'95 940 230 NT rough cold start

skip2 · Post by **skip2** » 14 Sep 2016, 19:10

I've perused previously posted advice for similar symptoms, and will attempt suggested fixes, but mine starts really, really rough - the engine shakes horribly and emits black and/or blue smoke - then smooths out and runs, smoke-free, as per normal...

93Regina · Post by **93Regina** » 20 Sep 2016, 12:18

skip2 wrote:...similar symptoms...emits black and/or blue smoke

If similar to B230F, then maybe ECU's temp sensor, but since this was stated,

engine shakes horribly

it would suggest a lean mixture, which would not be related to black and/or blue smoke, unless said smoke is oil coming down valve guides.

So, ohm spec ECU's temp sensor, check rail's fuel pressure with engine off, and then on at an idle. And check for vacuum leaks, which includes brake-booster unit.

And of course, replace a dirty air filter, if this is the case.

harryhendo · Post by **harryhendo** » 14 Oct 2016, 07:17

The fuel injection system on these cars is extremely simple. A common failure point is the fuel pressure regulator, a silver round object mounted on the end of the fuel rail that has a vacuum hose hooked to it. This regulator is a common part... I found a Motorcraft part that is exactly the same as the Volvo part but cost only $12.

The black smoke suggests that there is leakage into the pistons when the engine is at rest, So the car could also have a leaky injector.

skip2 · Post by **skip2** » 14 Oct 2016, 22:25

93Regina wrote:
skip2 wrote:...similar symptoms...emits black and/or blue smoke
If similar to B230F, then maybe ECU's temp sensor, but since this was stated,

engine shakes horribly

it would suggest a lean mixture, which would not be related to black and/or blue smoke, unless said smoke is oil coming down valve guides.

So, ohm spec ECU's temp sensor, check rail's fuel pressure with engine off, and then on at an idle. And check for vacuum leaks, which includes brake-booster unit.

And of course, replace a dirty air filter, if this is the case.

Your suggestions are much appreciated.

I've only owned the car since last spring, but have noticed, since then, that this problem doesn't exist when temperatures are pushing 75F, ie in summer, the car starts instantly (3-4 cranks), as per normal (ie ~1100RPMs for 30 seconds, then dropping to ~800RPMs, and purrs; no vibes, no smoke, black or blue, etc etc, but seems to behave as described at ~60F and below - ie in fall... excepting yesterday, October whatever, when temps were in low 50s, in torrential rain, I used the same starting technique as always (turn key one stop, listen for primary fuel pump to engage and then stop, then turn key to start), and away she goes -- clean start, no shaking, no smoke!

The engine has 98K on it, which is not a whole heck of a lot... before the Trump/Clinton debacle, when I was the eternal optimist, I might have ventured to say that that's a tad too soon for a valve seal to wear... obviously I now agree that a worn valve guide seal could indeed be the blue smoke culprit... but, as I said, it does occasionally start normally - smoothly, cleanly, with no smoke accompaniment. One would think that would not happen if it was a worn valve guide seal.

the whisp of blackish smoke in there, on those rough starts, is an ignition-based issue, I'm convinced.

When you say "ohm spec' I presume you mean check resistance of the ECU temp sensor... any hint at the values one should expect for a normal temp sensor? Also, given the symptoms, I could see potential (and potentially erratic) vacuum leaks remaining sealed when warm, but revealing themselves in the cold... in any case, if I play with the throttle a little (which I really hate to do), she eventually (30 secs or less) smooths out -- albeit at higher-than-normal revs ~2000RPMs - any smoking instantly disappears

thanks again

skip2 · Post by **skip2** » 14 Oct 2016, 22:52

harryhendo wrote:The fuel injection system on these cars is extremely simple. A common failure point is the fuel pressure regulator, a silver round object mounted on the end of the fuel rail that has a vacuum hose hooked to it. This regulator is a common part... I found a Motorcraft part that is exactly the same as the Volvo part but cost only $12.

The black smoke suggests that there is leakage into the pistons when the engine is at rest, So the car could also have a leaky injector.

thanks for that

The FPR is a great place to start... intrigued by that Motorcraft alternative you found -- got a number? Any advice on where to find a Volvo/Motorcraft cross-reference source? (probably on this website)
will check that leaky injector theory asap and will let you know what I find, eventually
quite busy at other things right now though, so that 'asap' might be a couple of weeks or more
but thanks again for your time

skip2 · Post by **skip2** » 15 Oct 2016, 11:33

found this spot o' data re: fuel pressure regs: "You will know there is a problem with your fuel pressure regulator from several noticeable symptoms. There will most likely be hesitation during acceleration, excessive load up during deceleration which may cause backfiring or emission odor, and you may even experience a choking sensation like the fuel or air is being completely cut off from the motor at times. Some vehicles may give you a warning light or trouble code to identify the problem.

Read more: http://www.redlinemotive.com/replacemen ... z4N8jCAGkr "
Being completely unfamiliar with Volvo FPR failure symptoms, I have to ask: Does the above ring true? If so, my '95 940 Non-Turbo (once the initial roughness smooths out) displays none of the symptoms suggested, ie: NO hesitation, NO load-up during deceleration (no backfiring, no emission odor), so wondering whether the FPR is at fault in my case... have not checked the trouble codes yet, but I will, and will check the unit's resistance (when I locate the 'normal' values for that), and get back.

lummert · Post by **lummert** » 17 Oct 2016, 16:29

Did you diagnose the ECU temperature sensor?