engine flutters on full throttle not partial throttle
Thread Starter
Safety Car
Joined: Oct 2008
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From: Los Angeles CA
engine flutters on full throttle not partial throttle
the car moves but does not pull, like it's bogging
just started recently, I thought it was a vacuum leak, and it was part to blame, the charcoal canister tube was dislodged by the transmission fellas.
it ran better, but didn't fix the problem, it will rev to redline in part throttle, and pull like crazy,in part throttle and run well with part throttle
the wideband readings are spot on with no lean spots, I even changed the air filter thinking I was air starved, it ran better but didn't fix the problem.
it problem starts at around 3500 rpm and when I rev past 4200 or so (I think it clears up), I don't think it's a valve float thing cause it happening at such a low rpm.
any ideas? otherwise the engine idles and run smoothly and beautifully, punch it part throttle in second and the tires spin. gas mileage went up with the lower stall and the governor reprogramming.
just started recently, I thought it was a vacuum leak, and it was part to blame, the charcoal canister tube was dislodged by the transmission fellas.
it ran better, but didn't fix the problem, it will rev to redline in part throttle, and pull like crazy,in part throttle and run well with part throttle
the wideband readings are spot on with no lean spots, I even changed the air filter thinking I was air starved, it ran better but didn't fix the problem.
it problem starts at around 3500 rpm and when I rev past 4200 or so (I think it clears up), I don't think it's a valve float thing cause it happening at such a low rpm.
any ideas? otherwise the engine idles and run smoothly and beautifully, punch it part throttle in second and the tires spin. gas mileage went up with the lower stall and the governor reprogramming.
Thread Starter
Safety Car
Joined: Oct 2008
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From: Los Angeles CA
they rattled when they were going out, and eventually hissed they were so clogged and the car would not move, maybe I am moving alot more air with the new tune and the exhaust is holding things up...
I did alter the timing table a bit to accommodate the differing torque and load characteristics of the off idle with the lower stall and shift points, actually the problem existed prior to my tweaking the tune.
Last edited by slickfx3; Mar 25, 2012 at 05:59 PM.
Thread Starter
Safety Car
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From: Los Angeles CA
would a lost of pressure lean out the wideband, or would the wideband miss the lost in pressure?
Last edited by slickfx3; Mar 25, 2012 at 05:42 PM.
Thread Starter
Safety Car
Joined: Oct 2008
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From: Los Angeles CA
it does not use a drop of oil, nor are the plugs greasy and the engine never smokes, not on cold start etc...
Safety Car
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From: Indiana PA
What is recently, have you checked the plugs since this started?
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Thread Starter
Safety Car
Joined: Oct 2008
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From: Los Angeles CA
Safety Car
Joined: Sep 2010
Posts: 3,752
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From: Indiana PA
Plug contamination from coolant, oil, fuel, etc..
Note the color of them, should be tan-ish and fairly clean. I've taken plugs out of newer stuff like V6 4.0 VQ's at 100K+, they looked I put them in yesterday except for the out of spec. plug gap.
Note the color of them, should be tan-ish and fairly clean. I've taken plugs out of newer stuff like V6 4.0 VQ's at 100K+, they looked I put them in yesterday except for the out of spec. plug gap.
Safety Car
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From: Indiana PA
I think 383Vett's idea is a good one. Just because something was ok, at some time in the past, does not mean it is ok now.
Thread Starter
Safety Car
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From: Los Angeles CA
how about codes, I have no codes?
i have no smoke pouring out of the tail pipes.
the car is in the shop getting a new water pump now. just doing some research for this bottomless money pit
Last edited by slickfx3; Mar 25, 2012 at 06:29 PM.
Safety Car
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From: Indiana PA
Vacuum test (idle and driving) is a good one. As long as you know what your looking for. Not just what it is, but how the needle (on gauge) acts can tell you a LOT about an engine.
Thread Starter
Safety Car
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1) vacuum check, I'll check online to compare what it is doing to what it should be doing... I engine has a cam etc... would that change what it should be doing?
2) pull the plugs...
then report those findings here
3) then if i need to rent a fuel pressure gauge from auto zone and tape it to the windshield and watch it behave on full throttle.
and then report the findings here
4)and lastly if I can't figure it out with the above then have a shop or maybe i can rent a compression tester from autozone, but wouldn't it be redundant to the vacuum test?
Safety Car
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From: Indiana PA
since i don't have a compression guage, I do but I bought it in the 1975 and it is a push in and ask your buddy to crank the engine one, so in order of what I can to
1) vacuum check, I'll check online to compare what it is doing to what it should be doing... I engine has a cam etc... would that change what it should be doing?
2) pull the plugs...
then report those findings here
3) then if i need to rent a fuel pressure gauge from auto zone and tape it to the windshield and watch it behave on full throttle.
and then report the findings here
4)and lastly if I can't figure it out with the above then have a shop or maybe i can rent a compression tester from autozone, but wouldn't it be redundant to the vacuum test?
1) vacuum check, I'll check online to compare what it is doing to what it should be doing... I engine has a cam etc... would that change what it should be doing?
2) pull the plugs...
then report those findings here
3) then if i need to rent a fuel pressure gauge from auto zone and tape it to the windshield and watch it behave on full throttle.
and then report the findings here
4)and lastly if I can't figure it out with the above then have a shop or maybe i can rent a compression tester from autozone, but wouldn't it be redundant to the vacuum test?
This might be of use to you:
http://www.secondchancegarage.com/public/186.cfm
http://www.centuryperformance.com/tu...e-spg-148.html
Man vacuum tests, still work on new school stuff, because an engine is still an air pump, but man we are getting old school with this stuff. Next thing ya know, I'll be breaking out my grandfathers old timing light and dwell meter. I'm 24 and know what a dwell meter is and how it works....there is something wrong with that.
Compression tests are somewhat worthless. They only tell you if you have compression in a cylinder and how much. A leak down test is better and for diagnostics far more accurate. I do what you are going to do first and worry about leak down/compression last.
Thread Starter
Safety Car
Joined: Oct 2008
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From: Los Angeles CA
Cam can and will change vacuum readings.
This might be of use to you:
http://www.secondchancegarage.com/public/186.cfm
http://www.centuryperformance.com/tu...e-spg-148.html
Man vacuum tests, still work on new school stuff, because an engine is still an air pump, but man we are getting old school with this stuff. Next thing ya know, I'll be breaking out my grandfathers old timing light and dwell meter. I'm 24 and know what a dwell meter is and how it works....there is something wrong with that.
Compression tests are somewhat worthless. They only tell you if you have compression in a cylinder and how much. A leak down test is better and for diagnostics far more accurate. I do what you are going to do first and worry about leak down/compression last.
This might be of use to you:
http://www.secondchancegarage.com/public/186.cfm
http://www.centuryperformance.com/tu...e-spg-148.html
Man vacuum tests, still work on new school stuff, because an engine is still an air pump, but man we are getting old school with this stuff. Next thing ya know, I'll be breaking out my grandfathers old timing light and dwell meter. I'm 24 and know what a dwell meter is and how it works....there is something wrong with that.
Compression tests are somewhat worthless. They only tell you if you have compression in a cylinder and how much. A leak down test is better and for diagnostics far more accurate. I do what you are going to do first and worry about leak down/compression last.
so looking at all the "scenarios" what I should check is
1)idle, look for steady needle
2) slow acceleration, if a symptom is discovered
3) rapid acceleration
Last edited by slickfx3; Mar 25, 2012 at 09:39 PM.
Thread Starter
Safety Car
Joined: Oct 2008
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From: Los Angeles CA
shop adjusted the fuel pressure from 27 ( huh? i thought it was 32 psi last time I checked with autozone gauge) to 45 psi... did not help...
the vacuum gauge is at 15 psi steady and does not flicker, i drove it for 5 miles and based on the links you sent me, there is no indications of mechanical issues...
wide band still read good... i may enrichen it a little
will pull plugs in the next few days
the vacuum gauge is at 15 psi steady and does not flicker, i drove it for 5 miles and based on the links you sent me, there is no indications of mechanical issues...
wide band still read good... i may enrichen it a little
will pull plugs in the next few days
Last edited by slickfx3; Mar 26, 2012 at 04:50 PM.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
shop adjusted the fuel pressure from 27 ( huh? i thought it was 32 psi last time I checked with autozone gauge) to 45 psi... did not help...
the vacuum gauge is at 15 in/Hg steady and does not flicker, i drove it for 5 miles and based on the links you sent me, there is no indications of mechanical issues...
wide band still read good... i may enrichen it a little
will pull plugs in the next few days
the vacuum gauge is at 15 in/Hg steady and does not flicker, i drove it for 5 miles and based on the links you sent me, there is no indications of mechanical issues...
wide band still read good... i may enrichen it a little
will pull plugs in the next few days
Do you have a adjustable fuel pressure regulator?
Thread Starter
Safety Car
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From: Los Angeles CA
that's what it reads steady at 15 psi, i have a cam in there, albeit and small one 220/229 114 lsa, 5.3 lift with the 1.6 crane golds.
yes adjustable fpr
Last edited by slickfx3; Mar 26, 2012 at 07:47 PM.