Backfire and now idling rough/sputtering.

[Deejpig]

My car was running fine 95% of the time. Cold start and normal driving were fine.

The only issues I had were after it was warm, it would not start right up after shutting it off and letting it sit for a bit (1-2 hours). I'd have to crank it a few times and tap the throttle to keep it from stalling out before settling into idle, and it would run fine after getting it started.

The other issue was at WOT, it would backfire a little and sputter/miss until I let off to 75%-80% throttle. I thought it might be from running a lower octane gas. Again, it didn't seem like big deal because it ran fine during normal driving and harder acceleration - just not WOT.

Then, I got on the throttle the other day, and at WOT it made a really loud backfire sound and began to sputter and cut-out while like it was only firing on two cylinders or something. I barely made it home because while it was idling/drifting and when I gave it some throttle, it still felt like it was only firing on two cylinders. The idle seemed to level off when I got close to home, but was still a bit rough.

I started it the next morning and it fired right up and idled fine for about 3 minutes. Then the check engine light came on, it started idling rough and sputtering/missing, and eventually would shut off. I let it sit for a little, it would idle fine for a minute and then do the same thing again.

I'm in the process of getting a scanmaster, but in the meantime, after reading some other posts, it seems like it might be a bad MAF or something with the cam sensor. Below is a link to a video of what it sounds like when I start it after its warm and it starts idling rough and shuts off. I'm not touching the throttle in the video.

Any suggestions or help is appreciated! Thank you.

 

[Nick Micale]

I can think of a dozen possibilities of what could be wrong, so when the Scanmaster is installed and working, report back on any codes or values which are skewed?

 

[gunzandgearz]

My car was running fine 95% of the time. Cold start and normal driving were fine.

The only issues I had were after it was warm, it would not start right up after shutting it off and letting it sit for a bit (1-2 hours). I'd have to crank it a few times and tap the throttle to keep it from stalling out before settling into idle, and it would run fine after getting it started.

The other issue was at WOT, it would backfire a little and sputter/miss until I let off to 75%-80% throttle. I thought it might be from running a lower octane gas. Again, it didn't seem like big deal because it ran fine during normal driving and harder acceleration - just not WOT.

Then, I got on the throttle the other day, and at WOT it made a really loud backfire sound and began to sputter and cut-out while like it was only firing on two cylinders or something. I barely made it home because while it was idling/drifting and when I gave it some throttle, it still felt like it was only firing on two cylinders. The idle seemed to level off when I got close to home, but was still a bit rough.

I started it the next morning and it fired right up and idled fine for about 3 minutes. Then the check engine light came on, it started idling rough and sputtering/missing, and eventually would shut off. I let it sit for a little, it would idle fine for a minute and then do the same thing again.

I'm in the process of getting a scanmaster, but in the meantime, after reading some other posts, it seems like it might be a bad MAF or something with the cam sensor. Below is a link to a video of what it sounds like when I start it after its warm and it starts idling rough and shuts off. I'm not touching the throttle in the video.

Any suggestions or help is appreciated! Thank you.

I agree with nick need to get codes out of it if you don't have a scanmaster you can use a jumper wire at the aldl connector and read the number of blinks, and this will give you the codes.I will take an educated guess and say from what ive seen in the past with this kind of driveability issue sounds like a flat cam.

 

[dank GN]

Double check your grounds , cam sensor ,crank sensor ,coil pack . As stated before u r shooting with a blindfold at the moon witout any data . I always tell ppl the first thing to buy is t a shiny throttle body or some bad ass headers . It's a scan tool . Read up there is a lot of useful info here

http://www.vortexbuicks-etc.com/index.html

http://www.gnttype.org/

 

[Chuck Leeper]

When you get the SM, get a fuel psi gauge, too.

 

[whitehot1]

I thought it might be from running a lower octane gas.

Don't ever run lower octane gas if you can avoid it, in this car.

 

[87GNSteve]

Did the pipe between the intercooler and Throttle body separate?

 

[robzombie]

Sounds like it might be a bad MAF.

What MAF are you running and how old is it?

You can try cleaning it first and then the tap test next, although neither will confirm it 100% unless the change is drastic.

When you get the S/M you will be able to check TPS, IAC and other info and post it for a more accurate diagnosis if the MAF isn't the problem.

If you or someone you know has a known good one [MAF] try that and see what it does.

 

[turbo chris1970]

Strange mine does the opposite my car runs fine in park but when I put it in gear it runs rough but no check engine light no knock no codes but I did let it sit over the winter in my garage with the same gas I changed the fuel filter and was getting the car ready for the season and did a new battery alternator and plugs plus when I give it had I have boost and full power but at a light the car is just rough and sputters I'm thinking of changing my wires

 

[gunzandgearz]

Strange mine does the opposite my car runs fine in park but when I put it in gear it runs rough but no check engine light no knock no codes but I did let it sit over the winter in my garage with the same gas I changed the fuel filter and was getting the car ready for the season and did a new battery alternator and plugs plus when I give it had I have boost and full power but at a light the car is just rough and sputters I'm thinking of changing my wires

If you want too see if your wires are breaking down fire it up at night time or pull it in a dark garage and use your wifes spray bottle with water in it and spray it on the wires with it fired up and running, you will see it arcing outside the wires if they are breaking down that bad, old school trick, but works most of the time.

 

[turbobob924]

watching this topic

 

[robzombie]

watching this topic

Are you having the same problem??

 

[turbo chris1970]

Hey gunzs I'm trying that trick you mentioned tonight just to be sure!!! But I think I have a bad wire on cyl#6
This will prove it

 

[gunzandgearz]

Hey gunzs I'm trying that trick you mentioned tonight just to be sure!!! But I think I have a bad wire on cyl#6
This will prove it[/QUOTEreport back, also if it doesn't work might have someone get in car and put it in gear to put a load on engine.good luck

 

[robzombie]

Hey gunzs I'm trying that trick you mentioned tonight just to be sure!!! But I think I have a bad wire on cyl#6
This will prove it

Using an OHM meter would be more accurate.

Spray test is only if they are really bad.

 

[gunzandgearz]

Hey gunzs I'm trying that trick you mentioned tonight just to be sure!!! But I think I have a bad wire on cyl#6
This will prove it

Using an OHM meter would be more accurate.

Spray test is only if they are really bad.

so how many ohms

 

[626gn]

so how many ohms

Ohms will vary depending on the wire. What you're looking for is consistency with the other wires. If the #6 wire is truly bad it will have a substantially higher resistance compared to the others of equal length.

 

[robzombie]

so how many ohms

That would depend on the type of wires being tested.

Solid cores are generally the lowest while graphite impregnated ones [cheap] are the highest.

In a case of not knowing what the resistance is of a certain brand/style wire it would be easy to find the bad one.

If five wires ohm out at 2000 +/- 10% ohms per foot and one has 3 to 5000 per foot you have your answer.

 

[robzombie]

Ohms will vary depending on the wire. What you're looking for is consistency with the other wires. If the #6 wire is truly bad it will have a substantially higher resistance compared to the others of equal length.

Damn you beat me to it. It sucks being slow at typing.

 

[gunzandgearz]

I used to go off of 2 to 3000 ohms per foot range its about standard but don't really like this type of test for troubleshooting, this is just my opionion, their are are other ways to get their.