I would appreciate/be grateful to any help anyone can give me.I have taken my Volvo 940 SE (Which used to be a Turbo model,but had replacement engine) in for two MOT`s now.It failed on various bits on the first MOT after putting in the non turbo engine,but the main issue was emissions.It failed for the 2nd time today on this problem.During MOT`s,I replaced the front downpipe and the Cat,which now has the lambda built into it.The MOT inspector reckoned the emissions where out again,due to the engine running lean,thus making the exhaust system run very hot,so much so,it melted the rubber hose to his probe of his emissions tester.
In replacing the engine,I replaced the ECU,MAM,etc,etc.I found out that the engine ran better using the turbo injectors,rather than the injectors which came with the non-turbo lump.Apart from this,I have a starting problem when the engine is partially warmed up.It is a pig to restart at about a 1/4 of its normal operation temperature,and surges forward at stand still,and runs very "lumpy".Once upto normal temperature,1/2 way on the temp gauge,it seems to run abit more reasonable.
On the first MOT test the emissions were less in value than on the last test today,even though the CAT,labda sensor and downpipe were replaced.Can anyone give me any suggestions if changing the injectors over would help the engine to run abit more richly,thus alterering the emmissions?Or any other suggestions which may help? I now have the statutory 10 dys to get the proplem resolved to save yet another £50-00 MOT fee.

Thanks in anticipation

 

Sorry about the problem.

Moderator Tech could give you the best suggestions, but Tech is busy at the moment. Please consider my suggestions as a temporary remedy.

I am wondering if the NA engine uses the same input parameters as the turbo engine. In the case of 850, some parameters exist in only one of the engines but not on the other one. Even with ECU replacement, if the ECU is receiving parameters that does not exist, it can cause problems. Check to see if the NA & turbo engines in the 940 use same sensors for electronic engine control.

This is something I would not recommend, as this would cause different types of problems, but if your only concern is to enrich the A/F mixture, you can:

- Remove thermostat and force the engine to run cool until you pass the test.
- Restrict/impair the air flow in the induction system.
- Dump a bottle or two of Techron fuel system cleaner into the fuel tank right before taking the car to the emissions test. This would not enrich A/F mixture but may let you pass the test anyway. Some people seem to have tried this with fuel line antifreeze (HEET/Dry gas) and have successfully passed the test.

Again, these will only make the engine run rich and may not let you pass the test. Wait to see if other members come up with better alternatives (I'm sure they will).

Best of luck to you,


JPN

 

Thanks.I`m going to replace the injectors today with the set that came with the engine,as a starting point,to see if that makes any difference.Then I guess it will be a process of elimination.

 

Well,having replaced the injectors,the engine now runs as sweet as a nut,no surging,no flucuations on idle etc,and I can now touch the exhaust system without fear of burning my hand.So....taking it back to the MOT testing station this afternoon to see if the emissions are now ok,and to hopefully get my ticket.

Thanks for all your help,and I will let you know if the car goes through its ticket OK.