Hello once again, 2003 mercury grand marquis, 2018k miles. changed the water pump on my engine, turns out the crossover pipe was blown and leaked coolant in the engines valley, slapped a new doreman manifold from autozone, no visible cracks. put everything back together following the rockauto video guide, right down to the bone, and now i get a cyl 1 misfire and a few other things. at idle its smooth, but when i accellerate it runs really rough, if i go over 70 the CEL flashes, but if i keep the engine spinning slow at 50-55 theres no CEL. i need help
Get out the scan tool to check for codes and record a snapshot of live data while the problem is happening.
codes i get are
P0301 cyl 1 misfire detected
p0113 intake air temp sensor circuit high bank 1
p1406 (DPFE) sensor downstream hose off or plugged
P0316 engine misfire detected on start up (first 1000 revolutions)
this is what i get, should i get the freeze frame too? also i rechecked all connectors, no corrosion at all
Check the sensors flagged by the codes. Freeze frame might also help if something suspicious shows up.
Also make sure you have no vacuum leaks. Pay particular attention to the intake manifold gasket.
thats my biggest fear, maybe one of the manifold gaskets are not seating properly, ill do scotty's cigar method of vacuum leaks tomorrow morning when its warmer, and hopefully its not that, we used black gasket maker on all rings on the manifold, so as to not take any chances
Another way to check for vacuum leaks is with some spray carb cleaner. If engine idle changes when spraying you've found a leak.
ok ill do that as im leaving work tonight, i'll just pray around the manifold and all vacuum hoses
well carb vleaner yielded no leaks, so as a last ditch effort, my mech buddy suggested we zip tie the retainer clips on both coils and injectors and what do you know, all codes never came back, and the car runs smooth again with no lack of power, tho the DPFE came back and it triggered the CEL. THAT im not too worried about because a year ago i got that and it went away on its own. so i think we are all good
Congrats and thanks for reporting back!