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2002 156 jts running rich

4971 Views 5 Replies 2 Participants Last post by  Monz156JTS
Hi all

Introduced myself a while back when I bought this 2.0 JTS as a project.

Replaced all valves etc (timing belt snapped)
Replaced clutch and concentric cylinder.
Replaced old fuel and ran injector cleaner through car.
I have replaced all wheel bearings and disks. Reconditioned the callipers. New copper brake lines fitted also.
Replaced various pulleys and fitted new timing belt kit.
New plugs. New oil etc.

Failed MOT however on emmissions : ( .......oh and one faulty windscreenwiper lol

No other advisories on MOT.

The problem is it runs rich (2.1 was the reading I think. 6x what it should be) at high revs.
runs very lean as it should on idle.

Replaced both lambda sensors and now it runs rich at idle and at high revs.....what the :eek::eek:??
MAF cleaned. Cylinder head was buildup of carbon deposits etc. There is a bit of 'white' smoke coming from exhaust when revving above 4-5000 revs.

FiatECu software is not giving any errors other than high readings for lambdas. Contacted rather unhelpful Alfa dealer and they suggested the JTS is known to have issues with air leaks which can cause this problem....then cut me off???

Any help with this would be appreciated.
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7 Posts
Discussion Starter · #3 ·
Appreciate the input Tommy.....

Will try that tonight......some parts on the car didn't age well while sitting on a driveway for 3 years lol

As for fuel injectors....its possible I suppose......what is weird is the problems with the mixture are worse than before replacing had really old fuel (5 years :p) when I first got the car.After rebuild it did run but very lumpy) Drained it and quarter filled tank with high octane fuel from Shell or somewhere). Also put 1/5 of bottle of injector cleaner through it.

It does misfire slightly at idle which settles after it warms up......oh and after MOT on the way home when we tried to accelerate hard it cut into emergency mode or whatever with engine management light on. No errors stored when checked. Will look later today.


· Registered
7 Posts
Discussion Starter · #5 ·

replaced MAF and removed filter temporarily from airbox...very slight improvement but still too rich. Disconnect lambda's and it run as it should eventually going slightly rich as the engine revs to 3-4000

the lambdas I bought came in a jiffy box.....we're not convinced they aren't testing again with the old at a time to compare readings on multiecuscan.

ecu 'might' b a problem also if not getting correct readings.....hmmmm

will post in a few days.....funeral to go to : (

· Registered
7 Posts
Discussion Starter · #6 ·
Thought an update was required.

Problem solved after some extensive research on the Bosch website (which has some great product info)

Lambda sensors are very sensitive. And the JTS needs the correct ones....also 5 wire not so common......4.9 wide are NOT going to cut it.....must be 4.1.......

Do not do what we did initially and bought the correct Bosch sensor but with the wrong connector.....the resister on the connector is calibrated for the specific car so you can't cut off and swap connectors.

Replaced 1x faulty coil......MAF.......Air Filter.........1x pre cat lambda (Bosch LS7156)

Self tested emissions and its passed so back in for MOT Monday......wish me luck :)

....and No I have not soldered the wires to the pins of the connector as some people have suggested......I still might but a 'wiggle' test produced no errors while MultiECUscan was running.....great piece of OBDII software btw.
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