Most power at 1/3 throttle, Anyone else? |
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Most power at 1/3 throttle, Anyone else? |
McMark |
Aug 27 2003, 09:29 PM
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#1
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
I've noticed that my car makes the most power at 1/3 throttle. Any farther and it just bogs and makes even less power. Anyone know what that's all about? What's going on?! (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/huh.gif)
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redshift |
Aug 27 2003, 09:52 PM
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#2
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Bless the Hell out of you! Group: Members Posts: 10,926 Joined: 29-June 03 Member No.: 869 |
Overly rich, under-volt, dirty rotor, mis-gapped, shifted points...
What car? M |
ChrisFoley |
Aug 27 2003, 10:13 PM
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#3
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I am Tangerine Racing Group: Members Posts: 7,924 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
At what rpm? Carbs or FI? Did this just happen?
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Bleyseng |
Aug 27 2003, 10:16 PM
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#4
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Something is big time wrong if that's the case. It should make the most power at full throttle. An engine is a pump nothing more, more air in more power.
Geoff |
McMark |
Aug 28 2003, 01:14 AM
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#5
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
It's been running like this since I got it running. It's a 1.7 with stock D-Jet. I have a rebuilt distributor on order, so I'll see if that helps. It's got a Pertronix which I won't be switching into the new distributor right away. I'm going to hold back on that and run points for awhile just to make sure the Pertronix isn't a problem. It's got a new rebuilt alternator in it. I've suspected the car was running rich for awhile, but I don't really have the tools or the knowledge to know for sure. If I press the throttle to the "sweet spot" it pulls nice and hard (as hard as a 1.7 pulls) all the way to redline. Cap, rotor, wires and spark plugs are new. Plugs are gapped at 0.035 since the Pertronix puts out more power. It runs smooth when it's at the "sweet spot" so I don't think the gap is a problem. I bought the rebuilt distributor because there is a slight bucking while accelerating and I'm pretty sure it's related to the vacuum advance. So maybe there's some dynamic timing issues. Any more ideas? It'd be great to be able to drive my car out of town. Thanks! (IMG:style_emoticons/default/lol3.gif) (IMG:style_emoticons/default/pray.gif) (IMG:style_emoticons/default/lol2.gif)
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Brad Roberts |
Aug 28 2003, 01:15 AM
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#6
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Pressure sensor.
B |
ChrisFoley |
Aug 28 2003, 05:49 AM
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#7
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I am Tangerine Racing Group: Members Posts: 7,924 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
The TPS provides additional enrichment as the throttle plate is opening, until it stops moving. Does the car accelerate better while you are depressing the pedal, as opposed to constant position? If so then the problem is a lean condition, not rich.
I too lean toward the MAP sensor being the culprit, but I've never had that symptom with the D-Jet. |
2teeners |
Aug 28 2003, 05:59 AM
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#8
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Member Group: Members Posts: 79 Joined: 2-January 03 From: Arlington DFW, TX Member No.: 78 |
I'd suspect a fuel supply problem, maybe a clogged fuel filter, or maybe an intake screen clogged with rust. (IMG:style_emoticons/default/smile.gif)
seems like a leaky mps would be be in full rich position and run better as the throttle went down. and the TPS is for "accelerator pump" type enrichment, and would still work if the throttle were held in constant position. but that's just my sense of it. i've been wrong plenty. (IMG:style_emoticons/default/sad.gif) |
TheCabinetmaker |
Aug 28 2003, 06:14 AM
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#9
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Maybe its that Napa Valley wine in the gas tank? LOL
Seriously, Brad is probably right. Check fuel pressure and pull a vacuum on the mps. I just repalced one this week, and man, what a difference. |
Bleyseng |
Aug 28 2003, 08:36 AM
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#10
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
I think that its both electrical and MPS. I think the dizzy's advance is not working rightand the MPS is having problems. A bad MPS goes rich but a car in good tune will still drive ok not the greatest but ok. Plugs will be black too.
Put a vacuum testor on the MPS to see if it holds 15hg for 5 minutes. If it doesn't hold a vacuum its toast. Install the dizzy when you get it and see the results. Geoff |
Brad Roberts |
Aug 28 2003, 10:24 AM
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#11
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Show us the vaccuum gauge you use Geoff.
B |
Bleyseng |
Aug 28 2003, 10:47 AM
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#12
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
I don't have the camera with me but I'll post a little tech article on "How to test one"
Geoff |
ChrisReale |
Aug 28 2003, 12:12 PM
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#13
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Sleazy Group: Members Posts: 2,665 Joined: 20-January 03 From: San Francisco Member No.: 176 |
I dont think you are supposed to re-gap the plugs if you use a Pertronix. They stay the same
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McMark |
Aug 30 2003, 12:23 AM
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#14
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Got my rebuilt distributor today, looks very nice. I didn't expect it to come with trigger points! Of course they're not brand new -- they've been bead blasted. I haven't installed it yet, but DAMN the shaft is tight in there. Now I know what a distributor is supposed to feel like! I'll get it installed tomorrow of Sunday and see how things are.
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Brad Roberts |
Aug 30 2003, 12:24 AM
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#15
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Mark..
can you stop by this weekend ?? I'll be around all day Sunday and Monday. B |
McMark |
Aug 30 2003, 12:25 AM
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#16
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
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