Evan Purple240zt Posted October 4, 2007 Share Posted October 4, 2007 Okay here is my list of mods first; S2 RB25det stock internally t3/t04E .63ar stage three wheels 550cc injectors Aeromotive fuel pump with pallnet fuel rail Tial external gate Front mount IC Apexi Power FC with datalogit software. Zeitronix wide band. Exhaust is 3" all the way back including a high flow cat. ACT sprung 6 puck (NOT slipping) Blow through Z32 maf HKS blow off valve (upstream, so if its leaking it would only effect spool). This is all in my S14 240sx. Here is my trouble. This damn car runs differently from day to day. Today, its feeling like running rich. Yesterday a/f was golden. It never seems to run lean. I street tuned this car. Some days I can tromp the throttle anywhere in 2nd gear and roast the tires. Some days when its feeling down on power it just pulls hard (which is accompanied by black smoke in the rearview from exhaust). Engine operating temps don't seem to have an effect. They don't move much. Ambient air temperature really does not have an effect either. Does anyone have any suggestions as to whats going on? I need to get this thing to a dyno but I don't want to go with it being so inconsistent. This swap is about 2 years old now. I have not rigged up a boost leak tester yet. I have no source of compressed air in my apartment so that sucks. Thoughts? suggestions? Thanks guys - Evan Quote Link to comment Share on other sites More sharing options...
ZDrifter Posted October 4, 2007 Share Posted October 4, 2007 Intermediate problem makes me think that a sensor is going out. I would start by checking your coolant temp sensor. Dont know the ohm reading off the top of my head but thats where I would start. If that sensor is going out then it wont let the car go into closed loop and cause it to run rich making it think its running cold all the time. When sensors start to go out they like to work one day and not the next...then finally just die. Hope this helps you out... Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 4, 2007 Author Share Posted October 4, 2007 I thought that it may be coolant temp sensor too, but the power FC shows consistent temperatures and nothing abnormal. Thanks though! - Evan Quote Link to comment Share on other sites More sharing options...
streeteg Posted October 5, 2007 Share Posted October 5, 2007 hey O/T but any idea on power level? I am about to run the exact same setup. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 5, 2007 Author Share Posted October 5, 2007 18psi on 275/35/18s results in massive wheel spin anywhere in second gear. No idea on actual power. This is on its "good" days though. I am going to start carrying my laptop religiously to find out whats going on. Evan Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 5, 2007 Author Share Posted October 5, 2007 Well I drove again tonight and power is definitely coming back as it cools outside. My coolant temps are the same. I think it has something to do with engine compartment heat and my blow through MAF setup. My maf is isolated from the exhaust manifold by a heat shield but I am thinking some wrap may be in order. I may try to find something at the hardware store that will work to test my theory. Fiberglass with foil backing would be good. Evan Quote Link to comment Share on other sites More sharing options...
ZDrifter Posted October 5, 2007 Share Posted October 5, 2007 Is the power fc showing anything abnormal at all?? Check for any possible vacuum leaks at the FPR? Is it an adjustable regulator?? Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 5, 2007 Author Share Posted October 5, 2007 Is the power fc showing anything abnormal at all?? Check for any possible vacuum leaks at the FPR? Is it an adjustable regulator?? Thats whats leading me to think that its engine compartment heat. Power FC is really showing nothing abnormal. Evan No leaks at the FPR. Quote Link to comment Share on other sites More sharing options...
ZDrifter Posted October 5, 2007 Share Posted October 5, 2007 Hmmm I agree with you on heat...Have you washed the car lately or has it rained and you drove it in the rain? I know that with my harness(which everytime I open it up somewhere its cut:cry2:) it will get water in there and make the car miss after I wash it. I would try what you said about making heat shields first since thats an easy way to start off. It seems wierd that when it runs like crap it doesnt show you any different info, infact thats really really wierd. O2 readings arent changing when it goes rich?? Nothing changing at all?? I would check your harness aswell to make sure its not stretching somewhere or rubbing on anything while driving. Hope you find something soon!! Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 5, 2007 Author Share Posted October 5, 2007 I never seem to have my laptop when it goes rich. The colder it gets the faster the car is. I am actually wondering if on hot days my tires are warmer and hooking up better, putting me in a different area of the map that I did not tune so well. I am going to watch for that too. I took apart my entire harness when i did the swap, this issue has been around for along time its just now that I have decided it drives me crazy. Ill let you know if anything comes up. Ill try some insulator this weekend. Evan Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 5, 2007 Author Share Posted October 5, 2007 Good call on the harness, I will make sure its not rubbing where it goes through the firewall. Evan I just picked up some foam pipe insulation and this sweet foil backed fiberglass type stuff that I can wrap around the maf. Not ideal, but for $15 bucks maybe it will shed some light on whats happening. One of my pipes runs right behind the radiator inside the engine bay. I am going to cover that in the foam. If I see any positive results Ill put more time/money into doing it right. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 6, 2007 Author Share Posted October 6, 2007 It seems I do have an overboosting problem. Performance varies at the same boost levels as well though. First I need to sort out the boost issue. I guess its possible that its cranking out pretty high HP #s when it overboosts. Evan Quote Link to comment Share on other sites More sharing options...
ZDrifter Posted October 6, 2007 Share Posted October 6, 2007 Sounds like when your overboosting you have the right air/fuel ratio thats why your seeing no black smoke and its faster. Once its boosting what it should you have too much fuel= black smoke, less power, flooding the cylinders. Yea I would fix that over boosting because if it happens again and you have the fuel set up right....and it runs lean if it over boosts again=boom. Do you not have a boost gauge in the car? Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted October 6, 2007 Author Share Posted October 6, 2007 Scary part is that I am running off the top of my boost gauge! Good news is I show no knock. I am working on a plan to pull my exhaust manifold and cut/weld on a flange for my tial external gate. I am going to be careful in the meanwhile. Evan Quote Link to comment Share on other sites More sharing options...
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