99 Suburban running very poorly and getting worse

Joined
Mar 8, 2008
Messages
5
Likes
0
Points
0
#1
was getting an intermittent error code of missing #4 cylinder, changed cap, rotor, wires, plugs and problem still there.
I've been researching this on-line and have found several posts regarding a problematic CSFI. The state of CA ordered a mandatory GM recall but other states aren't so lucky. I've also read that it could be my distributor. This problem started very mildly. . Vehicle drove great and on occasion I could feel a hiccup at highway speeds, (no codes and dealer unable to diagnose) after a few months I noticed the idle started getting rough but would smooth out once I started driving. Now it's very bad both in idle and while driving.
My question is whether there's a way I can determin if its the CSFI or the distributor? Also, Chilton's or Haynes do not go into the detailed teardown and replacement of the CSFI and I was wondering if it's hard to change it out. I've read on other sites that GM sent out a service bulletin # 00-06-04-003B that recommends a conversion to an MFI. Any idea on where I can get a detailed DIY repair manual on doing this myself? Or a detailed DIY repair manual to change out the CSFI.
I don't have the funds to take this to the dealer and have it serviced there. My wife lost her job recently and we've been hit hard financially so I'm trying to get this done myself. Any help would be appreciated.

Also has anyone had a chance to review or use LTS' new CSFI replacement? Lindertech. com "Recommendation: Replace the original poppet style unit with the NEWER mini injector style. This unit uses a mini injector at the end of each tube. There are plastic injector protectors attached to each injector that fits into the intake ports protecting the injectors from carbon and sticking. The unit is a direct replacement. Always replace the upper plenum gasket when replacing this unit. "
 
Joined
Jul 1, 2007
Messages
17
Likes
0
Points
0
#2
Is the same cylinder missfireing? Have you thought about haveing a fuel injection service before spending the money for conversion?
 

kev2

wrench
Joined
Nov 14, 2006
Messages
4,919
Likes
53
Points
48
Age
119
#3
lets get some information and look at some options ideas before we throw money at it... always simple easy inexpensive things first

Your Best source for information-how to and TSB's is -alldata.com. or mitchels - check your local library - you may have already paid for this


how many miles on truck? It is STOCK no add ons, aftermarket, or modifications? Chips, K&N, etc...
Is the SES on now?
the parts used cap rotor plugs etc. what brand? yeah its important..
Do you have a scanner, fuel pressure gauge?
 

Gus

wrench
Joined
Dec 8, 2006
Messages
2,421
Likes
1
Points
36
#4
Just check for spark at that cyliner with a spark tester at the end of the ignition wire.....pull the plug, does it look fouled?

I would try injection cleaning first, but not the crap you put in the tank...that's really just for maintenance purposes, not after the horse is out of the barn.....
 
Joined
Mar 8, 2008
Messages
5
Likes
0
Points
0
#5
Thanks for your responses.
In answer to your questions. . . . same cylinder error code read #4 cylinder. . . has premium cap/rotor/wires from Summit Racing, EC4 plugs and an AFE filter. The AFE has been on the truck for about 2 years and the cap/rotor/wires/plugs were replaced about a month ago because of the hiccup while driving and the SES light is continuously on and now has started blinking repeatedly. All plugs were fine when pulled except #4. It was wet with gas.
It just reached it's 100,000 miles last weekend and has a fuel filter and fuel pump changed at dealership about 6 months ago.
 
Joined
Nov 14, 2006
Messages
4,919
Likes
53
Points
48
Age
119
#6
Please tell me this filter is NOT an oiled type like the K&N POS, you did not use the Ccold air intake just the filter?

Who makes the EC4 plug- is that brand or application#?

NOTHING else done?? thermostat change (lower) ?

Check the fuel pressure regulator for leaking...streaking in manifold, also as mentioned
"Diagnostic Aids
The most likely cause for this DTC is the following:

a mechanical failure causing low cylinder compression.
a fuel leak at the high pressure fuel injection lines or injection nozzles.
a fuel injection nozzle stuck closed.
If an injection nozzle is suspected, it can be transferred to another cylinder to determine if the DTC follows the nozzle.

After the repair has been performed, it may take approximately 30 seconds for the vehicle to return to a stable idle."
 
Joined
Mar 8, 2008
Messages
5
Likes
0
Points
0
#7
AFE is an oiled filter with a cold air intake. . It was purchased at the local dealer parts dept. It has been on the Suburban for about 2 years now. The dealership indicated it was better than the K&N and was recommended as a simple and cost effective upgrade. EC3 plugs are the brand. Nothing else done, Thermostat was changed at dealership with water pump and Heavy Duty radiator about a year ago. I don't see any gas leaks or smell any gas under the hood.
 
Joined
Nov 14, 2006
Messages
4,919
Likes
53
Points
48
Age
119
#8
Something is funny about an authorized GM dealer selling an Oiled air filter when GM has a TSB exempting warranty claims for vehicles using them... talk about making money .....

I am still going with the suggestion of checking for a leaking fuel system component...Do you have a fuel pressure gauge- thinking we can check pressure leak down as its easier and quicker than opening manifold up.

There are NO other codes-p0304?
I will try to pull up the leakdown test and post.

PS -dealer recomendeed ??-anything is better than K&N and NOTHING is better than stock..
 
Joined
Mar 8, 2008
Messages
5
Likes
0
Points
0
#9
yup, Brown and Brown Chevrolet in Mesa, AZ used to sell them and even had display videos with testimonials, now they sell another aftermarket kit by a different manufacturer.

The only code it has displayed so far is Cylinder #4 Misfire Detected. I get a fuel pressure gauge today and check it out. I'll post the results tomorrow
 
Joined
Mar 8, 2008
Messages
5
Likes
0
Points
0
#10
sorry this has taken so long. . . same error code. . . did compression test (okay) fuel pressure test (okay) had injector service, upper intake and carbon service at Fletcher's (local shop). . . . also changed oxygen sensors and did the cfi to efi conversion. . . Fletcher's not able to determin cause after sinking $750 into it. . . car ran better. . . could not tell it was missing but their computer still kept registering an intermittent #4 missfire (plugs were also changed back to stock AC DELCO PLAT'S eventhough mechanic recommended Iridium Plugs??). . ran for 1 month with no probs and then last week went back to poor performance again. . now feels worse than before. . Could this be an ECU issue or ignition module??? I NEED A MIRACLE!!!! please help