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02' 4.3 runs so smooth but no power

This is a discussion on 02' 4.3 runs so smooth but no power within the Technical / Maintenance forums, part of the General Discussion category; My 02' 4.3 full size ex-cab truck runs perfect just like it was new but it has no power and ...

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    02' 4.3 runs so smooth but no power


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    My 02' 4.3 full size ex-cab truck runs perfect just like it was new but it has no power and gets about 14 mpg highway I was hoping someone had a similar exsperiance and could tell me what the solution is. I put it in the shop and they found nothing wrong, in fact the kid I talked to before I picked it up tried to tell me that the new trucks just dont run like the old ones. The hp ratings say this is not true. My 89' 4.3 will smoke this one in a race and pass more gas stations.

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    Re: 02' 4.3 runs so smooth but no power

    4.3 + fullsize EXT cab = no power

    .: Diamond Audio D3 components : Eclipse EA3422 Memphis 500.1 : Eclipse AVN Series :.

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    Re: 02' 4.3 runs so smooth but no power

    I understand that this is a small engine in a big truck but the power is really low. It will not hold overdrive over an overpass with the cruise on.

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    Re: 02' 4.3 runs so smooth but no power

    Is it 4wd or 2wd?
    What gears does it have?
    What tire size are you running?

    My girlfriend had a 1997 fullsize regcab shortbox with 3.08 gears. At the time I had a reg can shortbox 1992 TBI 350 also with 3.08 gears. When we dragraced my 350 truck would get a few lengths on her out of the hole, but by the end of the 1/4 mile she had mangaed to sneak by me.
    My TBI 350 had a torque advantage, but her truck was a tad lighter being a V6 and a WT, mine was a fully loaded Silverado. Both trucks were rated at 200 hp, I think the Vortec 4.3 really is a good engine, its a 350 engine with 2 cylinders cut off.

    I bet that your truck has 3.08 gears or maybe 3.42's. If it has trouble holding OD it needs a gear change.
    Because the gearing is so high, you are having to use a lot more throttle angle to attain a speed and hold it. If you switched to 3.73's or 4.20's I guarentee you will get better fuel mileage.

    I went from 3.08's to 4.10's in my 1997 GMC Sierra with the Vortec 350 its was a reg can shorty also. My cruise rpm at 62 mph(100kph) went from 1400 rpm up to 2050 rpm. I only lost about 1 or 2 mpg of fuel economy. Your 4.3 would be a different story, my 350 has quite a bit more torque than the 4.3 so the 4.3 truck has to use a lot more throttle than the 350 would. Instead of loosing fuel economy like my 350 did, I bet it would improve.

    There were some hills that would make my 97 come out of OD with the 3.08's but on the same exact hill with 4.10's the truck stayed in D with the converter locked the whole way. With teh cruise on the gas pedal didnt even move much, with the 3.08's it moved quite a bit thus forcing the downshift.

    If its a 2wd I would go with 3.73's with the 27" 235 70-16's, if its a 4wd with the taller 29" 245 75's-16's I would go with 4.10's. Towing, passing, fuel economy would all improve.
    I always thout that keeping rpms down is the way to save fuel, and it is to a certain degree, but if you operate the truck below its power curve and always lug the engine, fuel economy will suffer for sure.

    The TBI 4.3 in the 89 was 160 hp and the 1996 and up Vortec 4.3 is rated at 195 or 300 hp at 2600 rpm and 260 mlb ft of torque at 2800 rpm.

    the newer Vortec 4.3 has a slightly higher power band than the TBI 4.3 so it like to cruise at a little higher rpm than the TBI's did.

    Torque management has become more apparent as the years have gone by, TM started in 1996 in the trucks and now 10 years later it is pulling out a lot of timing, thus power, this happens whenever you leave hard from a dead stop, accelerate hard while at speed and just before and during each gear change. GM does this in an attempt to reduce warranty costs, but the 4.3 needs every bit of power it can get, removing TM will help your truck a lot. If the PCM reduces power by 20%, 20% of an engine making less power than a V8 is a bigger hit to the 4.3 than a 305, 350, 4.8 or 5.3.
    With my Tunercat I have set the TM settings to 0 and I have noticed quite a difference.

    Any PCM tuner can remove TM, Jesse at wait4me performance.com can do this for you for $79.00, this is what he charges for a FULL custom tune job, TM is just 1 small part of the tune but TM removal will help your 4.3 big time.

    While he is at it he can also make your shifts a bit better, the 4.3 trucks feel like they have a double shift from 1st gear into 2nd, that will be gone. he can also tune to give you a few extra hp and torque points. Normally Tuners charge $350US or more for this service, I have seen people charging $450.00US and more for your particular year of truck. He will work with you if there are problems, he has tuned over 6000 vehicles with a 99% satisfaction rate and many return customers.
    I had a different company tune my truck about 5 years ago and the diffrence was night and day on my Vortec 350, your 4.3 is in the same emgine family as mine and the results will be similar.

    With wait4meperformance.com, you call up Jesse and tell him what you want, he charges you credit card $159.00US and tunes a PCM and mails it to you, when it arrives you take out you original PCM and install the new 1. Now, if you want to keep your old PCM, thats it, if you dont want your old PCM, then send it back to Jesse and he re credits your card, so the tune only cost you $79.00US. This allows you to keep driving with zero down time, the PCM swap takes 5 minutes to do. Some people who get a PCM done by any Tuner get a camshaft-crankshft reation code. This is when a new PCM or a PCM from another vehicle is used in another. You may have to go to a garage or dealership and get a cam/crank position relearn done. The relearn is similar to having to format a computer disc before you save info on it. Every car and truck has small differences in them and the relation between the cam and crankshafts, these small differences are what cause the code. The code happens in a small percentage of PCM swaps, I just wanted to inform you of all the possible scenarios. Relearns are a very common procedure ALL new PCMs instralled at GM dealerships thru the normal course of service have this relearn done. The actaul relearn involve the dealership hooking up their scan tool, entering your vehicles VIN number and a few keys to be pressed. The whole procedure takes about 5 minutes and you shouldnt be charged more than 1/2 an hours work, now that you know this, you CANT get ripped off. But again the relearn is needed in a small percentage of instances.

    Hopefully this explains why your 1989 TBI feels and IS faster and better on fuel than your 02. Get rid of the GM tuning and you will be much much happier with your truck both with its performance and fuel economy.
    Sorry for all the reading.

    Pauly
    97 GMC 2wd RCSB 5.7, s10 2700 footstall, Hooker 24621hkr LT's , 2.5" cats dual 4"pipes exit B4 pass. side tire, custom driveshaft 3.42 G80 FIPK MAF descreen GM/Mercruiser Marine intake manifold 29lb LS2(EV6) injectors Ed Wright PCM(best mod), LT4 KM 14.8@94mph 2.007 4000lbs 122mph

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    Re: 02' 4.3 runs so smooth but no power

    Thanks Pauly that is exactly the kind of info I had hoped to find here, I really appreciate your help I will be calling Jesse asap.

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    Re: 02' 4.3 runs so smooth but no power

    how can I find out what rear end gears I have?

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    Re: 02' 4.3 runs so smooth but no power

    If you go into your glovebox, there will be a list of 3 digit alphanumeric codes(use numbers and letters) on a sticker, they will be like g80 t4s mx3 and there will be quite a few of them. It may take a while butif you want to know, jot them down and post them, I'll decode them for you. I am bettung they are 3.08's though(just guessing though). These code are the RPO(regular production order) codes for ALL the option on your truck. Also, if you want, sending me your VIN will help also. PM it to me if you want.

    Is your truck a 4wd or 2wd? What tire size is on your truck.

    take care
    pauly
    97 GMC 2wd RCSB 5.7, s10 2700 footstall, Hooker 24621hkr LT's , 2.5" cats dual 4"pipes exit B4 pass. side tire, custom driveshaft 3.42 G80 FIPK MAF descreen GM/Mercruiser Marine intake manifold 29lb LS2(EV6) injectors Ed Wright PCM(best mod), LT4 KM 14.8@94mph 2.007 4000lbs 122mph

 

 

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