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slight miss at idle


Guest 81'280zxt

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Guest 81'280zxt

i think i know already what you guys will tell me, "search", well i have and nothing seemed to match up to what my car is doing.

 

so, at idle the engine misses, but not alot, it just sort of runs rough. my instinct tells me that the air fuel mixture is too lean but i don't really know. the miss ethier goes away or gets alot better when above 3000rpm. i read some people just unattach and reattach their ecu conectors, i will probly try this tomorrow.

alright i have recently repaced the maf and checked the gap of the plugs, they did look lean, but, this has to be a symtom not the problem. i need to find the problem.

now for the other problems. the engine clicks, alot when cold and less when warm.

and i have an exhast leak, would the leak cause the missing?

and last i have a question, how do you change the timing on my car, since it is not done w/ the dizzy.

sorry for the noob questions but your help is greatly appreciated.

 

 

-kyle

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Guest 81'280zxt

oh i also did a compresion test and it was normal.

 

i'm sorry but what does this mean "oscillation in mainfold vacuum of 2 inHg or so."

 

should i run some oil w/ more detergent in it to try to get at the gunk?

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and last i have a question' date=' how do you change the timing on my car, since it is not done w/ the dizzy.

sorry for the noob questions but your help is greatly appreciated.

 

 

-kyle[/quote']

 

 

Timing on the '81 is adjusted by turning the phillips head screw on the CAS. You have to loosen 2 nuts on the trigger first, though. I can't remember which direction of the screwdriver does what at the moment.

 

My car does a similar thing at idle. I can hear a 'puh' and miss or something every few seconds. I've never been able to figure out what causes it.

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Guest DoTheDrew888

My ZX used to do the exact same thing at idle. It was becuase one of the injectors was clogged and was not firing properly. You may want to either replace your injectors or get them rebuilt.

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I have this same problem on my 77 280. It sounds as if it is only in the #5 and/or#6 cyl. I have done a valve adj and it helped a little. Also ran some seafoam through the intake manifold. Again this helped but did not solve the under 3K miss rough idle. I have cleaned and checked the injector connections and spark plugs. How would someone clean injectors at home? Remove and use a cleaning solution? If it is a sticking valve how would someone fix a stuck valve if this is the case? Remove head and clean? I think I saw a link earlier that was written on how to clean valves and guides without removing the head, it involved inserting cord into the cylinder and tapping on the valve on top when loose. Ill search for it and post the link in this thread. Also if it helps i checked for a vacume leak, my guage read 13 steady. I remember on anoter site that this is an indication of a stuck valve.

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Guest DoTheDrew888

That method will only tell you if they are firing, it will not tell you if they are clogged. What you need to do is push fluid (I used carb cleaner) through them as you use the 9v current.

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Guest 280kraZ

I bet the clicking he is talking about is from a leak at the exhaust manifold. You should check and see if the rear stud for the exhaust manifold is broken off. This is a pretty common problem with the zx's as far as i can see.

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Guest 280kraZ

now you get to have the fun of taking everything apart and fixing everything and puttin it back together lol. Make sure you don't get an exhaust gasket from felpro...

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Guest DatsunSigma

This sounds familiar to the problem I'm having. I have 83 Turbo ZX and when I takes 2 or 3 tries to turn on the car while simutaneously pressing the gas for some rpms. When it starts it just stays on. Before on cold starts it would be like at 800 rpm and if it went lower it would just die. I cleaned the AFM and now it stays on after the cranks! Sorta fixed the idle prob but I still have pops coming from it sometimes. The clicks you guys are referring too, are you sure it isnt the fuel injectors? They make like these ticks but what worries me is the poping noise you I get when I actually turn it on. After driving the car around there is no prob with it, seems to fix itself! Well I'm gonna be checking this once in a while maybe I can fix my problem also.

 

PS- CLEAN THE AFM, you will be suprised at how well this 30 min fix does for your engine. Just need some fast evaporating cleaning solution, some paper, and a small hand. Check it out here http://zdriver.com/forum/showpost.php?p=82392&postcount=1

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