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Signs of a vacuum leak? please help

22834 Views 8 Replies 5 Participants Last post by  67paul
hey all, I posted another thread a few days ago regarding amisfire I have. well it seems to be worse now. I adjusted the timing to stock 10 deg. changed out plugs with std. autolites old ones really werent in bad shape new cap rotor wires new coil. I drove the car maybe 1/4 mile and it was running fine stopped at gas station to get air and let it idle a few minutes no problems get back in and the misfire had returned car smells like it is running rich and barely made it home bucking and missing back to the house. really strong gas odor by this point. I checked the vacuum at idle when cold it's around 15 then it will drop to around 10 if it will actually idle at all. I have attempted the carb spray test and unhooked all the vacuum lines and plugged them etc sprayed around front and rear of intake the injectors no increase in rpmswapped out the pcv valve and grommet just to make sure it was not a hoax i sprayed some in the air filter sure enough the rpm went up I am at end with this car and really dont know what else could be wrong please any suggestions would be appreciated
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Vacuum leaks usually cause lean like symptoms, like pinging on acceleration, or idle problems. Over rich symptoms can be attributed to bad tps, ect, maf, overly high fuel pressure, bad exhaust leak fooling 02 sensors, or bad 02 sensors. Ignition control module could have issues, but that's reaching.
yup pretty much got it there if you can get a obd1 scanner on it that would definitely be of help
OBD 1 hook up

do you know which wire it is that is the jumper connector for the diagnostic hookup ? i see one in there next to the large connecor that is all white with id say a brown stripe ?
OK used the engine light test found codes

Engine off:

12 IAC kind of figured this was a problem
21--coolant sensor out of range measured resistance at 16 ohm's with a cold engine well here in houston the ambient aire is 90 degrees


84 EGR regulator /vent cutoff ???

85--purge valve--dont have one on the car

34 EVP sensor signal high

33 EGR EGR did not open / respond to test

these were all on the 2nd attempt the 1st attempt gave me some other codes but the car was cold from sitting 2 days and soome were the same ones

31 evp out of range
22 map out of range
91 system running lean
41 system lean

all this would appear to me to be associated with the egr system and a massive vacuum leak as a result would th egr codes contribute to a lean running condition and missfiring from idle to say about 2K rpm. seems to get worse as it heats up although it is hard to idle when cold anyway so hard to say. I really cant afford all these parts so is there a way to get rid of the egr system and fool the computer to think it is off ive read about some resistors you can buy

Thanks again for all your help!!!!!
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yeah you can remove all the lines associated with the smog system but to remove the egr valve you have to block off the lines coming out of the head somehow
I'm not sure exactly what your car's condition is, but here at ford we sometime can salvage the original parts. For example remove your egr valve and idle air control valve from your throttle body and clean them. Let them soak in throttle cleaner for a while and maybe take a pipe cleaner of sort and try scrubbing inside ports.
It is also possible that the Mass air is slightly dirty. If you want to clean it just spray it with BRAKE CLEANER. Don't touch it or it could make things worse. I hope I helped.
Yes, youd have to block the thermactor holes in the rear of the heads by the firewall. I did this while the heads were off, but should be able to find some sort of bolt to block the holes while heads are on. Do a search on this site, and you will be able to find the exact size that fits. Dont forget to pinch your mid pipes also where the thermactor lines connected to them.
Thanks to all for your help!!

Thanks for the advice folks I of course delved to far into the problem. The PO had installed a cheapo cold air intake with a cylinder stle K&N filter heh...well the filter was sitting down on the inner fender effectively blocking half of the filter so it was choking the engine down. I relocated it a bit and secured it with some cable ties for now until I can find a stock unit to put back in there runs like a different car now lol:shiny:

still has a bit of a raqndom idle so I'll try cleaning the valve out again and the whhel bearings sound like marbles so they'll have to change out but it will at east drive now

Thank you!!!
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