I might be out of fuel

[StarquestRescue]

Turn the boost down. You need to learn to drive the car with in the limits of what the stock sized injectors and your 3 knob tuning system will alow.

 

Or get more knobs, a msd type ignition and at some point bigger injectors are nessasary. But the stock ecu can't fire them right. It can't even fire the 650/950's right. That's why i run a injector drive box.

 

How much boost spike is envolved? Effective boost control is a must. Add an ebc to the list. There is no end to it. In the long run a stand alone ems would be the way to go.

[Lance_S]

Sqr,

 

There are plenty of peps running 20 lbs with a maft. Why would my setup be different?

[ptracy26]

ahhh, good read as I'm researching what I feel is the same problem i just experienced. Though this is my first post in about 2 years - hahahah.

 

Hope you get it solved as I'll be following this post and diligently researching olders.

 

Finally my car's engine was rebuilt and added those goodies I've been collecting over 5 years "20GTD06h 8cm2, custom equal length tubular header with a tial 35mm ext. wastegate, M7 rebuilt head HDschnSprings etc(all the goodies), L19 ARP head studs, trilogy 650-950 injectors, bosch 350 fuel pump, AEM FPR. Huge fuel cut post 15 lbs - way lean which I knew would happend with the 20g I won't be diving it again until I address it or I'll be rebuilding the engine again. But I figure now its time to upgrade to MAS/MAFT and run either two secondaries or two new higher flowing staged injectors, hence the research. As mentioned good luck Lance and I'll attempt to add any updates if I get mine straight and running well. Just to add DAN_TSI "Handyman Dan" is the gent who rebuilt it so we are both going to address the fuel starve as best we can.

[StarquestRescue]

Sqr,

 

There are plenty of peps running 20 lbs with a maft. Why would my setup be different?

Not every engine makes the same power at 20lbs. More power requires more fuel. P Tracys's post is a good example of that.

ahhh, good read as I'm researching what I feel is the same problem i just experienced. Though this is my first post in about 2 years - hahahah.

 

Hope you get it solved as I'll be following this post and diligently researching olders.

 

Finally my car's engine was rebuilt and added those goodies I've been collecting over 5 years "20GTD06h 8cm2, custom equal length tubular header with a tial 35mm ext. wastegate, M7 rebuilt head HDschnSprings etc(all the goodies), L19 ARP head studs, trilogy 650-950 injectors, bosch 350 fuel pump, AEM FPR. Huge fuel cut post 15 lbs - way lean which I knew would happend with the 20g I won't be diving it again until I address it or I'll be rebuilding the engine again. But I figure now its time to upgrade to MAS/MAFT and run either two secondaries or two new higher flowing staged injectors, hence the research. As mentioned good luck Lance and I'll attempt to add any updates if I get mine straight and running well. Just to add DAN_TSI "Handyman Dan" is the gent who rebuilt it so we are both going to address the fuel starve as best we can.

Even properly tuned this engine will likely max out the 650/950 injectors at 15-17 psi. It's a 400 hp turbo on a 250 hp fuel system. 950's / 1600's for gas would be more like it. Much more to it than just injectors though.

[Lance_S]

Not every engine makes the same power at 20lbs. More power requires more fuel. P Tracys's post is a good example of that.

Even properly tuned this engine will likely max out the 650/950 injectors at 15-17 psi. It's a 400 hp turbo on a 250 hp fuel system. 950's / 1600's for gas would be more like it. Much more to it than just injectors though.

 

 

Thanks SQR.

 

I will try another secondary as a primary. I installed a new walbro 255, new filters, etc. I have an FPR set at 38 lbs at idle. It raises with boost, I have checked it under boost, great pressure. I tried a new MAP sensor today, no change. Tried different timing settings, new knock boxes, etc. I have also tried a completely different set of injectors but they were also 650/950 so I will try twin 950's. That's about it. I have replaced all the hoses, no boost leaks, new wires, cap, rotors, different gaps on the 7031's etc, etc.

 

I am going to grab another 950 and see if I can make it fly. It's breaks up at exactly 18 lbs every time, no matter what I do differently, it's always right at 18 lbs under load. No, I can run it higher than 18 lbs in 2nd gear but as soon as I get 4th gear load on it, right at 18 lbs, it will misfire. I don't know if it's a fuel cut or a misfire because they will both show a lean bump on the AFR but it's always at 18 lbs.

 

The only other thing I can think of is that it's the manual boost controllers fault. It creates a major boost leak and boost leaks have been known to cause fuel cuts but that is my only guess at this point outside of hitting max duty cycle on the injector. Hopefully the bigger primary will solve it.

 

I will keep you informed, thanks again all, getting closer.

 

L

The only thing I that is left

[Lance_S]

Well,

 

Thanks to Lizzord30 having a spare 1050 trilogy laying around I am finally good to go. No more hesitation or bucking problem. She pulls hard right up through redline at 21 psi.

 

I am clearly thick headed. When you guys told me to swap out the secondary I thought you meant changing the secondary with another one thinking the secondary was bad. After re-reading the entire thread yesterday I realized you were talking about pulling the primary and replacing it with a secondary to run twin secondaries.

 

The reason i struggled with the notion was because I was still fat on my AFR. Logic told me that if I was fat that I wasn't short on fuel so I didn't need more fuel. What I now understand is duty cycle. That is why the car would run higher boost at leaner AFR's. The leaner the map, the farther it would boost. But in the end, no matter how lean you are, boost and load will eventually max out the duty cycle on the injector and the ecu will pull it out. This is what was happening to me.

 

So through this process I have learned quite a bit. I have gone over the car with a fine tooth comb. i have found small pressure leaks, rebuilt half the engine bay and tested just about everything under the hood. Not a waste of time, the car runs amazingly well.

 

On a side note, with a MAFT, the car runs surprisingly well with twin secondaries. There is a slight hesitation around 0 to 5 lbs of boost, it goes a little lean. I am assuming that is the transition point that SQR was speaking about. I can fatten it up a bit to make the transition smoother but it makes it a little rich in the mid range so I will live with it. Again, it's not terrible but I understand there are trade offs. The driveability is affected just a bit. Again, it's not significant, there is a slight lag around 0 to 5 lbs then it comes on strong. A small price to pay for the performance I now have.

 

Hope this helps anyone who is struggling with "cut out", "bucking", etc. If you have gone through everything else including: Proper plugs and gap, boost leaks, plugs, wires, rotor, cap, rebuilt dizzy, coil, knock box, MAF, etc. (because they can also cause those symptoms), you may just need bigger injectors.

 

Thanks again to everyone for their help and patience.

 

The Quest is now properly quick.

 

L

[Caliber308]

Well,

 

Thanks to Lizzord30 having a spare 1050 trilogy laying around I am finally good to go. No more hesitation or bucking problem. She pulls hard right up through redline at 21 psi.

 

I am clearly thick headed. When you guys told me to swap out the secondary I thought you meant changing the secondary with another one thinking the secondary was bad. After re-reading the entire thread yesterday I realized you were talking about pulling the primary and replacing it with a secondary to run twin secondaries.

 

The reason i struggled with the notion was because I was still fat on my AFR. Logic told me that if I was fat that I wasn't short on fuel so I didn't need more fuel. What I now understand is duty cycle. That is why the car would run higher boost at leaner AFR's. The leaner the map, the farther it would boost. But in the end, no matter how lean you are, boost and load will eventually max out the duty cycle on the injector and the ecu will pull it out. This is what was happening to me.

 

So through this process I have learned quite a bit. I have gone over the car with a fine tooth comb. i have found small pressure leaks, rebuilt half the engine bay and tested just about everything under the hood. Not a waste of time, the car runs amazingly well.

 

On a side note, with a MAFT, the car runs surprisingly well with twin secondaries. There is a slight hesitation around 0 to 5 lbs of boost, it goes a little lean. I am assuming that is the transition point that SQR was speaking about. I can fatten it up a bit to make the transition smoother but it makes it a little rich in the mid range so I will live with it. Again, it's not terrible but I understand there are trade offs. The driveability is affected just a bit. Again, it's not significant, there is a slight lag around 0 to 5 lbs then it comes on strong. A small price to pay for the performance I now have.

 

Hope this helps anyone who is struggling with "cut out", "bucking", etc. If you have gone through everything else including: Proper plugs and gap, boost leaks, plugs, wires, rotor, cap, rebuilt dizzy, coil, knock box, MAF, etc. (because they can also cause those symptoms), you may just need bigger injectors.

 

Thanks again to everyone for their help and patience.

 

The Quest is now properly quick.

 

L

 

 

That is why I run a 950/1150 injector combination I still can't understand why you having a lag or hesitation between 0 to 5 psi boost? I run my set up a little richer at mid-range: 14.2 AFR. What is your WOT AFR reading at?

 

Bill

Edited June 20, 2012 by Caliber308

[dadrab]

Well...GOOD for you, man. I'm glad you got it sorted.

 

I've been following this thread since its inception. Sorry I couldn't help. But, you had guys with real knowledge on your side that stuck with you.

 

I think I've learned a few things, too.

 

Well-done fellas.

[Lance_S]

 

 

That is why I run a 950/1150 injector combination I still can't understand why you having a lag or hesitation between 0 to 5 psi boost? I run my set up a little richer at mid-range: 14.2 AFR. What is your WOT AFR reading at?

 

Bill

 

 

Bill,

 

Right now my mid is around 12 to 13 and WOT is around 11.2. I haven't even started to dial it in yet so I still have work to do. This is just a base. I realized, just to check it that when I pulled the primary to replace it, I put in a 1050. So I have a 1050 in the primary spot and a 950 in the secondary. Of course I need to swap them since it's working against the computer this way. I just haven't had time yet to do that. When I say hesitation, don't get me wrong, it's really slight, nothing major.

 

I will swap the injectors so they are stepped correctly, 950 on the primary and 1050 on the secondary. Then I can spend some time really dialing in the fuel. But wow, she pulls like a freight train and it's smooth like butter, never run better.

 

Thanks again for the help.

 

 

Dadrab,

 

Thanks. It's a learning process. I have learned quite a bit as well, but it's satisfying when you finally pin it down and the car runs like a scalded cat. A few small things to work on then it's off to they dyno. I will look forward to seeing what it's making but I am guessing somewhere in the 260 to 270 range at 22 psi. Should be fun to find out, either way, it's quick enough for me....for now....

[bha280]

I have a similar set up as you and am wondering what your MAFT settings are? Didn't see it in the Great MAFT thread

[Metric-man]

Virtual Mechanic

 

A place to find help with questions relating to

the OEM power train set-up on your StarQuest.

 

If it wasn't for the GM MAS I would say the plugs need a close inspection.

but since you have a translator I'll suggest disconnecting your MPS.

 

Reset the ECU and start over.

 

It might be both.

 

EDIT

(I originally thought this thread was only two pages, because that is all that showed.)

So to others that might read all 9 pages, if your already using two secondaries.

the above advice may be relevant.

Edited October 8, 2012 by Metric-man

[Caliber308]

I have a similar set up as you and am wondering what your MAFT settings are? Didn't see it in the Great MAFT thread

 

Here's the problem with "OTHERS" Maf-Translator settings......Your car is not like mine,nor are your Maf-Translator settings going to be the same (Air density, Outside Air Temps and Modifications done)as other members cars. The best advice I can give you is this: Install a Wideband Gauge. This way, you can find out at what Air/Fuel ratio: Idle, Midrange and Wide Open Throttle your car is running at, and adjust the Maf-Translator accordingly.

 

Rule of thumb adjustments:

 

12.0 to 14.7 at Idle, Depending on your Camshaft lift: (The Higher lift,The Richer the setting) Roller camshafts WILL NOT Idle properly at 14.7 afr.

14.0 TO 14.7 at Mid range.

11.0 to 12.5 at Wide Open Throttle.

 

 

Bill

Edited October 10, 2012 by Caliber308

[bha280]

With the two secondaries my AFR's are within those ranges but at cruise it was high 10's low 11's and I couldn't get it down with the MAFT. Put my Trilogy's back in and my cruise AFR's are good again. Is they something I'm missing to get those cruise AFRs up?

[StarquestRescue]

The stock ecu is calibrated for injectors with size stagger. Stock oem injector test at about 550-580 /1000-1025. Few can get a tune the can live with running injectors with no stagger.

 

Aftermarket injectors will act different when powered by the stock ecu vs a flow test bench. This is why they sell you 650/950 Delphi's verses 550/1050. And the cars still tend to run lean at idle and cruise on the 650/950 Delphi's, so people have to jack the fuel pressure up

 

Two secondaries is about 25% more fuel.

 

750/1150 or 850/1150 Delphi's wound be a good point to start. About 16-20% more. Some say 950/1150 works ok, but i think more stagger is better.

 

You really need a peak and hold injector driver box to run the after market injectors properly. Or a stand alone ecu.

[Caliber308]

The stock ecu is calibrated for injectors with size stagger. Stock oem injector test at about 550-580 /1000-1025. Few can get a tune the can live with running injectors with no stagger.

 

Aftermarket injectors will act different when powered by the stock ecu vs a flow test bench. This is why they sell you 650/950 Delphi's verses 550/1050. And the cars still tend to run lean at idle and cruise on the 650/950 Delphi's, so people have to jack the fuel pressure up

 

Two secondaries is about 25% more fuel.

 

750/1150 or 850/1150 Delphi's wound be a good point to start. About 16-20% more. Some say 950/1150 works ok, but i think more stagger is better.

 

You really need a peak and hold injector driver box to run the after market injectors properly. Or a stand alone ecu.

 

Agreed. With the 950/1150 set up I have the stagger is fine. For others...maybe not.I have tried 650/950, 850/1150 and 950/1150. My car runs best with the 950/1150 combination.(1989 ECU)

 

Bill

Edited October 11, 2012 by Caliber308