After-cat sensor

[Jack Ratt]

Can anybody tell me how the after cat sensor is routed on a 1998 2.8 please? You may already be aware that I had the cat cut from my exhaust while it was parked on my drive.

Anyway, I've now got the car in my garage on jack stands and I'm starting some refurb work, ie rear subframe refresh, front suspension refresh, wings, sills, etc, etc.

When my cat was cut from the car they cut it after the pre-cat sensor so this sensor is still intact and I can see how it's fitted. The after-cat sensor however was taken with the cat as they cut the exhaust just in front of the mid section bolts.

I've been under the car to remove the back section and I was expecting to see the remnants of the wires to the after-cat sensor but I can't see anything.

Can anyone offer any advice please?

 

[jonco]

Garry,
There some pics in this description which may help. https://www.pelicanparts.com/BMW/te...ment/08-EXHAUST-Oxygen_Sensor_Replacement.htm

 

[Jack Ratt]

My car is a 1997 model but registered in 1998 and has the early set up similar to the 1.9 of the same year, ie it only has one cat, so should be similar to the illustration copied from Pelican write up. I'll have another look tomorrow when I get under the car again. Thank you @jonco

 

[Jack Ratt]

Been under the car again, removed the pre-cat sensor and then whole exhaust system. I still can't see any remnants of wires for the after-cat sensor. If the wires were ripped out I am expecting to see some evidence, ie loose wiring, hanging plugs etc, but there's nothing obvious

I looked on Youtube and found a vid of a guy changing an early 1.9 exhaust system that only had one oxygen sensor and that was pre-cat. There was no provision for an after-cat sensor. In the vid below it's at 12.20 mins.

Changing the Catalytic Convertor on a BMW Z3 - YouTube

I'm wondering now that if my car is an early 2.8 with original exhaust system if it was ever fitted with an after-cat sensor.

@Lee @GazHyde after being underneath many Zeds, could you enlighten me?

 

[Lee]

Been under the car again, removed the pre-cat sensor and then whole exhaust system. I still can't see any remnants of wires for the after-cat sensor. If the wires were ripped out I am expecting to see some evidence, ie loose wiring, hanging plugs etc, but there's nothing obvious

I looked on Youtube and found a vid of a guy changing an early 1.9 exhaust system that only had one oxygen sensor and that was pre-cat. There was no provision for an after-cat sensor. In the vid below it's at 12.20 mins.

Changing the Catalytic Convertor on a BMW Z3 - YouTube

I'm wondering now that if my car is an early 2.8 with original exhaust system if it was ever fitted with an after-cat sensor.

@Lee @GazHyde after being underneath many Zeds, could you enlighten me?

Some early 2.8's had a single sensor halfway down on the Y section.

 

[Jack Ratt]

Thanks @Lee

I'll keep looking as I carry on with the strip down. I've done a bit of research and the general consensus of opinion is that all new cars from 1996 were required to have both pre-cat and post-cat sensors. 1.9 Z3 were introduced in 1995 and 2.8 Z3 were first introduced in 1996 but not sold until 1997, so I'm thinking that some must have been made before the 2 cat rule came in unless it was statute on 1st January 1996.

Dumb thing is, I've got 2 of these cars, same engine, same year, but my other one is now in secure storage so I can't just have a look at my other car.

 

[Jack Ratt]

From RealOEM.com

Should have checked here first.

Last 7 numbers of my VIN shows that part number 17 (post cat sensor) was not fitted to my car.

Sorted. Got there in the end

No.	Description	Supp.	Qty	From	Up To	Part Number	Price		Notes
01	RP-exhaust pipe catalytic converter		1		09/1998	18301436829
	For vehicles with without catalytic converter	S199A=Yes
01	Exhaust pipe front silencer		1		09/1998	18101436691
02	Gasket Asbestos Free		2		09/1998	18301716888	$11.75
	Required for repair
--	Hex nut	M10	6		09/1998	18301737774	$1.65
03	Hex nut	M10	6		09/1998	18301737774	$1.65
04	Hex bolt	M8X55-8.8	2		09/1998	07119902957	$5.27
05	Hex nut	M8 SW12	2		09/1998	11621744323	$0.85
	For vehicles with Automatic transmission	S205A=Yes
06	Bracket		1		09/1998	18301435003	$28.63
	For vehicles with Automatic transmission	S205A=No
06	Bracket		1		09/1998	18311433168	$8.22
07	Torx-bolt with washer	ISA M8X18	2		09/1998	41618217419	$0.72
08	Reinforcement plate		1		09/1998	18301435006	$1.57
09	Exhaust support		1		09/1998	18311433165	$8.98
10	Self-locking hex nut	M8	2		09/1998	07129964655	$0.25
10	Self-locking hex nut	M8-8-ZNS3	2		09/1998	07129904002	$0.18
11	Clamp		1		09/1998	18311433167	$7.47
12	Hex bolt with washer	M8X18-Z2	1		09/1998	07119915132	$0.43
13	Hex nut	BM8-8-ZNNIV-SI	1		09/1998	07129904874
14	Hex bolt	M8X45	1		09/1998	07119900233	$0.82		ENDED
14	Hex bolt	M8X45-8.8-ZNS3	1		09/1998	07119902955	$0.62
15	Washer	A8,4-ZNS	1		09/1998	07119931019	$0.40
16	Oxygen sensor	SIEMENS/L=410MM	1		09/1998	11781433071	$215.65
	For vehicles with Automatic transmission	S205A=Yes
18	Lambda-probe bracket		1		09/1998	11781432741	$7.92
	For vehicles with Automatic transmission	S205A=No
18	Lambda-probe bracket		1		09/1998	11781432740	$7.92
	For vehicles with Automatic transmission	S205A=Yes
21	Fixing clamp	A=3,5 - 6,0MM	1		09/1998	07147547239	$0.58
	For vehicles with Automatic transmission	S205A=No
21	Cable clamp		2		09/1998	12527575212	$0.78

Notes

• ENDED = the part has been discontinued (no longer available).

 

[Stevo7682]

If its not a Tu engine it only needs to meet euro 2 requirements and should only 1 lamba uk.
Tu engine has 2 cats 4 lambda sensors

Stephen.

 

[jonco]

Thanks @Lee
..... all new cars from 1996 were required to have both pre-cat and post-cat sensors. 1.9 Z3 were introduced in 1995 and 2.8 Z3 were first introduced in 1996 but not sold until 1997, so I'm thinking that some must have been made before the 2 cat rule came in unless it was statute on 1st January 1996.

I have 12/97 build M44 and it only has one - pre-cat.