1990 2.3L shudders and misses until warmed up

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r3mix
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Joined: Tue Nov 15, 2011 12:22 pm
Location: Phoenix metro area, AZ

1990 2.3L shudders and misses until warmed up

Postby r3mix » Sun May 06, 2012 12:01 am

I've got a 1990 2.3L with the factory 2BBL on it. For the past few months, it's been idling very rough and almost stalling after a cold start. I've been holding it at about 2k rpm for 10-20 seconds after a cold start, which has been fixing the issue.

Just this past week, the issue has either gotten worse, or another issue has appeared. Holding the gas for a bit makes it idle okay, but when I try to take off, it will shudder and (it sounds like) miss. If I'm easy on the gas, it'll run decently, but if I give it more than about 1/3 throttle, it will miss and shake and not do much. It will do this for a few minutes, and stop shortly after the engine reaches it's normal operating temperature.

I did some Googling and found the choke control solenoid can go bad, but I was wondering if anyone else might have any other ideas of what could cause this.

I replaced the fuel pump about a month ago, and it had no impact on the cold start issue. My carb also looks spotless from what I can see removing the air cleaner. I ran a bunch of carb cleaner through it today just to try to eliminate that, and it did not change anything.

I did notice when I pull the throttle linkage with the motor shut off, the second barrel did not open. This is normal, as it requires vaccuum, correct?
1990 Isuzu Pickup 5 speed 2WD - All factory, 110k miles

fasteddie
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Joined: Thu Mar 17, 2011 8:11 pm
Location: Jersey City, NJ

Re: 1990 2.3L shudders and misses until warmed up

Postby fasteddie » Sun May 06, 2012 7:17 am

I had the same problem. After replacing the EGR, all vacuum hoses, plugs and wires it improved significantly. Still not perfect though. I'm probably due for a new thermostat, it's been running on the cool side.
1989, 2.3L, 5 speed pickup, original owner

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Awesomedude
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Location: Poulsbo, Washington

Re: 1990 2.3L shudders and misses until warmed up

Postby Awesomedude » Sun May 06, 2012 9:02 pm

Make sure your choke is engaging, and check your fast idle speed. Just sounds like your trying to take off before it's warmed up enough or the choke/fast idle stuff isn't working correctly. I don't know the specifics about the hitachis these came with, even more so since yours is most likely computer controlled, but just to give you an idea...and yes the secondary is vacuum operated. it will only open when you hit a certain rpm
'89 Pickup 2.6 4wd 2.3 head, Weber 38, Pacesetter header, Flowmaster 40, MSD Blaster coil, ball joint flip, 31's, Per-Lux fogs
'80 LUV aka "The Luv Machine" 1.8 4wd 3" body lift, 2" susp. lift, 31's, Weber 32/36 DGV

r3mix
Regular Member
Posts: 26
Joined: Tue Nov 15, 2011 12:22 pm
Location: Phoenix metro area, AZ

Re: 1990 2.3L shudders and misses until warmed up

Postby r3mix » Mon May 07, 2012 2:30 pm

It's recently started to run rough while warmed up, too. It seems pretty random, but it's mostly at low RPMs, such as accelerating under 40mph in 4th. I checked and the second barrel opens and sprays properly when I pull it's linkage.

I did check my plugs pretty recently, but I'm going to pull them and check them again once my motor cools down.
1990 Isuzu Pickup 5 speed 2WD - All factory, 110k miles

r3mix
Regular Member
Posts: 26
Joined: Tue Nov 15, 2011 12:22 pm
Location: Phoenix metro area, AZ

Re: 1990 2.3L shudders and misses until warmed up

Postby r3mix » Mon May 07, 2012 9:15 pm

I got her running right again.

I put some Circle K gas in last week around the time it started running rough. I put a half tank of Shell gas in when it got down almost to E. This helped a little, but it was still running pretty rough, so I figured the gas wasn't the issue.

I put a full tank of Shell gas in today, and it completely fixed the issue within a few minutes, so I guess the motor *really* hated whatever was in the Circle K gas.

I had already bought a new fuel filter, plugs and some carb/injector cleaner, so I threw all those in and it's running better than it was before.

Thanks for the help, guys.
1990 Isuzu Pickup 5 speed 2WD - All factory, 110k miles


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