Strange boost behavior

[soxnail]

This has been going on for while, just has not been enough to chase till now.
When the car is in full boost for the first time in the day (it is at operating temperature) and it does not matter if I have been driving for 10 minutes or an hour, as soon as it goes into full boost for the first time at 12 psi or more it starts to act like its getting a fuel cut, hesitation or surge. This is also reflected by the AFR going leaner, may even throw an AFR lean error (AFR getting to 13:1 while over 5 psi in my case). This only happens once, the very first time, after that the car behaves as normal, boost to 12 + psi, AFR 12:1 or lower and smooth power no hesitation or any thing.
-Fuel injectors were cleaned and flowed a month ago.
-Spark plugs are new 6 months ago, I have pulled them before using the car first time , clean no fouling etc.
-New rotor in the distributor 6 months ago.
-New TPS 6 months ago.
-Fuel pressure stays above 50 psi the whole time.
-New FPR and dampener about 6 months ago.
-New fuel pump and filter about 6 months ago.
-Air flow sensor stays consistent.
-Fuel delivery meets the specs.
-New DME relay.
-Pressure testing the system at 15 psi, could not find any leaks.

I am some what mystified....Any ideas ?
Thanks Sox

[huskerick1]

My aftermarket diverter valve was dirty and getting stuck... it's possible you may have some internal build-up preventing full operation on initial boost - easy enough to remove and clean.

Other thoughts - I suspect you are still running the stock KLR, cycling valve, and waste gate. I've seen cycling valves also act oddly and perhaps allowing the WG to open early. Check for strange vac leaks too.
Please keep us posted...

[soxnail]

huskerick1, Thanks
new BOV aluminum billet. The KLR is in use, but is only used to trigger a fault if present.
As my tag line says "Dual port WG, 4 port control valve with EBC ", it is a Tial 44-mv and a Mac 4 port solenoid.
Sox

[nize]

can you tell if you're hitting boost faster on the first try? if you are it could be the bov, wg, or boost controller solenoid getting stuck due to build up as mentioned earlier. my bet is on the boost controller solenoid.

is your billet bov clean and piston lubricated? is the vac line to the boost controller clean?

it could also be build up on your vac line to the KLR as that is known to accumulate oil over time.

[soxnail]

can you tell if you're hitting boost faster on the first try?

Sox: The spool up time seems pretty consistent.

if you are it could be the bov, wg, or boost controller solenoid getting stuck due to build up as mentioned earlier. my bet is on the boost controller solenoid.

Sox: I don't follow, how that could affect fuel flow...The waste gate is a new Tial mv-44 put in about 6 months ago, give or take a month or so. The boost controller solenoid works as advertised I have it in and out of the car as I do bench testing for my ongoing development work. Not sure how a BOV stuck open, which would cause low boost, and stuck closed would only cause a boost spike when the throttle is closed would cause a fuel type problem.

is your billet bov clean and piston lubricated? is the vac line to the boost controller clean?

Sox: I will pull the BOV and look at it, it is new as mentioned before, again as stated above I don't see how it could affect fueling?

it could also be build up on your vac line to the KLR as that is known to accumulate oil over time.

Sox: The line is clear from visual inspection. also the car's boost gauge shows proper reading as well as the after market dial type gauge which is hooked up to the tee point at the KLR pressure input.

Thanks for the suggestions keep em coming.
Sox

[soxnail]

Two trips out today...
No issues, now I am really confused. The ambient temp was same as all of last week about 90 Degs.
I swear sometimes this car can drive me nuts, and that is not distance that requires a drive, it is a very short walk
Sox

[soxnail]

No more issues in this regard. I am very confused....
Sox

[Odublack911]

Sounds like a classic first-boost hiccup. Since fuel delivery checks out, I’d take a close look at ignition (coil/grounds) or a possible sensor calibration issue, MAF or O2 might be giving an odd reading on first load.

[nize]

sox, are you still using the factory "barn door" air meter? maybe that's getting stuck on the first boost?

[soxnail]

Nize I monitor the air flow meter in my logging and it does not show any hang ups....
Also as I stated the problem seems to have gone away.


Sox