Backfire after 3 grand! (Video)
05-15-2010, 01:25 PM
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Backfire after 3 grand! (Video) Today I went to pass someone and when my car got to about 3100 Rpm it fell on its face and let out a huge backfire. If I hold it in first gear and ease into it it will pass 3100 and go to redline no problem but in second it back fires really terribly. The Opti on the car is 170 miles old (about a week). Here is a video (sorry for the quality) of what its doing. What could this be? Thanks guys.
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05-15-2010, 04:27 PM
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sounds like u are haveing a lean pop i just got done have the same problem nut mine was more in the uppier 4000 rang and higher mass air flow sensor was dirty and i was about 3 pounds to low on my fuel when i was on the throttle should be around 43 lbs at wot if not change filter thats what i did and i picked up my 3 lbs try it is only like a 12 part and only takes about 15 mins
05-15-2010, 04:42 PM
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I was just outside trying to figure it out and I revved it up to about 4500 RPM then let it decline but as it was revving down I couldnt get any throttle response out of it. I took it for a ride and lost complete throttle response at one point after getting on it. I was in the driveway and it completely shut off. Fuel pump? Not sure where to go here.
05-15-2010, 05:26 PM
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I was just outside trying to figure it out and I revved it up to about 4500 RPM then let it decline but as it was revving down I couldnt get any throttle response out of it. I took it for a ride and lost complete throttle response at one point after getting on it. I was in the driveway and it completely shut off. Fuel pump? Not sure where to go here.
If the fuel pressure is low you can lean out and if the tps isn't working you will also lean out. If these two check out ok clean the maf. It is most likely back firing because of a lean condition
That gives you a couple possibles to check
Good luck
05-16-2010, 08:58 PM
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I was unable to obtain a fuel pressure tester today so I didnt get much done. However I took my dad for a ride because he wanted to see how it ran and we noticed the car didnt do the aforementioned symptoms until the engine warmed up completely. Dont get me wrong I wasnt romping on a cold engine, but we did notice that after about 3, second gear pulls it started to cut out at about 3100 rpm.
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05-19-2010, 11:11 AM
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Also, with the recent replacement of your opti, double check all of your spark plug wires and their routing. It is very easy to have one get nicked on a pulley or burned by an exhaust manifold. Run along the full length of each wire to double check, a very small nick/crack can easy cause it to ground and not get all of the spark to the plug.
Double check your ignition coil wire as well, I had a time when the ignition coil wire connecting the coil to the opti was just plain worn out, and wasn't getting a good connection between the two.
05-23-2010, 11:46 AM
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Ok so I fixed the old elbow so that it isnt taking in unmeasured air any longer. I went for a drive and it seemed ok, until the car warmed up completely then it started backfiring at the same RPM (3100). I tested the fuel pressure and it read 34-35 PSI, key on-ignition off. At idle it was approximately the same. After some research I've seen that this is really low. I haven't taken off the vacuum line to simulate WOT yet but I will and bring back my results. The fuel filter is probably 6-8 months old, so does this point to the pump? Any help at this point would be great, thanks guys!
05-23-2010, 12:13 PM
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test with out vacum first. Could be a bad regulator too. People like to jump on the pump but sometimes they do that and it's not the problem, it's the regulator. Start with the cheapest first unless the pump gives a red flag that says the pump is the problem.
05-26-2010, 10:49 AM
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Update: I tested the fuel pressure and it was about 35 PSI at idle, which I considered really low. I tested it with the vacuum line off the FPR and it read 45 PSI, which is pretty normal. Why would it be really low at idle but at simulated WOT it would be normal?
