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Discussion Starter · #1 ·
I have a few more notes on how my car is acting up that may help track down my problem(s). This is the semi-stored turbo with the rough idle. There are two other things it does WHEN COLD besides bogging down.
1. When I first start it, the engine surges repeatedly -- VRRRmmmVRRRmmmVRRRmmm with the tach jumping up to 1000 or so then dropping all the way down and often dying. As soon as I give it just a touch on the gas pedal, it stops and runs normally (besides already mentioned problems). My mechanic checked my fuel pressure (checking the pump) and it was fine ... but I don't know if he checked it when cold. Is this the fuel pump -- or any chance it's the regulator?
2. A couple of times WHEN COLD I have tried to rev it up to see if it would stop bogging down, and I got what sounded like a small backfire ... a muffled "pop" from the engine compartment. What is that?

Thanks for the help guys!

P.S. I'm thinking of changing my fuel regulator and PCV valve before messing with the AFM. What do you think?
 

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I would verify the AFM. If the flapper in the AFM sticks it can cause that little pop you hear. I'm not saying that it IS sticking, but I know that to be a symptom of a sticky flapper. While it's off verify it's calibration with an ohm meter. There are plenty of us who can tell you which pins to check and what you should see. This way you can convict that AFM if its guilty, or you can exonerate it, and forget it, moving on to check other suspects if the car still doesn't run right.

Ken
 

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I had a problem with my old Turbo car that took me for ever to figure out, the fuel pressure regulator would STICK, and would back pressure up back to the pump. As a matter of fact I went through several pumps before I figured out what was going on. I would start the car, the idle would go up, then down, then it would eventualy stall, then I would have to turn the key on and off and listen for the fuel pump, eventualy there would be a suttle POP that would come out of the fuel pump, IE the Fuel pressure regulator finaly unstuck. Took me a long LONG TIME to figure out what the heck was going on, as once the car was running fuel pressure was fine. Don't know if this total relates to your problem or not, but maybe it is helpfull information.

Scott Milella
 

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<b>RE: Tracking down my problem -- 83T</b>

i have been driving 280 turbo zx's for many years here
is a check list on the most common ailments on a 280
turbo;

remove drivers side kick panel you will see the main cpu
take the connectors and remove and install them many
times, what you are doing is cleaning the connections
by scraping the corrosion off the terminals DO NOT SPRAY ANYTHING INTO THE CONNECTORS TO CLEAN THEM

a lot of times the wire inside the connector to the
oxygen sensor will break inside right at the ceramic holder clipped on the intake manifold ,this is from years
of vibration from the motor,you can resplice the wire
there is a noise sheath that surrounds the wire that
makes it tricky to splice,


if this doesent work the next common defect is the distributor it has a computer at the base that maps
out fuel delivery,advance,ignition, these can be
purchased from nopi parts for about $200


next up would be afm there is a air temp sensor in the
unit and also a carbon strip that wears out over the
years , replace whole unit,

good luck to you z brother keep us posted,
 

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<b>Fuel pressure regular same on turbo? 83T</b>

Pep boys only has one part # listed for '83 280 fuel regulators. But the turbo takes a different one than base doesn't it?

Thanks!
Brian
 

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RE: My 83 turbo is doing something similar.

The difference is, mine idles at the correct rpm when cold and as the temp rises under the hood, and the air regulator is bypassed, the idle drops to about 500 rpm's. The hotter it gets, the worse it is to do the up and down revving crap. VERY AGGRIVATING! I tested my afm with a multi-meter and it performed as instructed. The one odd thing related to the temp sensor. It was about 70 degrees outside and the meter gave a resistance of 1140 ohms. The book states the reading should have been double the one I got. I'm just speaking from memory on the exact number, but it was half the recommended value. I need to check my fuel pressure and injectors before anything else I guess.
One side note that I want to clear up is that someone installed a pot that is wired into my electrical fuse panel that richens or leans the fuel mixture when turned - like a volume knob. Two of the 15 amp fuses have been cut into so that one pole is exposed and soldered to that is the wire that runs to the pot. This is different then a pot tied into the afm as some have suggested on this forum. I haven't disconnected the stuff yet as I'm a little leary of yanking wires that I don't know where they terminate and what may be affected. Amazingly, the fuses have never blown in the long time they have been in there.
 
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