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Author Topic: Can't figure it out!  (Read 30488 times)

Offline Layne

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Can't figure it out!
« on: January 04, 2010, 11:39:12 pm »
I know this isn't a 73-87, but you guys are who I turn to when I'm stuck. Here is the situation: 88 gmc sierra 350 700r4. First bought it in sept. Test drove it and it was fine. Bought it, and drove home and I get a dtc. 43/44/45. So: New knock sensor, new O2 sensor, new esc, new cap, rotor, plugs, and ign module. Cleaned up some grounds. It started out as a kind of chugging at steady throttle. I've been throwing it in neutral at stoplights and holding the gas because it won't idle. The other day, I thought it was the IAC so I put one in it. Well, today I thought I'd go to Taco Bell and it did the same stuff, except when I got into my driveway. I sat there and lightly held my foot on the gas and it would bounce between 1000 and 1500 rpm. shook the whole truck and I thought she was going to blow up. Little more pedal pressure and 2000 is fine. Then my cab smelled like sulphur. I think I might replace my tps, but I'm tired of shotgunning parts at it. I know I rambled a bit, so if anything needs clarifying, let me know. I really appreciate the help. Thanks
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline Irish_Alley

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Re: Can't figure it out!
« Reply #1 on: January 05, 2010, 12:40:35 am »
I'm thinking  cat due to the sulpher smell
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Offline Lt.Del

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Re: Can't figure it out!
« Reply #2 on: January 05, 2010, 07:20:06 am »
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Offline Layne

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Re: Can't figure it out!
« Reply #3 on: January 05, 2010, 02:32:21 pm »
The diaphragm moves freely, should I Remove a vac line and spray carb and choke cleaner in there? I'm thinking th e cats seen better days, too. I'm planning on either replacing it or "cleaning" it out...
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline Grover 1

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Re: Can't figure it out!
« Reply #4 on: January 05, 2010, 04:47:25 pm »
I've found the best tool to use for "cleaning" cats is a torch - gets 'em real clean
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Offline Layne

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Re: Can't figure it out!
« Reply #5 on: January 05, 2010, 04:52:15 pm »
LOL! I C&C'd the little vacuum line to the EGR. Went down to shell, and as soon as it warmed up, it was doing it again. I put 15 bucks in the tank and C&C'd the line again. Ran AWESOME! It was sputtering a little, so when I got home, I seafoamed it and cleaned that line again. Took it around the block with my foot in the radiator and it seems to be doing better. I think I'm going to carb and choke it every so often to clean as much as I can. No CEL either ;D ;D
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline VileZambonie

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Re: Can't figure it out!
« Reply #6 on: January 05, 2010, 07:49:21 pm »
Pull the vacuum hose off the EGR valve and see what it does. The EGR sol is probably stuck open.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Layne

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Re: Can't figure it out!
« Reply #7 on: January 05, 2010, 08:15:00 pm »
Theres no difference. Wheres the solenoid at? I pressed the diaphragm in and it killed the truck.
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline VileZambonie

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Re: Can't figure it out!
« Reply #8 on: January 05, 2010, 08:20:31 pm »
The vacuum hose goes to the EGR valve from the EGR solenoid. There should be no vacuum at the EGR valve when you check it. If ok Pop the valve off and block it off. If it checks ok move onto checking your fuel pressure.
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                         /  _ _ _\_
              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Layne

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Re: Can't figure it out!
« Reply #9 on: January 05, 2010, 08:46:10 pm »
Vile, do you mean take the EGR off the intake manifold and put a plate on it temporarily?
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline Jim Rockford

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Re: Can't figure it out!
« Reply #10 on: January 06, 2010, 09:52:40 am »
just take the vac hose off and plug it. then test drive it.
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1973 k20 Camper special
1980 k20 custom deluxe
2004 Crown Vic LX sport

Offline Layne

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Re: Can't figure it out!
« Reply #11 on: January 06, 2010, 04:04:01 pm »
K will do. It seems to happen intermittently if that helps narrow it down any
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline Layne

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Re: Can't figure it out!
« Reply #12 on: January 06, 2010, 04:45:37 pm »
WOW WOW!!! Running like a top! No backfires, stumbling or chugging! She got a little grouchy with me at stoplight or too, but I didn't have to put it in neutral or "2 foot it". The idle dropped down to around 400 at some stops though. So it's prolly the egr solenoid?
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline Captkaos

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Re: Can't figure it out!
« Reply #13 on: January 06, 2010, 05:17:12 pm »
If you plugged it and it runs better, that is your problem.
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Offline Layne

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Re: Can't figure it out!
« Reply #14 on: January 06, 2010, 05:23:09 pm »
I plugged the vac line to the egr, so the egr is bad, or the solenoid?
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77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.
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