Last post on Dec 09, 2013 at 4:59 AM
You are in the Chevrolet Suburban & Tahoe
What is this discussion about?
Chevrolet Suburban, Chevrolet Tahoe, Chevrolet Silverado 2500, Engine, SUV
#27 of 209 Engine Running Rough On/Off
Jan 30, 2008 (7:50 pm)
My wife and I purchased a 2003 Chevy Suburban. At first, we had no problems until we had the vehicle for a few months. We ran the ODB II diagnostics and found several cylinders misfiring, and injector circut malfunctioning. We then took it in to dealer to have it further diagnosed and fixed. They did their thing and replaced one injector wire at first, but that did not fixed the issue. Problem reoccurred after we brought the vehicle home. So we took the Suburban in again and they said they had to replace 3 more injector wires. They did that, and everything was fine until another week passed. Same problem again. I got tired of the run around and didn't have the patience with the dealer, or the money we were throwing away. I did simple check of sparkplug, sparkplug wires, fuel injector wires, and to my surprise it was the main ignition coil connector wires. I ended up splicing up the wires together. I did more checks inside the wire jacket that leads back to the main computer in the engine. Found more wires that were worn down to the copper. Seems like either prior owner or dealer tried to fix the problem and couldn't find the main issue.
So now, my Suburban runs fine.
#28 of 209 Re: Vibration when idling or at red light [stash1]
Feb 04, 2008 (10:42 pm)
Don't know if you solved this problem, but YES 87 octane gas will cause this problem. Octane is an additive that is put into gasoline to reduce the spontanious combustion that happens when gasoline is compressed inside of the combustion chamber. The lower the octane the higher the chance of spontanious combustion. This is bad because if gasoline combusts (fires) before the spark plug ignites the piston will be on the way up in the cylinder. This is what is known as a "ping" or "detonation". A "ping" will eventualy destroy a motor.
#29 of 209 Re: Stalling while coming to a stop or idling [bc13]
Apr 01, 2008 (6:34 am)
I have a 99 Suburban with a 5.7. I had a leak on my intake gasket and got that replaced. After a week, engine runs rough and showing P0300. Replaced cap/rotors, plug, wires, MAP sensor, Cam Sensor, and Crankshaft sensor. Then I replaced the ecm. Still doing the same thing. Mechanic advised me that it can be the head gasket that will run be about $1200 to $1500. I don't think thats the problem. I did not let them fix the head gasket. After I replaced all the things that I replaced, now its showing p0304 cylinder misfire on 4. Please help if anyone solved the problem. Can it be my EGR valve, fuel injector? I checked the plug on cylinder 4 and it is firing fine.
#30 of 209 Re: Stalling while coming to a stop or idling [elorenzo39]
Apr 01, 2008 (2:12 pm)
You could have a bad head gasket around cylinder#4, right?
Have any compression tests done??
#31 of 209 Re: Stalling while coming to a stop or idling [elorenzo39]
Apr 01, 2008 (5:17 pm)
It is very important that A/C delco spark plugs, and spark plug wires are used on these engines. A p0300 is a general misfire and a p0304 is cylinder 4 misfiring. They both may or may not be related. Your engine has a problem that many people overlook, the distributer gear wears out--especialy after it is removed and put back in--as it was when you had the intake gaskets done. If the distributer gear wears too much it will misfire the engine. Also, the timing on your engine must be set with a computer scan tool, NOT a timing light--like in the old days. When the distributer was removed on your engine, it is almost impossible to put back in exactly perfect. This is a commonly overlooked problem also. A dealer is the only one who can properly time your engine. When the intake is removed from the engine, the injector electrical connector must be unplugged. This plug is very sensitive to damage. It is easy to bend the little pin that plugs into the injector. This could be the cause of cylinder 4 missing.Also make sure that all the ground wires are put back on the engine. The ECM fires the injectors by controlling the ground (not the hot or power wire). If a ground is off it could overload the ground system by putting strain on other grounds to pick up the slack. Grounds work just like power wires when it comes to overloading. This also could be an intake leak. Start the engine and let it run for a while. Now, get a spray can of electrical cleaner ( CRC ) or brake cleaner and spray it around the upper and lower intake while the engine is running. If the engine boggs down or starts to run bad-and -- then clears up when you stop spraying---you have an intake leak. If this is the case the intake gasket was changed wrong... The best way to determine if the head gasket is bad is to do a compression and leak down test on all cylinders. If the plug looks fine then it is probably NOT the head gasket---do a compression test to be sure though....
Your problem sounds like a leaking intake somewhere or most likely electrical.
#32 of 209 Re: Stalling while coming to a stop or idling [pear69]
Apr 02, 2008 (3:47 pm)
I Thank you all for helping me out. It really helped me alot. I think I got it figured out. The engine has no Vacuum leak. The problem is my #4 fuel injector. I pulled the spark plug that I have installed 2 weeks ago and it looks like the injector is bad. I will be replacing my fuel injector assembly this weekend and I will let you all know the outcome. Cross my finger that the problem is solve. I finally had another mechanic take a look at it last night. He checked the vacuum leak, compression and he came up with a bad injector on cylinder number 4.
Keep you all posted after this weekend.
Thank you again.
#33 of 209 Re: Stalling while coming to a stop or idling [elorenzo39]
Apr 02, 2008 (9:51 pm)
If you are changing the entire assembly I suggest installing the upgraded injector assembly. Your stock injector assembly is called a cpfi system--the upgrade is called mpfi. The only difference is that the injector itself is moved from the center of the assembly (stock location) to the port of the intake runner (upgraded location). The reason this is better is that it elliminates the (problem proan) poppet. If the 4 injector is the problem, then it is the poppet sticking --causing a "burp" in the fuel flow. I bet the 4 spark plug is all covered with black soot---carbon--isn't it?
#34 of 209 Re: Stalling while coming to a stop or idling [pear69]
Apr 03, 2008 (9:21 am)
Thanks for the information. I heard about the upgrade version and that is what I will be looking for tomorrow and I get the new injector assembly. I really appreciate all your help. I will keep you all posted by this weekend if I solve the mystery.
You are very right. The plugs are only about 2 1/2 weeks old and I have pulled number 2 and 4 plug to compare and you are right on. The number 4 plug was black and the number 2 was perfect. I have also pulled the plug next to 4 and it was fine looking too.
Anyway, I will keep you all posted and thank you so much.
#35 of 209 Re: Stalling while coming to a stop or idling [elorenzo39]
Apr 03, 2008 (10:53 am)
Go on Ebay type in sefi update and you will see the updated version of your injector assembly in DR. INJECTORS Ebay store...
#36 of 209 Re: Stalling while coming to a stop or idling [pear69]
Apr 03, 2008 (11:15 am)
I thank you again. I will check it out right now. Thanks and will keep you all posted.