Falls Flat....

[DeltaBravo]

Hello all,

I've got a new problem and would like some guidance please.

Recently, I've notice two things occurring. The first thing that started happening is at full throttle the car falls flat, like dropping a cylinder or two. 3/4 throttle she fells good and strong, but as soon as you go full throttle, she's like...what'evs...don't feel like going right now...maybe later.

Shortly afterwards...about a couple of weeks of driving and trouble shooting I started having issue of knock anywhere from 1-3 degrees in any gear.

Fuel pressure is 43 (line off)
Boost is 16 and seems steady
Fuel pressure rises 1lbs/ pound of boost and holds at 60psi.

Adjusting fuel pressure at the regulator or scan master up or down doesn't help. Also tried adjusting the timing...didn't help either.

Boost leak? Spark?

Thanks

 

[turbo89]

Hello all,

I've got a new problem and would like some guidance please.

Recently, I've notice two things occurring. The first thing that started happening is at full throttle the car falls flat, like dropping a cylinder or two. 3/4 throttle she fells good and strong, but as soon as you go full throttle, she's like...what'evs...don't feel like going right now...maybe later.

Shortly afterwards...about a couple of weeks of driving and trouble shooting I started having issue of knock anywhere from 1-3 degrees in any gear.

Fuel pressure is 43 (line off)
Boost is 16 and seems steady
Fuel pressure rises 1lbs/ pound of boost and holds at 60psi.

Adjusting fuel pressure at the regulator or scan master up or down doesn't help. Also tried adjusting the timing...didn't help either.

Boost leak? Spark?

Thanks

Check TPS, CAM Sensor , MAF ... in that order bet its one of the 3

 

[DeltaBravo]

TPS is good...

Don't know about the other two. How would I check them?

 

[turbo89]

TPS is good...

Don't know about the other two. How would I check them?

Cam sensor : Start the car .. disconnect the cam sensor connector .. take the car for a ride and see if the problem is gone .. if it is that's the issue
( remember to plug the cam sensor back in when your done with the test as the car will not start back up with it disconnected)

Maf sensor : easiest way is to try a known good one .. if not you will have to log with a scan tool to verify anomalies .

What type of MAF sensor is it ?

Also check your ALKY kit for the typical issues / proper settings

 

[DeltaBravo]

Cam sensor : Start the car .. disconnect the cam sensor connector .. take the car for a ride and see if the problem is gone .. if it is that's the issue
( remember to plug the cam sensor back in when your done with the test as the car will not start back up with it disconnected)

Maf sensor : easiest way is to try a known good one .. if not you will have to log with a scan tool to verify anomalies .

What type of MAF sensor is it ?

Also check your ALKY kit for the typical issues

Cam sensor seems easy enough...thanks.

The Maf sensor is a 'stock' type with one of the screens removed

 

[turbo89]

Cam sensor seems easy enough...thanks.

The Maf sensor is a 'stock' type with one of the screens removed

IF I had to bet its one of those 2 .. Cam sensor is a EASY check .. as is the MAF ... find a known good maf ( Can you borrow one from another Buick guy locally) .. don't use a reman Maf .. they almost never work correctly .. has to be a DELCO unit ...

If you find its the MAF .. do yourself a favor and throw that POS in the trash and get a LT1/ LS1 MAF and a translator they run much better .

 

[DeltaBravo]

IF I had to bet its one of those 2 .. Cam sensor is a EASY check .. as is the MAF ... find a known good maf ( Can you borrow one from another Buick guy locally) .. don't use a reman Maf .. they almost never work correctly .. has to be a DELCO unit ...

If you find its the MAF .. do yourself a favor and throw that POS in the trash and get a LT1/ LS1 MAF and a translator they run much better .

I will look into borrowing one locally. Thanks for the insight. I hope it is something simple like a sensor....I can deal with the price and the 10 min job too.

I will let ya know

 

[buddy]

Did anyone say valve springs yet.

 

[DeltaBravo]

Did anyone say valve springs yet.

just you...

would I have any other noise or symptoms that would point to valve springs.

 

[turbo89]

Did anyone say valve springs yet.

Starting with the "EASY" stuff ... if its not one of the common 3 culprits .. then springs are something that he will eventually have to look at along with an entire list of "SECOND PHASE" items ... but his sig shows "NEW SPRINGS"
so assuming they are correct and not woofed as COMP springs can go quick.

It could be stupid things like plug gap,... ignition module , coil pack , wires , etc etc .. but wanted to take the top 3 out of the equation .

 

[DeltaBravo]

Starting with the "EASY" stuff ... if its not one of the common 3 culprits .. then springs are something that he will eventually have to look at along with an entire list of "SECOND PHASE" items ...

It could be stupid things like plug gap,... ignition module , coil pack , wires , etc etc .. but wanted to take the top 3 out of the equation .

I agree. I definitely want to check and eliminate the easy stuff first. I figure it was either a air, spark, or fueling problem at first but my O2's are around the 800's.

I haven't checked my plugs in about 2,000 miles or 6 months. But when I did, they were good and gapped correctly. I will pull them after I try the cam sensor.

Again, I feel this is a 'sensor' issue, because it kinda just appeared from thin air...On day, I'm pushing 27lbs of boost with no issues and now I can't even run 15lbs without knock or the "flat spot" at full throttle.

 

[josh young]

I had the same issue, it turned out to be the cam sensor cap was bad. It was exactly as you describe, good at 3/4 throttle and fall on it's face full throttle.

 

[DeltaBravo]

I had the same issue, it turned out to be the cam sensor cap was bad. It was exactly as you describe, good at 3/4 throttle and fall on it's face full throttle.

I didn't get a chance to look at the other possible issues....cam sensor or MAF sensor. But I should be able to today. Just curious, did you also experience any knock when your cam sensor cap was bad?

 

[DeltaBravo]

update...

while doing a visual inspection on the cam sensor and cleaning the maf sensor, I notice a large boost signal leak. Coming from the turbo to my boost regulator. I believe this would cause some definite fuel/spark map issues. I simple cut off the bad part and reinstalled.

After reinstalling everything and updating my tune back to normal parameters (before the issue)...I am still getting knock. But only in 3rd gear, which is better than before. Also, still seems to falls flat...but is chirping the tires going into second, which is normal and wasn't doing that before.

So...knock is better (doesn't happen in all gears, only in 3rd).
chirping the tires into second, but still feels weak at times.

I will try the cam sensor test (disconnect)

Thanks again

 

[turbo89]

update...

while doing a visual inspection on the cam sensor and cleaning the maf sensor, I notice a large boost signal leak. Coming from the turbo to my boost regulator. I believe this would cause some definite fuel/spark map issues. I simple cut off the bad part and reinstalled.

After reinstalling everything and updating my tune back to normal parameters (before the issue)...I am still getting knock. But only in 3rd gear, which is better than before. Also, still seems to falls flat...but is chirping the tires going into second, which is normal and wasn't doing that before.

So...knock is better (doesn't happen in all gears, only in 3rd).
chirping the tires into second, but still feels weak at times.

I will try the cam sensor test (disconnect)

Thanks again

After seeing that Im pretty surprised boost was steady @ 16 psi .. I would have expected it to go higher .. good catch

 

[DeltaBravo]

update....

she's alive and well.

After double checking all of the tuning perameters (because I was messing with them trying to trouble shoot) I found the fuel was to rich for 1-2 gears. Adjusted back to normal and everything is much better. Doesnt fall flat anymore.

The exceleration is strong and consistant with boost set to 17lbs with about 1-2 degrees of knock in third.

So in conclusion- the boost leak was definetly the problem and after fixing that it was a tunning thing.

Thanks for the help...