Hesitation Issues. . .

bjones · 01-26-2009, 01:15 PM

Hey all,

I have a 1999 Chevy Suburban, Vortec 5700 on a 4L60E OD auto, 3:42 highway gears (going 3.73 when i find my old truck's rear axle) and I'm having an issue with it.

When I'm accelerating in 3rd or 4th, usually 40+ MPH, 1200-3500 RPM, the truck hesitates and bucks badly, its usually worse if I'm going uphill (on-ramps and stuff) or accelerating to pass in OD. I don't think the tranny is slipping, because if I downshift out of 4th or 3rd, and the revs pick back up, it stops hesitating. I believe the tranny to be strong. I SeaFoamed the motor, in case carbon buildup was messing with the Vortec. It worked great, but the hesitation is still present. I checked the plugs, which looked to be well worn, but not physically damaged. I replaced them anyway, just to be sure. Still has the problem. Its not ping, its hesitation and surge, like the truck is bucking.

I'm thinking, it has to be the torque converter, I'm thinking maybe the lockup function? How do i find out, and if it is, what is involved in fixing it?

Is that even the problem?

Ya'lls help is greatly appreciated.

bjones · 01-26-2009, 01:19 PM

Just remembered, it also is throwing two DTCs, O2 sensors low voltage (i don't think it would cause this) and MAF low voltage (i don't think it has anything to do either) I've bought 2 new post cat sensors and have cleaned the MAF, so all i need to do is have the code cleared, just included it for ya'lls reference.

leolkfrm · 01-26-2009, 02:00 PM

Have you changed the fuel filter?

bjones · 01-26-2009, 02:16 PM

Haven't even thought of that, but I certainly will look into it. . .

silverhairdeere · 01-26-2009, 02:26 PM

sounds like you need some injector cleaner , i love lucas products , also when was the last ime you changed the plug wires .

shd

bjones · 01-26-2009, 02:45 PM

wires prolly been there since new (i just bought this truck)

ill seafoam again, maybe more into the fuel this time.

leolkfrm · 01-26-2009, 02:49 PM

sounds like a full tuneup is a good place to start

bjones · 01-26-2009, 02:54 PM

probably so. . . more money more money

01-26-2009, 01:15 PM	#1
bjones Full Member Join Date: Oct 2008 Posts: 43	Hesitation Issues. . . Hey all, I have a 1999 Chevy Suburban, Vortec 5700 on a 4L60E OD auto, 3:42 highway gears (going 3.73 when i find my old truck's rear axle) and I'm having an issue with it. When I'm accelerating in 3rd or 4th, usually 40+ MPH, 1200-3500 RPM, the truck hesitates and bucks badly, its usually worse if I'm going uphill (on-ramps and stuff) or accelerating to pass in OD. I don't think the tranny is slipping, because if I downshift out of 4th or 3rd, and the revs pick back up, it stops hesitating. I believe the tranny to be strong. I SeaFoamed the motor, in case carbon buildup was messing with the Vortec. It worked great, but the hesitation is still present. I checked the plugs, which looked to be well worn, but not physically damaged. I replaced them anyway, just to be sure. Still has the problem. Its not ping, its hesitation and surge, like the truck is bucking. I'm thinking, it has to be the torque converter, I'm thinking maybe the lockup function? How do i find out, and if it is, what is involved in fixing it? Is that even the problem? Ya'lls help is greatly appreciated. __________________ 1997 GMC Suburban, RIP 12/7/2008 Vortec 5700 V8 300HP 380Ft-Lbs Torque (certainly not stock) 4L60E Tranny 238K Miles A truck, a brother, and a friend to the end.

01-26-2009, 01:19 PM	#2
bjones Full Member Join Date: Oct 2008 Posts: 43	Just remembered, it also is throwing two DTCs, O2 sensors low voltage (i don't think it would cause this) and MAF low voltage (i don't think it has anything to do either) I've bought 2 new post cat sensors and have cleaned the MAF, so all i need to do is have the code cleared, just included it for ya'lls reference. __________________ 1997 GMC Suburban, RIP 12/7/2008 Vortec 5700 V8 300HP 380Ft-Lbs Torque (certainly not stock) 4L60E Tranny 238K Miles A truck, a brother, and a friend to the end.

01-26-2009, 02:00 PM	#3
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,837	Have you changed the fuel filter? __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

01-26-2009, 02:16 PM	#4
bjones Full Member Join Date: Oct 2008 Posts: 43	Haven't even thought of that, but I certainly will look into it. . . __________________ 1997 GMC Suburban, RIP 12/7/2008 Vortec 5700 V8 300HP 380Ft-Lbs Torque (certainly not stock) 4L60E Tranny 238K Miles A truck, a brother, and a friend to the end.

01-26-2009, 02:45 PM	#6
bjones Full Member Join Date: Oct 2008 Posts: 43	wires prolly been there since new (i just bought this truck) ill seafoam again, maybe more into the fuel this time. __________________ 1997 GMC Suburban, RIP 12/7/2008 Vortec 5700 V8 300HP 380Ft-Lbs Torque (certainly not stock) 4L60E Tranny 238K Miles A truck, a brother, and a friend to the end.

01-26-2009, 02:26 PM	#5
silverhairdeere Senior Member Join Date: Feb 2008 Location: land between the lakes tn Posts: 1,616	sounds like you need some injector cleaner , i love lucas products , also when was the last ime you changed the plug wires . shd

01-26-2009, 02:49 PM	#7
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,837	sounds like a full tuneup is a good place to start __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

01-26-2009, 02:54 PM	#8
bjones Full Member Join Date: Oct 2008 Posts: 43	probably so. . . more money more money __________________ 1997 GMC Suburban, RIP 12/7/2008 Vortec 5700 V8 300HP 380Ft-Lbs Torque (certainly not stock) 4L60E Tranny 238K Miles A truck, a brother, and a friend to the end.

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