Considering the age of your car I would also have a close look at the vacuum
hoses off the Throttle Body. Best to make sure they are not leaking,
cracked, and fitting properly with correct tubing and all spring clamps in
place. Maybe somebody has changed things over the years or worse yet hasn't
done anything at all.
I put my IAC back on today and in the process noticed that one of the two
small vacuum hoses off the top of the throttle body was loose. Not only
that, the spring clamps were missing. It took the hose of and discovered
that it had been replaced, not original Volvo either. Someone had put on a
piece of 3/16th inch. Should really be 5/32nd or a bit smaller as the
3/16th was pretty sloppy on the nipple. What looks good may not be quite as
No question, my car seeks and finds idle quite nicely after cleaning IAC.
Still have rough idle on cold start so next step is this little ditty below
and if that doesn't work it's new distributor cap, rotor button, fuel filter
and wires (going for the Bougicord wires, sounds like they are worth the
Poor Cold Idle: B230F/T ECU E-Prom Needs Update. [Query] My wife's 95 945T
(90k miles) starts fine on a cold (below 40F) start, but idles like crap for
20 to 30 seconds. If I hold my foot on the gas and keep it at 1500 rpm for 8
to 10 seconds, its fine. Car idles nicely when warm, and runs like a dream.
When I pull the plugs, they look great. I've replaced ECT and other parts
and cleaned the TB. [Response: Abe Crombie] Go to a dealer and have them
look at Volvo Service Bulletin 28-102 "modified e-prom for cold start with
low rvp fuel". This says the symptoms are: car starts and then immediately
dies and requires re-start. Runs rough for the first 45 seconds and may
hesitate on acceleration. Recent EPA regulations have necessitated changes
in the formulations of gasolines (i.e. "oxygenated fuels"). The result of
these reformulations has been a decrease in the relative vapor pressures
(volatilities) of these fuels, which seems to be particularly problematic
for cold starts/idling. The updated eprom chip to be installed in the ECU
is the fix to make it have correct fuel mixture computations for cold start.
You must have the number from your ECU in order to cross-reference the
correct eprom update kit P/N. The change procedure described in 28-102
requires careful attention to static discharge.
I would think that most anybody would agree that an extra Throttle Body
gasket or two should be sandwiched in the old glove box in amongst the
Remember, don't be spraying silicone around intake anywhere if you might
have leaks, goofs up the oxygen sensor. (and they are not cheap)