Ok, my car has always had a popping noise form the exhaust, however, since I have reinstalled the manifold and had these idle problems it has become much worse. It is not like a continuous backfire. Could this be caused by a faulty head gasket or be related to the screwy idle in some way? I have searched and there are a few threads on this, but none have an answer.. they are all just a bunch of people guessing and no confirmation. If it is probably not related to these two things, what do you guys suggest it could be?

EDIT: My plugs and wires are less than 2 months old and I don't think they would be a problem since I didn't touch them during the manifold removal and installation. Normally a backfire is caused by running really rich and my fuel economy has been pretty bad lately. I am thinking maybe my fuel filter. It hasn't been changed in like 30000 miles. Not sure why it would happen right after the IM removal/installation, tho.

Well, I ma being told that it is an ignition problem, however, My plugs and wires are less than 2 months old. Also, my wires are Magnecore 8.5mm or 9mm (Can't remember exactly) wires and the plugs are NGK's. I doubt they would go bad so quickly. Is it possible that when I blew the headgasket I soaked the plugs in coolant and that fucked them up?

Ok, so when the car was in the shop, they couldn't get the o2 sensor out of the old exhaust manifold (It was cracked, so they replaced it). They didn't know if I wanted to try to get it out myself or just buy a new one, so they just plugged the hole. Well, since geting it back, It ran fine, even w/o the sensor, but he CEL was on, obviously. I findally got around to putting the new sensor in yesterday, and now that pesky popping noise on decleration is back. Only thing I messed with was the heat shield and the sensor, so only thing I can think of is the sensor is not tight enough and there is a small exhaust leak coming form the manifold. Is this a possible culprit for the noise? I tryed standing outside my door and reving the engine, but I cant hear a leak at all. There is, however,a smell when I rev the engine. I can't really tell for sure, but it smells like exhaust gas... That is what leads me to believe there is an exhaust leak. I tightened the sensor pretty tight. I didn't want apply too much pressure in fear of cracking the manifold.

Any ideas? Thanks.


Also, just thought of something else. Is it possible that my car was running really rich before due to having no sensor installed, and it messed up my plugs, and now that I am running leaner they are even worse?

I fixed it. The O2 sensor was just loose.

Well, turns out tightening the o2 sensor helped, but it was still there, so I replaced the plugs and the car RUNS alot better, however, when replacing the #1 cyl's plug, I pulled the little metal thing (the name escapes me) out of the plug wire... I tryed to fix it and the car does run, but there is a BIG backfire when downshifting at higher rpms. lol.. if its not one thing, it's another. _-_ Anyway,, just ordered some new wires... My bank account is running dry, fast. :x

Hmmm.. Got the new plug wires in the other day and the backfire/popping noise is STILL there! I am at a loss as to what it could be...

So far I have replaced:

-Sparkplugs (NGK BRP6ES-11)
-Spark plugs came pregapped, but I double checked gap anyway and they are all right on the dot (.044in)
-Plug wires (Magnecore 8.5mm)
-The distributor cap and rotor were replaced right before my HG blew, so they are less than 2 months old

I am gonna replaced the fuel filter next, if that doesn't work, I have NO idea what it could be.

Is it possible that the injectors could be bad? Could that cause these symptoms?

Anyone have any other ideas?

EDIT: Another thing I noticed is that after sitting for a while, when I start it up and go to take off, thereis like NO power. It feels like I am taking offf in second gear when I am in first gear. It's weird. Any idea?

Well, I was checking the gap on my plugs today in an attempt to fix the misfire issue. When I was replacing the plug wires on the distributor cap, I noticed that the distributor cap was VERY loose. I checked both the screws on the cap and found that the bottom screw was only threaded a couple threads! D:

After tightening the loose screw, and checking the top screw, I replaced the wires and took it for a test drive.

The popping noise SEEMED to be gone, however, it will have to wait until I go out today for a true test.

Well, After driving it today, it turns out it didn't fix the problem. Actuallly, it is worse now! D: I am going to check the distributor cap and rotor after the engine cools down (Just got home). Maybe being loose like that messed up the terminals or something. (I am hoping). If not, I am out of ideas as far as ignition goes. I have the new fuel system on its way, tho, so If the cap and rotor doesnt fix it, hopefully the fuel system will.

Well, so far I have replace:
-plugs
-wires
-distributor cap/rotor
-FPR
-fuel lines (except the lower feed line)
-injectors and o-rings


Only two things I can think of that I haven't changed would be the fuel filter, and MAF sensor. I removed the fuel filter and inspected it, and it stunk a bit, but seemsed to not be clogged at all. Gas flowed freely in either direction, so I don't think that is it.
As for the MAF I am currently looking for a means to test it. So far, noone can seem to tell me if there is a way, so I guess I will just have to hit up the JY when I get the money (then again, if my friend's dad's jy has a 1.8 in it, then I could probably get one for free. Will have to ask him about it.)

For now, does anyone have any more recommendations to try? I am at a complete loss other than those two items.

Im no expert in this area, but the Mass Airflow Sensor really cant have anything to do with a popping noise. Air just runs through it and the computer senses it. If you can get one for fee, then it may be worth a try, but other than that they are very expensive to replace. And there is no way to repair it. Ive never heard of a test for it either. But it could work.---The only thing I can think of is possibly the fuel pump or the fuel injectors. popping noises come from a lean air/fuel mixture. You said your pump was fine, but if you can get your hands on some new injectors, or simply try running fuel system cleaner (Im sure you have already) it should allow some more fuel into the mix. But test the fuel pump, make sure the filter is clean or new, and that there is no blockage in the injectors or fuel lines for that matter, because the lines being blocked could cause the same effects as the injectors being blocked.

So far, I have replaced:
-injectors and o-rings
-FPR (used a Fuel Labs AFPR set at 38psi)
-all SS fuel lines, Except the lower feed line (couldnt get it seperated fromt he sending unit... still working on that lol)
-o2 sensor

I also removed and inspected the fuel filter and it seemed to flow fine and did not have too bad of a smell.

I am told by everyone else that backfiring is caused by running too rich (backfiring is esentially what my popping noise is, and in fac tDOES backfire every now and then), but you tell me it is running lean? Hmmm...

I was thinking it could be the MAF cause it could be misreading the air coming in and dumping too much fuel.

that makes sense, if the air sensor is reading to little air, its putting to little fuel in to match the air flow, thus lean. Ive never heard of a sensor, sensing to much air though. if it was sensing to much air, obviously it would be running rich to try and keep up with the air it thinks its getting. If it was rich you would have smoke from the tail pipe, is this the case? I only think your running rich because I had this issue when I turbod my 3g, but did not yet put in the larger injectors, I would have violent popping because of all the air, and to lean of fuel. And there is no smoke from a lean mixture, (you'll see and smell if its rich.)

lean! I meant to say lean in that sentence that i said "I think your running rich" lol, sorry.

Well, I don't see any black smoke nor do I smell fuel (now that my o-ring leak is fixed), so I guess it makes sense that I am running lean. I just am running low on ideas of what to check. Gonna grab a MAF from the local pick-n-pull when I get a chance (and some money.. haha). Hopefully that helps. If not, I have no clue.

good luck, I hope it solves the problem.