I have a 1998 Chev. K1500 (4x4) 5.7L with 111,000mi.
My problem(s) started with a P0300 ODBII code (Random Missfire). I have not been able to retrieve any P030X for specific cylinders. The second problem is while driving at a steady speed mainly above 60mph the rpms will climb about 200-400 rpms above normal. I have had the TCC valve replaced, selinoids, and a new torque converter. As far as the missfire corrections that I have made are new plugs, wires, ignition coil, cap/rotor, EGR valve, temp sensor, thermostat, CPS, TPS, Have had fuel system flushed/cleaned numerous times. The exhaust seems to be normal, no excessive oil conumption, and all other fluids and lubricants are at normal levels and have been recently changed or serviced. I am assuming that this missfire is causing the vehicle to think that it needs a richer fuel or that it is underload telling the transmission to not allow the torque converter to lock out. My engine warmss up pretty fast but and operating temp is about 3 lines below 210 degree mark on the temp gage. Could you please give me some suggestions?
Try replacing the thermostat. There is a temperature sensor that makes sure the fluids are warm enough to operate. I had an 1987 Impala that did the same and the temp gauge read fine.
December, 15, 2006 AT 8:28 PM
I replaced the thermostat about 2 weeks ago. This problem has been ongoing for about 10 months. Also it seems to me that when I add any fuel additives, such as injector cleaner or HEAT it has this issue more often and not so intermittent.
December, 16, 2006 AT 3:01 AM
OK, you did not mention what type of fuel injection system you have. I am assuming you have a model 220 TBI unit.
I believe your problem is actually the " fuel pressure regulator".
The replacement part is actually called the FUEL METER COVER, with pressure regulator attached.
It is sold mostly through the dealership parts dept. But check the local parts guys for prices.
It is a simple 20 minute change over but you need a #15 torx screwdriver and Locktite 242 or 262 for all the screws when assembling.
You have been flushing or cleaning the fuel sytem. That stuff can actually make the problem worse when a problem starts. Build up inside is now loose, seals are weak allowing improper air/fuel mixture causing major confusion with you computor.
Do you smell raw gas? Is it hard to start after its been running? Fuel gage working?
Do you have the proper fuel pressure from the tank to the injection system? (Requires a special tool, mechanics have them) A quick check for this is to take off air cleaner, start engine, lift the alluminum ring arounf the tbi to see the flow of gas from the injectors. Should be constant even flow. Actuate the throttle by hand, flow should progress to a spray.
When release do you have an erractic idle? If yes, replace cover.
Very important note, before replacing the cover unhook the battery to prevent any spark, clean the gasket surfaces (2) with a lint free rag and the excess gas that will spill out. Let air dry and assemble.
If you have a transmission problem, you as the home mechanic cannot fix it. Call around to tranny shops and get a quote to scan your trans. You want a printout and no obligations. Do not let them drain it. You just want to see what the scan says first. If there is a problem, then you can shop that around for the best price to repair. This scan service may cost a few bucks. Ask first how much. To me this does not sound like your problem.
Let us know what happens or if you require more help.
PS, I know this because I did the same as you by replacing every single part and then the engine.
Everything new except the TBI fuel pressure regulator. Wasted a lot of money to get good spare parts. If you have flow out of the injectors, they are ok. In the future the only thing you should put into your tank is a good quality gasoline, 87 octane. Discount gas is usually 85 octane. Gas additives are bad for your engine over long periods of continued use. The age of yours, you should not need it.
December, 19, 2006 AT 1:08 PM
I do have a tbi but I am not too sure about the 220 part. Anyway I have contemplating replacing fuel pressure regulator for sometime. I did do this over the weekend. I had to remove the upper intake to get to it. Anyway to make a long story short. It did not work. Same problems, same symptoms.
December, 21, 2006 AT 2:31 AM
Are you able to have the fuel pressure checked by a mechanic with the proper gages. A TBI system should read 9 to 13 PSI.
CPI units run 55 to 61 PSI.
If all your emision parts are brand new, installed correctly, you need to unplug your battery for about 1/2 hour or longer. Let it reset completely.
If you did not unplug the battery before installing the new parts(or at sometime since), your computor is still responding to the fault codes that it was given.
Vacuum hoses: With all the new parts what about $2.00 worth of new vac hoses. Take each one off and blow through one end and finger on the other while bending the hose. Any air leaks? Double check all electrical connections and quick disconnects.
On your new EGR valve, did you take the old one off first and match it with the correct part # that is stamped on it? Did you also install the new washer properly by punching it with an awl at 4 points.
Give me an update and I can get back to you Thursday morn (dec21)
PS working on my brother in law's exact same truck and problem.
December, 21, 2006 AT 3:13 AM
To answer your questions. I match all my replacement parts to original OEM. Helps take the guess work out of things. When changing these parts the battery was always disconnected.
I do have CSFI in this pickup. My fuel pressure is about 60 psi when running and 54psi when the fuel pump initially engages. When I changed out the Fuel Pressure Reg. I noticed that there was not a vacumm hose or return line attached to the old one. I put it into the fuel meter body just like the old one was. Is this correct and if so what happens to the fuel that would be returned, or how exactly does this work?
As far as vaccum hoses, I have only visually inspected those. There are only 3. One to the EVAP canister, PCV valve and the Brake booster. I may have to look into those a little deeper. Maybe you will find the problem with your brother-in-laws vehicle before I do. My bank book is starting to hurt with all the suspected problems. Thanks for the reply
December, 21, 2006 AT 2:43 PM
Just stopped for lunch. We are going to my shop to scope it later today. I can't find whats wrong so I will scan the computor and scope the engine.
Will let you know the results asap.
December, 22, 2006 AT 3:47 AM
Thanks a bunch I'll be watching : D
December, 26, 2006 AT 10:25 AM
I am stumped. We cannot figure this out yet. All emmission parts have been replaced, plugs, cap & rotor, plug wires, fuel filter, pressure reg etc.
Compression test shows normal.
I will be working on this in the next few days.
The only thing I have left to check is to swap out the injectors with some others I have to see if there is a restriction in there, even though my pressure is correct, The actual amount coming out the end does not seem adequet.
I will keep you informed.
December, 26, 2006 AT 6:33 PM
OK I got this one fixed.
Couple of things I need you to check.
1) The pcv valve hose and end couplings. Take this right off the engine. Inspect it 100%. If it is loose fitting at either end replace it with one piece of fuel line hose. It is nice and tight when it goes over the pcv end and the manifold end.
2) Spark plug wires. This is what turned out to be my major problem. I never should have relied on my brother in law telling me that he checked them because they were new about 6 months ago. The # 2 & 4 plug wires bounced off the wire separator clip. The # 2 wire was resting against the exhaust manifold and burnt right through in 2 spots. I did not notice it because the burn was on the bottom side of the wire. This is why I am asking you to check the wires 100% even if it means pulling them right off.
3) Check to make sure the plug wires are connected in the correct firing order to the distributor cap.
Fire order is: 1 8 4 3 6 5 7 2
Hopefully you did not loosen the distributor at all.
Looking at the distributor from the from of the truck, the forward 2 pins on the cap, # 1 is on the right, #8 is on left and keep going clockwise.
Hope this info helps. If you were in Vancouver Canada I would come over and have a look at it personally.
Let me know what happens.