Weird problem..with...

[ski_dwn_it]

launch of 434 using Gen7. Running it through a Innovate WB, same setup as last year computer/ECM/Setup wise with the exception of two thing. Cam and injectors.

Upped the lift of the cam and went from 30lb injectors to 42lb injectors. Cam change was not that significant.

Drove the car around a little after the rebuild and it ran flawlessly, as did it the year before. Decided to up the injectors to 42lbers after seeing some higher duty cycles when spinning it near 7300rpm. Last year shifted at 6900rpm, and went best of 10.1@134.9mph.

After the install of the injectors can again cruised around fine, but when I would drop the hammer on the launch off an idle of about 2k, the car would bog/launch/bog/launch.... I would then let off and roll onto the throttle and the car would scream like a raped ape. Went nearly 30mph in the last half of the track. Went a best of 10.4@132 in worse weather than last year, when above ET was obtained.

This week I checked everything I could imagine. FIlter etc....all checked out.

Went out today to an 1/8 mile track and car instantly off the trailer started doing it again. Its like it knows when I drive 2hrs one way to start pissing me off! Tried about everything today. Added lots of AE, this aggavated the problem, the car then started to just cut out to the point of zero noise, like someone turned off the key. Would do it time and time again......

I loaded my old tune back in, left everything the same and car still acted the same. Didn't even go back out onto the track....just hit it on the pit road and it was obvious.....even in the GRASS it would cut out!

Came home and pissed off, I put the old 30# inj back in. Started the car and even hitting the throttle off idle sounded quick and crisp. Like last year. With the other injectors in it, it was laaaaaazzzzzyyyyy sounding even just punching it off idle. Pulled the car around in the driveway and hit the gas, the slicks instantly spun and the motor had zero hesitation.

Now with both inj there was time dialing in idle and part throttle, I was leaving the WOT to the track where its safer. LAst year when I got the system I was able to dial in the 30# injectors on the setup in within a few runs. This year NOTHING seems to be working.

WEird thing is the WB is saying that the motor is running lean like WAY lean when it acts up, yet NOTHING even leaving the constant at 30 in the system setting, with the 42 injectors did NOTHING to help it.

I was able to get 2 runs off all year clean with these injectors. Its like they are locking up or something. PLugs are white as a ghost also!

COuld these injectors be bad? Are there injectors that are not compatible with the DFI system? These are straight ford SVO 42# injectors. Just like the 30# injectors.

Any ideas?

 

[ijames]

If those are disc style 42 lb/hr injectors, they are pretty notorious in the Buick world for causing off-idle stumbles. They give a lot more fuel at short pulsewidths than pintle style injectors do, so you will have rework your AE tables to compensate. You say you tried adding AE, but I think you will need to remove a fair amount of AE instead. One big clue that this is the problem is the way it ran when you gently got to wot so not much AE was used. They are good injectors, they just need a different tuneup than your old ones. That's one reason the 50's are so popular here, they are "easier" to tune up since the stock AE (in the stock ecm and chip) actually still works pretty well. You should have seen the afr flatlining at 9-ish on the wbo2 whenever you blipped the throttle - were you logging the afr? Oops, just read the "lean" part of your post. If you go rich enough to misfire, the wbo2 gets fooled into thinking lean. Much as I love the wbo2, you can't trust it when there is any kind of stumble or misfire.

 

[ski_dwn_it]

Just got back in from more testing. appears with the 30# injectors that the fuel pump is not keeping up. Taped a gage to the windshield and its flutting/dropping pressure pretty badly when I get on it real hard, car stumbles at the same time.

Looks like the walbro that is 2yrs old is history. Going to double check the wiring, but I am pretty sure it will be ok.

I would rather stick with the 30# injectors if possible anyways. This explains why the 30s were going static when I first started driving the new combo, when last year they were fine. The throttle response and stuff last year was enough to rip your head off+ my tuneup from last year should be REAL close.

I will keep you posted, but I think that is the real problem at the present time. Was able to repeat the failure several times.

Thanks for the help....

 

[norbs]

Just changing the injector constant is not going to help in most instances. Each injector has different flow at the same pw, rich on the bottom or lean up top or the opposite. YOu going to have to remap the whole fuel map and all your settiings for AE, which could take a long time as you have found out.

The gen 7 wil throw a code if the duty cycle is over 100% for 5 seconds also.
Fix the pump first and see how it goes.

 

[ski_dwn_it]

Just changing the injector constant is not going to help in most instances. Each injector has different flow at the same pw, rich on the bottom or lean up top or the opposite. YOu going to have to remap the whole fuel map and all your settiings for AE, which could take a long time as you have found out.

The gen 7 wil throw a code if the duty cycle is over 100% for 5 seconds also.
Fix the pump first and see how it goes.

Thanks Norb, always appreciate your input.

I am pretty confident that the problem lies in the pump. Today after my other post, I went out and checked the pump voltage at the wiring entering the tank to dispell any possibility the problem might be with wiring. As we all know, or should know, the pump output is directly proportional to the voltage it sees, so I wanted to make sure this was not the problem.

I checked the voltage at the battery, at the alternator(where the hot wire kit is for the fuel pump) and right at the tank. In all instances, the voltages were within .25volts of one another, and this was done at different RPMs (well as good as my 4yr old boy, who is always with me like my shadow helping me with the car could hold the gas peddle at a given RPM.). I let him do a little more with the car each time, he gets a kick out of it. He really thought he was king crap revving it up today. Then he had to tell me that he was NEVER suppose to do it on his own....lets hope he follows through with that same thought process.....

Anyways, all leads point to the the pump itself. I am going to call Racetronix tomorrow to see if there is any test to give the pump, and if this is somewhat common with these pumps to go after about 2 years of pretty minimal use......seems a little premature to me.

I will keep you posted.

Thanks everyone.

 

[Craig Smith]

Just changing the injector constant is not going to help in most instances. Each injector has different flow at the same pw, rich on the bottom or lean up top or the opposite. YOu going to have to remap the whole fuel map and all your settiings for AE, which could take a long time as you have found out.

The gen 7 wil throw a code if the duty cycle is over 100% for 5 seconds also.
Fix the pump first and see how it goes.

Now I forget what the term DFI uses for it, but there is an adjustment for injector opening time that will dramatically reduce the need for remapping AE tables and the VE table with an injector change. I think I may have used the term injector constant in a PM to ski but that isn't the right one - sorry. You'll see it just to the right of the injector constant in the engine config editor. Once you get the pump issue resolved, try starting with your original tune, change the constant (yes, the constant this time) to 42 psi, and then tune this other parameter that I can't remember the name of in small increments. You will most likely see that it will bring your original tune fairly well in line with the behavior of the new injectors.

Norb, any DFI box I ever worked on set a code 71 the instant the injectors went static. What firmware is in yours?

 

[norbs]

Ya Craig your correct, i must have been breathing too many fumes when i said 5 seconds, its instant. I have now a 5.0 box and 5.0.2 software and i found its the best softwar so far of all the versions.