Limits Of 30# Injectors

[87-WE2]

My .02 worth.

My current setup is VERY similar to OP's and I'm having same condition as OP. A while back I ditched my old PitBull chip & bought a TT 5.7 and 60's package. I have the same thing happening, although my fuel pump hasn't been replaced. In order to remedy my slightly lean condition (low 700's on the SM - same as OP), I have bumped my fuel incrementally to the point that the car would barely run and still had the low 700's at top of 3rd. I've since backed WOT fuel down to 142 I believe, but it still leans out at the top end of 3rd gear with no knock.

I figured a tired pump may be the culprit, but I'm not a fan of throwing money at a problem unless I'm sure of the problem. I had decided to wait until I started getting some KR at the top of 3rd before I submitted the requisition for the new DW pump, but this thread caught my attention. So many times I have heard "all cars are different", and "tune for no KR".

No hi-jacking intended. Just though I'd say that 60's may not fix your problem, and the problem may not be a real problem.

 

[~JM~]

I've had the car for about 3 years, but it sat in the garage for the first 1.5 to 2 years. I'm the 3rd. owner. The car was originally special ordered by a woman who drove it as a DD to just past 100k. Then the second owner was the first to change anything. Now me. I have plenty of receipts & documentation from both the P/O's. Nothing about a turbocharger replacement. To the best of my knowledge it is the original turbo with 130k miles on it.

Thank you
~JM~

 

[pacecarta]

knock at over 16# doesnt mean lean , you could (should) need octane at that point

once you hit about 15psi the injectors are commanded 100% maxed out whether you increase the chip or not and jacking the chip will not improve your wot O2 it will only make the mid spool up richer (and you may run even slower ET) ,
ive run stock motors with race fuel to just over 20psi before the injectors were done needing a slight fp increase and a reduction of the chip WOT fuel to where logs showwed 100% to prevent early spool over fueling

 

[ZNix]

If you are not getting any knock at 16 PSI, what is the big deal? 16 PSI is probably the max for 93 octane anyways..

 

[Pronto]

How did you test your FP to see it was raising 1/1 to more than 16lbs of boost? You could be starting to build F/P but once it gets to a certain point it could peak or drop b/c of something like a split hose on the pump or kinked return line, etc. I have a friend that had a S/C 3800 with a brandy new Walbro and it was running lean. His hose from the pump to the sender had a split in it. As soon as higher demand came to the pump the split would open and he would lose pressure. If you do indeed have some issue with fueling and don't resolve it, 60lb injectors willl not solve your lean condition. BTW, you are running 93 or better octane right?

 

[deezdad]

Not necessarily...turbodave runs 20#'s or more on 93 with a pte front mount, op is running an rjc megacooler...just pointing that out, I realize there's more to it..

If you are not getting any knock at 16 PSI, what is the big deal? 16 PSI is probably the max for 93 octane anyways..

 

[~JM~]

How did you test your FP to see it was raising 1/1 to more than 16lbs of boost? --->snip>--- If you do indeed have some issue with fueling and don't resolve it, 60lb injectors willl not solve your lean condition. BTW, you are running 93 or better octane right?

I had temporary use of a remote mechanical fuel guage. I did not go past 60# FP from what I recall.

I'm only able to run 92 octane 76 premium in this area.

I find it interesting that another member has had the same problem. It just doesn't seem right to never see O2's over the low 700's.

Thanks
~JM~

 

[87-WE2]

I'm the other member with the same problem (if it even is a problem). I'll admit that I'm not too worried about it right now due to Eric's comment. Although I will be checking cc's to verify oxygen sensor is worth a darn. Even if I were able to get my o2's in the 800-850 range @ the top of 3rd under WOT, it really wouldn't do anything for me and may possibly slow me down as it might be too rich for "what my car likes". I suppose I could possibly turn up boost a little more or advance spark a tad to go faster, but it may only yield a slight increase in performance. At my level, a 13.2 ET isn't much better than a 13.4.

I also plan to dig deeper to find out when the FP on my car was either made, purchased, or installed. That may help tell me whether or not I should chase a new fuel pump or not before the alky.

My immediate problem is the leaking axle seal on the driver side. Time to go buy some MORE gear oil for this weekend and a new pair of non-oil-soaked brake shoes!!!

 

[87GN_70GS]

To answer your original question on the limits, the answer is about 85 psi total fuel pressure, if everything is operating correctly. At 85 psi, a single 340 pump supplies about 36 gph and 30# inj's (against 20 psi of boost) static will flow about 36 gph. That's enough fuel for about 430 fwhp.

 

[~JM~]

To answer your original question on the limits, the answer is about 85 psi total fuel pressure, if everything is operating correctly. At 85 psi, a single 340 pump supplies about 36 gph and 30# inj's (against 20 psi of boost) static will flow about 36 gph. That's enough fuel for about 430 fwhp.

Thanks for the reply. I'm not even close to that HP#.

I'm beginning to believe that my chip & the injectors that I have, just don't match up as well as they could. I was originally unable to provide an ID of the injectors to the chip burner, just a rating. He had to work under some assumptions. I think a new chip with matching injectors should be my next step.

~JM~

 

[richy rich]

What if he has 30lbs inj.and the chip is not burned for 30's?Could that cause this problem?
If that were the case a new chip chip would cure your lean issues.
1 or more of the injectors could be old and plugged as well?
BTW that RJC plate that fits under the stock upper is a must as well,cheap too!
Keep us posted.

 

[turbofabricator]

I've run 11.77 @112 on 30 lb. Tomco injectors and a single Bosch 286 external fuel pump. Back in those days I replacd head gaskets like most folks change oil. Back then there wasn't a bigger injector available unless you went aftermarket ECM. Crappy chips back then, too. Buy a wide band O2 swnsor to verify the actual O2 readings. Buy the 60's and a TT chip, too. No help needed to make that decision. Buy a fuel pressure gauge to run all the time. THese are NEEDED items to help "tune" your car. If you don't know what is going on you are just making a crap shoot tune-up. Things end up broken doing it that way. (just like the old days learning this stuff) JM, add an Alky kit, too.

87-WE2 you NEED to buy a good fuel pump and a hot wire kit. The stock pump is questionable at best.

 

[87-WE2]

Thanks

I've run 11.77 @112 on 30 lb. Tomco injectors and a single Bosch 286 external fuel pump. Back in those days I replacd head gaskets like most folks change oil. Back then there wasn't a bigger injector available unless you went aftermarket ECM. Crappy chips back then, too. Buy a wide band O2 swnsor to verify the actual O2 readings. Buy the 60's and a TT chip, too. No help needed to make that decision. Buy a fuel pressure gauge to run all the time. THese are NEEDED items to help "tune" your car. If you don't know what is going on you are just making a crap shoot tune-up. Things end up broken doing it that way. (just like the old days learning this stuff) JM, add an Alky kit, too.

87-WE2 you NEED to buy a good fuel pump and a hot wire kit. The stock pump is questionable at best.

Thanks for the tip, Ken. I'm pretty sure I have a Walbro 340 in there. I have found the empty box in with the several boxes of junk I got from the PO. I have not caught him in a lie yet. I will eventually pull the pump & replace it, but I have several other things on my "to-do" list that will take priority for now. Latest purchase was RJC powerplate and boost controller from Jason yesterday. I will see if the PP will even out my WOT 02's - if not, fuel pump shopping I will go.
By the way - I finally read your twin-turbo story - pretty cool!! Didn't realize that pic in your avatar was a twin turbo Buick. The avatars are kind of small and my eyes aren't what they used to be. Even when they WERE what they used to be, they were never GOOD!

 

[turbofabricator]

Dan, You might also want to step up to a wide band O2 sensor, too. They work much better than stock. They are alot mor accurate, too.

 

[87-WE2]

WB's on the list - it's down a ways, but it's on there. Before anything else happens I've got to get an axle seal done in the rear. My list is long and will take MUCH time. I'm in no hurry.