Poor idle when cold & fault code

[Greg_S]

evening chaps, been having a bit of an issue with poor idle when the car is cold for a few mins then its fine after that. The revs tend to drop and it hunts a little, then when on part throttle it feels like it holds back for a second then is ok again. After about 5 mins warming up the issue disappears completely.

Any Ideas? I have cleaned the ISV already but that hasnt solved it.

Also I pulled the codes this evening.

The codes stored were:

00537 - Lambda sensor control
- Maximum control limit exceeded

- Minimum control limit exceeded

00525 - Lambda Sensor, G39
- Signal to B+
- Signal to ground
- No change in signal

65535 - Engine Control Module Malfunctioning

I then cleared the codes and re checked them and the 65535 code remained but the others cleared.

Now there seems to be a common theme on the descriptions for the fault codes on S2central:

• Check J220 wiring, B+ and ground connections
• Ground wire between pin 10 on J220 and engine block open circuit
• Open circuit to J220

Now my questions is what is J220 and pin 10 since it looks that it could likely be an earthing problem that needs to be sorted out to solve these issues.

[A80Avant]

this is most definitelly an earth thing. I had it for a little while myself when the 2 earth cables were loose on the inlet manifold

[S2central.net]

Yep - sounds like a ground issue. Pin 10 should be 0V earth on ABY... Check the integrity of brown/yellow wire on the inlet manifold... http://www.s2central.net/S2_Schematics/C/C50-04.pdf

[Rusty]

If the mixture control ocmes back then get a new Lambda, I had similar on-throttle symptoms and codes and a lambadadadadada sensor cured it.

[Greg_S]

After a bit more investigations and reading into the issues with this I am going to start by checking the water temperature sensors since the ECU fault includes pin 10 which is for water temp. And if that is poorly read the lamda is likely to go out of range because it is running too rich. I will also change the lambda once the water temp stuff has been checked.

[Greg_S]

Where are the single wire water temp sensors locate? Is on on the water rail next to MFTS and other on the back of the head under the intake pipe?

[Jamo]

The coolant temp sensor for the ECU is in the back of the head turbo side AFAIK

The MFTS is for the dash

[Greg_S]

Yeah i thought there were two coolant sensors other than MFTS. One for ECU and one for ISV from reading the SJM site or is that not the case?

[Rusty]

Isn't t'other one for the after run pump?

There is

The ECU one on the back of the head.

The small one on the water rail.
The dash one (MFTS) on the water rail.
The radiator fan one on the base of the rad.

Also worth checking the inlet air temperature sensor.

[Greg_S]

Yeah I downloaded the diagnostic stuff for the Air temp sensor too, the small one on water rail is gonna be a pita to test but will see how we go.

[Greg_S]

Well i managed to get out there for a little while this morning and the findings are as follows:

The temp sensor on back of head is two pin with white connector and has ro/gn wire and black/purple wire. I have checked the connections on these to the ECU connector and continuity is fine. The ro/gn goes to pin 45 but cant remember where black/purple wire went to off top of my head.

The P/N on it is 130 037 364 and measuring the resitance it came out at 3.67K Ohms @ 14 deg C. Now I dont have a reference for the correct resistance reading for this and was hoping someone could tell me?

I have yet to check the other two pin sensor on water manifold under IM and the MFTS. But my understanding was it was the one on the back of the head for the ECU control?

[Flat on my back]

.

If it's the same as the 7A as follows...

20 degrees should be approx. 2500 ohms,
80 degrees " " " 330 ohms.

Hth.

Beginning to suspect a 'slow' lambda.

Dont spose you have an AVO?

[4WheelDrifter]

That G62 reading sounds right. That's the one the ECU is interested in for fuel enrichment and so on.

s2central as ever is your friend.

[Greg_S]

Thanks guys, that rules that sensor out. I havent got an AVO at the moment but certainly be considering getting one in recent weeks. I will continue the search. I have a spare Lamda I can try yet, but will start by checking the continuity of the other earths on ECU pins 10, 14, 18 and 24.

I'll check out the S2central.net pages and SJM pages on the lamda too

[Greg_S]

Well I got out there for a few mins yesterday with the help of claire to check the connections to the ECU. The lamda wiring checked out fine, but I checked the MAF wiring and the burn off cable had a high resistance of 9.8kOhms. It looks like it is just by the connector the cable has got twisted and needs reterminating.

Anyone know where I can get a new connector pin so I can reterminate the MAF cable into the connector?

Also I disconnected the Lamda to check if the idle improved and it seemed more stable without it connected even from startup. from what I have read though, the lamda shouldnt be used by the ECU until 1-2mins of engine startup?

Also where is best source for a new lamda, didnt know if GSF or ECP were worth a try?