backfire during high speeds

[danny_l_2005]

I have recently been having this problem. When im going high speed at wot say at 70+. I get a loud pop and my car seems to lose power but this doesn't happen during partial throttle. I do however have a weak spark on my 4th cylinder (coil). But I really don't think that would be the problem because I never had a backfire with the same coil before (knew that it was still weak). Does fuel-cut have the same symptons or is it totally different?

 

[Defiant]

So, you're pumping unburned fuel into your exhaust system. Hm. What could it be, what could it be. Hm.

 

[danny_l_2005]

Defiant there is no need to be sarcastic. If your willing to answer my question, please show me a way on how correcting it. Moving on, I do have water injection and it is making me go rich, do you think that is the cause of my problem? Also another question, will a backfire make you lose power at that very moment when it happens?

 

[oldman]

He was being sarcastic because you possibly have already answered your own question in your OP, he was just trying to make you use your brain.

I do however have a weak spark on my 4th cylinder (coil).

If the cylinder didn't properly fire, exhaust popping is exactly what you'll get. Aside from that, have you done a BOOST LEAK TEST?

 

[Ja17Bmx]

Check your plug on the cylinder that the spark is weak, more than likley its fouled out. Your going to have to replace that coil to fix the problem in the long run, but possible changing the plug out now will help for a little bit.

 

[danny_l_2005]

Thanks. I have done a boost leak test a while back but I haven't since I took my car to the transmission shop. I'll make sure to do that within next week. I've heard that Autozone's coils are POS, if so why? Also, I'll be posting pictures of the plugs later on today if that helps any.

 

[danny_l_2005]

Ok I got some pictures of my plugs (BPR7ES). Also I just bought new plugs (BPR6ES) and new pepboys ignition wires (free) and bought a coil pack from a local dsmer (haven't installed it yet). I will be installing the coil pack tomorrow and show results.

 

[DSMunknown]

If you're looking for feedback about those plugs in the photos, it looks like they're gapped way too close (even though the pictures aren't very clear). Gap your new 6s appropriately and see how they work for you. If you choose to stick with the 7s, make the gap on all of them larger. The plugs should not be white on the top like they are. They should, instead, be a nice brownish color. If they are black, that means the gap is too big.

By the way, what did you have the 7s gapped at?

 

[Rice Over Wheat]

Need better quality pics than that. So fuzzy those could be feet holding the plugs!

 

[oldman]

So fuzzy those could be feet holding the plugs!

You mean they're not?

 

[Defiant]

This is what we're up against. You'd not mentioned you were running plugs too cold for your setup. You didn't mention anything about water injection. We have less to work with -unbelievably- than you do for taking a picture with.
Also check your exhaust for cracks or leaks. Those, too, will cause backfiring.

 

[danny_l_2005]

how can those be toes; I don't know but you guys must have wierd feet. I took the picture with a phone. Yes all plugs have white on top (don't know what it means). The plugs (BPR7ES) were gapped at .028. I just put the new plug in (BPR6ES) gapped at .028. Yes I do run water injection (using windshield washer fliud) using two injectors a M2 and M1 from Enginerunup. (I need to update my profile). Oh yes, I do have a manifold leak (stud broken inside the head w/ a drill bit in the stud). I wonder if the high temp ultra copper silicone work to temporarily fix the leak.

 

[danny_l_2005]

OK guys I don't think its a backfire because when I hear that loud pop the car feels like if i really slammed the brakes. I think it's fuel cut; Damn I almost hit my face on the steering wheel. It happens in all gears except 1st.

 

[donmagicjuan]

The number one cause of fuel cut is a boost leak. The easiest way to tell for sure is to hook up a logger. I'd make a leak test my first priority right now.

As an aside, fuel cut usually doesn't mix very well with alcohol injection. I'm not sure how the water in washer fluid will weigh on its behavior, but the ignition of alcohol in the absence of any fuel can make for a wickedly lean condition. And we all know that's not good.

 

[danny_l_2005]

Yes, I do have a logger. I use Palm n' Stein, i'll will post a log just need to know what to log eg. rpm o2 timing. Ok i think understood what you meant about my alky injection. So your saying that at the time of fuel cut where no fuel is present, I'm having knock because of the alcohol in the "air".

 

[Ja17Bmx]

From the look of the plugs, your defintley on the lean side. I would try not using your water injection because there might be some alcohol in the washer fluid itself causing this. Try without using it, and add some more fuel if you can. But definitley do a leak test first

 

[Defiant]

The amount of alcohol in washer fluid is there only to lower the freezing point. It's not enough to be flammable.

 

[donmagicjuan]

That is probably true for most summer mixes, but the winter stuff I use here is labeled 49% methanol, 49% water, and 2% blue dye. I'm still not sure if that means it would burn by itself in an oxygen-rich environment when vaporized, but hey-- I'm no chemist.

 

[danny_l_2005]

Well I'll be logging tonight. I have Palm n' Stein. I will log RPM, Timing, O2, Airflow. I'll make two logs; one with Alky and another without it. I'll post it later tonight.

 

[danny_l_2005]

As you know my car is automatic. I did a log run from 2nd going to 3rd and having that fuel cut. its done by palm n' stein and it can be played through tunerstein player. I think im awful rich . So here is the log with out alky. Change file .dat to .db1

 

[donmagicjuan]

I don't want to leave you hanging, but I don't have a program that allows me to view your log. You can either hold out for someone who does, or you can post a table as commonly done in the log file advice forum. Click here for an example. Because you suspect fuel cut, it might be more helpful to include injector duty cycle as one of the parameters rather than airflow.

 

[danny_l_2005]

Thanks, how do log idc on palm n stein?

 

[danny_l_2005]

I did a boost leak test yesterday and found three pretty bad leaks at 20psi. Two were at the fuel injector insulators and the other was on my alky injector. I fixed the one for the alky injector w/ JB weld. So my question is can I find a o ring same as my FI insulators? Can someone please tell me the size. Also, would the bad leaks at the FI insulators cause me to run lean at partial and run very rich at wot? I was getting .95v on my o2

 

[oldman]

I did a boost leak test yesterday and found three pretty bad leaks at 20psi. Two were at the fuel injector insulators and the other was on my alky injector. I fixed the one for the alky injector w/ JB weld. So my question is can I find a o ring same as my FI insulators? Can someone please tell me the size. Also, would the bad leaks at the FI insulators cause me to run lean at partial and run very rich at wot? I was getting .95v on my o2

20 psi on the boost gauge during the test? I find it hard to believe that you were able to reach 20psi on the boost gauge unless your air compressor control/release valve was set to 50psi+. As for injector insulators, most of our sponsor vendors who carries injectors will carry them.

 

[danny_l_2005]

Believe it or not, I did have 20psi exact on my boost gauge. Thats shows how my little compressor has potential even though it stays on all the time .