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12-21-2011, 10:01 AM
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#1 |
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Registered User
Join Date: Feb 2004
Location: NE PA
Posts: 11
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Dead spot in throttle
I have an 02 GMC Savana 5.7 4L80E 3.73. I have replaced the fuel pump and filter. Done the central port to multi port conversion with a new regulator. Checked the cap, rotor, wires and plugs all looks fine there. It is not throwing any codes.
I have a dead spot in the throttle. When I go to accelerate it goes fine if I am light on the gas but as I increase throttle pressure the output does not equal the input. It goes flat for a good portion of throttle travel about 15% to 70% and then starts to equal out. I have no power at all ever. Not off idle or WOT or anywhere in-between. Heaven forbid I have to start off on a hill. Does the TPS go bad on these? Can I put an OHM meter on it and what should it read? I am only getting 8MPG. Can someone please help? |
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12-21-2011, 07:55 PM
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#2 |
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Registered User
Join Date: Mar 2008
Location: williamsport,pa
Posts: 329
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Re: Dead spot in throttle
where in ne pa u from? yes u can chesck it but it would be better with a scan tool.
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12-21-2011, 08:18 PM
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#3 |
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Registered User
Join Date: Feb 2004
Location: NE PA
Posts: 11
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Re: Dead spot in throttle
According to google about 2 1/2 hours from you. Moore TWP.
I have Scan XL Pro w/GM enhancements. I just found out that the dealer screwed up my cam retard when they did the intake manifold gasket. It was at -14 so I set it to 0. Really didn't help. Maybe I will reset the computer and see what happens then. I was looking at the data stream and I am only getting 4.4 volts at WOT. 83 degrees open. I think that I should have closer to 5 volts but I'm not sure. |
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12-21-2011, 08:46 PM
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#4 |
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Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: Dead spot in throttle
TPS sensors rarely fail, You can check the voltage output on the Blue wire......Roughly .75 vdc at closed throttle....Steady increase to 4.95 at wide open throttle. These are estimated open & closed values....The part in between is important.
Your symtom sounds like a bad mass airflow sensor. |
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12-21-2011, 09:58 PM
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#5 |
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Registered User
Join Date: Feb 2004
Location: NE PA
Posts: 11
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Re: Dead spot in throttle
I was watching the data stream for the TPS and I don't think that I saw anything abnormal. I will have to look at it again.
I thought that the MAF might be bad so I sprayed it with MAF cleaner. I saw no difference. What should the values be? |
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12-22-2011, 10:21 PM
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#6 |
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Registered User
Join Date: Mar 2008
Location: williamsport,pa
Posts: 329
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Re: Dead spot in throttle
i just had this descusion with gm tac about a mass air sensor. take the number 1.8 times the displacment 5.7 and that will give yoyu the grams per sec that is needed for your truck to run correctly at idle. this is a good way to tell if mass air is reading ok or if you have a vac leak.
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12-22-2011, 10:51 PM
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#7 |
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Registered User
Join Date: Feb 2004
Location: NE PA
Posts: 11
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Re: Dead spot in throttle
Ok, So let me see if I am understanding this right. 5.7*1.8=10.26 grams /sec @idle.
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12-23-2011, 07:03 PM
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#8 |
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Registered User
Join Date: Mar 2008
Location: williamsport,pa
Posts: 329
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Re: Dead spot in throttle
yep
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12-26-2011, 02:01 AM
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#9 |
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Registered User
Join Date: Jan 2011
Location: Edinburg, Texas.
Posts: 194
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Re: Dead spot in throttle
Typically I see maf readings at idle are closer to 1.0 grams per 1.0 liter give or take a little. Unfortunately there is no definate spec. Another good thing to check is your catalytic converter. They plug up and restrict the exhaust. They make guages you can install in a pre cat O2 sensor hole which will read backpressure.
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