Retune After 8 Years

[351stang]

Guys,

I'm wondering how many people have had to retune their cars with just the passage of time. I pullied my 2004 Cobra back in 2008 and haven't done any engine/air/fuel mods since then. I noticed that the car was running leaner via my Wideband, so I replaced the oxygen sensor to eliminate that variable. I also checked for vacuum leaks and found none.

I put the car on the dyno and used both my wideband to log and the shop's wideband. It appears that the A/F ratio has drifted up from 11.5-11.9 range to 11.8-12.4 range.

I went back and looked at the old 2008-year livelink data logs and RTLS_FPUMP_DTYC maxed out at .96. The new 2016 dyno runs show RTLS_FPUMP_DTYC hitting .99 at 5900 RPM. Ambient air temps were 20 degrees cooler and lower humidity comparing the two files. The corrected power numbers dropped from 460 rwhp to 445 rwhp.

It looks to me like the car has always been close to maxing out the pumps, so I've ordered a boost a pump.

What I don't get is why my A/F ratio has drifted up prior to 5900 RPM when the pump duty cycle is not yet maxed.

I'm planning on adding the BAP with 10 AWG power feed, re-logging, and will get a new tune if necessary. Am I missing anything here or should I investigate something else?

 

[351stang]

I'm also going to do some logs when the ambient temps are 70 Deg F and higher. The car rarely gets run in North Texas when the temps are bellow that.

Could this be a multiplier issue for ACT in my tune?

 

[ViperRed91GT]

Fuel filter changed? Injectors cleaned? If the pump is having to work harder, while also running leaner, it seems that you have an issue with your fuel system.

I agree with adding a BAP, it probably should've been done a long time ago. What's your injector duty cycle look like?

With the advances in tuning, I'd say it's a good thing to do regardless of the differences you're seeing. Take advantage of new technology/ability.

 

[351stang]

I changed the fuel filter when I did the IRS cover recently, a WIX from autozone. Not my first choice, but Motorcraft was not available.

Sent from my SM-T350 using Tapatalk

 

[Rambro]

If you still have the factory PCV setup your intercooler could be coated with oil. I had pre filters and catch cans and still got oil in the intake. I now run breathers with lower intake plugged and that eliminated that. It could be a small difference but every 5~10 horsepower gained back from a clean intercooler is worth it. I also think oil in the intake can lower the octaine as well.

 

[SID297]

It could simply be a change in fuel formulation, ei more ethanol now.

 

[04sleeper]

All good theories. I have seen pumps simply not flow the same after years of use. Luckily it can be logged and adjusted for, but as these cars get older, a fuel pump could easily be replaced.

That's why I always recommend a good wideband and keep an eye on it on any boosted car.

Good thing you saw it and were smart enough to log it.

 

[351stang]

If you still have the factory PCV setup your intercooler could be coated with oil. I had pre filters and catch cans and still got oil in the intake. I now run breathers with lower intake plugged and that eliminated that. It could be a small difference but every 5~10 horsepower gained back from a clean intercooler is worth it. I also think oil in the intake can lower the octaine as well.

The downstream ACT temps were good, so I don't think that is the issue.

It could simply be a change in fuel formulation, ei more ethanol now.

Interesting theory. Winter blend fuel in North Texas compared to Summer blend fuel in Houston, plus a 30 degree ambient temperature change could make a difference.

I'll see if the Boost A Pump will correct the issue and report back in a couple weeks.

 

[351stang]

Finally got the BAP installed with a "wire upgrade". I have a hard time calling simply running a 10 awg wire with a relay an "upgrade".

Logs show that RTLS_FPUMP_DTYC dropped from .9999 to .79-.80 max. Unfortunately INJ_DUTY_CYCLE is .9531 at 6550 RPM and goes up to .9921 at 6650 right before I shifted. AIR_CHARGE_TEMP was 76 F and DOWNSTREAM_ACT was 136 F. It was unseasonably warm in Dallas today and I had made about 5 partial pulls.

Looks like I still need a retune, but pump issue is resolved.

Is the injector duty cycle an issue or can this be tuned out?

 

[nxhappy]

it appears your injectors are maxxed out. have a tuner look at the logs. But I think you need bigger injectors. probably 60lb or more.

 

[351stang]

Reporting Back:

Changes
1. Added BAP pre-FPDM with 10 awg power feed
2. 04Sleeper Tune with increased rail pressure

Results
1. Pump duty cycle down to .87 peak at lower ambient temps (low 60's)
2. Injector duty cycle down to .90 peak ""
3. AF Ratio is richer/flatter at 11.4 - 11.8 everywhere

I'm going to take it to the track this weekend and see how she does and get some more data logs.

Thanks to 04Sleeper!

 

[04sleeper]

Glad I could help Scott! Car is very clean and drives great!

 

[c6zhombre]

Very nice outcome.....so no new pumps or injectors necessary?

Having a great tuner like 04sleeper can actually save money and provide excellent drivability.....lesser quality tuners probably would have had you tossing more money at parts first....then figuring out a tune

 

[351stang]

Only hardware added was a BAP with a 10 gauge power feed and relay.

 

[FromGTtoSVT]

So I guess the short answer to your original question is that it doesn't hurt to have the tune checked.

I am in the exact same boat, I had my car tuned in 2008 and haven't touched it since. Might be time........

 

[351stang]

So I guess the short answer to your original question is that it doesn't hurt to have the tune checked.

I am in the exact same boat, I had my car tuned in 2008 and haven't touched it since. Might be time........

I'd recommend it, especially if you don't have a wideband. Get a wideband!

 

[StrayBullitt]

Sounds like you are back on track, but just throwing this out there. Maybe try cleaning your Maf sensor and see if that helps at all.

 

[FromGTtoSVT]

I'd recommend it, especially if you don't have a wideband. Get a wideband!

I know I know...gauges have been on my "to do" list for a few years now......

 

[351stang]

Done, because you told me to do it.

Sounds like you are back on track, but just throwing this out there. Maybe try cleaning your Maf sensor and see if that helps at all.