vacuum leak??

[VistaBlue09GT]

Hey there everyone new here and wanted to run some stuff by everyone see if someone has had a similar issue and or a correction to my problem. I have recently started experiencing a backfire when in WOT mostly in second gear around 2500 to 3k only a few times has it happened in first gear. It has not happened any other time in normal day to day driving or at idle but only when in full throttle. I did some data logging and sent it off to be looked at an all they have come up with so far hasn't helped me much. To paraphrase a little they are telling me by the data shown is that at idle I am getting 20% more fuel but when the vehicle is under load the problem goes away an that the data they are looking at leads them to believe that it is a vacuum leak and they are sticking by that story. I have since ran multiple test of which when running a vacuum test at idle the pressure was holding at 13in and I also ran a test on fuel pressure which held at 37psi and when the vacuum line was removed from the regulator is increased to 41psi showing to me it was working properly. I have also tried spraying some carb cleaner around the intake and lines to see if it would effect the idle at all but nothing. I don't hear any whistle noise or anything abnormal either. I am not convinced that it isn't in the tune it's self any help given or ideas are appreciated. list of mods if needs are listed in my signature.

 

[sman247]

Sounds like a tune issue to me. Who do you have a tune from

 

[46addict]

Plug gap is good and the MAF has been cleaned recently? And they may be right on the vacuum leak so I would smoke test the car at least to rule it out. If all of this checks out it's a tune issue.

 

[VistaBlue09GT]

[sman247 Sounds like a tune issue to me. Who do you have a tune from]

Tune is currently from Bama until I have time to make a drive out and get it dyno tuned. No local shop around here unfortunately tunes on them.

[46addict Plug gap is good and the MAF has been cleaned recently? And they may be right on the vacuum leak so I would smoke test the car at least to rule it out. If all of this checks out it's a tune issue.]

I haven't dug as far as the plugs go yet, I installed them a little over a year and a half ago and at the time yes gap was good. I will have some time in the shop today so I'll clean the MAF but throttle body has been clean within the last month. Don't have a smoke machine at this shop but going to double check a the line and intake again today and if need be will locate a smoke machine from a sister store that I may be able to use. so far all test that we have ran on it hasn't given us a sign of a vacuum leak present.

 

[redfirepearlgt]

As I recall the cams you are running were similar in spec to the Detroit Rocker Cams I had in my 2005. At idle my vacuum was 11-13" Hg.

An old old timer showed me a similar trick to verify vacuum leaks rather than to use TB cleaner. He used a propane torch (unlit obviously) cracked slightly. It is heavier than air and would easily get pulled into any area where a vacuum leak may be.

I would recommend putting your factory COP's back on the car and see if that helps. After market COP's have been known to cause issues and will gain you nothing on an N/A setup like yours. The stock COP's are good for better than 500RWHP.

Otherwise I agree that a good tune would be of the most benefit. The 3V guys on here have a love/loyalty for Lito (and apparently rightrfully so). I would not hesitate to go that route if I were still in a 3V. Unfortunately Lito does not do Coyote to date as I understand it.

When I get home I will check my notes on LT fuel trims and how to analyze them for potential problems and post that as well. I found that information recently in one of the Ford diagnostics manuals and put it on paper for reference. It may be of help if you have your datalog file to look at.

 

[VistaBlue09GT]

redfirepearlgt

I may try that propane torch have a few of them laying around to see if that may show anything.I may have to look into that with Lito though but was hoping this problem could/should be resolved through bama whom I got the tune from originally. I'm still set that it is in the tune and should be taken care of there. I do have my datalog handy so I would appreciate that very much. Should have some free time shortly to mess around with the car.

 

[redfirepearlgt]

OKAY! LT Fuel trim diagnostics right from the Ford Tech manual:

http://iihs.net/fsm/?d=8&f=Adaptive Fuel DTC Diagnostic Techniques.pdf&p=1

Some basics -

MAF DIRTY - MINUS numbers at Idle, and PLUS numbers at higher RPM
VACUUM LEAK - PLUS numbers at Idle, and stable/small numbers at higher RPM
PLUGGED FUEL FILTER/DELIVERY - Stable/Small numbers at idle and PLUS numbers at High RPM
Values differ on only one bank or the other will have issues specific to that bank. Things like MAF, Fuel delivery up to but not including FI's that are common to both sides will not be probable issues.

Hope this helps. There is more in the link I provided

 

[VistaBlue09GT]

redfirepearlgt

Thank you going to read over this tonight, before I leave work we are going to check out the injectors to rule them out and make sure I don't have one stuck open. I have also given another call into bama to see if I could get them to relook at the logs as I have had 3 other techs now take a look at live data that are telling me they believe it is not a vacuum leak at all and are leaning more towards it being in the tune.

 

[redfirepearlgt]

I have also given another call into bama to see if I could get them to relook at the logs as I have had 3 other techs now take a look at live data that are telling me they believe it is not a vacuum leak at all and are leaning more towards it being in the tune.

Not at all surprised. Good luck.

 

[VistaBlue09GT]

Okay so after checking the injectors everything seems to be working properly there, hooked up one of our shop scanners and ran some live data showing my o2 sensors on bank 1/2 sensor 1s looked at the voltage and graphed them side by side. My bank 2 seems to lag behind sensor 1 quite a bit and is giving out readings but as you can see in the image provided bank 1 is showing it's in closed loop after warm up but I'm getting no reading on bank 2 as if it has been disabled ?? I know when they did my tune they had to do this for my sensor 2s as I don't have them at all, wondering if by chance they may have fat fingered and done the same on bank 2 sensor 1. talked with a few people around here and they seem to think if the vehicle is only getting readings on bank 1 it would in theory think it is running lean giving me more fuel to try and compensate for bank 2 but bank 2 is still running based off of the live data therefore I am getting to much fuel which is my issue. ?? not sure but something doesn't seam right about it any suggestions?

 

[46addict]

Are you able to get any STFT readings on bank 2? And you've checked the wiring going from the b2s1 sensor plug to the PCM?

 

[VistaBlue09GT]

46addict

I am able to get those readings and they looked good, I checked the wiring as well earlier today and it was okay.

To update bama got back with me and against what he thought he took away some fuel I was getting at idle which helped in the sense I wasn't bathing in it due to how much was being dumped out. I did some datalogging again and then did a couple of pulls keeping my fingers crossed but as of right now it seems to have done the trick with the new tune. I am going to run it over the next week and keep an eye on my fuel trims, I sent them the current datalogs as well for them to compare. seems that right now it is fixed...

I'll wait to hear back what they see in comparison to the other one and give it a little more drive time, I'll post on what I find out but hopefully all good news.

 

[VistaBlue09GT]

well drove it for a while and have made a few more adjustments to the fuel, problem was a poor tune and car has been running so much better. Thank you everyone for your advice and help.