Jsblkram Posted October 5, 2021 Report Share Posted October 5, 2021 Hello I have 1999 Deville, 4.6. Approximately year ago pulled motor replaced head bolts with oversized stud kit, had heads checked installed new valve seals replaced timing chain and gears. Ran great for 6 to 8 months. Then started having issues on start up. Cold start ups sounds like motor I out of timing but eventually starts and runs great. So far I have throwed parts on it. Camshaft and crank sensors, coil packs, and even put new pcm. After pcm lnstall started up ran fine for 2 weeks without any problems or weird sounds what so ever. Let sat for week while on vacation, went to start and doing same thing. Sounds like it is out of timing on start up but when it does eventually start runs great. Got fuel pressure gauge on it, soon as I turn key on ( not starting it ) fuel pressure is at 43psi after starting stays at 41psi. Shut off and it pressure does not bleed off. Watch it for 15 mins and maybe lost a pound of pressure. Let it sit for couple hrs I might get couple cranks of the backfire sounds then starts up really rough but eventually smooths out. Only code it has is po155 ( o2 heater bank 2 ). Could this be causing the hard start ups ? I personally wouldn’t think so ???? Any help ???? Quote Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted October 5, 2021 Report Share Posted October 5, 2021 Anytime I hear backfire I think fuel pressure regulator. I see you checked if the pressure is holding but did you check the fuel pressure regulator for leakage? Every start/run problem always comes back to air, fuel, and spark all delivered in the right amounts at the right time. Quote Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Jsblkram Posted October 5, 2021 Author Report Share Posted October 5, 2021 Yes I have checked, was no sign of fuel in vacuum line but went ahead and replaced anyway. I’m stumped !!!!! Runs great after u get it started ???? Quote Link to comment Share on other sites More sharing options...
Logan Posted October 6, 2021 Report Share Posted October 6, 2021 When they sound out of time.....they are often are. Sounds like something may be coming loose or failing in the timing chain system. Maybe off brand chain? Bunch of work.....but a lot cheaper to go in and look now. Curious.......Is the engine sipping some coolant? Maybe coolant is getting in to a cylinder. Why Big Serts? Why not the standard inserts?......Time Sert or the other ones? (I cant think of the name) Hopefully not Heil-Coils. Bruce Nunnally 1 Quote Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
Jsblkram Posted October 6, 2021 Author Report Share Posted October 6, 2021 10 hours ago, Logan said: When they sound out of time.....they are often are. Sounds like something may be coming loose or failing in the timing chain system. Maybe off brand chain? Bunch of work.....but a lot cheaper to go in and look now. Curious.......Is the engine sipping some coolant? Maybe coolant is getting in to a cylinder. Why Big Serts? Why not the standard inserts?......Time Sert or the other ones? (I cant think of the name) Hopefully not Heil-Coils. No not heli-coils !! Never have had any luck with those. Bought a stud kit from Nortstar Performance. Have pulled all plugs and cannot find anything in cylinders Quote Link to comment Share on other sites More sharing options...
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