What would cause decrease in timing?

[haze324]

Hey guys I posted recently that my P1SC blower sucked something in and spit into the intercooler and was having issues. I ended up replacing the headhunt with a P1X and a new IC. In between that I also put a griptec pulley, green belt, new clutch, etc....did a few upgrades. Now the car is making less timing than it did on the same tune by 2-3 degrees. Few things:

- Can an exhaust leak cause decrease in timing? Yesterday on the way home one of the band clamps popped off the X pipe. I wonder for how long it's been sliding off and potentially had a small leak there.

- Also when I got WOT between 3-4kRPM I see boost rise to about 5psi, then it drops 2psi and quickly picks up around 4500-5kRPM. On the log I see under load where it climbs then dips in that range and pics back up. I don't see any belt dust, still going to adjust the tensioner, and it happens more on WOT's than gradual acceleration. Not sure if what's causing that also effects timing?

Had none of these issues when it was the P1SC set up a few weeks ago. Set up is P1X, HO IC, 6510's gapped to .32, BAP, and GT500 injectors.

Thanks guys

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[SheepDog]

Are you sure none of that foam ended up in the intake manifold?

An exhaust leak at the xpipe will not cause timing changes.

Are you seeing any knock in the logs?

.032 gap is probably a little to big, you may be getting some spark blowout. Go down to .026ish

 

[haze324]

Thanks Sheep.

I pulled the MAF sensor, and throttle body when I replaced the IC and looked for any foam, dust, etc. and didn't see any, MAF sensor on the logs look fine. I don't think any got through but I'll re-check.

I'm not seeing any knock on the logs, I'm running IMRC lockouts with sensors unplugged.

I'll get the plugs down a little smaller. I was thinking maybe the P1X is blowing more than the P1SC and they're gapped too big. I just don't know how to see that in the logs. Can't hurt.

I appreciate the advice.

 

[SolarFlare]

Is airflow higher now?

 

[haze324]

Is airflow higher now?

Solar - Im assuming it is. I put a larger air filter on, and the P1X (in theory) should push more air than the P1SC....I just don't know how to look for that between older logs and recent ones. If it's show under MAF, then yes new logs are .5-1.0 more across the RPM range at WOT.

Thank you for the help.

 

[SheepDog]

Solar - Im assuming it is. I put a larger air filter on, and the P1X (in theory) should push more air than the P1SC....I just don't know how to look for that between older logs and recent ones. If it's show under MAF, then yes new logs are .5-1.0 more across the RPM range at WOT.

Thank you for the help.

You should probably check with your tuner and see if a -retune is necessary with the P1x.

Look for MAF lb/min. I believe the sensor pid maxes out at 86 lb/min but you could see if you were reaching that value at a lower/sooner RPM. Or just compare the MAF lb/min at the RPM you are seeing the boost drop

 

[haze324]

You should probably check with your tuner and see if a -retune is necessary with the P1x.

Look for MAF lb/min. I believe the sensor pid maxes out at 86 lb/min but you could see if you were reaching that value at a lower/sooner RPM. Or just compare the MAF lb/min at the RPM you are seeing the boost drop

Tuner's working it now and making adjustments. This was more for my education on how it works and me reviewing logs. I hate being that customer that pays for a tune, but shows up with a million other questions. Again, thanks for the help fellas, I'm going to re-gap the plugs tonight.

 

[SolarFlare]

Look at air load on both logs see if there’s a change

 

[Cory S]

Boost should not drop from 5psi to 2psi anywhere in the RPM range under WOT….. Belt slip or something. What is it at 7500rpm?

is your spark adder active? Or it the timing table capped based on RPM?

What was peak spark at previously above 7000? And now?

 

[haze324]

Boost should not drop from 5psi to 2psi anywhere in the RPM range under WOT….. Belt slip or something. What is it at 7500rpm?

Im not sure why boost is dropping then coming back up. It will drop between 4-5k then by the time at 7400ish RPM Im around 10pis. Ive seen up to 13 PSI but not sure what was different. I definitely feel the lag as I'm accelerating.

Every new or old file that I try the car does it, what Ive noticed in the logs is Short Term Fuel Trims spikes when load dips (no clue what that means). Few things I plan on doing this week

1. Pull the bumper and check for any leaks. Last time I had a boost leak though it just prevented it from going past a certain psi number, it never kept going. I'll double check it.

2. Belt tension. Could the stock tensioner be giving out? I have the ProCharger tensioner pulling the stock one till about 60-70% max before bottoming out? Should I get it snugger? I have green belt or standard micro V and have a grip-tec pulley installed.

3. Re-gap plugs to .28

4. I have a Summit BOV with a Tial 2lb spring. It come with a 3.5lb spring. I don' think it's opening at WOT but I could try putting the heavier spring back in.

5. What else?

Thanks for the help guys.

Here's what the current log looks like (brown line) and you see the dip at 4K.

Here's what it used to look like with a smooth increase in load (yellow line) through the RPM range

 

[LOL WUT]

Are your STFT spiking positive or negative?

 

[wazslow]

Is traction control/advanced track on and closing the throttle body/ pulling timing?

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