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Throwing $$ @ loss of power ISSUE

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FenderChest

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:dunno:
Hi all, I have a 88 K5 5.7 TBI O/D Trans. Stock other than my removals,(No emissions, cruise control, or cat.)

Here is my story.
About a year ago, I was driving home and noticed a loss of power a under a load. I took the TB apart and noticed the fuel pump regulator diaphragm was shot, and gummed up ( ETHONAL ?? :doah: ) Before this I had no indication of any issues~~truck ran fine.

After a little investigation I found the passenger exhaust manifold was cracked. I decided it was time for a tune up.

New parts
plugs, wires, cap, rotor, coil, spark module, ex. manifold. Re build TB. The truck ran good for a month or so ~~~then lack of power under a load again .

More new parts: AIC, TPS, MAP, EGR & Module, All vacuum lines, Fuel sending unit & module, Fuel filter, & connectors.

To be Continued~~~More to come ~~HAVE to take WIFE to the movies :bow:
 
Part 2

Ok ...Back to the story.

I also had new temp sensor, knock sensor, battery cables & gas tank hoses installed.

Installation notes: TB spray nozzles show a nice spray pattern, AIC Is the adjustable type and was set to same length as old unit, I had normal idle so no need to try the reset process. TPS is the non adjustable type ,pick up lever is above the throttle actuator lever tang. EGR didn't seem to be stuck, just didn't hold vacuum. Plugs colors looked good, no play in the dist. and locked down. Pick~up coil has no visual abnormalities?

The part that get's me is the truck will start, idle , and drive as if all is normal ?? When I get to 35 to 40 mph it will seem gutless and sound like a exhaust manifold leak( only on passenger side, not very loud either) . I have no cat and strong flow coming out tailpipe(no ex leaks). Checked trans fluid~normal, didn't touch TV cable.

With all the new parts I figured fuel pressure should be good??? The only thing I haven't changed is the O2 sensor. QUESTION.~~~ What would be the proper O2 for my rig with no cat and stock Exhaust??? The EGR is neg. type


PS I have never had the check eng. light come on. I checked with a paperclip today and just got the standard 12 code (its working), No heavy fuel smells , no black or white smoke out tail pipe ,No over heating, or stalling~~~~NOTHING that would indicate a problem:dunno::dunno:

Any help welcome
Thanks ~~~ "FenderChest" (Bent over the fenders to long ~ chest HURTS):confused:
 
Last edited:
Two things your missing here.

One is fuel pressure. It has to be checked with a gauge, the ECM has no way to know what the pressure is and can only adjust so far when pressure is differant.

Two is some kind of data. Can be done with a scantool if you know what numbers should be. My choice is a better data log that can be saved and sharred so thothers can look for issues. Take a look at TunerPro RT.
http://coloradok5.com/forums/showthread.php?t=302680
 
I am willing to bet its your TPS. I had to oblong the crap out of the holes to get the proper reading ~.56V at idle. My truck was doing the exact same thing and didn't find it until mark helped me with tuner pro and data logs. I suggest you invest in an ALDL cable or build one and use tunerpro rt.
 
Thanks guys, Can you suggest a link on how to check your TPS and how to connect a fuel pressure gauge to a TB ???


I'm very interested in the Tune Pro RT download, but will have to get more info and ask many questions .

Thanks :waytogo:
 
Good set of needle probes and a digital volt meter. Blue and black wires on the TPS should read .54-.58V DC at idle or key on.
 
eagle mark said:
the ECM has no way to know what the pressure is
Click to expand...

af*ckinmen brudda..... :waytogo:

one of the reason's I run a "pointless" fuel pressure gauge on my hood... :whistle:

it's the one variable sensors, codes, etc don't take into account.. and factors HUGE in the mix with EFI.. :deal:

as I've said MANY times in here, it's one of the first things we'll do on the boats diagnostic-wise, even, and ESPECIALLY with MPFI systems, is drop a gauge on it...
 
I have seen fuel pressure change more than 1 pound just replacing the diaphram. That is alot on a tbi system, and the reason that I check fuel pressure after the diaphram is replaced.
 
I've seen stock tbi's at 8, 9 psi... bump them to 12, 13, 14 makes all the dif in the world.. more seat o' pants improvement than any headers or bolt on part I've ever done..

I run 14 on Mutt and the mill LUVS it..
 
Yup! Although a stock system will run at 8 PSI, it's way past what it can adjust for and your running lean, usually pick up a lean code by then.

Getting an adjustable regulator and setting to 13-14 PSI is the best thing you can do for one of these TBI systems.
 
While these guys are far more wise to your TBI injection system, have you checked for vacuum leaks, or perhaps the intake manifold gasket? :dunno: just a thought...
 
.54v is perfect and on these systems per GM specs. As per hard code it is not an issue until .94 volt, even then I never found why the .94v is in code or what it was used for? I don't worry under .70v and never had issues. TPS% is more important. With modified engines you need to adjust throttle blades for a low IAC count, just enough to control idle, but leave the max amount of air coming through the throttle blades to mix the fuel with air. Injectors above throttle blades and wet intake. Not as important on MPFI.

All ECM/PCM are differant but most will set TPS to 0% when key on. This is why you never touch the gas pedal when key on before starting. If you do then ECM is confused as to where idle/TPS 0% is. Some ECM/PCM need power removed after you reset TPS voltage so ECM/PCM can recalculate 0% TPS.

Probably more then you asked for... :haha:
 
Not at all. The reason I was wanting your input is because I can count on your knowledge on the TBI systems.

Thank you for the lesson. But I could of swore I got those numbers from you a couple years ago. I have mine set at .50V. Seems to run good. Every other day I get code 32 but it runs fine. This usually happens after about 10 miles into my drive. I checked the EGR for vacuum and holds well. Swapped out the solenoid and didn't cure it. Might need to pull EGR and check for deposits or crud. I'll have to do a datalog but can't right now.

Hi-jack off.
 
Thanks for the continued support,

I have read quite a bit of info in regards to what I have done, what I have Not done and what Must be done.

The first thing I'm realizing is "Not to fight the WORK" I was not looking forward to learning the TBI system. I was hoping to throw $$$ at it for easy fix :smokin2: Didn't Work.

So, the first thing I want to do is the AFPR, I was thinking on modifying my stock unit

http://www.google.com/url?sa=t&rct=...RjhgKEgmpcdVcyISYTFlNJQ&bvm=bv.63934634,d.cWc

Also get this

IMAG0031.jpg



With the gauge, however I might try to re-route (just the gauge) elsewhere to avoid more mods with lines, brackets etc... Has anybody done this?????

I will set the fuel pressure to 13~14 psi , then on to adjusting As wheels87k5 shared above. ( Don't know how to do the Quote thing ):doah:

:bow::bow: FenderChest
 
Oh, man.........that is sweet, royken. Now I'm gonna have to do mine that way.

The wife is looking over my shoulder shaking her head. She wants to know who is this ryoken character. And she wants to thank you for putting more ideas into my drain bamaged head.:haha:

Sorry, dude.:doah:
 
FenderChest said:
More new parts: AIC, TPS, MAP, EGR & Module, All vacuum lines, Fuel sending unit & module, Fuel filter, & connectors.
Click to expand...


This is how I got spares for everything. And then found out it was the EGR, which was the most expensive. After that I just started asking questions and the help followed. Saves you some money in the end. :waytogo:
 
pretty sure I've been cursed by many a better 1/2.... :doah: :haha:

eh, I've always found it to be a valuable bit of info at a glance, a bit excessive maybe...

came in handy today actually when I was running on fumes and it went from my usual 14 and change psi, to fluttering at 12... apparently my rig likes to have more than .2 gallons in it! :doah: :whistle: :haha:

but I've also been informed it's pointless too... :rolleyes:
 
13-14psi adjustment Q.

hello all,
I just finished making my modifications for an adjustable fuel pressure regulator and I set it back to stock specifications as per instructions . Question. while , I have the unit still out , I'd like to set it closer to 13 to 14 as possible, I would like to know is the spring tang a little bit lower in the housing as towards the manifold or is it higher towards the top of the unit.???? at the stock setting, the tang is pretty much in the middle .

any help deeply appreciated picture would be nice
Thanks
 
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