78 280z idling and warm starting problems

[s14280zx]

It was in the 50's today, so I decided to take my new 78 280z 2+2 for a ride, and had some problems. When I start it it idles rough, (sounds like it has a big cam in it. ) but when I rev it , there is a slight stumble at first, then it revs smoothly, and runs pretty good. I drove it for about a half hour,and I stopped at Burger King, went through the drive thru, sat for 10 minutes with it running (idling rough) , and decided to shut it off. Sat for 5 more minutes to eat, and tried to start it back up, and it acted like it was flooded. I tried starting until the battery died. Walked to the Firestone dealer (3/4 mile), they wouldn't help me, so I walked to Sears (another mile), and borrowed their booster, walked back to the car(1/2 mile), and it cranked right over, but idled rougher, and accelerated very roughly. It ran rough for about 5 miles, but started to run smooth like someone flipped a switch on it. Any help or suggestions would be appreciated. Tried searching, but didn't find what I was looking for. THANKS

[genomz]

try cleaning the electrical connection to your cold start valve. had the exact same cold start issue. this fixed it for me...

also, make sure the connectors to thermotime switch and watertemp sensor, which are both located at the thermostat housing, are not switched around. this fixed the hard warm start issue i was having.

good luck, hope this helps...

[s14280zx]

Thanks, I'll give that a try, and let you know.

[Sailor Bob]

I had some rough idle problems when I got my 77 - turned out to be the wires/connectors to the fuel injectors were very poor (common problem). I was able to clean the connectors and fiddle around till it ran smooth, but the solution was new connectors. They are available (aftermarket) on ebay or oem.

[s14280zx]

As a matter of fact, I just bought a set of those injector connectors last week , but haven't had time to install them yet. The old ones are missing a few metal clips that hold them on. I'm probably going to get new connecors for the water temp. sensor,and the thermotime switch also. I'll have to give that some attention when I get a chance. Thanks for the input. Any suggestions are appreciated.

[genomz]

if what i mentioned above doesn't work, try removing and cleaning out your auxillary air valve with carb cleaner and a rag or q-tip. the AAV is the trumpet shaped thing that is bolted onto the intake manifold right behind the throttle body. the AAV is really sensitive to little crap and can gum up.

[BuDavid]

thermotme switch might cause those stuff, but if I were you, I would inspect more things (just to make sure that there are not more accumolated problems) since you are allready under the bonet.. such as vacume leaks, and you can use a Voltmeter to make sure that the Auxiliari air Regulator gets power.. and if it is running rich, you might have a passing cold start injector or (valve) check it's signal also, it should open during cold start for a moment, and then shut off.

good luck.

[s14280zx]

Thanks for all the good advice. I've only owned the car since Thanksgiving,but here is a list of things I've done so far to the engine: Changed the cap, rotor, plug wires, changed all vacuum lines on engine one at a time (didn't check under dash yet), replaced all fuel lines including between rail and injectors, with FI hose and clamps, and fuel filter. I put new spark plugs in (champion plat.) But it flooded out once before and fouled them out, so I put the old ones back in (they looked pretty new). They were Bosch Platinums. I've read a few threads about the Bosch's not working good in L28's. Could this have something to do with the engine missing? I appreciate everyone's advice.

[DatsunZsRule]

s14280zx,

There are 3 things I would test for this type of problem. Water Temperature Sensor, Thermotime Switch, & Cold Start Valve in that order.

If one of those 3 parts go faulty then it will cause symptoms like your having. On the Bosch plugs- You read correctly Way back when I first bought my Z, the previous owner used the bosch platinums and she ran very rough. I first started doing basic tune up stuff to her and those were the first things to go Nothing but NGK's for my beautiful Z Just changing those alone made a big difference and the bosch plugs in my Z were like new too. Also you said you replaced the distributor Cap & Rotor- Hopefully the rotor you bought is the same brand as the cap you got. Mixing brands can cause an incorrect air gap. Thought I'd mention that too being that I've seen a few people make that mistake.

Best of luck and let us know how you come out.

[slobound76]

Glad I saw this listing, my 77 280Z is doing the identical thing, it starts great if cold, then after running it for a while, parking for a few, and if its hot at all, runs super sluggish, sounds flooded, then after running a while, like previously posted, seems as if a switch is pressed and it then runs good as new, I have the Bosch platinum plugs in, they were the best available at local auto parts store, so will now be hunting down NGK's...anyone happen to know the specific part number for the NGK's for ease of ordering should I not be able to find?

[sblake01]

B6ES-11 is the correct NGK for the EFI cars. The Nissan part number is 22401-P8816.

[slobound76]

great, thanks a million, kinda embarassing to pull into a place looking and sounding great, then go to leave and you're looking great, but getting looks more for the horrible sound you're making