PINTO CAR CLUB of AMERICA
Welcome to FordPinto.com, The home of the PCCA => General Help- Ask the Experts... => Topic started by: 74WagonMeadowGreen on October 11, 2011, 11:15:48 AM
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I recently bought a 1978 Pinto 2.3L with 4-speed, no air, bare bones but not Pony. 52,00 ORIG. miles... absolutely stunning condition. Car ran OK, but no idle and backfiring on deceleration. I got home OK, and proceeded to check/replace certain things. It now has a new air pump (old one was very noisy), rebuilt carb, cleaned distributor, new wires, plugs, PCV, all vacuum hoses carefully, one-by-one replaced, fuel filter, etc. The timing belt was replaced at a Ford dealer by the previous owner. I CHECKED carefully both ignition timing AND that the cam belt was properly installed. It is spot-on correct. Timing is precise and correct to spec. When overhauling the carb I discovered the pin holding the choke linkage had come loose screwing up choke operation. I repaired it and all works perfectly. The only thing altered from original is the drop-down solenoid (anti-dieseling) was removed. When I fired it up it ran exactly as badly, unable to idle and backfiring on decel. Living in Colorado I MUST pass emissions so all that equipment needs to work. Can anybody suggest what next to check (there are a load of sensors yet to check) that might cause this condition? I did discover cylinders 2 and 3 are oily (on plugs). Possibly stuck rings or valve guide seals? Please help! Thanks,
Don
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Might you have a deceleration valve? It is mounted on the base of the intake manifold and sticks out towards the firewall. One single backfire will burn the valve diaphragm making it completely useless and causing a vacuum leak.
I don't know of anyone who reproduces them though. I would think you might be able to take it off and plug it, the cap off the vacuum line.
Back when I had to get my 78 tested, I had it passing WITHOUT the EGR valve or plumbing, and even with the catalytic converter hollowed out. It was rebuilt shortly before, but still...
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Mine did that years ago,I took it to be checked and they said it was the dump valve, that goes to the air pump and the exhaust manifold. They cut a hole in the vacuum hose to it and it quit, I just took it out and blocked off that vacuum port.
It backfired at every stop sign on my way home from work until I had it checked.
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Thank you very much for your input... I am still attempting to identify each little valve and sensor (it surprises me just how much more emission garbage appeared between my '74 Pinto wagon and the '78). I will verify that particular valve and remove it, once I am certain which it is. I will also verify the dump valve, and look into it. One more question... has there been a consistent problem with the Ford valve guide seals on this motor? I have read a lot of folks commenting the need to replace them as well as how-tos... I am afraid it might be my oily plugs problem, but I have to fit an adapter to use a compression gauge thanks to the 7-mile-deep and narrow plug placement!
I will keep you posted as to what I discover... what I do not like is what is causing the backfire, even if the decel valve may be blown regardless...
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Usually when valve stem seals go bad the oil goes past the guides and into the combustion chamber where the oil is mixed with the fuel and it gets burned...hence blue smoke but that will show up as carbon on the plug. With enough oil being burned the plug may foul and since the oil isn't being burned it settles on the plug and shows oily. An oily plug may also indicate that the rings are the issue. When oil comes past the rings it's not mixed with the fuel as much as coming past a guide. The oil still settles on the plug and can foul it or lessen its ability to properly burn the fuel/air mixture. A compression test will tell you a lot.
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Thank you all for your help! For the sake of clarity, please see the attached diagram, and my questions are-- Is the "dump valve" identified as number 9B289 (circled in the illustration), and is the "deceleration valve" identified as number 9D473 (also circled in the illustration)?? I have not had time to do the compression test yet, that is next. I did managed to remove, test and clean the EGR valve. The diaphragm works perfectly, but the gasket had dissolved and vanished, not that it mattered, as the manifold chamber was blocked 100 percent by carbon buildup. I carefully decarbonized it and have a new gasket to install. It is now cleaned thoroughly and ready to reinstall. I doubt it will help running very much but it cannot hurt! With 52,000 original miles it is difficult for me to imagine the motor requires substantial work done to it. Please let me know about the valves. Thank you!
Don
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Thats the dump valve, at least that was the name they gave it when I had it `fixed`. Im not sure what the two vacuum hoses are for it, I guess one is a control signal from a switch in the air cleaner I cant remember anymore.
The other one you show looks like a ported vacuum switch that goes into that piece in the intake maifold. Im going to get my Chiltons out and look,but Im pretty sure the decel valve is mounted right at the carb. I might be wrong. Im not even sure they all had one mine doesnt. But like many other things it may have been removed over the years.
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Attached to the intake manifold. A hose connects it to the carb
But, "Use of the deceleration valve on the Pinto/Bobcat was discontinued after the 1977 model year"
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The anti back fire valve is what you should have....It's name should be clear...It stops the back firing........ .You can find them on any Ford with a 2.3 except the Turbo Engines....The y do not need one...
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Again, thank you for the suggestions and insight. I finally managed to successfully accomplish a compression test... unsurprisingly, all cylinders have 130 lbs very evenly, and that with a questionable seal on the compression gauge, so I am not too concerned about any internal engine traumas. I will indeed check the various devices starting with disconnecting the divertor valve (a.k.a. dump valve, blow-off or bypass valve, anti-dieseling valve, etc) and see how it runs. I will consider doing a reseal on the valve guide seals before long, but really should drive the car a bit first, to help loosen any gumming up, as it suffers mostly from both sitting and aged seals/rubber parts. BTW- you are correct, there is no "deceleration valve" on my 78. There is a vacuum valve (as circled on the above diagram) on the intake manifold, but that is it besides a load of vacuum connections and devices all sprouting from the air cleaner.
On another note, did Ford use the same "faceplate" for their AM/8-track radio as for the standard AM radio?
Thanks to everybody once again! I will post when I track down the problem.
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I have a 1976 Pinto if you need pictures of what the vacuum lines look like... Your carb may have more lines but the anti backfire system did not change.......
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Brand new Anti-backfire valve, brand new vacuum temp control valve, brand new canister valve, brand new handful of other valves going to and from the distributor and vacuum lines. EGR cleaned and tested. It is flawless. Even with the air pump disconnected it stumbles and backfires miserably. Bear in mind the carb was carefully cleaned and overhauled, and all functionality restored. Some previous owner has definitely messed with the catalytic convertor, and as noisy as the exhaust sounds (with a correct, new factory-muffler) I am thinking the Catalytic convertor may be a shell, so to replace the needed back pressure and operational ability I will get a new, correct unit. As, in respect to emission garbage, one MUST either have ALL (working) or NONE... half-assed does NOT work... I am wondering, could the ignition box be going south to cause stumbling and backfires? I am running out of valid possibilities, and quite frustrated.
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Have you checked the vacuum advance on the distributor... ...Just a thought, my car is having some of the same issues and I when I went over the owners log book for the car it said it had a problem with the timing IE the vacuum would not advance the timing based on r.pm. changes...Of which leads me to believe that the vacuum advance has failed....
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Thank you for the excellent suggestion. I did check the vacuum advance as well as timing and both seem to be working correctly. I have not been able to test the ignition module as we are now on an every-three-day 14" snowstorm routine... please, Lord, not another fall/winter like two years ago!!
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Quick update: the ignition module is perfect, no problems. I am running low on possibilities! Thanks to all for your suggestions!
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Is your EGR valve working properly?
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How did you test the vacuum advance, with a vacuum source like a mity-vac ? Or just disconnect it......Also I just got done changing the spark plugs and spark plug wires and can say it's a lot better, not perfect but a lot faster, more power etc......Have you checked the routing of the wires if it's not right it could cause some timing issues like a cross fire in the firing order....
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I checked the vacuum advance while checking timing with a timing light... it seemed fairly obvious when disconnected. I routed the new wires and plugs carefully, so although I can never be entirely able to disqualify them, it seems unlikely. Thank you!
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Is the car still backfiring when you decelerate or has it changed? Seems like your saying it backfires all the time..maybe it's just how I'm reading it. Does the engine diesel sometimes when you shut it off?
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I reread and reread but it doesnt really say anywhere,is it backfiring out of the exhaust or the carburetor. If youve done everything you said already it might be time to start back at the beginning.
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Car ran OK, but no idle and backfiring on deceleration. (This is what he said in the first post) Even with the air pump disconnected it stumbles and backfires miserably. (This comment is made later)...Kinda confusing as to when it really does backfire.
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Think it could be a burned or sticking valve or weak valve spring? Doesnt say a compression test was done might be a good idea, like I said maybe start at the beginning.
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I finally managed to successfully accomplish a compression test... unsurprisingly, all cylinders have 130 lbs very evenly, and that with a questionable seal on the compression gauge, so I am not too concerned about any internal engine traumas....he did a compression test and it looks good as far as that goes. Sticking valve is what I'm starting to think...or something along those lines. If it were a burnt valve the compression would be down on that cylinder.
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Quick clarification: EGR is cleaned and working perfectly. Compression test was indeed accomplished and it was even and good in all cylinders, but I cannot guarantee a perfect seal on the gauge, so will retest now I have a good gauge. The car seems to be backfiring in the exhaust, what some refer "more accurately" as "after fire". It does not backfire through the carb. It does not smoke or make mechanical noise in the motor, like a valve problem would. I am going to revisit the vacuum advance on the distributer despite all indications it is working correctly. It is possible the carb needs readjusting since rebuild, but still should not be a major cause. My friend has an analyzer and I will plug that in as opportunity permits. Right now, I am seriously looking at the catalytic converter... the more I read, the more it may be contributing to my problem...
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So this happens when you let off of the accelerator slowing down...correct?
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Where have you set the timing, as per the emissions sticker ? If so try to advance it a couple of degrees, like to 6 if its a 2 degrees because the original owner has had a similar problem and this helped fix it.On my car...
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Given our elevation, that may be a wise idea... yes, the timing is currently set precisely to the emission sticker settings... your suggestion is great, thank you, I will see what it does.
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So this happens when you let off of the accelerator slowing down...correct?
When I step on the accelerator, the engine revs perfectly fine, and as it comes back down, it "backfires" in the exhaust, on deceleration. I have not had time to test it, but ever since I drove the car home,the exhaust has always seemed louder than it should, even with a correct muffler installed, so I still suspect the catalytic converter to be empty. I have a new one ready to install, as time permits.
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Is your EGR valve working properly?
EGR and passagewayis cleaned and tested, works perfectly.
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I know this is not a Pinto I am going to be writing about, but I thought I'd mention it anyway. I am haviing a problem with backfiring when decelerating on my bus. One of the guy's an the Samba said that it is possibly caused by an exhaust leak. He told me to check all my doughnuts and gaskets on my muffler.
Could this possibly be the same senario for a Pinto? Maybe the exhaust system has an air leak?
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"The timing belt was replaced at a Ford dealer by the previous owner. I CHECKED carefully both ignition timing AND that the cam belt was properly installed. It is spot-on correct. Timing is precise and correct to spec."
I know this may be a LONG SHOT but it sounds like the timing belt may have been installed one tooth off. With the cam slightly off (cam degree), the exhaust valve may stay open too long causing raw fuel to pass through and going boom when it enters the hot exhaust manifold. Just a thought...
71HANTO
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I tend to think an exhaust leak or gutted Catalytic converter may be contributing to the problem. I plan to look into it as soon as time permits, thanks!
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Have you checked the distributor spark delay valve ? It's a small plastic disc black and white in color that has a vacuum line going from the carb to the distributor.If it's clogged or not connected in the right direction it could be the problem...It's marked on one side carb and one side dist.
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Have you checked the distributor spark delay valve ? It's a small plastic disc black and white in color that has a vacuum line going from the carb to the distributor.If it's clogged or not connected in the right direction it could be the problem...It's marked on one side carb and one side dist.
I replaced it, but after getting the car on a lift and doing some tests, a friend and I discovered ., I WAS right, the catalytic convertor was a shell, totally empty, so we installed a new one. 2. The TVS valve, which controls air going from the pump into the exhaust was shot, so a new one is ordered. I am quite certain that will fix the problem.
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Keep us posted,it's all ways a good thing to know more about these cars.
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That tvs valve is the one on the air cleaner cover isnt it? I think thats what was bad on mine and they cut a chunk out of the vacuum hose that goes from it to the diverter valve. Its was over 10 years ago, but thats all they did to `fix` it. I dont remember if I had a vacuum leak or what happened but its all been redone since then.
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if it backfires on decel, check the vacuum line going to the air pump dump valve.
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As soon as our 18 inches of snow clears, and temps rise above the single digits, I hope to verify the TVS (TVR??) valve, the little circular plastic job located in the air cleaner and connected directly to the air pump, amusingly shoved on several Ford products well into the 1990s, has been the culprit, as I was able to install the new one the night before the latest onslaught of snowstorms, and although covered, my poor car has to sit outside.
Has anybody encountered difficulty removing air from the heater lines when servicing the water pump? The previous owner did a lovely job replacing the water pump, until I drove the car in cold weather and discovered there was no heat! Does anybody know any easy (outside of "bleeding, hence leaking fluid out to get rid of bubbles) method to remove air in the heater lines?
Happy holidays, and thanks for the input!
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You really shouldn't have to "bleed" the lines going to the heater core. Usually after a few minutes of running the core is full and the air gone. There might be a possibility of a restriction in the core or in the lines. When the car was running before, did you feel the hoses to see if both were hot or at least one of them?
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I did not, as time was of the essence, I simply planned to get back to it. I will check several things, including hose temp (when warmed up) as well as if the valve is working/conected, etc. Thanks!
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As for your early question on valve guide seals, I have to replace mine every 12-15 years (avg 75k miles) when oil consumption is sky high. They deteriorate, wear, and no longer seal. Not sure if it is a design issue or i expect too much from them.
Did you notice how much total timing advance at idle you had when checking your timing? Check it with the advance hose hooked up as well as removing it and plugging it.
I am leaning towards an ignition / cam timing issue here.
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As of yesterday, the backfire problem is solved... exactly what we discovered... That TVS valve in the air filter housing WAS the cause, and except for needing a choke adjustment the car is running nicely when warmed up. Add to that, the heater bled itself! Once I left the valve open it purged the air block and works nicely. It still tends to stumble a bit when cold, but again, the choke is not in the correct position, so it improves enormously once warmed up. I am confident it should do OK passing emissions at this point, and as soon as both time and weather permit, I will head over to the testing station. Then I can finally get my plates and drive it!!
Thanks everybody for the help.
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Out standing, now what is the testing process to find the TVS failure in the first place? Hook it up to a Mitty Vac ?
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Once the valve was removed, it was easy to see if it was jammed open, which it was...no special testing required!