Guys I have a completely standard 3 door Cosworth that has been in storage for some years. The car gets started around every 4-6 weeks.

I have a party interested in buying the car pending some running issues being sorted.

The original issue was when starting from cold the car would cut out as soon as the throttle was touched , if the car was left to warm up a little all was good. Although the car smelt as if to be running on the rich side.

I removed the throttle body to replace the TPS with a spare PFO1 and while the throttle body was off I removed the carbon build up from the body and butterfly. On replacing the throttle body the engine tickover increased to 1100 RPM. I am unable to adjust this even with the idle control screw screwed all the way in.

In order to eliminate any air leaks I sprayed the inlet side of the engine with brake cleaner, no notable changes in engine speed noticed. As a precaution I have replaced the inlet to head, the inlet to plenum, the throttle elbow and throttle body gaskets. I have also replaced the injector seals and checked vacuum pipes for leaks including clamping off the vac line to the interior boost gauge. The car has now also developed a massive hesitation /misfire when warm as well as cutting out from cold. I have also replaced the spark plugs with new AGPR 12 PP Gapped at 0.6MM.

Checked the fuel regulator vac line and have no petrol in the line. The original tamper proof plug is still in place. Checked the gaps for the CPS and phase sensor. I have also done some checks on the ECU results below.

Check at ECU plugged in with ignition ON

1. Main power check DC volts pins 19 & 20 = 12.28v
2. Reference check DC volts pins 11 & 30 = 4.97v
3. Map sensor check DC volts pins 11 & 15 = 1.54v
4. TPS check DC volts pins 11 & 17 throttle closed = 4.99v
5. TPS check DC volts pins 11 & 17 throttle fully open = 0.42v Note: while depressing throttle gently I have 0.0v between 0.381v and 0.379v (possible faulty TPS? Causing flat spot on cold start?).

Check at ECU connector unplugged ignition ON.

6. CPS check resistance pins 3 & 4 = 671 ohms
7. CPS check AC volts pins 3 & 4 engine cranking = 0.5v
8. Phase sensor check resistance pins 5 & 23 = 790 ohms
9. Phase sensor check AC volts pins 5 & 23 engine cranking =3.4v
10. Injector resistance check pins 18 & 20 = 2.3 ohms
11. Injector resistance check pins 20 & 35 = 2.4 ohms
12. Injector resistance check pins 20 & 33 = 2.4 ohms
13. Injector resistance check pins 20 & 32 = 2.4 ohms
14. Ignition trigger voltage pins 24 & 25 = 3.5v
15.Temp wire link check energise ECU relay pins 1 & 10 = clicks. OK
16. Check fuel pump run quick link pins 19 & 28 = NO RUN
17. CTS check resistance pins 11 & 29 = 3635 ohms
18. ATS check resistance pins 11 & 31 = 4810 ohms.

Any input /feed back would be appreciated as I’m on the other side of the world without any Cosworth tuner support.

 

Hi,

Re the TPS, it should be open circuit when idle, with the output decreasing the further the throttle is opened.

The ECU looks for an open circuit to active it's idle and overrun strategies.

The idle screw sets the base idle only (which will need to be setup, as you have adjusted it now) I suspect if you disconnect the ISCV it will stall now.

To do this the car has to be at running temperature with no electrical load and the ISCV disconnected, the idle should be 850 RPM (IIRC) and when you reconnect the ISCV the engine speed will increase for a moment and immediately drop again.

Both the TPS and the base idle should be corrected first, as you will never get it idling nor running correctly otherwise.

Martin

 

Hi Martin
Thank you for your reply. Please be patient with me as I am not an electrician, so are you able to explain how I set the TPS up to achieve open circuit at idle. Please outline the process which pins to be tested, ohms or volts etc.

 

It sounds like yours may be ok, essentially you want it to be 5V with throttle closed, 4.99 is fine.

If your meter has a continuity function it should not beep when you measure between the TPS pins then will beep/register resistance when the throttle is opened.

Another thing you can do is start the car with it unplugged and see if it makes any difference to the idle.

Irrespective of this, the base idle will need to be setup, as it's been adjusted.

Martin

 

Thanks Martin. I’ll let you know how I get on tomorrow as it’s 10;50 at night here now