Random miss at idle, new plugs & coil packs

[Kamran Khan]

Bump... any input would be greatly appreciated

Do a compression test on all cylinders. Low compression can cause misfire and rough idling.

 

[SeaCruise]

Do a compression test on all cylinders. Low compression can cause misfire and rough idling.

Thanks for the suggestion. However, I highly doubt it's a compression issue; I also have an old 86 Toyota pickup, the 22RE motor in it has low compression in one of the cylinders and that is a consistent rough idle and it lacks full power - the issue being discussed here is very random, as can be seen in the video. Might not do it at all for one trip, then the next trip it's doing it at every other stop. The truck runs perfect otherwise.

Bozncsurf let me know he is having a similar issue, and his appeared right after replacing a valve cover gasket. While I haven't replaced on mine, it is prompting me to investigate whether an old / leaking (or improperly installed) gasket would cause something like this.

 

[Kamran Khan]

Thanks for the suggestion. However, I highly doubt it's a compression issue; I also have an old 86 Toyota pickup, the 22RE motor in it has low compression in one of the cylinders and that is a consistent rough idle and it lacks full power - the issue being discussed here is very random, as can be seen in the video. Might not do it at all for one trip, then the next trip it's doing it at every other stop. The truck runs perfect otherwise.

Bozncsurf let me know he is having a similar issue, and his appeared right after replacing a valve cover gasket. While I haven't replaced on mine, it is prompting me to investigate whether an old / leaking (or improperly installed) gasket would cause something like this.

There aren’t many things that causes misfiring. All I can think of
1. Spark plugs, ignition coils
2. Vacuum leaks
3. Weak engine, low compression
4. Electrical wiring to Ecu.
In first gen Lexus sedan cars ECU circuit board use to accumulate corrosion that use to cause all kinds of strange problems.
Check your car’s ECU, look for swollen resistors or bad soldering joints. Check your fuses clean your fuses inlets with electrical cleaning spray.

 

[Kamran Khan]

Lastly unplug MAF sensor, if the car dies that indicates that MAF is good but if it’s still idling that indicates that MAF sensor is bad.
Do resistances test on all O2 sensors.

 

[SeaCruise]

There aren’t many things that causes misfiring. All I can think of















1. Spark plugs, ignition coils















2. Vacuum leaks















3. Weak engine, low compression















4. Electrical wiring to Ecu.















In first gen Lexus sedan cars ECU circuit board use to accumulate corrosion that use to cause all kinds of strange problems.















Check your car’s ECU, look for swollen resistors or bad soldering joints. Check your fuses clean your fuses inlets with electrical



There aren’t many things that causes misfiring. All I can think of



1. Spark plugs, ignition coils



2. Vacuum leaks



3. Weak engine, low compression



4. Electrical wiring to Ecu.



In first gen Lexus sedan cars ECU circuit board use to accumulate corrosion that use to cause all kinds of strange problems.



Check your car’s ECU, look for swollen resistors or bad soldering joints. Check your fuses clean your fuses inlets with electrical cleaning



Lastly unplug MAF sensor, if the car dies that indicates that MAF is good but if it’s still idling that indicates that MAF sensor is bad.

Do resistances test on all O2 sensors.

 

[SeaCruise]

Thanks, I'll check these things first. It may not even be accurate to call it a misfire, I just couldn't think of a better description. It's like a hesitation, and less dramatic than a coil failure related misfire, which is very constant and obvious (and also has the benefit of a CEL to help one isolate the problem!)

Thanks again for the replies, much appreciated!

 

[bozncsurf]

Thanks, I'll check these things first. It may not even be accurate to call it a misfire, I just couldn't think of a better description. It's like a hesitation, and less dramatic than a coil failure related misfire, which is very constant and obvious (and also has the benefit of a CEL to help one isolate the problem!)

Thanks again for the replies, much appreciated!

This is a very accurate description. With symptoms this inconsistent and rather vague in nature it calls for the help of the ih8mud 100 series gurus to chime in

Appreciate all the comments so far and would welcome any additional!!

Any thoughts @hoser @2001LC

 

[DBULL]

I have the same miss/stumble only when the engine is cool and only at idle and off idle acceleration.I attributed it to bad gas,added a large bottle of Techron and a tank of 89 octane. It seemed to be better but after I ran that tank and another it came back. I did find a small amount of water when I changed my fuel filter and drained it into a clear bottle.Like the original poster I have no codes showing on my scanner and after I reach normal water temperature the miss is absent which makes me lean towards a vacuum leak or crappy fuel..I’m still looking…