Chevy S10 Lurches in 2nd,3rd,4th gear... please help!

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JOSH26
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Hello, hoping someone can help me with my problem.

I have a 1996 Chevy S10, 2.2L, 4 cylinder, manual transmission, 57,000 miles. It ran like a dream until recently.

The problem I have is once the truck warms up. (rarely ever happens when cold, or when truck has sat for a day or two)

When shifting between 2nd to 3rd and from 3rd to 4th, the truck will bog down and then lurch forward. This seems to only happen just after shifting gears, and only while first accelerating in that gear. It never happens in 1st or 5th gear either. I replaced the spark plugs and spark plug wires. After replacing the wires the truck ran fine for about 2 weeks, but now it's back to doing it on a regular basis. I tried using some fuel system cleaner thinking maybe my injectors are clogged up, but it didn't seem to help. Is this a transmission or fuel system issue or something else? What can I do to test and/or fix this? I'm really hoping it's something simple and inexpensive! Thanks for any and all help with this!
Feb 6, 2007 at 5:48 PM
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Have seen a fair number of chevy fuel pumps becaome problems around that milage your at. How often has the fuel filter been changed? I'm not too sure on it.
Feb 6, 2007 at 6:22 PM
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JOSH26
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The truck was a one owner before me, so it could very well be that the fuel filter is clogged. The filter or pump is what I'm hoping it is, instead of something more costly or serious like a transmission issue. I know little to nothing about fuel systems or tranmissions, so I was hoping to get some guidance here.

The only thing I find telling about this issue is it only occurs after I just shift and am accelerating, it only happens between 2-3-4th gears, and it "usually" only happens once the truck has warmed up. Possibly deposits in the fuel system getting stirred around and/or clogged in the filter?
Feb 6, 2007 at 8:04 PM
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Becareful of what you wish for, a fuel pumps are expensive on these.


https://www.2carpros.com/forum/automotive_pictures/30961_scarry_2.jpg

I'd get that filter changed for sure regardless of the issue. I may post back after I give this some thought.
Feb 6, 2007 at 8:32 PM
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JOSH26
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Thanks man, any help is greatly appreciated. I'll take the truck to have the fuel filter changed out. If you can think of anything else it may be I'll check in often!
Feb 6, 2007 at 8:58 PM
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I don't believe it is tranny related. With it warming up and the problem changing, I am wondering if the the iat sensor isn't right. Whatever it is is is affected by temperature. Is it something that sends a bad signal, or comes unglued when it gets hot. How old is the cap and rotor?

Yeah, I'm guessin!
Feb 7, 2007 at 7:03 PM
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JOSH26
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The IAT sensor should be easy to change out right? Isn't that located right behind the air intake?

Someone had mentioned that they thought it might be a vacuum leak causing incorrect pressure resulting in not enough O2 igniting causing it to bog down... is this feasible? Why would it only happen in 2-3-4th gear also? Have never once had a problem in 1st or 5th. 1st is of course higher RPM, but then why is it not happening in 5th when the RPM's are low?

Is there any way I can test a theory to help rule things out without taking it for diagnostics? I've got a rudimentary level of mechanical knowledge, but I'm more than willing to get my hands dirty to try and isolate this. Thanks again for all your help!
Feb 7, 2007 at 9:28 PM
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I talked to Chris, another mod on this site who is pretty damn sharp. He was leaning towards a vacuum leak also. He felt the IAT was real long shot. He also mentioned O2 sensor possibilities. Sorry I can't be of more help on this, but I am certainly in a learning process.


https://www.2carpros.com/forum/automotive_pictures/30961_frown_1_1.jpg

I wish you luck, maybe someone else can step in.
Feb 8, 2007 at 5:37 PM
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JOSH26
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Your help has been greatly appreciated!

A vacuum leak seems to be the majority opinion. I understand how they go about testing for one, but is isolating it and fixing a vacuum leak something that's difficult, or is it more of a minor to moderate repair?
Feb 8, 2007 at 8:35 PM
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Some guys use an unlit propane torch and run it around suspicious areas. When Idle changes you know you're very close. Other use carb cleaner and will spray it at suspected areas to do the same. Keep in mind where vacuum is originated. The cylinders are pulling the air in from the air intake, andything attached to the intake and the intake are all suspects.


https://www.2carpros.com/forum/automotive_pictures/30961_inspector_1.jpg

Feb 9, 2007 at 2:54 AM