ransomnotes

Temp sensor is located on the thermostat housing. Check your service manual. You'll need a deep socket...can't remember what size. I had to sand the plastic edges of the new connector to be more rounded so the socket would fit over the top of it. Definitely take your old sensor into the parts store to compare. Easy stuff, but make sure you drain some of your coolant first or you'll have a mess. Check and clean your connectors before you buy another sensor though. Could just be dirty connections. I replaced my temp sensor and connector but that didn't fix my low idle when warm problem. I removed the connector to my cold start valve and now my idle is right where it should be. I haven't been driving the car much since it's been snowing, so we'll eventually see if that valve or connection is the culprit. So far so good though. Starts right up even in below freezing weather.

If it's only running good after you get over 2k it wouldn't hurt to check the throttle valve switch or throttle position sensor...whatever you feel like calling it. If that's the case, I don't know why it would run fine only until it warms up. Mine will be running along fine and eventually I'll feel a little lack in performance, and that's the cue to me that the next time I push in the clutch or stop at a light my idle's gonna drop. The car almost dies at a stop but won't. It just idles low enough to make my lights dim and i start to lose my brakes. Once I start moving again I feel a little lack in performance but not terrible. It's very unpredictable and can "fix" itself as I drive. I may sit at two lights with a crappy idle, but by the third one it's idling fine. Weird. I'm no expert by any means, this is my first Z, so I'm sure you'll get some better answers here than I can give. It just seems like our problems are similar.

I've been having the same problem with my 78. I've done so much troubleshooting/work on it that I think I have it narrowed down to the fuel rail and/or injectors. The rail is stock, but reassembled poorly by the PO when he rebuilt the engine. I think he just threw it together enough to get it running. Any time I get out for a few minutes on the highway I have to deal with my rpm's dropping to 4 to 500 when I get off at an exit. I have to keep it alive at a stop sign, and I can feel the engine struggle a bit at take off. It happens less often with in town driving, and any other time it runs great. The fuel rail in such bad shape that I'm either going to get another stock rail from one of my mom's z's, or go with a custom Pallnet rail. I'd like to keep the car mostly stock, but the custom rail is very tempting to me for many reasons. Definitely keep us posted on your findings, and I'll do the same. I have to replace my exhaust manifold soon due to a broken bolt, so I'll be doing the rail, injectors, injector connectors, and new vacuum lines at the same time. All stuff I need to do anyway, but hopefully those things will fix the low idle/wanting to die problem. I don't know the condition of your rail, but you may want to go through it and check for leaks. Is your car running hot? Mine isn't getting any hotter than normal.

sunflower seeds everywhere! and a never opened pack of the kind of gum that tastes like black licorice....i can't think of the name of it. beechnut or something like that. the po also liked to put stickers everywhere (inside and outside of windshield, dash, under center consul arm rest), and there was a big wad of chewed gum conveniently placed in the corner of the windshield. maybe he was saving it for later.? i did find the original manual in the glove box that showed the car bought in 1978 in wisconsin. black pearl model.

you got it! after rechecking the timing we realized we did have it off a bit. so i got my power back now and i feel dumb for not checking something so obvious. kept thinking the problem was bigger than it was. i'm still getting very low idle after getting it out on the highway for a few miles though, and this car has done this since i bought it. i have an exhaust leak towards the rear of the exhaust manifold from a broken bolt, so my theory is that it's heating up the fuel rail and causing a sort of vapor lock. sound like a legitimate theory? the po sloppily pieced together the fuel rail with parts from a 77 and it needs some attention. luckily my mom has two 77 parts cars so i plan on taking a complete fuel rail and exhaust manifold from them. i've thought about an aftermarket header but i've heard some mixed things about using them. a lot of people seem to think stock is the best route to go. i would like to keep about everything under the hood stock, but a header is tempting.

actually i did have them switched after i put the new temp sensor in and figured out what i did pretty quickly. i've got a bit more pep back but still running sluggish after heating up. i'm not positive that it helped much because it's been getting damn cold out for the past couple days, so it may just be that it's taking longer to build up to temp. still idling very low when stopped after the car heats up so i've had to open up the idle speed almost all the way. does nothing for the performance but keeps the car from dying at a stop sign at least. another thing to mention is my spark plugs are white on the end now, so i'm running lean? and this is the water temp switch? mine doesn't have one. it has everything but this. do the 78's not have this or am i missing something important?

that's what i was thinking initially. there was some coolant spilled in that area while changing the thermostat and upper radiator hose, so i checked and cleaned the temp sensor connector and it's good, but i haven't checked the actual sensor yet.

hey thanks a lot for the help and here's an update. it ended up being the tank. even though it didn't look so bad, there was still some blockage. dropped and cleaned it, and it's been running with good consistent fuel pressure ever since. but....after replacing the thermostat and flushing the radiator, my performance went out the window. it's like my horsepower was cut in half, and it gets worse the longer i drive it. it's not overheating though. it starts out with a good normal idle but that drops to about 4 to 500 once it heats up. it doesn't die but comes really close. i'm stumped again because we went through so many diagnostic tests on this car less than a month ago and everything seemed to work just fine. went through all the ecu tests with no problem. now i'm back to checking and cleaning connections again but haven't found the problem. my fuel pressure is still good but i still need to run ecu tests again. gonna do that this weekend. does anyone have any other ideas? why would this start happening right after replacing a thermostat? or could it be just a coincidence?

hey thanks for the replies. i blew out lines with a compressor and nothing but clean gas came out. checked fuel pressure between filter and injectors again....still showing about 5psi. then from fuel pump and after damper. both times i was only getting 10psi max. the fuel pump is new and i'm not seeing much sediment at all. there was a tiny bit that came out of the line from the tank, but i didn't think it was enough to be concerned with....just very tiny sand like particles. but like i said, it was a very tiny bit that i almost didn't even notice in the bucket. how do i test if the fuel pump is bad or weak? it's definitely working. should my next test be the fuel pressure regulator? i really, really don't want to pull the tank....but i guess i'll have to if i can't figure anything else out. is there an easier way to check the tank?

hi, i'm new to z's and not much of a mechanic besides basic stuff, but i have a friend helping me who knows a lot more than i do. we've been working on this car for several days. the car isn't some rust bucket that's been sitting in a field for years....well kept black pearl. the previous owner kept it in a garage when he wasn't driving it. claimed he rebuilt the engine along with a lot of other work and drove it daily for two years. then it was garaged for a short time after he got a Z28. not long enough for me to think the tank is in that bad of shape, but you never can fully trust someone your buying a car from. i've been through so many forums and threads searching for answers, and have downloaded pretty much every manual on the car and have the chilton. some of it's just foreign to me but i'm pretty confident that if i had some key points to start testing/repairing on the car then i can figure it out. sometimes it will start right up while other times it just cranks. if it does start, it revs up to 2000 and back down to 500 before dying. the longest i've had it running is probably a minute or two while giving it gas at the times it dropped down to 500, and i'm getting misfires? out of the intake. a popping sound like it's out of time but it's not (used a timing light and adjusted as necessary). i know it's getting gas pass the fuel filter but it won't stay running long enough to test the pressure. didn't want to start hardly at all using the pressure gauge. i've tried to test the injectors with a stethascope but couldn't hear any clicking other than the normal sounds of the engine (how fast is the click usually?). plus it makes it hard for me to finally start it, jump out, and hope it doesn't die before i can see what the fuel pressure gauge says or put my ear to the injectors (my friend can't be here every time i get the urge to work on it). we've put in new plugs (ngk), wires, rotor, dist. cap, fuel pump, fuel filter, various hoses replaced that were obviously bad, fusible links, cleaned injector contacts, replaced all fuses, and attempted a seafoam treatment. there wasn't any nastiness when we put in the new fuel pump so i figured the tank was in good shape. the new plugs became fouled (black) very quickly from gas. if we spray carb cleaner up into intake it will run at 1500 to 2000. there are some vacuum lines and a ground off the distributer that aren't hooked up. i have no idea where they go. we replaced a lot of the smaller ones, but there are still some of them that don't seem to go anywhere. we're stumped yet again and if i don't get it running in about a week and a half i will have to tow it to the inspection station since it's an out of state car and i'm reaching my time limit before they start fining me. not that big of a deal but still a pain. + i'm really itching to finally drive this car. any help is greatly appreciated.