Intermittent pop - Intake

[cesarp]

I'm posting here also because maybe some of you guys can help. Thanks.

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I'm clueless. I have an 84 Hot Air. Replaced the following: fuel filter,pcv valve, egr valve, spark plugs AC at 0.32, new 8mm wires.

I've checked fuel pressure at it sits at 30~31 PSI at idle and 37~38 with the vacuum hose off.

I've turn down the boost to 10 PSI and I still get popping.

Knock gauge lights up sometimes on the first 1 or 2 green lights. The popping sometimes is very loud, sometimes not as loud. Like it flutters. flu,flu, flu, pop.

This is ONLY under boost on hard accelaration and very seldomely under light accelaration .

I hear a light tik, tik , tik somewhere in the fron of the engine. Somewhere in the pulleys area.

I don't want to give up on it. The car runs real good most of the time except for that annoying and sometimes enbarassing POPPING !!!!

Don't have scantool just the knock gauge. The knock that it sometimes read, I believe is because of the popping is sometimes loud causing it to be false knock but not sure. When the popping is light then I get no green lights.

This is if I'm just gunning the pedal. I will try my best to simmulate :

turbo..ssssssss, flut,flut, pop, pop, ssssssss

is intermitent.

 

[1970gsx]

Sounds like a bad coil pack to me. One way to check if you don't have a coil pack tester is to ohm across the paired towers. They should read between 11k and 13k ohms.

 

[cesarp]

well, we put the car to a scope. The # 1 cylinder seems to be the problem.

I checked the gap on all new plugs but noticed that the #1 spark plug seem like is not even firing because the is the only plug that almost looked new.

I don't want to just start buying parts without knowing for sure what it is.

#1 - is the problem for sure.

should I go ahead and buy a coil pack from Auto Zone and Adapter for it to fit an 84 hot air ?

I'm thinking it could be the injector# 1 also but not sure.

The coil pack towers are reading 13.50 give or take a few but there pretty much even all accross.

Any ideas guys....

 

[Ormand]

Injector?

It seems to me that if the number 1 cylinder had an ignition problem, then the cylinder it is paired with (number 4) would also have an ignition problem, since they fire in series, both at the same time. If the problem is on only one cylinder, it would be more likely an injector issue than ignition. I guess there might be a problem with the plug wire short to ground, or a problem with the plug itself that could affect only one cylinder, but the module or the coil pack should affect two, not one. (I think)

 

[cesarp]

I did change the #1 wire with a new one and nothing changed. Can anyone veryfy about the coil pack.

 

[cesarp]

Here is what I'm getting when I test the coil pack after driving it and letting it sit for like 5 minutes.

Coil pack
1-4 = 13.80
5-2 = 13.75
3-6 = 14.20

Does this definetly mean the coil pack is no good under HEAT !!!


This is an original 84 HOT Air module & coil pack !!

 

[cesarp]

thanks to everyone that helped me !!!

I went to Autozone and they tested my coil pack. It tested fine and it showed to be ok according to specs. I was kinda disapointed because I tought that would for sure state that the coil pack was bad. The manager said "It's not the coil pack" ....

Guess what ?

I still bought it with an adapter to fit the 84 Hot Air.

It was the coil pack oon:

Even though it tested fine it was no good !

I'm happy....

 

[1970gsx]

Glad to hear you got it fixed. That is why I like to go to the junkyard and pick up spares of all the electricals for these cars. Just swap 'em out to you find the problem.