Hesitation @ lower rpm

notnilc20
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Hesitation @ lower rpm

Postby notnilc20 » Wed Jul 18, 2018 7:37 am

Engine is a largeport bluetop 3 rib. Keep in mind this would happen before i got my timing set properly too....Just got my timing set up properly @ 16-17 deg. Btdc via diagnostics mode....but when i accelerate from a rolling or stop...@ ~1500-2000 rpm in 1st gear, the car really stumbles and really can't pull itself out to accelerate. I'll have to push in the clutch to rev it higher to get it to accelerate....you can hear the stumble just revving it in neutral as well.

I think it may be I didnt clean the fuel tank out as well as I had hoped and maybe the strainer at the bottom of the fuel pump is clogged?? Or maybe I got trash in the fuel line??...but i'm not sure and was wondering what other issues it could be possibly before I invest in a new fuel tank and pump? Maybe I could take it somewhere where they could test my air/fuel ratio and see if it leans out when the problem presents itself. Thx.

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jondee86
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Re: Hesitation @ lower rpm

Postby jondee86 » Thu Jul 19, 2018 1:10 am

If you have an AFM, check that the flap inside is free to move and not binding or
sticking at low throttle openings.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

davew7
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Re: Hesitation @ lower rpm

Postby davew7 » Thu Jul 19, 2018 4:15 am

Two probable causes, You do not have enough fuel pressure or the TPS functioning.
Put a pressure gauge in the fuel line from the pump. The easiest spot is in front of the in-line filter. At a min you need 38-40 PSI. If it below the 38PSI get a new pump and strainer. Check out Rock Auto for a good price on the pumps and strainers.
To check the TPS, you will need a VOM, to check resistance between the 4 pins. You can try advancing the TPS slightly, but you really need to follow the trouble shooting guide to verify the TPS function and that it is set correctly relative to throttle movement. Davew7

notnilc20
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Posts: 562
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Re: Hesitation @ lower rpm

Postby notnilc20 » Thu Jul 19, 2018 7:06 am

jondee86 wrote:If you have an AFM, check that the flap inside is free to move and not binding or
sticking at low throttle openings.

Cheers... jondee86


I do have an afm...i'll check it for sure.... thanks.

davew7 wrote:Two probable causes, You do not have enough fuel pressure or the TPS functioning.
Put a pressure gauge in the fuel line from the pump. The easiest spot is in front of the in-line filter. At a min you need 38-40 PSI. If it below the 38PSI get a new pump and strainer. Check out Rock Auto for a good price on the pumps and strainers.
To check the TPS, you will need a VOM, to check resistance between the 4 pins. You can try advancing the TPS slightly, but you really need to follow the trouble shooting guide to verify the TPS function and that it is set correctly relative to throttle movement. Davew7


Thanks Davew7...i will see about checking my fuel pressure and recheck my tps...

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notnilc20
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Posts: 562
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Location: Memphis

Re: Hesitation @ lower rpm

Postby notnilc20 » Sat Jul 21, 2018 8:26 pm

UPDATE:

Had some time today so I thought it'd try to figure this hesitation out. So i tested the resistance of all the terminals on the afm per the service manuals..... everything checked out perfect and i also checked the afm door inside to make sure it was not binding up... it was silky smooth with no binding whatsoever....

So then i checked the new autozone duralast tps again... and right away things were not setup correctly. The resistance between the idle and e2 plugs with a .35mm feeler gauge was not correct. Also between vcc and e2 no good....I tried to get it set up properly but to no avail...so I got my old spare oem tps and set it up and viola...car is accelerating smooth again. Dont know why the duralst tps went out of whack because when I first installed it....it checked out good and set up good but oh well...

.anyway, thanks Davew7 and Jondee86 for helping out with sound advice like always!

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