Cobra Jet Issues

[Punisher_Coyote]

Let me start by saying I'm all ears. At this point I just cant figure out what's wrong. So full mod list for my car, it's a 2016 mt82 car, 3.73s, stainless works catless 1&7/8 long tube headers, ford racing x pipe, roush quad tip axlebacks, cobra jet intake manifold, vmp twin 67mm throttle body, ford racing cobra jet cold air intake, running on a 91/93 tune from lund racing. Before I put the whole cobra jet setup on, and i just had the exhaust and a roush intake and lund tune, once I put the headers on it seemed like the car got a huge boost. Torque felt really improved, and horsepower gains were also noticeable. I loved it. So I figured adding the cj would only help, but i feel like it made it worse. Car feels extremely sluggish. Before you could feel the power in just about every gear, now it seems like the only time it really pulls is in second gear starting at like 4k rpms. I read up on it and some people also said they noticed a small amount of torque loss, but maybe as not as much as I was. So I decided to get the car on a dyno. On the dynojet, the best of 4 pulls i got was 417hp, 356tq. Now being as novice as I wasn't positive which gear was 1:1. I thought it was 5th, but the guy working the dyno said it was 4th so that's what we did it in. I now know that was wrong, but I still don't think it makes that much of a difference (correct me if I'm wrong please). So I talked to my tuner and sent him some logs and he said he thinks it's my timing, he said I was about 4 degrees off, and that could have been why the number was so low. So all in all how do I fix this? What could be causing it? I don't really understand timing that much so I really have no idea. I just know some other guys running similar setups say they notice a huge difference and their dyno sheets back it up.

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[wildcatgoal]

I was recently in a conversation with a tuner who described a few situations with Stainless Works headers that required them to somehow pry the header pipes apart a little to stop them from rattling against each other enough to cause false knock. Surely this is rare, but I would consider speaking to your tuner specifically about possibilities of false knock.

Also, I'm sure you had to lower your engine or cut your stock hood to fit the CJ, right? If you lowered your engine, did that cause a header clearance issue? If you cut your hood, did you cut it appropriately such that the CJ doesn't contact it ever?

Just some thoughts.

 

[Punisher_Coyote]

I was recently in a conversation with a tuner who described a few situations with Stainless Works headers that required them to somehow pry the header pipes apart a little to stop them from rattling against each other enough to cause false knock. Surely this is rare, but I would consider speaking to your tuner specifically about possibilities of false knock.

Also, I'm sure you had to lower your engine or cut your stock hood to fit the CJ, right? If you lowered your engine, did that cause a header clearance issue? If you cut your hood, did you cut it appropriately such that the CJ doesn't contact it ever?

Just some thoughts.

The hood was cut, and as far as I can tell it's not touching anywhere. And as far as the rattling goes, I can't hear it happening, but I'm going to be talking to my tuner again and i'll bring it up. I've never even heard of this issue actually

 

[Frenchy480]

I have a 2016 performance pack as well, thinking about going the cj intake route. From everything I've been reading, it looks like the fuel injectors need to get upgraded as well. I didn't notice anything mentioned about the fuel injectors in The first post, not sure if you upgraded them or not, but do you think that could be causing the issue?

 

[CGADAMS]

as stated earlier check for false knock, even though we cant audibly here doesn't mean that the sensors aren't picking it up. 4* can rob power but I don't know if it is enough to kill off damn near 40hp (450-460hp average from what I've seen with no cams). also curious to know what injectors you are running as well.

 

[CGADAMS]

Also I believe 5th is 1:1 or closest to it on MT-82

 

[wildcatgoal]

I doubt you'll hear the causes of false knock.

Make sure you get gas from a different station if you are going to the same place.

 

[Punisher_Coyote]

I have a 2016 performance pack as well, thinking about going the cj intake route. From everything I've been reading, it looks like the fuel injectors need to get upgraded as well. I didn't notice anything mentioned about the fuel injectors in The first post, not sure if you upgraded them or not, but do you think that could be causing the issue?

I'm running stock injectors, everything I've heard says they're not that necessary, but I was thinking the same thing. Guy who did the install has built many coyotes and said i'd be fine, but i'm thinking im going to get some 47's and just try them out. Sad thing is I'm getting deployed in 9 days so the car will have to stay like it is until I get back

 

[Frenchy480]

I'm running stock injectors, everything I've heard says they're not that necessary, but I was thinking the same thing. Guy who did the install has built many coyotes and said i'd be fine, but i'm thinking im going to get some 47's and just try them out. Sad thing is I'm getting deployed in 9 days so the car will have to stay like it is until I get back

Wow, I hope everything goes well with the deployment. Yeah, I almost pulled the trigger on the cj intake, but I wanted to save up just a bit more for upgraded injectors. I called/emailed around and was told to upgrade the injectors for any new intake manifold, especially since I want to go with e85 (e54 here in az) and i was told the stock injectors wouldn't be able to handle the amount of fuel for a bigger manifold, especially cj manifold.

 

[Punisher_Coyote]

Wow, I hope everything goes well with the deployment. Yeah, I almost pulled the trigger on the cj intake, but I wanted to save up just a bit more for upgraded injectors. I called/emailed around and was told to upgrade the injectors for any new intake manifold, especially since I want to go with e85 (e54 here in az) and i was told the stock injectors wouldn't be able to handle the amount of fuel for a bigger manifold, especially cj manifold.

Thanks man. And yeah that's what i thought but i was told it didn't really matter. I guess all in all it doesn't really matter because as soon as i come back the goal is 700 at the tire so my cj setup will be irrelevant anyways, just don't want to run into any more issues down the road lol. Would suck to be a whipple car putting down 550whp/ and 390tq lmao

 

[Austinj427]

Wouldn't the logs show if there was knock?

 

[smann]

Post your logs here so we can check for knock.

5th is 1:1, some dyno guys like doing it in 4th because they don't want to spin em that high lmao.

Just make sure to tell them next time

 

[Punisher_Coyote]

Alright I’ll try to post them up after work. What can I do to get a better understanding of knock and timing and all that? Like I’ve tried to read more into it to see if I could find out on my own what the problem is but I haven’t been able to find anything. When it comes to that kind of stuff I don’t really know that much

 

[Punisher_Coyote]

Post your logs here so we can check for knock.

5th is 1:1, some dyno guys like doing it in 4th because they don't want to spin em that high lmao.

Just make sure to tell them next time

So it won't let me post the logs because its a csv file, but i checked over and all the knock numbers are either 0 or negative, which is a good thing correct?

 

[Bartly]

So it won't let me post the logs because its a csv file, but i checked over and all the knock numbers are either 0 or negative, which is a good thing correct?

edit. Crap, thought i was in the FI section, my values below are with a blower, your AFR and timing advance should be different if not FI.

Yes, that's a good thing. It took my my whole year of working with a tuner and reading on here before I started to understand only 1/10 of all the PID relationships. Its pretty tough to pick up reading through all the threads over time. When you do a WOT log the spark advance is one of the #s you should look at in a log during the WOT event and look at Knock at that same time. If it's measuring + knock you will see the spark advance decrease as +knock increases and vice versa, spark advance with increase as it's seeing - knock values. Sounds like you don't have to worry about that though, no + knock for you is great. To post your log on here change the extension from .csv to .txt and then anywone who wants to look at it can change it back. Or you can do what others have done is use datazap and then post that somehow, not sure as I've never used it.
Other important PIDs in that WOT part of a log are Lambda (or AFR) on bank 1 &2, short term fuel trim (bank 1 & 2). When I'm looking at charts of logs I usually have RPM, Speed (so I can see what gear I'm in), Spark Advance, Knock, STFT1, STFT2, Lambda1, Lambda2, Throttle position (actual and desired).
Here is a plot of one of my recent ones with the PIDs grouped so I can see how they are reacting. The verticle light blue line is in the middle of a WOT event and you can see the values at that RPM. My tuner said it's running good, so all I can say is those are the kind of values you should be seeing during WOT, unless.. Haha, someone sees something in the plot I don't know and tells me engine is going to blow, cause I barely know enough to be dangerous.

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