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> help with diagnosis, popping through exhaust
joeav8tor
post Oct 15 2008, 03:13 PM
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Hi guys,
I go back and forth with wanting to sell my 73 Phoenix Red 914 2.0 with stock fuel injection, but the weather in the Northeast has been nice and I have been driving it, and want to keep it but its driving me crazy...I'm having a problem that maybe you could help me with...I bought the car and took the engine out for new fuel lines, vacuum lines, pushrod tube seals, shifter seals, oil cooler...the works....I recently painted the car (with the engine in) only the exterior was painted...after 1.5 years of paint and body work....there is a popping through my exhaust and the idle is not steady, sometimes 1000, sometimes 500, sometimes 900-1000...the popping is new, but the idle was always a problem...yesterday I replaced the points, set the dwell and the timing...still popping through the exhaust and the idle is still acting up, when I turn the distributor and the RPM increases...the popping goes away and my idle is higher, but the car is not timed correctly (using a timing light and the Haynes manual, process was done correctly) when the car is timed correctly...the idle adjustment screw when turned and sucking a lot of air will only get the idle to around 1100 and I have to adjust the D Jet control unit to try to get the idle from bouncing, but its not running right...I did reconnect the tranny grounding strap when I put the engine back in...I never replaced the PCV valve or adjusted the throttle switch...I want to keep the original fuel injection in the car if I could...but I could see why guys want to tear this stuff out...it has been driving me crazy for years.
thanks (IMG:style_emoticons/default/flag.gif)
Joe
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jmill
post Oct 15 2008, 03:34 PM
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Popping through the exhaust tells me your timing is too far retarded or your valves are out of adjustment. Is the vacuum advance on your dizzy working?
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KaptKaos
post Oct 15 2008, 04:00 PM
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Dunno if this applies to FI, but check the nuts on the intake manifolds where they bolt to the heads. Make sure they are torqued to spec. Extra air does weird things.
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Rod
post Oct 15 2008, 04:04 PM
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9 out of 10 times the erratic tickover on the FI is a vacuum hose of some sort - get some spray out and see where you have a leak. The popping is retardation imo. I don't think the two things are related.
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joeav8tor
post Oct 15 2008, 04:15 PM
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thanks guys for the replies, I adjusted the valves about 1200 miles ago...I am going to check the vacuum on the distributor...the car runs without the popping when I thurn the distributor and the RPM increases, but its not timed...maybe the vacuum on the distributor. I thought also about an exhaust leak, but when the popping goes away with turning the distributor, I dont think thats the problem...one other thing I'll check is the condensor.
thanks
Joe
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jmill
post Oct 15 2008, 09:31 PM
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When you turn the distributor and the RPM increases your advancing the timing. Too far advanced and you'll pop through the intake. Too far retarded you pop through the exhaust. I know you say you followed the manual but I have to ask. Did you remove and plug the vacuum line to the distributor when you set the timing?
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joeav8tor
post Oct 15 2008, 10:45 PM
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good catch!!!! I did remove the vacuum hoses to the distributor, but I did not plug the hoses! Thats probably it, and the fluctuation in the RPM is probably from having the D Jet brain not properly adjusted to compensate for the timing...the adjustment is not in the middle but turned all the way to the right.
thanks, I will let you know what happens.
Joe
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jmill
post Oct 16 2008, 09:52 AM
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That will give you a vacuum leak but it wouldn't affect total advance. I was hoping that you didn't disconnect the vacuum line. Total advance is initial advance plus vacuum and/or mechanical advance. If you left the line on you wouldn't have enough total advance. That would explain why the car runs better when you advance the timing. Check that your vacuum advance diaphragm doesn't leak. Put the line on the distributor and suck on the end of the line. You should see the vacuum advance move and you should only be able to suck a little bit. If you can just keep sucking and nothing moves your vacuum line or the diaphragm is bad. Check that your mechanical advance moves freely too. I think that the FI dizzies have both mechanical and vacuum advance.

If it's an FI problem I'm out. I'm a carb guy. Just swagging it, if it's not a timing issue, I'd say you have a vacuum leak. At higher RPM you wont notice a small one. At idle it would cause the problems you described.
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Root_Werks
post Oct 16 2008, 10:21 AM
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QUOTE(joeav8tor @ Oct 15 2008, 09:45 PM) *

good catch!!!! I did remove the vacuum hoses to the distributor, but I did not plug the hoses! Thats probably it, and the fluctuation in the RPM is probably from having the D Jet brain not properly adjusted to compensate for the timing...the adjustment is not in the middle but turned all the way to the right.
thanks, I will let you know what happens.
Joe


You have it leaned out if I remember my turning correctly. (IMG:style_emoticons/default/idea.gif)
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joeav8tor
post Oct 16 2008, 08:33 PM
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NO GOOD! I timed the car with the vacuum hoses plugged...still popping...when I disconnect the green vacuum line (the bigger one that goes to the back of the throttle body) the rpm increases and the car runs better (with an occasional low sounding pop)...Next? runs really great other than when I have to stop for a light or a stop sign... (IMG:style_emoticons/default/confused24.gif)
Joe
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orange914
post Oct 16 2008, 08:48 PM
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QUOTE(joeav8tor @ Oct 16 2008, 07:33 PM) *

NO GOOD! I timed the car with the vacuum hoses plugged...still popping...when I disconnect the green vacuum line (the bigger one that goes to the back of the throttle body) the rpm increases and the car runs better (with an occasional low sounding pop)...Next? runs really great other than when I have to stop for a light or a stop sign... (IMG:style_emoticons/default/confused24.gif)
Joe

sounds to me like a leaking valve or a too tight valve. do a comp. and leakdown test (IMG:style_emoticons/default/beerchug.gif)
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jmill
post Oct 16 2008, 09:14 PM
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If it runs better with a big vacuum leak your set too rich. I don't know jack about adjusting the FI idle circuit
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