When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I got the code today during my drive to work. At low speed and idle, car seems to idle rough and backfire. It appears that cylinders 1 and 3 are misfiring. 3 more so than 1. I pulled the the plugs and wires and they appear normal. I have a Tech 2 clone and took the following pics while idling. Appreciate any help.
If you are pretty certain the plugs and wires are OK you can take a mixture of baking soda and water (conductive) and spray it around those 2 plug wires and see if you see arcing but best to do this in a dark garage...this may an electrical issue too so I would look at this area in the picture because there are chaffing issues here...it is at the rear of the left fuel rail...coil pack and injector wiring runs in this harness...what do your long and short term fuel trims look like at idle ??...with an injector misfire your long terms on that bank will be high...around 15% or so because of the excess oxygen in the cylinders. GREAT you have a Tech 2…very powerful piece of machinery there !!
C5 Diag
Thanks for the reply. I'll spray the wires tonight. The first pic is my wiring. It looked ok to me. The rest of the pics are my fuel trims and O2 sensors. I'm still learning to use the Tech 2. bought it to exercise my ABS and bleed the brakes. I'm finding other uses. The car has 36k on it and resides in the garage.
Mike, your fuel trims look fine…looking at O2 sensor voltages really don’t tell you anything and you have to really graph them to get any useful information…you can graph them with the Tech 2…upstreams should oscillate between 200-800 Mv and the downstreams should be fairly constant at around 700 mv’s or so…if an upstream O2 is reading high well over 500mv’s (stuck rich) the PCM will be taking away fuel (shorter injector pulse) and you can get lean misfires this way.
I just sprayed 1 and 3 wires with a baking soda water solution. Didn't get any arcs. The P 0300 code I read off my DIC. Using a scanner I read P 0303. Thoughts? And thanks again.
Well the P0303 is cylinder 3 misfire….is the misfire only at idle or higher RPM ??…the misfire can be ignition, fuel, or mechanical such as valve springs etc…I’m extremely fortunate to have pretty advanced diagnostic equipment so for me it’s not hard to diagnose a misfire but without this equipment it will be necessary to change or swap parts. If you have a fuel pressure gauge you can do an injector balance test and see if you have a faulty injector…ignition coils are pretty bulletproof but you can remove the #3 plug wire from the coil pack and see if the spark jumps from the coil pack to the plug wire or swap #3 with another coil pack and see if the misfire moves… As in the video you can do a do a quick “cranking” compression test…keep the gas pedal to the floor while cranking the motor over…the car won’t start but listen for an even cranking cadence…this can signify low compression…you can try swapping plugs to see if the misfire moves too.
Update: I swapped coils from 3 to 5. No change. I then moved the plug and wire from #3 to the opposite side #2. The misfire moved to the other bank. I swapped out the wire. No change. Put a new plug in #2 and the problem is fixed. The plug I plulled out is an irridium tipped plug with about 5k miles on it and no visible cracks or damage. Thanks to C5 Diag for his help.
Update: I swapped coils from 3 to 5. No change. I then moved the plug and wire from #3 to the opposite side #2. The misfire moved to the other bank. I swapped out the wire. No change. Put a new plug in #2 and the problem is fixed. The plug I plulled out is an irridium tipped plug with about 5k miles on it and no visible cracks or damage. Thanks to C5 Diag for his help.
Mike
Glad to hear !!…sometimes a visual inspection is not good enough…that’s where swaptronics comes into play !!
P 0300
