05 GMC Sierra surging at lower rpm - The 1947 - Present Chevrolet & GMC Truck Message Board Network

2wd73blazer · 12-31-2011, 01:03 AM

I have a 05 GMC Sierra with a 5.3. Cruising between 40 and 55 it surges. I can feel it really when its under load like pulling a long slow incline. The rpms jump anywhere from 200-500. It does it in lockup and in drive. It is more noticeable in od though. I changed the spark plugs and wires with oem. I had the throttle body and maf cleaned. I had the fuel pressure checked (holds 60). I had the trans fluid and filter changed. Anyone have any ideas?

MadManAndrew · 12-31-2011, 02:40 AM

Unless I'm mistaken, that would be your lockup torque converter locking and unlocking while you maintain a speed that is right on the lockup threshold. I'm not sure if it's supposed to be that noticable, but I am pretty sure it's the lockup.
Posted via Mobile Device

2wd73blazer · 12-31-2011, 07:33 AM

Does the lockup engage even when i have the trans in 3 and not od?

usmcchevy · 12-31-2011, 10:29 AM

Quote:

Originally Posted by 2wd73blazer

Does the lockup engage even when i have the trans in 3 and not od?

Yes it will lock up in 3.

**bwood** · 12-31-2011, 03:43 PM

Does it do it when the engine is cold (before it reaches operating temp). I believe the lockup is diabled until the engine is warm and in closed loop.

2wd73blazer · 12-31-2011, 04:50 PM

It does it at all temps. I can leave my house first thing and within a couple of miles its doing it and the temp isnt up to operating temp.

**Boog** · 12-31-2011, 05:06 PM

If the AC or defroster is turned on you will feel it when the compressor cycles on and off. Try it without those on and see if it's still noticeable.

2wd73blazer · 12-31-2011, 08:26 PM

I feel it with ac and defroster off. On the way to work tonight engine temp was about 180 when I felt it start. It usually runs a bit warmer closer to the 200 range.

12-31-2011, 01:03 AM	#1
2wd73blazer Registered User Join Date: Jan 2008 Location: North Augusta,SC Posts: 801	05 GMC Sierra surging at lower rpm I have a 05 GMC Sierra with a 5.3. Cruising between 40 and 55 it surges. I can feel it really when its under load like pulling a long slow incline. The rpms jump anywhere from 200-500. It does it in lockup and in drive. It is more noticeable in od though. I changed the spark plugs and wires with oem. I had the throttle body and maf cleaned. I had the fuel pressure checked (holds 60). I had the trans fluid and filter changed. Anyone have any ideas?

12-31-2011, 02:40 AM	#2
MadManAndrew Registered User Join Date: Mar 2011 Location: Dallas, Texas Posts: 920	Re: 05 GMC Sierra surging at lower rpm Unless I'm mistaken, that would be your lockup torque converter locking and unlocking while you maintain a speed that is right on the lockup threshold. I'm not sure if it's supposed to be that noticable, but I am pretty sure it's the lockup. Posted via Mobile Device __________________ 1955 Chevy 3600 http://67-72chevytrucks.com/vboard/s...61#post8589061

12-31-2011, 07:33 AM	#3
2wd73blazer Registered User Join Date: Jan 2008 Location: North Augusta,SC Posts: 801	Re: 05 GMC Sierra surging at lower rpm Does the lockup engage even when i have the trans in 3 and not od?

12-31-2011, 03:43 PM	#5
bwood Registered User Join Date: Jan 2003 Location: Denison, Texas Posts: 1,919	Re: 05 GMC Sierra surging at lower rpm Does it do it when the engine is cold (before it reaches operating temp). I believe the lockup is diabled until the engine is warm and in closed loop. __________________ 1998 GMC Sierra SLE 1/2 ton 2WD 305 Vortec -Gibson Stainless Cat Back Swept Side -SS Wheels 2005 Honda CRF250R 2006 Honda CRF150F

12-31-2011, 04:50 PM	#6
2wd73blazer Registered User Join Date: Jan 2008 Location: North Augusta,SC Posts: 801	Re: 05 GMC Sierra surging at lower rpm It does it at all temps. I can leave my house first thing and within a couple of miles its doing it and the temp isnt up to operating temp.

12-31-2011, 05:06 PM	#7
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,559	Re: 05 GMC Sierra surging at lower rpm If the AC or defroster is turned on you will feel it when the compressor cycles on and off. Try it without those on and see if it's still noticeable. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

12-31-2011, 08:26 PM	#8
2wd73blazer Registered User Join Date: Jan 2008 Location: North Augusta,SC Posts: 801	Re: 05 GMC Sierra surging at lower rpm I feel it with ac and defroster off. On the way to work tonight engine temp was about 180 when I felt it start. It usually runs a bit warmer closer to the 200 range.

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