sion Posted December 19, 2007 Report Share Posted December 19, 2007 Hello allThis is becoming a tad perplexing...The problem surfaced in our Summer over here - hard starting when the ambient temps began to creep up. At times, the engine will fire & quickly stall with the second attempt successful, albeit a lovely cloud of black smoke out the tailpipe...Stage 0 all done during an 18 month break off the road. I checked fuel pressure & the FPR which were AOK. Next stop was the ECT sensor which I replaced last night. This really seemed the most logical culprit, as the rich start will almost always occur in the heat of the day, particularly if the car has been sitting for 2-3 hours since driving it.I've even pulled the injectors again for flow testing suspecting leakdown, but all 100%. Plug colour is great.The MAF was replaced by the previous owner not so long ago - what else is sensitive to ambient temps affecting starting?Where to look to next? :huh: Link to comment Share on other sites More sharing options...
JBVolvo Posted December 19, 2007 Report Share Posted December 19, 2007 Hello allThis is becoming a tad perplexing...The problem surfaced in our Summer over here - hard starting when the ambient temps began to creep up. At times, the engine will fire & quickly stall with the second attempt successful, albeit a lovely cloud of black smoke out the tailpipe...Stage 0 all done during an 18 month break off the road. I checked fuel pressure & the FPR which were AOK. Next stop was the ECT sensor which I replaced last night. This really seemed the most logical culprit, as the rich start will almost always occur in the heat of the day, particularly if the car has been sitting for 2-3 hours since driving it.I've even pulled the injectors again for flow testing suspecting leakdown, but all 100%. Plug colour is great.The MAF was replaced by the previous owner not so long ago - what else is sensitive to ambient temps affecting starting?Where to look to next? I know you said you flow tested the injectors, but did you pull the injectors out of the intake and leave them in the rail to watch for leaks?i.e. - leave the fuel line hooked to the rail and remove the injectors within the rail and just turn the key to the priming position.watch for drips underneath with a paper towel. Check your fuel pressure regulator if you have one at the rail. Pop off the vacuum line and see if gas drips out.If so, its bad and should be replaced. Link to comment Share on other sites More sharing options...
AlvinL Posted December 19, 2007 Report Share Posted December 19, 2007 Any codes? Link to comment Share on other sites More sharing options...
sion Posted December 19, 2007 Author Report Share Posted December 19, 2007 I know you said you flow tested the injectors, but did you pull the injectors out of the intake and leave them in the rail to watch for leaks?i.e. - leave the fuel line hooked to the rail and remove the injectors within the rail and just turn the key to the priming position.watch for drips underneath with a paper towel. Check your fuel pressure regulator if you have one at the rail. Pop off the vacuum line and see if gas drips out.If so, its bad and should be replaced.No, had them cleaned 5,000km ago. Suspecting I had a leaking injector, I had them rechecked for bad spray patterns/leakdown etc & they were fine. I haven't tried your method though...The FPR is fine - no fuel odour on the vac side & fuel pressure rises when it's disconnected.And to Alvin L, no CEL's thrown whatsoever. Link to comment Share on other sites More sharing options...
JBVolvo Posted December 19, 2007 Report Share Posted December 19, 2007 No, had them cleaned 5,000km ago. Suspecting I had a leaking injector, I had them rechecked for bad spray patterns/leakdown etc & they were fine. I haven't tried your method though...The FPR is fine - no fuel odour on the vac side & fuel pressure rises when it's disconnected.And to Alvin L, no CEL's thrown whatsoever.could be an 02 sensor that just hasnt thrown a code yettry the injector method I mentioned Link to comment Share on other sites More sharing options...
sion Posted December 20, 2007 Author Report Share Posted December 20, 2007 could be an 02 sensor that just hasnt thrown a code yettry the injector method I mentionedActually, I did try something similar when I popped the injectors out for testing a fortnight ago. Before removing them, I primed the fuel pump to place some residual pressure on the injectors for a while. After an hour, I took them out & found no evidence of leakage.Can the O2 sensor cause rich starts? I would've thought I'd see evidence of a bad sensor on the plugs which are as clean as can be. Of course, the tailpipe is the usual sooty colour these things seem to all be :D Link to comment Share on other sites More sharing options...
sion Posted December 25, 2007 Author Report Share Posted December 25, 2007 More enlightenment needed if possible guys...Injectors have tested fine with 50psi applied - no leaks.I started her up yesterday morning & got the big black cloud of smoke. I've also noticed when the engine is cold, it surges quite noticeably under load. Once warm, it's fine - maybe a link there??Seeing we've got the T-5, are there any parts worth interchanging as part of the process of elimination? Reiterating Stage 0 done, new MAF, temp sensor etc.All I can think of that might be related to this fault are the IAC motor & the oxy sensor...Many thanks & best wishes for the festive season. Link to comment Share on other sites More sharing options...
Jippi 855 GLT Posted December 26, 2007 Report Share Posted December 26, 2007 my cars doing the same thing im getting ready to test the injectors, regs, etc. filter is new and teh pump is new and the pressure is good. gonna do a leak test anf a few other test Link to comment Share on other sites More sharing options...
sion Posted December 26, 2007 Author Report Share Posted December 26, 2007 my cars doing the same thing im getting ready to test the injectors, regs, etc. filter is new and teh pump is new and the pressure is good. gonna do a leak test anf a few other testMmm, always good to know you're not suffering alone, but it will be a relief to get to the bottom of this... My problem is intermittent as well which adds further confusion. Whatever it is, it seems the injectors are cycling up to full output for a regular cold start, however the engine temp doesn't warrant it. I suspect the issue has been there all along & now with our hot Summer almost upon us, it's rearing it's ugly dial. In the Winter, it was perfect.If anyone out there has had a similar problem & found a fix after addressing the regular culprits, please post a reply Link to comment Share on other sites More sharing options...
Mike_P Posted December 26, 2007 Report Share Posted December 26, 2007 Shot in the dark, but could it be a faulty evap purge valve letting excess fuel vapor into the manifold at startup? These don't always throw a code right away. Link to comment Share on other sites More sharing options...
JBVolvo Posted December 26, 2007 Report Share Posted December 26, 2007 Shot in the dark, but could it be a faulty evap purge valve letting excess fuel vapor into the manifold at startup? These don't always throw a code right away.test the purge valve with a vacuum tester on the side that runs into the intake.if it test good as holding vacuum, you should be fine.check resistance on ECT sensor even though you said its new Link to comment Share on other sites More sharing options...
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