This is topic 92 LX stumbling/backfiring! in forum Tech Talk at Northern California Ford Owners .
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Posted by JohnB (Member # 969) on
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OK folks, here goes- picked up a 92 LX 5.0/auto and it runs good at high rpm (2,000+) but at idle/acceleration...it stumbles and hesistates. At idle, it will backfire (very small and noticable) and barely hold an idle. Car is completely stock, no mods. Any ideas? My first change will be the MAS, the computer, then the distributor...any other thoughts? thanks!
Posted by st5150 (Member # 51) on
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Its pretty rare for the computer to go bad. Is the back fire through the intake or exhaust? Your EGR could be stuck open. Pull the codes form the computer, that should give you a start.[ March 07, 2002: Message edited by: st5150 ]
Posted by 91sleeper (Member # 779) on
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My buddy brians 90gt is doing the exact same thing but it only does it when hes letting out the clutch and his is in the intake. Were changing his plugs first. You might wanna try that before u spend some bucks on a whole new comp.
Posted by JohnB (Member # 969) on
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The backfire is through the exhaust. Unless it idles for an extended amount of time(more than 45 sec) it just sounds like a pop through the pipes. I plan to give it a full tune-up, clean the throttle body and idle air bypass valve, and go from there. As for the parts swap-out, I've got the items readily available, so it makes the troubleshooting a lil easier...
Posted by st5150 (Member # 51) on
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Through the exhaust means rich, through the intake means lean. Check your O2 sensors. Instead of spending all that time randomly swapping parts, why not pull the codes so you have a much narrower list of parts that could be wrong.
Posted by PunkINa5.SLOW (Member # 10) on
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Check to see if #3 and or #4 plug wires are crossed.Also check #7 and or #8.
The firing order is counterclockwise
13726548
That is the problem.
Posted by JohnB (Member # 969) on
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I tried to pull the codes, via the key on/key off method...it didn't generate anything. I don't have a handheld, so that's out the window. Did a "poor-mans" spark check, turns out 1 and 3 are dead(engine ran the same w/o them), so the next thing is new plugs/wires. Hopefully that checks good afterwards. The firing order was correct, that was my first thought. Checked the EGR, all is working fine.
Posted by PunkINa5.SLOW (Member # 10) on
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Check the gap John.Im sure youll find a bad fluctuation or a horrible set of plugs.
It could also be the MAF I have seen this sensor cause your problems.
If you need one to swap out look me up.
Dan Starkey.
Posted by JohnB (Member # 969) on
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Ok, did a full tune-up (plugs,wires,cap,rotor)...and it runs like a champ! All the parts were the originals...all the way down to the plugs. The gap was somewhere around .080, as the electrodes were fried. Thanks to all of you for your advice-
Posted by 91sleeper (Member # 779) on
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My buddy brian and i hooked up his car to a diagnostic analyzer in auto at school and it said that his 3 and 4 cyl were either not lighting properly or backfiring. So as we were going to change the plugs we noticed that his 3 and 4 plug wires were switched around. What a dumba22.
I'm just glad that we got him off 6 cyl and back to 8.