Alright, I think my car is finally running right. I’ve been meaning to make a new post here to update what’s been going on with my build, but it seems like every time I cut out a problem, two more take its place.
I decided to do a front end swap (04-06 to 02-03) while I was brainstorming and troubleshooting the main issues the car was having. Here’s how it’s turned out so far:
I may continue to paint more parts of the car in this blue in the future if I’ve got nothing better to do. It’s a real mess with 6 different colors at the moment lol. The hood scoop is just an aluminum vent air diverter that I attached to make clearance for the rogue intake manifold plenum. I want to believe that cold air on the intake manifold may cool down intake temperatures but it probably won’t make a measurable performance benefit.
Here is a picture of my engine bay as of today, it will help visualize everything I’m talking about in the next troubleshooting part of my post;
I chased my tail around for a while trying to diagnose the poor idle and misfire code. I first tried installing an OEM hitachi coil only on cylinder 4 but it didn’t seem to change much. I also added a large size cable from the alternator to the battery to improve voltage consistency at idle, but it didn’t fix any issues yet. The next thing I did was install a new baffled oil catch can between the PCV and intake manifold (The black mishimoto can on the firewall). At first the engine started running much smoother, but unbeknownst to me, this catch can immediately started filling up with oil. I didn’t notice until my car started having stalling and starting issues, so I (falsely) associated these issues with each other. Several ounces of oil would be sucked into the catch can on every 20-30 minute trip, so at first I kept a waste oil container in the trunk to empty the catch can between each trip. I fixed the catch can issue by installing a breather filter on the outlet of the catch can and plugging the intake manifold. The crankcase should still have vacuum on it from the vent to intake line, so I believe having the PCV venting to the catch can at atmospheric pressure should be fine. The crankcase vent to intake line also has a catch can installed (The red mishimoto can on the red bracket), so oil consumption is minimized and my engine is running smoother as a result.
I fixed the catch can oil issue and still had problems with starting and stalling, so I went back to square one. On cold start and warming up to operating temperature, the car would have zero issues. It also never had issues as long as the car was moving. After warming up to operating temperature, idle would steadily become more rough and stall if I didn’t blip the throttle to keep engine rpm’s up. If I let the engine stall or shut it off after warming up, it would refuse to start unless I waited to it to cool off or spray motor starter fluid into the intake to force it to start. The engine would also still have issues stumbling or dying when turning the AC on or off.
I found that when the engine was stumbling or stalling, it was always when the radiator fans turned on. I assumed the problem was electrical so I started by checking the relays since the AC and radiator fans both were powered with relays in their circuits and both were affecting the engine idle negatively. All of the relay contacts functioned when applying 12 volts, so I could rule them out as causing the issue. The radiator fans and AC were functional when voltage level was good, so my next guess was that there was a high resistance connection somewhere. I added a grounding jumper from the relay grounding point to the alternator grounding point (it’s a blue cable that’s going over the coolant reservoir), which is also jumped to the engine front cover and then jumped to the negative battery terminal. The stalling issue was improved but not fixed; the engine would stumble when the radiator fans turned on and recover more often but it would still eventually stall. I used Uprev to watch the voltage level when this was happening and the voltage would drop from 14V to 12.5V without dying when the fans turned on, but if voltage level was at or below 13.8 bolts before the fans turned on then it would kill it. I then added another jumper from the grounding point on the chassis behind the intake pipe (I believe this is where the fans are grounded. It’s a red cable.) to the negative battery terminal, and I have not had any stalling or starting issues since. When the fans turn on, they will typically drop voltage from about 14V to 12.8V which seems to be plenty enough to keep the engine running so far.
I think I will go ahead and add more grounding jumpers with the excess cable I have left from any remaining grounding points I may have missed. I don’t think that I really NEED to replace my radiator fans yet, but I think it would definitely help to have fans that have less current draw (that causes voltage drop) on startup.
I hate the stock wiring harness and grounding so much lol. All of the mods on the car are kinda fucking useless if I can’t drive it reliably, so I would say adding big cables to all the ground points on this shitbox is probably the most important thing anyone needs to do to it. Hopefully my car stays running right this time lol.