wd cosworth engine in my mk2 escort. It has dark green injectors, 3 bar map sensor and i can't confirm but should have a chip to suit.

it is chucking out lots of black smoke when revving and runs as if it has a misfire. It has a spark and I have checked for compression and I'm getting about 125 on the gauge. I messed about with the spark plugs and ended up getting new ones and it ran smoothly for a bit and then the lumpiness came back.

Im under the impression that it could be maybe the coolant temp sensor, the map sensor, a wiring issue or the CO pot could do with adjusting. How can these be tested with out replacing?

thanks

[katana]

Sounds like chronic over-fueling to me!
Don't know much about Cossie's but thought they came with grey or light blue injectors rated at 400 / 440cc/min? The Dark greens - 0280-150-803 are only 381cc/min.?

[Jon_d_h]

They are the green ones. think they are the 803 ones

[Jon_d_h]

Right, I disconnected the coolant temp sensor and checked its resistance cold and it's about 4.5k ohms which sounds about right. I checked voltage to it at it was 4.3v. I decided this was correct so plugged back in and now I can't start it at all??!!

I have tested back at the ecu plug between pins 11 and 29 which are the 2 from the sensor and I have 4.5k ohms so it is connected right. I haven't touched anything else, I have tried reconnecting other plugs still nothing. I have a spark and I have fuel pressure but it just doesn't fire!

Any ideas?

[Jon_d_h]

Right, I have got it running. I replaced the "new" spark plugs with brand new plugs and it fired up. It's lumpy and sounds to have a miss fire and doesn't idle well. What could the issue be now? I have obviously checked the coolant temp sensor which is good. I'm thinking maybe the map sensor but do not have a replacement to try. Any way I can test it? Any thing else that could give this issue? Injectors, leads etc? It is booked into the specialists but I can't drive it there at the moment!

Thanks

[BigErn]

Copied and pasted from a file on my laptop. This was written by Simon Johnson, the man who created the SECS monitor among many things.

BASIC FAULT FINDING GUIDE FOR COSSIE ECUS

NOTE: Some of these results can be affected by an alarm system or immobilizer. I have assumed the car has a 2.5 bar/3.0 bar map sensor.
If SECS monitor is fitted, unplug it! (A faulty monitor or incorrectly fitted can cause engine not to run)

1) Ensure ignition is OFF.
2) Remove rear of ecu plug cover and insert plug back into ecu.
3) Turn ignition back on (do not start engine)
4) MAIN POWER CHECK: Check for DC voltage of at least 11.5V between ecu pins 19 and 20.
5) REFERENCE CHECK: Check for DC voltage of around 4.8 to 5.2V between pins 11 and 30.
6) MAP SENSOR CHECK: Check for DC voltage of approx 1.8 to 2.5V between pins 11 and 15.
7) THROTTLE CLOSED:
4x4: Check for DC voltage less than 0.5V between pins 11 and 17.
2WD: Check for DC voltage greater than 4.5V between pins 11 and 17.
8) THROTTLE FULLY OPEN:
4x4: Check for DC voltage greater than 4.5V between pins 11 and 17.
2WD: check for DC voltage less than 0.5V between pins 11 and 17.
9) Turn ignition off, unplug ecu, and turn ignition back on (don’t forget immobilizer if fitted)
10) CRANK SENSOR: Check resistance between pins 3 and 4 between 300 and 1200 ohms.
11) CRANK SENSOR: Check AC voltage on pins 3 and 4 while cranking engine - should be at
least 2V.
11) PHASE SENSOR: Check resistance between pins 5 and 23 between 300 and 1200 ohms.
12) PHASE SENSOR: Check AC voltage on pins 5 and 23 while cranking engine - should be at
least 1.5 - 2V.
12) INJECTOR: Check resistance from pins 18 to 20 should be 2 to 5 ohms.
13) INJECTOR: Check resistance from pins 35 to 20 should be 2 to 5 ohms.
14) INJECTOR: Check resistance from pins 33 to 20 should be 2 to 5 ohms.
15) INJECTOR: Check resistance from pins 32 to 20 should be 2 to 5 ohms.
NOTE: INJECTOR TESTS MAY NEED MAIN RELAY ENERGISED ON L1 and L6 ecus (link pins 1 and 10 first)
16) IGNITION TRIGGER: Read voltage between pins 24 and 25, should be at least 4.5V.
17) IGNITION TEST: BEWARE DANGEROUS VOLTAGES ON PLUG/COIL LEADS.
Quickly link pins 24 and 25 on and off this will FIRE the ignition coil. Rotate dizzy by moving car in gear to point rotor arm at one plug lead and remove spark plug (earthing it on chassis or engine) to see spark. Try for each plug in turn. Or remove king lead at dizzy and place end within 1 centimetre of earth to see a big spark.
18) Place a temporary wire link from pin 1 to pin 10 (energises ecu power relay) - you should hear a click.
19) Quickly link pins 19 to 28 to test fuel pump runs.
20) COOLANT TEMP: Check resistance pins 29 and 11 for 800 ohms to 5000 ohms (depends on temp)
21) CHARGE TEMP: Check resistance pins 31 and 11 for 800 ohms to 5000 ohms (depends on temp)

Unplug the ecu and turn the ignition on. If the fuel pump runs the relay has been wired to run permanently or the relay is jammed.
However, if the pump is running continuously, this WILL NOT stop the car from starting.

Some chips don’t drive the fuel pump relay output properly as this is used for other features like ALS etc.... (PECTEL/AHMED chips mainly). In these situations, the pump is rewired to run continuously.

If however, the pump is wired correctly and working properly, if it runs continuously when the ecu is plugged in only, then the ECU and/or chip may have failed.

The pump is ok to run continuously

[Jon_d_h]

Thanks, will give that ago and see what's up.

Thanks

[Jon_d_h]

Right, I have done the above and have found the following issues. Which of these could cause this issue:

The voltage between pins 11 and 15 for map sensor is 1.5v which is a bit low. Could this be a faulty map sensor?
The ignition trigger is 3.6v which is low between pin 24 and 25. Pin 24 is to ground which is pin 3 on ignition module. Not sure if this is correct?

[BigErn]

If you car have the car idling and then nip the map sensor pipe does it run any different? Usually if the car runs well and you nip the vac pipe to the map it will over fuel in a big way and run lumpy then will be fine when you release the pipe again. Simple thing to try to see if it makes any difference.

[stevieturbo]

I have an issue with my recently fitted 2wd cosworth engine in my mk2 escort. It has dark green injectors, 3 bar map sensor and i can't confirm but should have a chip to suit.

it is chucking out lots of black smoke when revving and runs as if it has a misfire. It has a spark and I have checked for compression and I'm getting about 125 on the gauge. I messed about with the spark plugs and ended up getting new ones and it ran smoothly for a bit and then the lumpiness came back.

Im under the impression that it could be maybe the coolant temp sensor, the map sensor, a wiring issue or the CO pot could do with adjusting. How can these be tested with out replacing?

thanks

Unless you are sure the ecu/chip is correct for all those parts, you're on a road to nowhere.

By all means test the map sensor though to see if readings are sensible.

But wrong/larger injectors and map sensor on a std ecu...will probably be dumping loads of fuel in.

[BigErn]

Didnt read that bit about not being sure if chip is correct for spec, thats kinda essential so you need a look at it fella. Also what fuel pressure is it running, plenty of people dick on with the regulator for some reason. Last cossie I had someone had turned it down to 2.5 bar cos the ecu was fried and was just overfuelling like mad so instead of looking into the cause they just wound it down. Madness!! Has the cap been removed from the top of your pressure reg or look like it has been dug into before with a screwdriver? You want to be setting it at 3.5 bar on idle with vac pipe removed.

[midnightman]

Firt you must get right chip for your injectors and MAP. That is FIRST what you must do. Then you can start check any faults....

[Jon_d_h]

Sorted now, there was a number of issues with timing, spark, air leak and fuel pressure but mechanic sorted it and running approx 290bhp on rolling road

Thanks for all help now just to sort the cooling on it