Samson Posted October 15, 2012 Share Posted October 15, 2012 Okay, so i attempted to get my car smogged but the CO and HC were ridiculously high, from running rich. Drove it home and just started looking around the engine bay and i saw that the Water Temp Sensor was unplugged! It was missing the connector and all, the 2 black bullet connector wires for the sensor were just dangling around the engine bay, how didn't i notice that before? ugh. Well i'm PRETTY sure they are for the water temp sensor, anyways i bought a connector and a new sensor it was fairly cheap and figured why not, I wired it up and when i connect the sensor the engine idles super rough and if i were to give it some gas it'd just die. If i unplug the sensor, it runs OK. but still running rich, i noticed that even when it's plugged in i don't smell the excess fuel anymore but unplugged i can smell it. Any insight on this? Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 15, 2012 Share Posted October 15, 2012 You need to get some numbers. Fuel pressure, coolant sensor resistance versus temperature at the ECU plug, etc. If it runs better with the sensor unplugged, then you have a lean problem. Maybe low fuel pressure, for example, or clogged injectors. Quote Link to comment Share on other sites More sharing options...
Samson Posted October 15, 2012 Author Share Posted October 15, 2012 I will get a fuel gauge soon to measure pressure and check the ECU plug tomorrow, I also looked into the 1k potentiometer what if i were to put that in place of the water temp sensor to richen up the mixture just a bit? But then again i don't want to start messing with stuff if that isn't even the problem. To give u a more detail reading my HC was measured at 405 max is 214, CO meas 5.49 @ 15mph 7.53 @ 25mph max is 1.36 & 1.16. So yeah it's Ridiculously high. Quote Link to comment Share on other sites More sharing options...
Samson Posted October 16, 2012 Author Share Posted October 16, 2012 (edited) Okay, i wasn't able to get a fuel gauge but i did measure the resistance at the ECU plug for the water temp sensor it's reading was 1193 ohms and at the sensor itself it was about 1200 ish ambient temp was around 80 Degrees F. I also measured the AFM resistance went by the EFI bible page i'm referring to are (49-51) the #1 measurement was 321 Ohms, #2 was 257 Ohms #3 was 145 Ohms. Also went ahead and measured Air Regulator & Fuel pump circuit, reading was 82 Ohms, did the Fuel pump relay circuit and it was also 82 Ohms, I measured all the control unit's ground and all Four pins showed 0 ohms, i guess i know my grounds are good on that part. All fuel injectors are getting voltage aswell from the plug, thought i'd put that in too. Looked around the engine bay a little closer and noticed the hose for the PCV valve is some half ass rigged line picture is attached Could this be one of the probable causes why the car runs so crappy when the temp sensor is plugged in? NOTE: The spark plugs are also fouled from having the rich mixture condition it has, plugs only have about less then 10 miles put on them too.. could this be a probable cause aswell? I don't want to go through another set of plugs given that these are fairly new.. Edited October 16, 2012 by Samson Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 16, 2012 Share Posted October 16, 2012 (edited) it's reading was 1193 ohms and at the sensor itself it was about 1200 ish ambient temp was around 80 Degrees F. I also measured the AFM resistance went by the EFI bible page i'm referring to are (49-51) the #1 measurement was 321 Ohms, #2 was 257 Ohms #3 was 145 Ohms. The EFI "bible" is easier to use but the Factory Service Manual has the specific numbers you need to compare your readings to. www.xenons30.com/reference There is a table of resistance versus temperature for the coolant sensor in the Engine Fuel chapter. The proper numbers for the AFM readings are there also. I'm not sure what you mean by #1, #2 and #3, but I assume that those are the tests for the AFM potentiometer. I do know that the 77 AFM should have a 180 ohm and a 100 ohm reading at the AFM. Looks like your AFM readings might be off. Here's a picture from the 76 manual, the procedure is the same as for 77. AFMs are expensive. Some people have had luck with cleaning up the carbon trace and contacts. If yours is bad, you might try that. The ECU uses the AFM to determine how much fuel to add. From what I've seen they usually go bad on the lean side, so that might not be your only problem. Edited October 16, 2012 by NewZed Quote Link to comment Share on other sites More sharing options...
Samson Posted October 16, 2012 Author Share Posted October 16, 2012 The EFI "bible" is easier to use but the Factory Service Manual has the specific numbers you need to compare your readings to. www.xenons30.com/reference There is a table of resistance versus temperature for the coolant sensor in the Engine Fuel chapter. The proper numbers for the AFM readings are there also. I'm not sure what you mean by #1, #2 and #3, but I assume that those are the tests for the AFM potentiometer. I do know that the 77 AFM should have a 180 ohm and a 100 ohm reading at the AFM. Looks like your AFM readings might be off. Here's a picture from the 76 manual, the procedure is the same as for 77. AFMs are expensive. Some people have had luck with cleaning up the carbon trace and contacts. If yours is bad, you might try that. The ECU uses the AFM to determine how much fuel to add. From what I've seen they usually go bad on the lean side, so that might not be your only problem. Okay, the measurement #1 was pins 6 & 8 now this was from the ECU plug( ALl three measurements were) which was 321 Ohms the EFI bible says measurement should be at approxiamtely 180 Ohms so.. that is definately not righ?, measurement #2 which is pins 7 & 8 257 Ohms EFI states should read (Continuity, small resistance) measurement #3 Pins 8-9 measured 145 Ohms EFI bable states should read approximately 100 Ohms. I haven't actually measured from the AFM itself but i did clean out the flap which Air flow cleaner. Quote Link to comment Share on other sites More sharing options...
Samson Posted November 18, 2012 Author Share Posted November 18, 2012 Okay, so I've finally had the time to work on the Z again i did the measurement pin 8 & 6 at the afm an it was about 183-187ohms around there so that's within specs right? As for 8 & 9 it was around 105-120 ohms.. hard to get a reading on those stupid pins.. Quote Link to comment Share on other sites More sharing options...
Samson Posted December 11, 2012 Author Share Posted December 11, 2012 (edited) So i've been doing a lot lately on the car but totally forgot about updating this thread, i've been replying on another forum instead but i'll try and post in what i left off here from the other forum. I hope this will be helpful and informative for other members in the future if they have some similar problem as I did. It's going to be a long post! Nov, 20ish 2012 ---- Okay, so the car has been sitting for about a month since last i've started it. Today, i've replaced fuel filter, spark plugs, wires, replaced majority of vacuum hoses, aswell as the radiator hoses, replaced the AAR connector, CSV connector, and WTS connector and i've added a maxi fused block as a replacement for the fusible links that were SUPPOSED to be there but the previous owner for whatever reason decided splice all (4) white red stripe wires to the (4) white power wires having it not fused i didn't like this so i added the fuse block. Anyways onto the problem now. The car doesn't start no more this has happened before i don't hear the fuel pump kicking on the car will attempt to turn over but no sound of fuel going in, but at one point there pump kicked on for a couple of seconds but it went off. What can it be now?Thanks Nov, 24? 2012 ---- Okay, so i got the fuel pump to kick on, to find out the power wires from the fuel pump were snipped and the Previous owner just got about a 16-18 gauge wire and ran it from the pump all the way to the front of the car to the inside fuse box and had it wrapped around the AC fuse i believe it's the air conditioner or fuel gauge. Fiddled with that and changed that fuse and wah-lah the pump kicked on. Now, the car still doesn't want to turn over. I know it should be getting spark because the plugs are new aswell as the wires.. Dec. 8, 2012 ---- Sorry for the long awaited response but i finally had some time to work on the car within the week, and i got the car to fire up! EDIT: AFM was the culprit and a huge leak between throttle body and intake manifold (Fixed) Now there's very very small leak. Re did the fuel pump wiring, traced the wiring back from the fuel injection relay back under the passenger seat where the wires were snipped, routed the fuel pump wires back into the car and wired the wires accordingly. Removed the "hot wired" fuel pump wire and turned the key over and she fired up! The voltmeter in car kept fluctuating, got my DVOM and measured the alternators output and got a wopping 11.35 Volts! that is not good. Bad alternator so i had to get that swapped out changed the belt aswell because that was in horrible condition. Now reads at around 14.35 Volts. Drained coolant, replaced thermostat and gasket went to retighten bolts and the damn things stripped, but i didn't notice it at that point in time i had my buddy's 78 AFM that he let me borrow on, start the car seemed to idle at around 1300 then slowly started dropping to around 8-900 or so.. but after car would reach operating temp coolant would shoot out the thermostat cover, so i had to helicoil the threads now they're good as new. I definitely think the AFM that came with this car was no good if it was able to run "okay" with my buddies on. Didn't get to use my buddy's AFM this time because i had done returned it, but a AFM i bought off a member on another forum came in and i had that installed. Put a fuel pressure gauge on, vacuum gauge, started her up once more. Idle's at around 1500-1700 and stays like that through the whole way pretty much even after operating temp is reached. Fuel pressure gauge shows around 31-34 psi it fluctuates tho, but when i rev it shoots up to around 36 psi. Vacuum gauge shows a steady 20-21in HG. I did notice there is a very VERY small leak between the throttle body and intake manifold it's like comparable to the diameter of a toothpick. When i turn the vehicle off the fuel pressure would slowly decline to 0. Whats the deal with that? Also, when i would snap the throttle a puff of black smoke would shoot out so i'm guessing it's still running rich? Sorry about the long story! Here is a video i recorded on this day when it was having the fast idle issue, just to note the small leak at the throttle body and intake manifold was still here. http://www.youtube.com/watch?v=WuFZM9rmwBU Dec. 9, 2012 ---- Okay guys, was able to mess with the z for about a half an hour today and i think i found the problem to the fast idle it was having. The throttle is sticking! Just to note this is not the stock throttle body, the PO had installed the upgraded 60mm throttle body MSA offers, there is a spacer that's suppose to go in between the throttle body and intake manifold but i had that removed because that was blocking off the AAR hose that goes into the throttle body so i don't see how that was suppose to work? Unless it was designed like that? .. I noticed when i would hit the throttle the Pivot ball looking thing on the throttle linkage it would not go back "all the way up" There is some play from the throttle body and the throttle linkage. If i would hit the throttle it would go normal but after i let go it would stick and stay at around 1400 RPM, If i fiddled with the Pivot ball thing moving it up very slightly and the idle would drop back down to 900-1000. The idle adjustment screw seems to have fixed it self or something because it seems like it still has some turns that'd drop the idle slightly, but if i started turning it in more i would hear weird noises, i may need a valve adjustment? Also filled in that small leak between throttle body and intake manifold with some RTV ain't the best looking but it seemed like it worked. I have some pictures attached of the linkage... How would i go about fixing this? Or is there adjustments to be made.. Thanks all! Dec. 10, 2012 ---- Just bought a valve cover gasket, feeler gauge set, timing light (need to figure out how to use this properly) and some sea foam. Hope to do a valve adjustment and check the timing on this car I'm new to all this ignition adjustments. Even more afraid to pull the cover off and mess with the valves. Question, when i'm adjusting the first exhaust valve (i know you're suppose to put it on TDC which allows the cam lobe to point up? Correct? So pretty much every single valve (Exhaust & Intake) i want the cam lobe pointing up to make the adjustment from #1 all the way to #6 cylinder? Edited December 11, 2012 by Samson Quote Link to comment Share on other sites More sharing options...
Samson Posted February 1, 2013 Author Share Posted February 1, 2013 Another Update: Installed the new EFI harness, ECU and dropping resistors all from a 76 280z. Replaced the injector connectors that were on the new harness since they were all old and dying. I'm not sure if i fixed the Rich mixture part yet given i don't have no Gas Analyzer to look at the numbers but i do have pictures of the plugs, anybody here pretty good with examining them? Much Appreciated.Here are 2 plugs side by side. Left one is the new plug how it looks right now. Also one point these plugs were installed on the car before the whole EFI electrical part was replaced, i'm not sure if that has an affect of the left over carbon fouled burn the car used to produce? Just a better picture of the new plug's burn. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted February 1, 2013 Share Posted February 1, 2013 Wow you have been doing a lot to the engine. It should run good as new by the time you are done going through everything. Quote Link to comment Share on other sites More sharing options...
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