Running rich

[gary g]

Checking for help one last time before going to the dreaded dealer.

Car starts and runs normal for about 30 min then it runs way rich with accompanying smell (not rotting egg smell), terrible idle and dark smoke from tailpipe. Local mechanic said codes were all over the place and seemed to be unrelated to each other. He cleared them unfortunately and only found a loose intake hose. Symptoms persist, but codes have not returned.
I welcome any feedback. I haven't found these exact symptoms in any previous threads...

2001 xc70, 185k

[hoonk]

What codes did you have, ie - air mass meter, fuel trim, o2 sensor? Code numbers would be helpful, preferably Volvo but generic obd2 can help also. If the intake hose was loose you may need to reset the adaptation by disconnecting the battery for a few minutes. I had a 3.2 in a couple of months ago with the intake hose loose at the throttle housing - after it was reinstalled the engine would not start or run until we reset the adaptation. If it were a later model I would suspect a fuel pressure sensor but a 01 does not have one.

[gary g]

It is an early 2001 model. Amazing that it still has original throttle body and trans. Anyway, I Tried the negative terminal trick the other day. No luck.

Some of the generic codes that the mechanic mentioned were a turbo code, o2 sensor code, trim and a throttle body code. That is about as specific as I remember. He thought they would be resolved when he connected up the hose.
I am reasonably sure the codes will eventually return -the engine computer cant possibly thing the car is running properly...

[hoonk]

I've seen several 99-01 Marielli (sp) throttle bodies with sticking or stuck open sometimes throttle plates - if the throttle plate sticks open when your foot is off the accelerator (you are wanting the engine to be at idle speed) the control unit will cut cylinders off until the idle speed gets down to a normal range. I don't recall odors or black smoke being present with a sticking throttle plate but there is certainly a bad idle with cylinders being randomly cut out to keep the idle speed down.

Vida can test the throttle plate - if you have access to that program. Or just push the throttle plate open with your finger (unfortunately not easy to get to) - the sticking ones I've replaced were obvious.

[gary g]

interesting. Thanks for the info. Someone else I know suggested the ETM but I could not see how that could cause the richness. IF that is the problem, replacing the ETM is the only option?

[hoonk]

IF that is the problem, replacing the ETM is the only option?

yes, and there are aftermarket solutions available - Zemodex is one of them.

[gary g]

I would still need the dealer to set up any new ETM to work with the computer, right?
Dont have any access to VIDA or DICE.

[hoonk]

I would still need the dealer to set up any new ETM to work with the computer, right?
Dont have any access to VIDA or DICE.

Traditionally yes, I have programmed many new throttles with a VIDA subscription and a VCT2000 or Dice unit.

Or - the aftermarket company Zemodex can rebuild yours (thus no programming needed) or sell you a preprogrammed unit.

(I don't work for them but have purchased a DIM for a customer from them recently and was very pleased with the entire transaction from order to core credit.)

[I_am_perfect]

With Xemodex you don't need to go to the dealer. You order it, they send you one and you install it and send yours back. Well at least for the core return. You should really find out what the codes were though. A throttle is expensive especially if you don't know if that's going to fix your problem.

[gary g]

Agreed.
As usual, I picked up a heap of useful knowledge here. Many thanks guys.