'88 Hardbody low-to-high fuel combustion chokes

[luiguiv]

Hello everyone, I'm new to the forum and I hope you guys can guide me on finding the solution for my truck's problem. Ok, here i go. My truck is a 1988 hardbody single cab 4x2 Z24 engine one, and from a few years ago it started working in a wrong way; the problem description is a little messy so i hope you can understand me. If i'm in the city, which has a high traffic almost all day long you have to cruise at a low speed lets say 30kph to 50kph so techically truck works well but the problem comes when i'm on the road on frecuently work trips. Problem: when you speed up carburators change from low to high right?( i've heard mechanics call it that way is it right? ) so my truck chokes when it tries to make that change and i can´t get the full power of the engine it used to have when i bought the truck about 10 years ago.
The complement to this problem is this: truck chokes only at certain altitudes ; for example this city es over sea level so here truck works aparently well. When i go to cities near sea level or at sea level truck chokes and chokes when i try to speed up; i can only cruise at low speed but if i need to step up the pedal to get power to pass another vehicle i have to change gears when it is about to choke to compensate that power loss.
I took the truck to many mechanics around my country but the don´t know nothing the always say things like "oh change that engine" or "is the carburator, i can sell you another engine with a good one" but the never seem to know what the problem really is, they take the easiest way possible saying "change the engine". I can tell you the main engine is in great condition you can even tell that by examining the exhaust pipe residuals i mean i've taken care of that engine, so it is not in bad shape
A mechanic told me sensors could be dead, other said maybe the car computer is not sending the low-to-high switch signal to the fuel system which i guess it is sending because truck chockes at that change. Stupid question but, does this trucks have an "altitude" sensor that could be wrong?
Do you guys think this could be a sensors problem ? if thats the case, what sensors should i check and where to find them?
Could it be a dead carburator ?
See i have a 1987 nissan pathfinder and man, that engine rocks!!!!! i'd really love to get my truck like that pathy's engine again.
If you need any further data to get the idea for the problem just let mi know.
Thanks a lot for reading this extensive thread :

[zanegrey]

wow ...

read the codes ...

you should check the secondary coil..

[luiguiv]

by the way zanegrey, do you know if there's a guide or site or pdf where i can know more about this truck's computer codes?

I'll check that coil right away and post as soon as possible.

[zanegrey]

referring you to another site as they have itas a sticky...

http://www.nissanforums.com/hb-truck...ror-codes.html

[luiguiv]

Thanks for the link zanegrey, now y know a little bit more about my nissans
Just want to ask you something else. By secondary coil do you mean the ones in the left side inside the hood, near the left lamp? I found those two coils there(i guess this is one for intake and the other for exhaust) one over the other pointing to the engine; please correct me if i'm wrong. If that one is the coil, tests are to check for spark and to switch cables between them right?

By the way guys, a guy at nicoclub told me american carburated z24 gasoline engines had "altitude compensators" and if that was the case of my truck, that could be the part that could be in bad shape. My truck was bought in the US and took down here to Guatemala. could that be my case?

Anyway, i'll be around soon, i'm checking for the computer codes. Still following the plan

[zanegrey]

as the truck is ideling ..pull one mani coil wire off and check for spark..

then pull the other off and check it. don't switch them ..


read the codes ..

[luiguiv]

New update!!! checking the coils, my dad first did it but he just switched cables...car was still running bad...

today the truck was precisely running bad, i accelerated it at idle and it didn´t got over 3000rpm...there it was, choking again...

but then i took the cables off one at the time as you said, and then i saw there was no spark in the intake coil just on the exhaust one. So, did the same test on the pathfinder and i got spark on both coils. So i took out that intake coil from the pathy and replaced the dead one on the truck and i got spark on both. I plugged everything and at start i got it way up over 3000rpm without chokes!!!!!!!! its running good right now, so i'll get back on work to check the codes and i guess i'll take it for a test now...

By the way, the dead intake coil on the truck, was like blown, it has cracks on almost every side of it...like if a big mess happened inside of it

stay tuned, i'll post as soon as i get the code info and the test info

[zanegrey]

i have those coils for sale..

[luiguiv]

Hi guys...i didn´t post before, because i took this truck for a ride back there where it choked before changing the coil. Man, the problem is gone. That intake coil was the one dead. This truck is roaring like beast now woojoo!! Thanks for the great tip zanegray Oh, about the coils, thanks for the offer man. I found them from a crashed hardbody in a spare part shop. They charged 25$ for it (it was a good price right? :S) Thanks for your help guys. I'll be around the forum from now on, i've learn a lot this days!!

Thanks all.