Chevy & GMC Vans

Originally posted on A/S on April 04 2006,8:34

As some people have needed it, I have condensed a bulletin from GM so that everyone could access it. For the full version of this you will need bulletin #00-06-04-003B.
Note: If your vehicle has Californina Emissions (RPO code YF5) there is a special policy, (Kind of a recall, so free ) #99066G on the injectors for 10 years or 200,000 miles.

Rough Idle After Start, And/Or A Service Engine Soon (SES) Light (Unstick And Clean Central Sequential Fuel Injection (CSFI) Poppet Valves or Convert to MFI)

1996-2002 Chevrolet and GMC M/L Models with 4.3L, 5.0L or 5.7L Engine (VINs W, M, R -- RPOs L35, L30, L31)

Some owners may comment on rough idle after start-up, especially if the vehicle has sat overnight. These symptoms may be intermittent. The Service Engine Soon (SES) light may also be illuminated. Current misfire or history misfire codes may be detected with a scan tool.

Cause
A deposit build-up on the CSFI poppet valve ball and/or seat may cause the poppet ball to stick open or closed. In either case, the specific cylinder will be mis-fueled, resulting in a cylinder mis-fire condition.

Correction
A new MFI fuel system has been developed that will back service the CSFI fuel system. The MFI fuel system eliminates the CSFI poppet valve ball and seat. The CSFI fuel system will need to be replaced as a unit.
Notice: Individual CSFI injectors can not be replaced with MFI injectors. The entire CSFI fuel meter body will need to be replaced. The bracket used to retain the injectors in the fuel meter body is different between the CSFI and MFI unit. The unit may not seal if you mix injectors. Severe engine damage could result.

1. Remove Upper Intake Manifold plenum and SFI Fuel Meter Body.

(1) Cyl. #1 tube
(2) Cyl. #2 tube
(3) Cyl. #3 tube
(4) Cyl. #4 tube
(5) Cyl. #5 tube
(6) Cyl. #6 tube
(7) MFI Fuel Meter Body
2. Remove the Fuel Meter Body bracket and discard. Install the new bracket as shown in Figure 1.

(1) Cyl. #1 tube
(2) Cyl. #2 tube
(3) Cyl. #3 tube
(4) Cyl. #4 tube
(5) Cyl. #5 tube
(6) Cyl. #6 tube
(7) MFI Fuel Meter Body
3. Position Fuel Tubes of MFI Fuel Meter Body as shown in Figure 2. Tubes must be oriented away from the fuel pressure regulator end of the fuel meter body.
Notice: The number 3 Fuel Tube must be positioned behind the number 1 Fuel Tube to eliminate interference with the Upper Intake Manifold plenum when installed. See Figure 2.
4. Insert the MFI Fuel Meter Body into the Fuel Meter Body Bracket on the Lower Intake Manifold being careful not to bind the Fuel Tubes. Make sure that the number three Fuel Tube is routed in behind number 1 and 5 Fuel Tubes as shown in Figure 2. Push down firmly on the fuel meter body locking it into the bracket.
Notice: Use caution when inserting injectors into lower intake manifold to be sure the correct injector is being placed into the correct hole. Injectors should not be removed once they have been installed. Removal of injectors from the intake manifold may cause damage to the retaining lugs on the injector.
Important: The Injector holes are numbered on the Lower Intake Manifold. The injectors are numbered on the side of the Fuel Meter Body.
5. Insert the number 3 injector into the correct Injector hole in the Lower Intake Manifold first. Install the number 5 injector next and then number 1. This sequence must be followed correctly to prevent interference of the Fuel Tubes. Injectors 2, 4, and 6 are then installed.
6. Insure that the electrical connectors of the injectors are positioned so that they do not interfere with each other and are pointing towards the center of the Intake Manifold. If necessary, rotate the electrical connectors inboard.
Notice: Lack of lubrication will make installation of the Upper Intake Manifold plenum difficult and may cause damage to the O-ring.
7. Lubricate the Fuel Meter Body Upper Manifold O-ring (orange in color) with clean engine oil.
8. Inspect the Upper Intake Manifold plenum gasket and replace if necessary. Reinstall the Upper Intake Manifold plenum.
Important: Lubricate the Fuel Inlet and Return Lines with clean engine oil before inserting them into the Fuel Meter Body. Make sure that the Fuel Line Retaining Bracket is properly oriented with the tabs down.

For some more information or cost on replacement checkout Lindertech injection service. They have some good information on reasons for upgrading & prices.

Here is some more info/discussion I found on this subject;


Posted by V8famvan on Mar. 23 2006,11:25
To answer the 'general question'

The '92 - '95 4.3 had the optional injection called CPI (central port injection) which was 1 centrally located injector with 6 remote poppet nozzles.

The '96 - '05 4.3 had CSFI (central sequential fuel injection) which was 6 centrally located injectors with 6 remote poppet nozzles.

You can upgrade this with the latest version of injection system from GM. This is 1 centrally located supply pod (which is very similar to the old one) & 6 remotely mounted injectors. (look closely at the above pic)

On the 1st generation injection system ('92-'95) you could put the poppet nozzles in any hole & it would make no difference because all the poppet nozzles fired at the same time by the 1 central injector.

On the 2nd & 3rd generation injection system, the injectors being seperate, were timed so it matters which hole they are installed into.

The 3rd generation were more critical to the routing of them due to the close tolerances inside of the manifold & the injectors being at the end of the hoses.

I hope this either sates or peaks your curiosity.
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Posted by Loopie on May 11 2006,6:50
Quote (V8famvan @ Mar. 23 2006,11:57)
...this upgrade...a simple & good upgrade.

Why?

I was just reading up about cleaning my throttle body and came across this thread.

Thx for elaborating:)
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Posted by OughtSix on May 12 2006,4:14
Am I understanding this correctly?

Gen1(CPI) = Batch fired multi-port fuel injection? One injector feeds 6 poppet valves that all fire at once.

Gen2 = Sequential multi-port fuel injection with remote mounted fuel injectors individually spraying through poppet valves.

Gen3 = Sequential multi-port fuel injection without poppet valves. The fuel meter body is just a fuel manifold (A chunk of metal with one supply and six outlet ports)

If I understand correctly Gen 2 and Gen 3 are pretty much the same when it comes to electronics. There will be a CPS (Cam Position Sensor) reading the position of the cam shaft(s?) alowing the computer to determine when the valve is opening and to start firing the fuel injector at this time. So the injector for a cylinder will be firing when the cylinder is actually taking in air resulting in better air/fuel mixture and more complete combustion? So a Gen 2 can be easily upgraded to Gen 3 to eleminate the dreaded poppet valves that only stick if you are driving in the state of California?

A gen 1 to gen 2 (or 3) upgrade would require a new computer, a different wiring harness and the addition of a CPS?

Do I also understand properly that the advantaged of Gen 2 over Gen 1 is Gen 2 will idle a bit smoother and may have a little advantage in lower RPM but because of injector cycle time and how fast the valves are moving at high RPM's Gen 1 and Gen 2 are going to have very little difference in this high RPM range? And if you install A Gen 2 or Gen 3 with the poppets or injectors in the wrong order you are basically back to the efficiency level of a gen 1 system with a slightly rougher idle?

And this thing in this picture is a gen 3 fuel injector?


Honestly, I am not trying to be a smart a$$ (It just comes naturallly) I am genuinely interested in trying to understand Chevy motors and their injection systems!
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Posted by e7ats on May 12 2006,8:29
OughtSix you are right on with most everything you have said.
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Posted by V8famvan on May 13 2006,12:32
OughtSix,
You got it mostly right.
Quote
So a Gen 2 can be easily upgraded to Gen 3 to eleminate the dreaded poppet valves that only stick if you are driving in the state of California?


No matter where you live, these poppet valves can stick. You just might get them replaced (upgraded) under warranty (a special extended warranty) for free. Anyone can upgrade to these if they want to.
Quote
A gen 1 to gen 2 (or 3) upgrade would require a new computer, a different wiring harness and the addition of a CPS?

No. To do this upgrade will require more. The intake manifold & heads are different along with the additional crank sensor (in the composite timing chain cover) & the cmp sensor as you stated. If you look at these next 2 pics you will see how different they are.
First pic is of a CPI (1st gen).


2nd pic is of a gen 3.


This injector pic is a gen 2.


Gen 3 has a small micro injector where the poppet nozzle is on gen 2. See pic 2. For more reading info on this see
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Linder Technologies in Indy. makes these and sells them for 300.00, multi port injectors where the poppet valves were. I have installed 3 of these on Astros and one on a V-8. Everyone tells me the performance is better than new. And you don't need the 59-62 lbs fuel pressure.

Here it is installed

What type of HP & Torque numbers are capable on 5.7 with the CSFI to MFI upgrade? With maybe a roller .475 lift cam w/222' duration @.05 lift, vortec heads w/2.02 intakes, & headers. I'm kind of stuck with this FI setup because I have '97 4.3L w/CSFI and I want to swap a '97 5.7L w/CSFI, but I need to get more power out of the 5.7 then it puts out stock. I need to stay Fuel Injected, with a PCM, and with a working error code free obd II port. The CSFI to MFI upgrade looks like a great swap but I'm wondering what kind of performance can be achieved with a reworked vortec 5.7 with the MFI upgrade? Any help would be appreciated. Thanks

I emailed Linder Technical Services and asked
"Do you know how much fuel a injector(on the mini-injector setup) put out in #/Hr?"
I got a response from Doug Garriott "The Injector Wizard" (his title on his emails)
"Don't know exact spec, but when I flow them out they act like approx. 22- 24 Lb/hr. Hope this helps!"
This is good news for people that have to use this system, because the poppet based injectors flow 19#/Hr. from what I've read.
I know I used a HP calculator program on the internet that let you input different parameters. I can't seem to find it right now(I should have bookmarked it), but a mildly cammed Vortec 5.7L and free flowing exhaust with 22-24#/Hr. injectors easily will get that motor over 300HP.

So is it a free replacement from the dealer? Or do I have to purchase it on my own?

Ya gotta buy it yourself. No dealer freebie.

How to replace the spider injector on a Cheyv motor. 4.3 or 5.7 liter.
http://www.youtube.com/watch?v=LrPrPUgNLf0


Is the MPFI system more fuel efficient than CSFI?

Linder Tech says that the 2002s should have the MFI in them. I described what I saw and they said I have the newer style. Now whether or not it was upgraded prior to me buying it is a mystery. I am having to replace a head gasket so I figured I would go ahead and upgrade but no need for it now.