98 Discovery emission problem

[desperadodc]

Hi all;
I have a 1998 Discovery and in Toronto we have something called emission testing which my DISCO failed... seems that the mixture is too rich ... plugs have carbon deposits on them. Initial start results in very rough idle ..only clears up when you accelerate a bit and she warms up a bit ... Changed the MAF and got really worse .... Any ideas...

 

[desperadodc]

New MAF sensor caused more problems .. replaced the original one ...tech said he will check Catalytic converters .... anyone have any ideas out there?

 

[greg409]

New MAF sensor caused more problems .. replaced the original one ...tech said he will check Catalytic converters .... anyone have any ideas out there?

You can sucessfully clean the MAF on D1's

Buy specifically MAF cleaner - I've done my '97 D1 & my '96 RR se
Worked great Don't shock it, let the MAF & cleaner get to room temp, (although cleaner will spray cold) & let MAF dry well (2-3 mins. )
b/4 using

I believe the ECU has to relearn after compensating for decreased performance
(a few starts, a couple hundred various miles)

I think that the cats will clean up if your MAF was causing your engine to run rich (take it out for a 1/2 hr highway ride)

Remember, most of these run a little rich to begin with, both of mine run excellent, but the tailpipes are black until I take a roadtrip.

Oh, we emission test here in chicago, Il. too. I've always passed

luck,greg

 

[desperadodc]

Thanks Greg .. so are you saying that the CATS may not be the problem?

 

[desperadodc]

The new MAF cause an immediate MAF code to pop up ... is that normal? ( That's why tech went back to the original)

 

[joey]

What plugs are you using? And have you cleaned the intake?

 

[greg409]

Thanks Greg .. so are you saying that the CATS may not be the problem?

I can't say for sure, but I believe that I'd try driving a good distance above 2200rpm & see if that blew out some of the crap.


There's tips for cleaning up your intake, but I'm sorry, I can't type faster than you can search the forums for it in fact I can't type

luck, greg

 

[greg409]

The new MAF cause an immediate MAF code to pop up ... is that normal? ( That's why tech went back to the original)

was it the same exact MAF?
I've changed back & forth between RR & D1 the (3) MAFs I have & not thrown a code. (they're all identical) I can't imagine JUST changint the Maf would cause it to throw the code, but as I said, if your old one was dirty, the new values sent to the ECU may have ****** it off (can i say that?)

It may take some cycles to relearn new values

 

[desperadodc]

There was a problem with the CATS .. changed them .. emission passed .. but slight roughness on initial cold start still there .. runs rough for a little while about 10 secs .. then everything is fine ...

 

[desperadodc]

Joey .. not sure what plugs the guys out in last time they replaced them.. will find out and update you ...