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Discussion Starter · #1 ·
I have a 1978 Datsun 280Z Convertible. It has new plugs, wires, cap, alternator, and starter. When it is cold, and even not as cold but it hasn't been hot here lately, it struggles to start for the first start of the day. When it finally gets running it dies right away. Then I go to start it again and it starts flawlessly no more than 10 seconds later. Normal?

Also when I rev it up high, 4-5K rpm, it seems to backfire but it doesnt seem as loud as a backfire. I was told this was condensation escaping.

I also read in the archives that white smoke/steam is a sign of a blown headgasket. My car has this white when it is first started but it goes away when it warms up. It doesnt seem like the engine has much power, but then again these aren't powerful cars in stock form.

Any insight would be great.

Russell
 

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What you are describing above is not entirely abnormal, but the degree to which it is occurring is abnormal. I often have to start my 78 twice. It sounds to me like you have a vacuum leak, a major one. That would cause it to lose a loty of power. It sounds like you have your PCV hose disconnected or something stupic. Check out all fo your hoses. You story about backfiring does not wash with me. It sounds more serious. If you don't have any vacuum leaks then you have something tuneup-related. I don't think you have a blown head gasket. WHat you are seeing is normal condensation.
 

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I agree with JC — white "smoke" on cold start up is completely normal. Every car does it to some degree. As for vacuum leak, here's a really easy test: with the car at warm idle, unscrew the oil filler cap. If the engine stumbles and dies (major vacuum leak), then there is probably NOT a vacuum leak with the cap on. If the idle does not change appreciably, then there likely IS a vacuum leak. You might also try disconnecting, cleaning and reconnecting every electrical connector under the hood, one by one of course. Zs are very sensitive to electrical glitches and most of them start with dirty or slightly corroded connectors. Don't forget the battery, injector connectors or ground wires when you do this. It takes a morning or so and is a pain on some of the harder-to-get-at connectors, but I've owned three Zs that I've done this on and every one of them ran MUCH better after I did it, even if I didn't find any obvious problem.
 

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Discussion Starter · #4 ·
Thank you so much for the feedback. This is my first Z-car so I don't know the ways yet. Back to that backfire issue.....I have heard cars backfire and it sounded like a gunshot or something. This is not nearly that loud. It only happens when I am accelerating up to about 4-5k rpm and it makes the pop when i am shifting from 1 to 2 or 2 to 3. Definately a pop out the exhaust. Again, thanks for the insight. I know what I am going to spend my morning doing tomorrow.
 

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jr is very correct in his recommendation of the simple vacuum leak test. I also agree with him with respect to his other comments. the only thing I might suggest is that what he is saying may tqke more work than he says. Cleaning the battery terminals is easy and this is excellent advice. Clening th econnectors is another matter. I just finished replacing them all and it was alot of work. I would recommend that you clean the battery terminals and concentrate on the vacuum leak issue. The simple test he suggests is very accurate. Afte that, I would worry about cleaning/replacing connectors. I guess also there may be something not connected up, but it does not sound likeit. You would have more majopr symptoms.

He is right, if you replace your connectors the car will run better. on mine, it was smoother and had lots more power (longer injection pulse).

Oh, and about the backfire, you are backfiring on deceleration. This is just a form of backfire. It is more liable to happen during decelration. That is why various devices have been created over the years (BCDD, Anti-Backfire Valve) to deal with it in various ways.

Good luck.
 

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Two things to check. First the air regulator. The idle should go up to 1200-1500 rpm or so when cold then slowly step down as engine warms. If yours doesn't do this it is most likely the air regulator stuck closed. Take it off and look though it. When cold it should be pretty much wide open and when warm it should be closed. You can test this in a freezer and a 200-250 degree oven. Leave it in each for 20-30 minutes and look through it at the end of each time period. It should be open after freezer test and pretty much closed after oven test. Next listen to each injector with a long screwdriver touching your ear and each injector, or a mechanics stethoscope. You should hear a distinctive 'clicking' from each injector. If one is not clicking check the condition of each connector and clean them and the injector connectors too. If still missing the click, the injector is probably bad. Also check and clean the coolant temp sensor connections (do a search on rich running this is described a bunch). A misfiring injector or rich running can cause the pop in the exhaust that you are describing. Even though you have new ignition parts, clamp on an inductive timing light and make sure that each cylinder is firing regularly. I have a 78 project car right now that has almost new wires that came on it and it is not firing all of the plugs all of the time. Next to investigate is the reluctor in the distributor looking for cracks.
 
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