My grandmother has an 05 Buick Rendezvous. It has started skipping on #1. She has had the plugs, coil packs, and the #1 injector replaced. But it's still showing that #1 is skipping. Any thoughts ?

You might want to try and take the number 2 cylinder spark plug out and look at it it should be a Gray or very light Brown color.
It's also possible that there's number 2 spark plug had water splashed on it and it was very hot and could have cracked the porcelain on the spark plug. Does your Buick have over a 100000 miles on it or near a 100000 miles if so they may be original spark plugs and need to be changed you can try one Thing, try changing number 2 spark plug with number one or number 3 and see if the problem moves with the spark plug, if it does the spark plug is definitely bad if it doesn't you may have to start looking at the spark plug Wires or maybe even the fuel injector but, you can do the same thing with the fuel injector change it with number 1 and see if the problem moves. Shield injectors usually just pull out of the fuel rail but be careful there's an O ring on them don't lose it it should stay on but you never know.
Anyway good luck to you

What the codes you have ?who tell you to change coil pack, 2002 ,did you change spark plugs, wires, last ting module !!!

what about the most important and vital unit that makes the engine run ---the injector
the item that should be checked first as it blocks with dirt , suffers low fuel pressure and bad wires and connections

Hi patricia, If you have a faulty coil and your car's running rough to find the faulty coil just pull a spark plug lead off and start your car, If it runs (ROUGHER) than before then that coil is ok. Turn the car off and replace that spark plug lead back on to the spark plug. Repeat with the next spark plug lead and so on until you start your car and it runs the same as if THAT spark plug lead is on or off, NOW TO MAKE SURE THIS IS THE FAULTY COIL, Put a spark plug into the spark plug lead that's off and earth it to the motor or body (it has to be touching steel), Start the motor and if that's the faulty coil the spark plug won't spark I hope this helps.....

I'd suspect a sticking injector--car should have set the check engine light. Read the code(s) to progress further. If the coil pack were a problem, it would not be likely to fix itself. If the codes indicate an injector problem, try an injector cleaner in the fuel--worst case, replace the bad injector. The codes should indicate which cylinder to change the injector.

IF VECHICLE HAS OVER 100000 MILES, REPLACE SPARK PLUGS AND WIRES,REPLACE AIR FILTER,CHANGE FUEL FILTER AND CLEAN FUEL INJECTORS.WEAK COILS MAKE CAR SKIP SPUTTER, IF ALL FAILS YOU HAVE LOW COMPRESSION WORN VALVES.

Do you have a code for a misfire?

If a crank sensor goes bad the vehicle will typically not start at all.

If you have spark to all the cylinders than the next step is to either check compression or check the injectors. Usually the injectors will stick when this happens they will ohm out fine but will not spray fuel. To check them you will need either a high end scan tool or and injector tester and an fuel pressure gauge. The tester is connected to the injectors one at a time using the bulk connector near the alternator. The injector is then triggered by the tester as you watch for a drop in fuel pressure. Whichever injector does not drop fuel pressure when triggered is the bad injector.



I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

The very first thing that you should do after finding a cylinder mis-fire that can not be easily explained such as a fouled spark plug, is to take a compression test especially of the mis-firing cylinder to be certain that the mis-fire is not caused by a mechanical problem, and I have seen people spend a lot of time and money trying to hunt down an electrical problem when the actual problem was a mechanical one, and no electronic part will repair a burnt or bent intake or exhaust valve.

I'd suspect a sticking injector--car should have set the check engine light. Read the code(s) to progress further. If the coil pack were a problem, it would not be likely to fix itself. If the codes indicate an injector problem, try an injector cleaner in the fuel--worst case, replace the bad injector. The codes should indicate which cylinder to change the injector.

The firing order is 1-6-5-4-3-2  the engine from the passenger side to the drivers side, radiator side 1-3-5 and on the fire wall side 2-4-6
The 3 coil from the radiator to the fire wall. #1 coil 1-4 #2 coil 5-2 and coil #3 3-6 Good luck and keep me posted, be glad to help. Its harder to explain then show, hope i made sense.