If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.
That combination suggests that the catalytic converters are bad. But before replacing them you should make sure that there are no intake leaks and the everything in the engine management system is working like it is supposed to.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
i used to have a LeBaron with a blown head gasket, the guy hooked all the shit up then started to warm up car, obviously it was blowing smoke all over, i played dumb and said "so you think it will pass?", he said, "*laugh* uhhh NO!"
so i looked at him and..."DUDE, if that shit doesn't pass i'm not fucking paying you"
him-"what?!?!?!"
me-"why the fuck would i pay if it didn't pass?"
him-"ok ok ok"
he made it pass :D.
just bribe someone. cough cough
NO is really low at 25mph though, which suggests the cats are good and perhaps not hot enough. HC are both high though. The car is running rich and he has some room with the CO. So he needs to lean it out a bit and get the cats nice and hot. What car is this? 325i?
"I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj
NO is really low at 25mph though, which suggests the cats are good and perhaps not hot enough. HC are both high though. The car is running rich and he has some room with the CO. So he needs to lean it out a bit and get the cats nice and hot. What car is this? 325i?
How would you suggest leaning the car out? It is a 325i.
NO is really low at 25mph though, which suggests the cats are good and perhaps not hot enough. HC are both high though. The car is running rich and he has some room with the CO. So he needs to lean it out a bit and get the cats nice and hot. What car is this? 325i?
I would agree, except that the NOx is high at idle. The engine may be running rich, but the high HC could as easily be from misfires on a lean engine. The high NOx says that the engine is lean or that the catalytic converters aren't working properly. If the engine had run long enough to reach normal temperature and the catalytic converters were good and the mixture was normal with no misfires the NOx level would be much lower.
HC & NOx are higher than normal at 25mph, though within limits. The high HC could be from the DME increasing fuel trim to compensate for intake leaks, which have a greater affect at idle, and/or an aged O2 sensor. But the high NOx points to the catalytic converters. The catalytic converters aren't completely dead, but they may be damaged and not functioning as they should.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
Which is why he should definitely do a tune up, check for vac leaks and other maintenance to try an rule out these factors. It's cheaper/easier than changing the cats. Plugs, universal O2 sensor, filters are all pretty cheap if he hasn't changed them already.
"I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj
Which is why he should definitely do a tune up, check for vac leaks and other maintenance to try an rule out these factors. It's cheaper/easier than changing the cats. Plugs, universal O2 sensor, filters are all pretty cheap if he hasn't changed them already.
Absolutely. As I said in my first post before replacing the cats make sure that everything else is right. At the minimum I would:
Have a smoke test run on the intake and fix any leaks found.
Run the fuel system test suite in the Bentley and repair as indicated
Replace the ignition wires, rotor, cap,and plugs (with NGK or OE)
Replace the O2 sensor
Adjust the valves
Verify or replace the ECT sensor
If the car has 150k (or more) on it I'd also have the injectors cleaned and flow tested.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
Absolutely. As I said in my first post before replacing the cats make sure that everything else is right. At the minimum I would:
Have a smoke test run on the intake and fix any leaks found.
Run the fuel system test suite in the Bentley and repair as indicated
Replace the ignition wires, rotor, cap,and plugs (with NGK or OE)
Replace the O2 sensor
Adjust the valves
Verify or replace the ECT sensor
If the car has 150k (or more) on it I'd also have the injectors cleaned and flow tested.
Thanks so much guys for all your input! All great suggestions. I'll start with the basic tune up procedures and report back. The car has 2xx,xxx miles on it. ODO stopped at 256,000 a year ago.
Comment