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Nemo914 |
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#1
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Member ![]() ![]() Group: Members Posts: 76 Joined: 11-July 03 From: Cape Cod, MA Member No.: 902 ![]() |
OK, I have posted before on help with a sputter (or light "backfire") on deceleration with my 1972 1.7. It happens at around 2-3k RPM and is worse when loaded on decel. Sounds like "phfft, phfft, phfft".
Most of you suspected an exhaust leak, and in agreement, I replaced the heat exchangers with SS, with new copper seals and the works. The stock muffler is also new. It all seems solid as a rock, and I don't think it could still be leaking. In George Hussey's "tech tips" (I know, everyone's favorite dude) it says, "If your 914 "pops" or backfires when suddenly backing off the throttle, suspect..." 1. Leaking muffler or heat exchanger to head connection 2. Fuel pressure too high 3. Throttle switch bad But, I have had it tuned by a reputable shop, fuel pressure checked, and installed a new throttle switch. Even tried different octane gas. It is a completely stock FI 1.7. It starts, idles and runs perfectly, except for this!! It is embarassing to drive as people admire the car and then laugh as it sputters and coughs on decel (IMG:style_emoticons/default/headbang.gif) Does anyone have any other ideas?? I have driven this car since I was 16 (21 years to date) and it never did this until about a year ago. Any help would be appreciated. Here are a few phots just because we all like pictures: Attached image(s) ![]() |
Nemo914 |
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#2
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Member ![]() ![]() Group: Members Posts: 76 Joined: 11-July 03 From: Cape Cod, MA Member No.: 902 ![]() |
Another:
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ArtechnikA |
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#3
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rich herzog ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None ![]() |
is that the model that's supposed to have the vacuum retard in the dizzy ? if it is, you might check to see that's working - that's the engine management regime it's supposed to help...
beyond that i donno... |
robby750 |
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#4
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Senior Member ![]() ![]() ![]() Group: Members Posts: 646 Joined: 6-April 03 From: Lexington, Ky Member No.: 521 Region Association: South East States ![]() |
I have no idea what the problem might be, but that sure is a clean engine!
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Brad Roberts |
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#5
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914 Freak! ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None ![]() |
This is the decel valve. It could possibly be bad or leaking. You can easily block it off for testing (plug the lines running to it)
Let me know what you find. B |
Nemo914 |
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#6
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Member ![]() ![]() Group: Members Posts: 76 Joined: 11-July 03 From: Cape Cod, MA Member No.: 902 ![]() |
OK, will ops check the decel valve.
Also, can the vacuum unit on the distributer fail? If it failed, what would be the result? Can they be purchased alone or does it come with the distributer? How about the ECU adjust. Could it be set wrong? Thanks, Nemo914 |
fiid |
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#7
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Turbo Megasquirted Subaru Member ![]() ![]() ![]() ![]() Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California ![]() |
Not much can be done about the ECU - it's probably not dead though if the car is running properly the rest of the time.
You can do a complete checkout of the fuel injection system by following Kjells guide to D-Jet maintainence. http://www.914fan.net/djet.html This will also tell you how the stuff is supposed to work, if you are interested in the theory of it. Probably not the root cause, but checking the valve clearances is always a good idea. Also, you might want to get an Optima Battery just so that you don't get hellhole rot ever, which is a terrible thing to happen to such a clean and fantastic looking car. Fiid. |
Bleyseng |
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#8
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Aircooled Baby! ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 13,035 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest ![]() |
Hey, I was gonna suggest the Optima battery!
Check the decel valve by pluging the vacuum side hose to see if that helps. If your ECU has the idle adjustment screw you can turn it a couple of clicks to richen the mix at idle. I suspect the problem is a vacuum leak somewhere which you should try to find. Look at those silly rubber elbows that crack and the engine vacuum hoses and connections. Nice clean engine and bay!!! Geoff |
Bleyseng |
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#9
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Aircooled Baby! ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 13,035 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest ![]() |
These crack....
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joea9146 |
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#10
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Senior Member ![]() ![]() ![]() Group: Members Posts: 663 Joined: 10-February 03 From: Denver, NC Member No.: 283 Region Association: None ![]() |
Have u tried to search for an exhaust leak recently.... Put the car up on Ramps...
make sure it is well secured. Start it up when it is cold get a piece of vaccum hose about 3 feet long.... hold one end to your ear get under the car now search all the joints and connections for an exhuast leak. |
Nemo914 |
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#11
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Member ![]() ![]() Group: Members Posts: 76 Joined: 11-July 03 From: Cape Cod, MA Member No.: 902 ![]() |
Good idea on the leak. I am pretty sure I put everything on tight, but maybe something is still leaking out at the head. Could it be warped or something? Would high temp silicone help? I only used it to seat the copper rings. I didn't use any before the heat exchangers went up in there. It sure sounds like an exhaust leak and the symptoms fit. I will keep you posted.
Thanks! |
Brad Roberts |
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#12
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914 Freak! ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None ![]() |
I coat the backside of the copper gasket and I file the HE's flat and put high temp silicon on them as well.
If you have SSI's... make damn sure you bought them new.. people break the ears off and have them rewelded 99% of the tim incorrectly causing them to no seal properly to the gasket. B |
Nemo914 |
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#13
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Member ![]() ![]() Group: Members Posts: 76 Joined: 11-July 03 From: Cape Cod, MA Member No.: 902 ![]() |
Where is the best place to get them new and how much $$$$?? If these are bad, I will be in the market for new ones.
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