GT6152 maxing out 42.5 injectors @ 13 PSI

[nuclearxp]

Hopefully I've got this in the right area....

So the basic list of mods are below. I recently just got a hang of my boost controller, which is nearly pointless because 13psi (just before the boost controller becomes necessary) is maxing out my PCM MAF frequency. I know I need a translator, but I want to address my injector problem first.

I've been told 42.5lb injectors on my motor are good for around 400whp on a turbo 3.8L motor. However, my injectors are seeing 100% duty cycle @ 5300RPM @ ~22.5 IPW (at about 13psi of boost). I really don't think my car is making 400whp right now. I have a fuel pressure gauge... it boggles between 45-55psi at idle (fairly big cam) but under boost it goes up 1psi for every 1psi of boost, so WOT I'm seeing ~65psi of fuel pressure so I don't think fuel pressure is the culprit here.

I've attached a HP Tuners screenshot of a run where I sailed past my MAF ceiling and the car cut the timing. But regardless, you can see that the injectors are maxing out pretty quick, when I don't think they should. My wideband reads 11.5-12.0 under WOT which could still probably use a touch of richening up.

So, down to the question: Anyone have any ideas why my injectors are getting maxed out soo fast? Are they actually spot-on and my car is just making more power than I think? Any other comments/ideas?

 

[Brutusturbov6]

Sure sounds like the wrong chip for the injectors, also make sure the voltage is not dropping suddenly to the pump., could also be a ground problem check cables to the Fuel injectors harness.

 

[nuclearxp]

I don't know what you mean by the "wrong chip for the injectors". I completely agree about the injector and pump wiring. I know I have a short somewhere because my two front batteries die if the car sits for more than a week or two. I noticed when tightening the turbo bolts that if my ratchet extension touched my intake tube (through the paint) and turbo it would spark. I have no idea where the short could be in that area... the front end is a wiring nightmare.

As far as the pump, any idea how to test for load voltage?

 

[GNVYUS 1]

That is really odd, 103kps is just over 14.7psi so how you are seeing 48lbs/min already?? This is saying you should be making around 480hp if the car has supporting mods, that would put you at the end of the 42's. What cfm do those heads flow, what are the cam specs and is it stroked?

What he means by the wrong chip is simply maybe you have a chip burned for 50's in there. You might want to pull the chip and take down any identifying # on it and call the manufacturer to confirm it's specs.

That turbo can run high tens so 42's are not matched up well unless you have alky injection.

On gas, 11.5 to 12.0 AF/R is just fine as long as you are seeing zero knock. If you are concerned just keep it under 12.0 knock free.

 

[nuclearxp]

Oh.. well the car doesn't have a "chip". I used HP Tuners to modify the car's computer to run for 42.5s. Do take the lb/min figure with a grain of salt. What I've done is tuned my MAF frequency table to completely handle the fueling. Rather than relying on blindly dumping in fuel from power enrichment. And another thing, my car's MAP sensor is from a n/a motor, so it actually stops reading at 100kpA. If you look close you can see the purple line maxed out before that snapshot was taken. What has me even more worried is that snapshot was taken around 5200rpm and I currently have it shifting closer to 6000, and worse on top of that the cam REALLY wants to make power up to about 6500.

Head specs:

Intake (28" of water, clay radius to repeat)
.100" - 69 cfm
.200" - 127 cfm
.300" - 175 cfm
.400" - 208 cfm
.500" - 224 cfm
.600" - 235 cfm

Exhaust (28" of water, 1.75" pipe to repeat)
.100" - 60 cfm
.200" - 117 cfm
.300" - 172 cfm
.400" - 199 cfm
.500" - 212 cfm
.600" - 222 cfm

Cam specs:
Stage 3 Turbo Cam, duration @ .050": 223º/214º, lobe lifts: .338"/.332", valve lifts with 1.60:1 rocker arms: .541"/.531", lobe separation angle: 116º, intake centerline: 110º

Keep in mind the motor is a 3.8 from a Grand Prix GTP. Non-stroked.

 

[galoush]

Oh.. well the car doesn't have a "chip". I used HP Tuners to modify the car's computer to run for 42.5s. Do take the lb/min figure with a grain of salt. What I've done is tuned my MAF frequency table to completely handle the fueling. Rather than relying on blindly dumping in fuel from power enrichment. And another thing, my car's MAP sensor is from a n/a motor, so it actually stops reading at 100kpA. If you look close you can see the purple line maxed out before that snapshot was taken. What has me even more worried is that snapshot was taken around 5200rpm and I currently have it shifting closer to 6000, and worse on top of that the cam REALLY wants to make power up to about 6500.

Head specs:

Intake (28" of water, clay radius to repeat)
.100" - 69 cfm
.200" - 127 cfm
.300" - 175 cfm
.400" - 208 cfm
.500" - 224 cfm
.600" - 235 cfm

Exhaust (28" of water, 1.75" pipe to repeat)
.100" - 60 cfm
.200" - 117 cfm
.300" - 172 cfm
.400" - 199 cfm
.500" - 212 cfm
.600" - 222 cfm

Cam specs:
Stage 3 Turbo Cam, duration @ .050": 223º/214º, lobe lifts: .338"/.332", valve lifts with 1.60:1 rocker arms: .541"/.531", lobe separation angle: 116º, intake centerline: 110º

Keep in mind the motor is a 3.8 from a Grand Prix GTP. Non-stroked.

The first few lines you said you have your problem , get a chip ,i like Turbo tweak and get the right MAF , i ran 42s W/O problems for years and i ran Nitrous 100shot with them too no problem .

 

[nuclearxp]

I'm not sure how a chip would help my situation... and just to reiterate, the car is a Firebird. Never heard of a "chip" made for them.

 

[GNVYUS 1]

You got it flashed then, probably not a chipped ECM but the LT1 Camaro/Firebirds had a chip in them.

I don't know what program or what the colors on the right meant so I didn't bother trying to figure them out but it sounds like you don't exactly know how much boost is being made since the stock MAP is pegged out. If that's the case hold off until you get an aftermarket gauge. But your fuel pressure #'s look to be showing a 20psi level of boost and the only gauge that can bounce from 45 to 55 are those NON liquid filled ones, I'd swap that out.

Looks like you ran over the injectors plain and simple, you have a decent set of flowing heads ( considering our ported stockers are flowing 205 at .500 ) and you have good lift and duration so the car can suck down some cfm at WOT.

I'd personally get it reflashed for 60lb injectors or add alky ( better since you can up the boost :biggrin: ). Alky and 42's can go a long way with a good hot wired fuel pump.

 

[nuclearxp]

I have a boost controller and boost gauge to monitor the levels. 12.6psi is average max and anything over ~13 maxes the MAF.

About the fuel pressure gauge, I didn't even know there were different 'types'. I'll have to look into that. It's an autometer, part of a 3 gauge pod of that means anything.

I'd rather upgrade to 60s than use alky. I'll have to look into how much of a pain it'd be to swap new ones in. How involved is the fuel pump hot wire process?

 

[galoush]

I didnt know we were talking about a different car here i thought you had a Buick ,........................................ in that case you may need bigger injectors or maybe you need to adjust elsewhere .

 

[bison]

How many cubes?

 

[nuclearxp]

231. It's the 3800 Series II block out of a Grand Prix GTP. I'm tossing around a few ideas. I know that even if I shouldn't be maxing out 42.5lbers right now, I'm probably close anyway.

A few members have suggested possible ground or fuel supply issues, and I agree I need to look into that. I know there is a bad ground or something somewhere around the engine because like I said earlier I was getting sparks when putting the turbo back on. I have a Walbro 255 pump but I'm unsure whether it was rewired or not... I need to look into that.

I'm also curious whether the larger cam overlap is passing fresh air through the cylinder out to the o2s and wideband making them read leaner than the motor is really running. I'll look into the ground issue and injector wiring, but getting the car in the air to check the fuel pump wiring could take some time.

 

[buttonfly]

You got it flashed then, probably not a chipped ECM but the LT1 Camaro/Firebirds had a chip in them.

I don't know what program or what the colors on the right meant so I didn't bother trying to figure them out but it sounds like you don't exactly know how much boost is being made since the stock MAP is pegged out. If that's the case hold off until you get an aftermarket gauge. But your fuel pressure #'s look to be showing a 20psi level of boost and the only gauge that can bounce from 45 to 55 are those NON liquid filled ones, I'd swap that out.

Looks like you ran over the injectors plain and simple, you have a decent set of flowing heads ( considering our ported stockers are flowing 205 at .500 ) and you have good lift and duration so the car can suck down some cfm at WOT.

I'd personally get it reflashed for 60lb injectors or add alky ( better since you can up the boost :biggrin: ). Alky and 42's can go a long way with a good hot wired fuel pump.

alky and 42's can go a very long way!!

 

[bison]

In a 3500 lb F-body you should be able to go at least 120mph on 6-42.5lb/hr injectors before running out.

 

[Chuck Leeper]

Huh??

"I know there is a bad ground or something somewhere around the engine because like I said earlier I was getting sparks when putting the turbo back on"...
FIX the shorts/grounds, etc, B4 you burn the harness out of the car. [Or, worse the entire car.] Then worry w/ how it performs.

 

[nuclearxp]

In a 3500 lb F-body you should be able to go at least 120mph on 6-42.5lb/hr injectors before running out.

I'm not sure how mph correlates to injectors? It should do WOT at 120 in general? Or they can take it to 120 in the 1/4? FYI my GVW on the door says 4200 and add another 200 in stereo crap.

As to the wiring problem, I'm not good with engine wiring troubleshooting. Anyone point me to any guides or lend any tips?

 

[Chuck Leeper]

Speed??

"I'm not sure how mph correlates to injectors? It should do WOT at 120 in general? Or they can take it to 120 in the 1/4? FYI my GVW on the door says 4200 and add another 200 in stereo crap."

The poster is probably referring to 1/4 mi MPH.. when the wt is known, you can roughly estimate the HP, by using the wt and terminal speed.
FBody.com - A place for Camaro, Firebird, RS, Formula, Z28, TransAm, SS, WS6, Firehawk stuff
Scale the car, and find out what it really weighs.
Correct the electrical problems.[LS1tech.com may have guys that can help.]
Any of the "stereo crap" have elec problems?? Maybe your stereo guy can help w/ the troubleshooting?
Why not use your HP tuner programmer, and put a speed density tune in the car, and do away w/ the MAF sensor?
There are ways to tune around the MAF, but a SD tune would do a better job, IMO.[The guys @ LS1TECH - Powered by vBulletin can help]

First things first!! Get the electronic gremlins cured, then worry about inj size, etc. Until you do, you are "just strokin your loaf"!!

 

[bison]

Thats what i mean Chuck. The cars net weight is around 3480lbs. 4200-720(4 seater=4x 180 lbs)+200(stereo components)=3680+your weight=? Still pretty heavy.

 

[nuclearxp]

I'll see if I can't get to Milan dragway within the next week or two and post up a nice long scan.

I'm also concerned about the mileage I've been getting lately. My fueling overall is darn near perfect and it's the best I can do to get 13mpg. I swear just driving around or letting the car idle I can smell gas in the exhaust but the o2s and wideband are reading normal.....

 

[nuclearxp]

Update: I just happened to check under the hood this morning and the EGR valve has a tiny leak where it bolts to the header. Would this really have all that significant of an impact on gas mileage/performance?