grantf

If you have been reading my timing and mpg thread you will get more info. I think I found the culprit being the TPS. My car was running good today up until I decided to clean some crud from the engine using simple green. The engine was still hot when I sprayed lightly on all sides of the engine block then I rinsed it with water out of a squirt bottle being careful not to wet the electrical components. the car sat for about 2 hours and then after starting up it ran like crap. I hooked up the mighty vac to test for vacuum and got about 10 hg :tapemouth I was getting near 16 before. after revving the engine I saw what looked like exhaust coming from the rear end of the manifold gasket. It looks like I need a new one. I have never replaced this gasket before and it looks like a TON of work to replace. Any advice please

Oh my, That car is going to be a thing of beauty. Already is really.

No prob

http://www.xenons30.com/reference.html

Ok sorry about so many posts. I revisited the tps and readjusted it. it looks as if the left contact was almost always closed. I noticed this by unplugging it and the engine ran better, also the vacuum jumped back up to about 15 hg. again I played with the AFM wheel and this time only a slight improvement but moving it cw by about 2 deg. (my vacuum climbed to near 16). I believe that my previous AFM test was compensating for the TPS not being set properly. So I have found two potential culprits, but I don't think I am out of the woods yet. yogurt cup test later today for shure (my girlfriend saved a cup for me).

Regarding the AFM: since swapping the sensor conections my vacuum has dropped back to 14 in HG, though I suspect it is due to a vacuum leak somewere. While the engine is idling if I jently move the wheel on the AFM clockwise I get better vacuum, around 16 in Hg the engine idle increases and sounds better . CCW and the engine sputters. I would say CW about 5 to 8 degrees at most before the engine starts to degrade. Here are some better pictures of my AFM guts. It almost looks like it has been set way on the rich side. Am I wrong?

Ok I drove around a little and warmed up the car (mostly I needed coffee). guessing that the water temp is around 160, tested resistance and got .26 k .So though this is not accurate as far as temp and it seems a little low this is closer than the .05 ish I was getting before. Regarding the tps: at idle both contacts are closed I adjusted it to open between center and right contact between 1300 and 1400 rpm, it was staying closed till about 1600. not much of an adjustment at all. one thing is that the left contact always seems to stay closed is this normal? no adjustment seems to effect the right contact. I verified these settings with a meter.

Ok I am trying not to run in circles, but I think I noticed something strange: It appears that perhaps the connectors for the thermotime switch and the temp sensors have been swapped. I checked for continuity between the connector that is plugged into the cold start valve and the temp sensor and I got continuity on each pin respectfully! I need to look again but this strange. Also I checked the continuity between one pin on the connector that was plugged into the termotime switch and got continuity to pin 13!

new wires, cap and rotor day before this thread was started, new plugs (and I gapped them) same day I posted the photo of them in thread. it's getting late. Also I am pretty sure I have a ZX dizzy (new cap for a 77 280 did not fit, new 79 cap was identicle to my old one. I have not really played with the TPS yet. Will do some reading on it tonight and look tomorrow morning. I am trying not to through parts at the problem for two reasons, 1: it is expensive and 2: I am really learning a lot about the efi system and my engine in general tracking this down systematically has lead me to make minor repairs along the way that I normally would not even look at for example the PCV hose I found out yesterday was so loose I could slip it off with my fingers on the crank case end (tightened up now).

here are some pics the soot is mostly around the tailpipe... and that is a brand new bumper installed after I was rear ended, washed 3 times

I really doubt that the injectors have ever been replaced. And my mileage really sucks, how accurate my odometer is? I do not know for certain but I am pretty sure it is close to accurate. I put 5 gall in yesterday and after a little driving around today I am on empty. about my tail pipe, it is coated in black sh!t. I can even see residue forming on the bumper and rear valance (pics soon). The funny thing is the car runs pretty good, no backfiring steady idle and pretty good power, no knocking. With the windows down I get the common exhaust fumes but they smell of gas.

Nice hot day (around 70 deg here in Seattle). Drove my car home, dash temp gauge is right in the middle, so about 180 deg (if that is accurate at all). measured between 13 and ground and got .045 k, this is with my meter set to the 2k range. double checked it with my other meter (a greenlee) it read 046. air temp measures .99, I understand that they should not be the same I am just testing both. Also I pulled the cold start injector, plugged to hole and ran the engine for about 1 min no gas came out. For shits and giggles I connected a 9 volt battery to the injector and gas squirted out. I am ruling out the cold start injector. Good to know though.

My first Z was an orange 260, I missed it and ended up buying my current 280z. I still miss the 260 :disappoin

Wow! they never let me off the hook.

oops testing wrong connectors between 13 and ground I get .068 engine is probably 120 deg now. But I did notice all resistance readings and temperatures should measure the same for air and water temp sensors so if they differ from one to the other, one or both may be suspect. I cleaned the contacts and will test again tomorrow.

Two more updates with my engine warmed up, I am guessing a little over 130 deg my resistance is 1.85 this seems a bit high. time for a new temp sensor?? also I have gotten my vacuum up to 15 in Hg. by replacing one small hose and the biggest difference seemed to come from tightening the valve cover bolts they were all loose, I did not tighten them much just snug. I would never had guessed this but after seeing what effect taking off the oil filler cap I was surprised. I know 15 is still low but it is an improvement. tomorrow may be yogurt for supper. I am thinking of just replaceing all the vacuum lines and perhaps replacing the valve cover gasket.

yes it looks tampered with. Sorry about the crappy cell phone photo (my camera is at my girlfriends house). You can see that 2 screws have been glued with gobs of silicone.

No I am not sure, but it is very possible.

measuring the temp sensor: I get 2.27 k at the ecu connector it is about 65 f outside my car is a little warm been cooling for about an hour and a half. I will check again before I head out later tonight but I would think that it is at least working and I have a signal. So at this stage I think tracking down vacuum leaks seams like the best thing to do, I feel that adjusting the AFM before doing this would be working backward, meaning that I would be using those adjustments to potentially compensate for inefficiencies elsewhere in the system. Does this make sense?

My fuel pump always runs with the key in the on position. I know it shouldn't but it does. Also I do have an aftermarket fuel pump. I am still looking for vacuum leaks, perhaps It's time for yogurt (I don't really like yogurt).

Hey I just said the joke was dumb, that's all, no offense. Really I did not mean to offend the people who are offended by people who are not offended by people that are not like those that are offended easy. Blessed be those touched by thy noodly appendage.

That joke is just dumb. not offensive, just Dumb. Sounds like something a closeted homosexual teabagger might propose.

seems impractical. But at least you are not boring huge holes through out the rest of the interior. Like the PO of my car did :ogre:

Ok, I did a little testing: I let the engine cool after work for a good 2 hours.. fuel pressure : 40 psi (not running) Fuel pressure: 36 psi (running at 800 rmps) I let the engine warm up for about 25 min, normal running temp Fuel pressure: 36 psi (running at 800 rpms) disconnected the vacuum line to FPR: 42 psi applied close to 20 in Hg to get the fuel pressure to drop to about 28 psi. So I do note that vacuum is having an effect on fuel pressure, I am not certain that my fuel gauge is accurate, if it is, fuel pressure seems high. I am not sure this is where I need to look though. I tested the vacuum at the brake booster hook up with the mityvac it read 14 in. Hg this seems low. I will test the vacuum advance with the mityvac and the timing light tomorrow but everything seems to be operating ok, smooth running engine, stable idle ect. I guess I need to test the connections at the ecu using the EFI bible but how would I know or adjust mixture. I am weary of messing with the AFM at this stage. I think I would do that as a last resort.

Now that is Sick!