Jsblkram

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

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 ????

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 ????

Thank you Logan. After checking all fuse blocks for corrosion, which I found none, started looking into wiring to stereo system. Found one loose wire, the remote wire from stereo to amp. Reattached with new ends and car fired right up. Runs like a top now. I knew it was all tied in with computer system but actually never thought about a bad connection on stereo system. Thanks again Logan !!!! This site is the best !!!!

My stereo guy has been installing for over 30 years and has one of the best shops. I am very confident in his work, but I will definitely check everything out. Something really havnt given much thought. I will post results that I find. Thank you !!!

Yes it does have aftermarket stereo and small amp and subwoofer but was professionally installed. Been in car for couple years with no previous problems like this.

From what I’ve looked at the cables are good but have not looked into fuse block other than checking fuses. I will dig deeper tomorrow see what I can find. Will keep u posted on what I find. Thank u for ur time !!! This is the best place to find out anything about Caddy’s !!! Thank u !!!

The keep alive memory ????

I had issues with it start, sounded like it was out of timing, changed the camshaft sensor and it fired right up and ran great. Drove it back and forth to work one day and next afternoon it’s right back to sounding like out of time again and throws the 603 code. Research I’ve done leads me to the pcm ?????

Anybody ever use the so called plug & play pcm’s that are available? Are they really that easy to change out ? Fist time really messing with system but pulled PO603 code which is by what i can figure out is for keep alive memory ???? Faulty PCM ???? Any help would be greatly appreciated !!!

Ok I’ll have to a gauge then and pull codes tomorrow evening. Thanks

Ok thanks was no sign of any gasoline in vacuum hose but didn’t quite get regulator seated properly first time so fuel squirting everywhere so gotta a back out for little bit. Getting plenty fuel there. Gonna give little bit to air out then I’ll go check out codes. Thanks

Ok gentlemen, replaced fuel pressure regulator and still doing same thing. Tried to pull codes but really don’t know what kind of code looking for IPC, PCM, etc ?????

Not every time at first but last 4 times started it did. Didn’t try it tonight but wouldn’t start last time tried yesterday morning

Not losing any coolant, already took heads off and replace bolts with oversized studs. Check engine light is on but havnt had time to pull codes yet. 12 hr midnights makes time limited. Just trying to get some idea where to start when I do get some time off. It only started this after sitting for few days in cold weather ????