Engine studdering

[Ray Brown]

This time of year when I need to use my heat and defroster, my engine starts to shake during acceleration. Also while trying to accelerate to get onto the highway. It feels like the engine is about to fall out. The engine light flashes for approx 30-40 seconds then goes off. I have checked the codes and it says misfire. I changed the coil packs before but this situation only arises with the heat and defrost. It works fine when the air conditioner is on. Could this be something different then coil packs? Please help with this situation.

 

[Bryan E 2]

Sounds to me like possibly fuel filter?

 

[Yardsale]

What is the OBD code? This will help to know where is the misfire (left bank, right bank, before or after one of the oxygen sensors, etc.) and what may be the cause(s).

... when I need to use my heat and defroster, my engine starts to shake during acceleration.

I assume that you ARE using them. Try using them independent of each other (i.e., defrost on, no heat; defrost off, with heat). Also assuming that there is no stutter with heat and defrost off. Trying to isolate the cause and or contributing factors.

Also while trying to accelerate to get onto the highway.

Is this a different problem, or just a different scenario that causes the stuttering? Does this happen whether or not the heat and or defrost are on?



Shaking while accelerating can be from by badly worn tire caused by alignment, shocks, tire defect, suspension bushings, bad motor and or transmission mount.

The engine light flashes for approx 30-40 seconds then goes off.

When does this occur - at start-up (cold, hot, or both?), cruising, any time you are accelerating?[/quote]

 

[Vic Sorlie]

How many miles on this Trac - and same question for spark plugs. You're saying misfire code(s) present, but for which cylinder(s)? Are you getting any other indication of fuel starvation? I'd start with the basic tune-up items: Fuel filter, air filter, spark plugs, PCV valve, battery condition/connections, check intake boot integrity.

 

[Yardsale]

I'd start with a diagnosis ...

 

[Ray Brown]

I think I want to try changing the fuel filter. It has 77000 miles on it and I don't know if it has ever been replaced. Any fast ideas where it is located and if it is easy to change?

 

[Vic Sorlie]

There's some info on FF replacement in Projects>Maintenance section of this website. Additionally there's plenty of DIY YouTube videos out there. Just do a search. A local quick lube will probably charge you $50 or so for this service; you can do the job yourself quickly for $20 or less. Wear safey glasses.

 

[Jack MacThomas]

had this in seattle area, if the gap on spark plugs erodes and it's humid AND cold you get condensation on the plugs and it acts weird for a while. dunno why but it happened.

 

[Gavin Allan]

Change a bunch of parts and fluids and see it that helps. Maybe try premium gas too. Nitrogen in the tires. Oil additives. Something is bound to fix it.