Fresh engine and new setup runs like crap and I’m lost..
I really hope someone can give me some pointers, I’m at my wits end, sorry for how long this is going to be haha. Will not run right with fresh engine that I rebuilt. My truck is a 95 Dakota with 96 Dakota obd2 electronics that I installed years ago for custom tuning. It had a 408 already that was built before I obd2 swapped it so it had a small cam and was weak for its size But ran great for 23000 miles. In past years I’ve been upgrading brakes, suspension and driveline stuff to handle a supercharger, have averaged 2000 miles a year the last 4 summers up to the point of tear down and driven between modifications.
This past winter I decided I had saved enough and this year was the year, in September of 18, I mocked up the Vortech centrifugal supercharger setup with front mount inter cooler and had everything running well but did not put the belt on the blower and only ran a few miles because it was just in mock-up and ran all summer fine and didn’t change anything electronic at that point. Then began tear down.
My mopar performance r/t 2.02 heads got all new valves, springs, and hardware, along with a major porting job from reputable local company. I reused my stroker crank, rods, timing chain, oil pump and 2618 forged pistons. I installed a comp 236/242 114+4 lsa cam .579/.580 lift cam installed to 110 centerline per cam card (I hope well get to that later) my block machinist fit upgraded main caps and a girdle, studs and line honed and honed cylinders to akerly and child’s recomended grit, and installed new cam bearings freeze plugs etc. I assembled the engine with all new gaskets, lifters, gaskets etc. new pushrods measured and installed last and have a great pattern, new comp xd rockers. It is 9.1:1 compression with -+0.045 quench I did install a new flywheel (6spd viper trans has been in it for two driving seasons) but needed a better clutch to handle the upgrades, I got a twin disc manic clutch and the flywheel to match, the factory electronics run a crank pickup off gaps in the flywheel so the computer knows the engine position.
Since the first startup it has not run quite right, I assembled engine and installed in truck, my ryan sent me a boost/start up tune for the new 2 bar map sensor, bigger injectors, and complete new setup. The truck started right up, I used break in oil and did not let the engine idle for the first 30 minutes, roller cam but wanted to ensure ring break it, once at base idlle it was obvious it had a very slight miss, I verified cam/crank sync with scan tool, and got an idle datalog off to my tuner, he made a revision and it idled great so time for first test drive, which it feels rough like an old farm truck, bad tip in response, engine feels shakey on acceleration but will pull up to 3,000rpm ok on light acceleration but feels shakey, ryan sent a new tune based off test drive from datalog and new tune feels better but still shakey/misfire feeling when accelerating, Ryan can’t see any issues based off datalogs, but I notice cylinder 2 plug black and sooty compared to the rest, I swapped fuel injectors, plugs, wires, cap, rotor, engine computer, verified valve adjustment, compression tested, cylinder leakage tested, running compression tested all 8 cylinders and find no issue, so I send him another datalog and he sends another tune which I upload think it’s gonna fix everything and it’s like I feel the tune change but the shakiness continues, I don’t believe I mixed up pistons to disturb engine balance and new flywheel is for neutral balanced engine, my compression tests came back 120 on all cylinders, (which I thought low but all even) leakage tests all only 5psi loss, running compression results same on all cylinders, I think I degreed the cam right but at this point anything is possible I guess. The one time I accelerated to half throttle and 3100? Rpm, trying to get 1 pound of boost it back fired out the intake hard enough that it turned on the check engine light for a throttle position sensor code. It was loud and not cool and ran terrible afterward untill it stalled, restarted fine and ran like nothing ever happened.
I still get the sooty #2 plug, I’ve swapped cap, rotor, wires, injector twice, pcm, listened to injector with stethoscope, verified spark with hei tester, ran compression and cyl leakage, verified cam syn, verified valve adjustment, counted teeth on flywheel and find two cylinders MAYBE are off a tiny bit but have to assume slight error looking through starter hole and counting teeth watching the gaps, vacuum gauge reads a dead steady 8, if slowly increase rpm vacuum climb steadily up then spikes up further if let off throttle and on a quick blip it drops hard but comes right back to 8”. verified valve lift with dial indicator.. running out of ideas on what to check or where to look. I can feel the shakiness/miss but don’t really hear it out exhaust or anywhere blipping throttle in neutral, when driving it just feels shakey like a dead hole miss, if maintain higher engine speed it’s fine but throttle transition feels stumbly . The only thing electronic changed was srt4 map sensor which Ryan is aware of and the new gerko flywheel.. I was going to compare my new flywheel to my old flywheel to exactly compare crank pickup gaps but can’t remember if I actually did or just thought about doing it. Both flywheels made by same company.
I did notice after doing leakage test and rotating engine by hand 100 times that there is some oil on top of the dished pistons, it doesn’t smoke and passes all tests, I get nothing but pure water in my catch can. The whole build has maybe 20 miles on it, after to backfire out the intake on one pound of boost at half throttle/3000rpm I’m scared but have retested everything again and have no ideas, feels like a dead miss when accelerating but fine at idle. I know the timing marks are different now then when I took it apart but assumed different cam degreed differently but now I’m wondering.. crank sprocket is 2 teeth clockwise compared to my old cam, I did degree it but wondering if I did it wrong
World record post length here probably.. thanks for any ideas!!!!!