2bbl to 1bbl mod.

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2bbl to 1bbl mod.

Postby max12ima » Wed Jul 03, 2019 8:17 pm

I have a 90 LS pickup which i replaced the 2bbl throttle to a 1bbl but now i have intermittent erratic idle. i changed out the upper intake and the throttle body. anyone with this issue.
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Re: 2bbl to 1bbl mod.

Postby gb89amigo » Thu Jul 25, 2019 2:24 am

Max,

Please tell us why you changed from 2bbl to 1bbl. Was the 2bbl damaged, leaking, or just plain ugly to you? To get best operational results, it might be best to acquire a new or rebuilt carb for your ride, to restore better ride, milage, operation, and will not decrease its value. Best of luck

GB
'89 Amigo XS RWD, 4ZE1, MUA5, HC6 (Rear Wheel Drive, 2.6L Fuel Injected, 5 spd trans f/ 2.6L and up, 4.56:1 differential 2WD/4WD)
Future: Install the "Big Brake" upgrade, so I don't break things! . Acquired '95 V6 Passport/Rodeo front rotors (11.04") and assemblies. Need to pull G80/LSD rear from '92-'97 Trooper. Got one out of a '95 Trooper LS auto, very clean, only a zillion miles on it!


More FUN!!! :)
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Re: 2bbl to 1bbl mod.

Postby Ed Mc. » Thu Jul 25, 2019 4:37 am

I believe he's got an EFI ITEC 2.6, and he changed out the old 2-bbl throttle body for a later-style single-throated T.B. Not really a carb. Unless it's a 2.3 that had a progressive 2-bbl carb. But also talked about changing the upper intake, which you'd do when going to the later-style throttle body.

Either way, maybe a vacuum leak or vacuum hose improperly routed? Check valves' adjustment, if a valve is too tight it may cause issues. Check the ign coil for cracks or arcing. Check timing adjustment & spark advance, maybe something's wonky there. Check the dist cap for arcs/carbon tracking. Take a look at the spark plugs, any one different than the others?

Intermittent issues are sure hard to find! It could be a bad sensor kicking in/out, or something similar. Any particular time it acts up or is it inconsistent? As I recall there's a throttle position switch on the T.B. that might cause strange things to happen if it's out-of-whack.

HTH.......ed
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
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Re: 2bbl to 1bbl mod.

Postby max12ima » Fri Jul 26, 2019 6:08 pm

Hello fellow isuzus, when the truck is cold it starts normal and idles high and after about 20 seconds it starts to sputters and dies i restart it have to keep my foot on the accelerator to keep it from dying, and once i drive it at least a 1/4 mile it stabilizes, but if i stop and at restart it, it sputters again i have to keep my foot on the accelerator and brake at the same time to keep it from stalling, it goes away after i drive it a bit.
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Re: 2bbl to 1bbl mod.

Postby max12ima » Tue Mar 16, 2021 11:57 pm

i believe i found a fix the rough/erratic idle, but first i replace vacuum hoses that were cracked, i cleaned the injectors, performed a injector leak down test and the injectors were ok, replaced the engine temp sensor. i was getting an o2 sensor code so i replaced it, replaced the spark plugs, spray water on the distributor and wires to see if the idle would get worse, but it stayed the same. in the past i would open the air box and block the air inlet to the MAF and the idle would stabilize, the after trying this again i put a rag in the airbox on top to the airfilter and close the airbox, the idle stabilize, but i did want to leave a rag in the airbox, so I cut a piece of sheet aluminum placed it in front the air intake and it starts up right away and idles beautifully, wiil add pics.
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Re: 2bbl to 1bbl mod.

Postby max12ima » Wed Mar 17, 2021 12:05 am

i forgot to mention that these airbox leak bad around the the lip were the top and bottom connect.
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