I'm wondering if a 120 amp alternator will help this problem. I have a Walbro 340 f/p with a hot start kit. When tested, the stocker puts out 83 amps. I thought the Walbro needed 13.5 v to operate properly at the pump. I don't believe I'm seeing that, but the stock alt. and battery test within specs. I will take it for a test drive and write down the numbers on the scanmaster for AF and millivolts in case it helps you all to know this information. I'm running 50 injectors, a PT51, and 15/16 lbs. Many other changes from stock. Please help as I am still a newby.
Falling on face at WOT
- Thread starter dbeers1
- Start date
- Joined
- May 28, 2001
1.The alt output will only be as much as called for by the regulator.
2. The fp volts will have to be checked at the pump connector, engine running. U R rite.. 13.5VDC is what U should see.
3. "Falling on it's face" can be caused by weak valve springs, and a host of other items that may cause timing retard, other than fuel delivery.
4. Put the FP gauge on the windshield, and see what the FP is at WFO....
2. The fp volts will have to be checked at the pump connector, engine running. U R rite.. 13.5VDC is what U should see.
3. "Falling on it's face" can be caused by weak valve springs, and a host of other items that may cause timing retard, other than fuel delivery.
4. Put the FP gauge on the windshield, and see what the FP is at WFO....
More info
Here are my numbers generated with scanmaster 2.1 At 70+/- cruising down interstate O2 mlv fluctuated between 101 millivolt and 550. Retard shows 0 degrees no matter what, backfires at boost -- can't reach WOT. AF reading 05 at idle, 32-47 on road. Bat voltage reading 12.3 to 12.9 TPS reads .40 at idle, can't read WOT. Can only sneak up on 12-13 lbs boost with TPS reading 3. Cross counts reading fluctuates between 07-240 on road. I'm concerned that O2 millivolts drop to 0 when at light throttle while still reading 5 lbs of VACUUM on the aftermarket boost gauge. You can imagine how badly it runs at 5 lbs of BOOST. If I coast at 65-70 fluctuating O2 numbers which may be at 07, etc. at light throttle will jump to 650- 750 momentarily. I really need guidance with this. Cruise O2 numbers get worse and then car stalls.
We drove 40 miles to get a 120 amp alt from NAPA. On the off ramp it quit and would not start. After a few minutes, I took off the gas cap which sucked air. Car started. After getting back with an alt and O2 sensor, it was cutting out, took off gas cap, tank was pressurized, ran better home, home, O2 numbers back up from 00, say 400ish, but a pig at boost. Bought a vented cap. Am headed out to install alt and O2 sensor. Anyone know of a Buick turbo master in vicinity of Carbondale/Marion, Illinois where I can drop it off? Sorry for the long post but I hope the info will help.
Here are my numbers generated with scanmaster 2.1 At 70+/- cruising down interstate O2 mlv fluctuated between 101 millivolt and 550. Retard shows 0 degrees no matter what, backfires at boost -- can't reach WOT. AF reading 05 at idle, 32-47 on road. Bat voltage reading 12.3 to 12.9 TPS reads .40 at idle, can't read WOT. Can only sneak up on 12-13 lbs boost with TPS reading 3. Cross counts reading fluctuates between 07-240 on road. I'm concerned that O2 millivolts drop to 0 when at light throttle while still reading 5 lbs of VACUUM on the aftermarket boost gauge. You can imagine how badly it runs at 5 lbs of BOOST. If I coast at 65-70 fluctuating O2 numbers which may be at 07, etc. at light throttle will jump to 650- 750 momentarily. I really need guidance with this. Cruise O2 numbers get worse and then car stalls.
We drove 40 miles to get a 120 amp alt from NAPA. On the off ramp it quit and would not start. After a few minutes, I took off the gas cap which sucked air. Car started. After getting back with an alt and O2 sensor, it was cutting out, took off gas cap, tank was pressurized, ran better home, home, O2 numbers back up from 00, say 400ish, but a pig at boost. Bought a vented cap. Am headed out to install alt and O2 sensor. Anyone know of a Buick turbo master in vicinity of Carbondale/Marion, Illinois where I can drop it off? Sorry for the long post but I hope the info will help.
latest changes
This is where it stands now. I've changed the O2 sensor, MAF sensor, vented gas cap, and replaced the alt. with a 120 amp model. Car feels better, has 13.5 volts, and shows better numbers for O2 millivolts. At WOT, it goes to 0.00 millivolts almost immediately and still shows 0.00 degrees retard on scanmaster. At about 10-12 lbs boost it will backfire. I don't have a fuel pressure gauge yet to check where it is set on regulator. I'm thinking it is not getting enough fuel at WOT.
Any more ideas why O2 drops to 0.0 and scanmaster shows no retard? Anyone know of a turbo guru in Southern Illinois? I will gladly take it in if someone can point me to one. Thanks again.
This is where it stands now. I've changed the O2 sensor, MAF sensor, vented gas cap, and replaced the alt. with a 120 amp model. Car feels better, has 13.5 volts, and shows better numbers for O2 millivolts. At WOT, it goes to 0.00 millivolts almost immediately and still shows 0.00 degrees retard on scanmaster. At about 10-12 lbs boost it will backfire. I don't have a fuel pressure gauge yet to check where it is set on regulator. I'm thinking it is not getting enough fuel at WOT.
Any more ideas why O2 drops to 0.0 and scanmaster shows no retard? Anyone know of a turbo guru in Southern Illinois? I will gladly take it in if someone can point me to one. Thanks again.
Looks like your gaining ground but the only thing the SM indicated was not in spec was the MAF.
What does the MAF indicate now?
A post by TurboDave on backfire.
There's two general areas of concern with similar symptoms. If it bucks, and backfires and generally doesn't want to go at all with ANY amount of throttle, it's likely the MAF sensor.
If however the bucking/backfiring doesn't start until you get into boost, you're likely looking at a back coil pack or coil module.
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What does the MAF indicate now?
A post by TurboDave on backfire.
There's two general areas of concern with similar symptoms. If it bucks, and backfires and generally doesn't want to go at all with ANY amount of throttle, it's likely the MAF sensor.
If however the bucking/backfiring doesn't start until you get into boost, you're likely looking at a back coil pack or coil module.
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GNVYUS 1
Well-Known Member
- Joined
- Dec 15, 2002
This can be a lot of stuff. Go through all the normal things, plugs, wires are not cracked or burnt etc.
1st, don't worry about millivolts while cruising, only at WOT.
Read the BL and INT while cruising and post back those numbers.
Your alt was low but is not gonna help this issue.
Maf was fine at 05 at idle, I bet your new Napa one does not read 255 at WOT.
You never posted your fuel pressure line off settings???
I think PRO TRACK TURBO is down by you, 815 723 2530
1st, don't worry about millivolts while cruising, only at WOT.
Read the BL and INT while cruising and post back those numbers.
Your alt was low but is not gonna help this issue.
Maf was fine at 05 at idle, I bet your new Napa one does not read 255 at WOT.
You never posted your fuel pressure line off settings???
I think PRO TRACK TURBO is down by you, 815 723 2530
I am in Champaign but you don't have to drive all the way here to get your problems solved.
You have two issues- bad spark plugs are causing your O2 volts to hit 0 and then pick up, And if you check your fuel pressure at WOT you will probably see the cause of your "falling on face" problem. You will probably need a new fuel pump. Happened to me twice so far. A bad pump will also cause hard starting, too. Check your fuel pressure before you lean out and blow a head gasket. You might want to buy the fuel pressure gauge from Caspers with the 3 foot line for $39. Just place it by your powermaster when not in use, and put it under your wiper to monitor FP when the need arises. Here is a link: https://www.casperselectronics.com/...creen=PROD&Product_Code=102070&Category_Code=
There is also a knowledgable GN owner in Paris, IL who would be closer to you. We may be headed to Charleston track Friday if you want to meet us there, but that is probably a two hour drive for you. Email me for his name and phone # if you think you might need it.
- Joined
- May 28, 2001
???????
1.U can read TPS open, by depressing the throttle, key on/ engine off.
2. If the gas tank is pressurized, or is operating in a vacuum, then the charcoal cannister line is either plugged off, or kinked shut. That tank is NOT designed to use a vented cap. Doing so, under hard accel, will slop gas out the fill neck.
3. A vac on the tank will kill the pump. Gas boils at about 135*F. A vac at the pump inlet will cause cavitation, and elevated fuel temps.. both of which will kill it. [Boiling point goes down, as the vac level goes up.]
4. Low WOT TPS will not allow the ECM to go to accel enrich..
5. With only 12+ VDC, the pump may be seeing considerably less than that. Check it B4 you put the new alt on, and compare.
6. The pump may be on it's way out, and all the "tuning" won't help.
Buddy Ingersol, the master of BUICK racing, is/was in Ziegler. He had a shop there, and was working on every day cars. Don't know if he/his son are still in the business.
1.U can read TPS open, by depressing the throttle, key on/ engine off.
2. If the gas tank is pressurized, or is operating in a vacuum, then the charcoal cannister line is either plugged off, or kinked shut. That tank is NOT designed to use a vented cap. Doing so, under hard accel, will slop gas out the fill neck.
3. A vac on the tank will kill the pump. Gas boils at about 135*F. A vac at the pump inlet will cause cavitation, and elevated fuel temps.. both of which will kill it. [Boiling point goes down, as the vac level goes up.]
4. Low WOT TPS will not allow the ECM to go to accel enrich..
5. With only 12+ VDC, the pump may be seeing considerably less than that. Check it B4 you put the new alt on, and compare.
6. The pump may be on it's way out, and all the "tuning" won't help.
Buddy Ingersol, the master of BUICK racing, is/was in Ziegler. He had a shop there, and was working on every day cars. Don't know if he/his son are still in the business.
Thanks!
Thanks to everyone for helping my brother and I on his car -- you turbo guys are first class. I came down to southern Il and helped tinker and, as Dan said, it's going to Ingersol's shop Monday. He's happy to find a good shop as he was getting discouraged.
I, on the other hand, am now looking at my 455 Pontiac T/A and wondering what THAT would be like with twin hairdryers. Whaddya think?
Thanks to everyone for helping my brother and I on his car -- you turbo guys are first class. I came down to southern Il and helped tinker and, as Dan said, it's going to Ingersol's shop Monday. He's happy to find a good shop as he was getting discouraged.
I, on the other hand, am now looking at my 455 Pontiac T/A and wondering what THAT would be like with twin hairdryers. Whaddya think?
Did you replace the spark plugs too?
turbojimmy
Supporting Member
- Joined
- May 26, 2001
I know I'm late to the party, but I was going to suggest the fuel pump. The same exact thing happened to me last year. The Walbro 340 I had in it was only about a year old, but it was toast. I tried just about everything else before I taped a fuel pressure gauge to the windshield and watched the pressure drop off.
Here's my original post:
http://www.turbobuick.com/forums/ge...stion-dropping-double-digits-under-load.html?
Jim
