G'Day Gang,
I have just joined the forum to see if the knowledge base can help me with a problem I'm having with my 92 model TR.

When I start from cold the motor only just starts (most times) and runs really rich until it clears the excess fuel. The revs slowly build up to normal cold fast idle. If it dosn't start I have to disconnect the injectors and crank the motor. There is enough fuel in the manifold for the motor to start and run for 3-4 seconds before it dies. I then reconnect the injectors and most times it will start, although it still over fuels then clears. The fuel economy is also not very good (about 14lt/100km) I have checked air flow and air temp sensor voltages also the power and earths to the ECU.
I'm not sure if this has a bearing on the problem but the tacho reads slow as well.

Has anyone come across this problem?

Cheers
Dennis :confused:

If the lazy tacho is part of the fuel fault then it could possibly be a problem with the crank angle sensor. In a 4cyl this is in the distributor body.
The 4pin wiring plug to the distributor body often corrodes it's terminals and causes problems and the CAS do sometimes fail.

The engine computers often play up and fail, the most common fault (capacitor oil leakage) is visable as a small brown stain and corrosion near the middle of the circuit board.

another possible and likely cause is an injector or injectors that are part blocked and unable to close completely- a minor leak would release the pressure in the fuel rail when parked and could flood the manifold in a few hours.
To simply test this theory, before starting a cold engine remove the inlet duct from the throttle body and open the throttle butterfly. If the manifold is full of fuel the petrol smell should be strong.

Hope this helps and maybe even prompts someone else to think of a possible cause.

Thanks Benau,
I'm sure it is not injectors. I disconnected them before a start and the engine didn't even cough. When they were reconnected it started but with the over rich symptoms. I didn't state which motor I have. It is the 4cyl 2.6lt.
The tacho on mine gets its signal from the coil driver transistor so I don't think it would affect the fuel system.
Cheers
Dennis

i would be testing the coolant temp sensor
it is injected isnt it?

HI mate,
I did read your first post so I do not have to ask if your car is injected:nuts:

Initially I was thinking more an injector leaking however you state you unplug them and you do not have the problem. I assume you unplug the wiring and not the fuel line.

I would say no to coolant temp sensor as when the motor is warm you will have less fuel supplied.

Now you mention about the Tacho, I assume you have done a check to determine the engine speed? There is a common problem in the distributor of the astron engines, the shaft wears and then the timing fluctuates. I would be getting perhaps a second hand unit and checking this, although this would not account for the rich cold start.

Magna's like most cars have a cold start map in the ecu, have you access to another ecu to check this. Also check that the ecu is not getting a start signal when cold as I did a SAAB once where the owner had lubed the ignition with graphite, when cold the start injector was getting a start signal and flooding the motor, although this was a k jetronic system which is totally different, the Magna system will still richen for cold start, only not with an additional injector.

get a life madmagna

i was making sure it was injected

if the coolant temp sensor is out of range it can cause this type of problem
the tps cam also cause this problem
if the airfilter is choked up this can happen

i would trying a nother airflow meter

and check all the earths to motor and ecu

Thanks mate, I have one. IF you have nothing to say that either has not been said or is of assistance, just be quiet....

He did post that he has checked earths, voltages from airflow and temp sensors.

To test for injector leakage, simply put a pressure guage in before the regulator, get up to pressure, turn off. The pressure should hold.

Another thing you can try, and I have had this happen a few times, the injector pintle sticks when open, if you disconnect the injector it will stay closed, once it activates you can have this problem. Just another idea

Thanks Gang,
I did some checks today and found that the plug on the coolant sensor was corroded. (Thanks Magnus) I cleaned it as best I could but it still starts a bit rich. I then put a 300 ohm resistor in place of the sensor and it started fine, although there was a huge flat spot due to the CPU thinking the engine temp was 80 deg. I will now get a new temp sensor and do a bit more of a clean on the plug.

Thanks again guys

Cheers
Dennis :)

should also buff the end thats in the coolant if not replacing it as they get a build up of crap on them