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Misfire Troubleshooting, Clogged Injector, No Overdrive
I have a 2002 Z71 Suburban, 5.3 vortec, 143,000 miles. I have done many things to try to isolate a P0307 (Misfire Cylinder #7) and a P0171. I have installed new (AC Delco) wires, and a new set of AC Delco Iridium Plugs. I'm at the point where I'm ready to move around a couple of injectors to see if the problem moves with the injector. My parts guy at the Chevy dealer says the injector (one) is right around $100. Oh well, I can live with that, if I can be sure it is causing the problem. Apparently it is pretty easy to remove the injectors, by removing two screws, one on each end of the rail, and lifting the rail and pulling out the injector which is held in by o-rings. Is it really that easy? It LOOKS that easy, but how many times have I worked on something on this truck and it almost never is as it appears. Is there a correct method to clean these soleniod/injectors?
Thanks in advance for your help.
Add on: I've put two bottles of Chevron Proguard Injector Cleaner with Techron, and filled up the tank... , let's see what happens now. I can't seem to find the newer verision of the cleaner: Chevron TECHRON Concentrate Plus Fuel System Cleaner except at the chevy dealer. 20 oz. is around $19.00. Can't seem to find it on-line either. I guess it is a HAZMAT material for shipping?
New news::great:
After swapping wires one at a time across the engine, then the coils, then the plugs, I finally got to the injectors. It was pretty easy to remove the injectors, of course there is some gas that comes out each time, no big deal, easily cleaned up. I finally swapped them over to the other bank, one at a time and found the bad one. $120 for a new one and the truck runs great again. I soaked the remaining 7 injectors in top engine cleaner available at Chevy, mixed with gas as it recommends. I then ran about a gallon (maybe less) through the rails while the engine was running, using a pressurized tank setup I made. Similiar setup to the rail cleaner at the shop I normally go to. WOW, that made everything else clean. Poured some of the mixture in the brake vacuum line as it was recommended to me by the helpful parts guy at SUN Chevy on Sunrise Hwy in Suffolk County NY, and then ran the Techron cleaner. Spotless! The techron cleaned everything else up. If you mess with the injectors, buy the seal kit first, just in case you nick an o-ring. Definitely good to have around, especially if your truck has the same amount of mileage as mine. Now I'm at 184,000.
Another side note: I had another problem and did not know it was related. My tranny would not go into overdrive all the time at highway speeds. I took it to several transmission shops, and everyone said it needed to be replaced. Since it was some serious money to do this, I wanted to make sure I fixed all the codes that showed up on the diagnostic reader, before shelling out this money. These codses were the bank lean code and the misfire code. NO CODES for the tranny...
Once I fixed the injector, and both of the codes stopped coming up, THE TRANNY SHIFTED GREAT. I found out that the computer stops the tranny from shifting into overdrive (High stress situation on the drive train) when it detects misfires etc. I must have had misfires for awhile, since this problem was happening and slowly getting worse. The codes were not showing up as check engine, since it was not often enough. I also found out if the code was pending ( it didn't happen three times) and you went through 3 or so engine warmup and drive cycles, it would automatically reset the code. Not all codes reset after this few cycles, only a couple of them, and misfire is one of them.
All I know is that using good gas, that may mean more money per gallon , is better than trying to find where the next misfire is coming from. I now run injector cleaner periodically, to maintain clean injector.
I love my Chevy Z71 Subruban. Here's to another 180,000!
I have a 2002 Z71 Suburban, 5.3 vortec, 143,000 miles. I have done many things to try to isolate a P0307 (Misfire Cylinder #7) and a P0171. I have installed new (AC Delco) wires, and a new set of AC Delco Iridium Plugs. I'm at the point where I'm ready to move around a couple of injectors to see if the problem moves with the injector. My parts guy at the Chevy dealer says the injector (one) is right around $100. Oh well, I can live with that, if I can be sure it is causing the problem. Apparently it is pretty easy to remove the injectors, by removing two screws, one on each end of the rail, and lifting the rail and pulling out the injector which is held in by o-rings. Is it really that easy? It LOOKS that easy, but how many times have I worked on something on this truck and it almost never is as it appears. Is there a correct method to clean these soleniod/injectors?
Thanks in advance for your help.
Add on: I've put two bottles of Chevron Proguard Injector Cleaner with Techron, and filled up the tank... , let's see what happens now. I can't seem to find the newer verision of the cleaner: Chevron TECHRON Concentrate Plus Fuel System Cleaner except at the chevy dealer. 20 oz. is around $19.00. Can't seem to find it on-line either. I guess it is a HAZMAT material for shipping?
New news::great:
After swapping wires one at a time across the engine, then the coils, then the plugs, I finally got to the injectors. It was pretty easy to remove the injectors, of course there is some gas that comes out each time, no big deal, easily cleaned up. I finally swapped them over to the other bank, one at a time and found the bad one. $120 for a new one and the truck runs great again. I soaked the remaining 7 injectors in top engine cleaner available at Chevy, mixed with gas as it recommends. I then ran about a gallon (maybe less) through the rails while the engine was running, using a pressurized tank setup I made. Similiar setup to the rail cleaner at the shop I normally go to. WOW, that made everything else clean. Poured some of the mixture in the brake vacuum line as it was recommended to me by the helpful parts guy at SUN Chevy on Sunrise Hwy in Suffolk County NY, and then ran the Techron cleaner. Spotless! The techron cleaned everything else up. If you mess with the injectors, buy the seal kit first, just in case you nick an o-ring. Definitely good to have around, especially if your truck has the same amount of mileage as mine. Now I'm at 184,000.
Another side note: I had another problem and did not know it was related. My tranny would not go into overdrive all the time at highway speeds. I took it to several transmission shops, and everyone said it needed to be replaced. Since it was some serious money to do this, I wanted to make sure I fixed all the codes that showed up on the diagnostic reader, before shelling out this money. These codses were the bank lean code and the misfire code. NO CODES for the tranny...
Once I fixed the injector, and both of the codes stopped coming up, THE TRANNY SHIFTED GREAT. I found out that the computer stops the tranny from shifting into overdrive (High stress situation on the drive train) when it detects misfires etc. I must have had misfires for awhile, since this problem was happening and slowly getting worse. The codes were not showing up as check engine, since it was not often enough. I also found out if the code was pending ( it didn't happen three times) and you went through 3 or so engine warmup and drive cycles, it would automatically reset the code. Not all codes reset after this few cycles, only a couple of them, and misfire is one of them.
All I know is that using good gas, that may mean more money per gallon , is better than trying to find where the next misfire is coming from. I now run injector cleaner periodically, to maintain clean injector.
I love my Chevy Z71 Subruban. Here's to another 180,000!
