**I know this issue has been done to death on these forums, I can’t find any that match my exact description**

My car keeps going through spark plugs. It has intermittent start/stall issues rough idle and hesitation/stumble when accelerating. The old plugs always have a build up of carbon. When the plugs are replaced all the problems vanish. I have to do this every couple of months.

My Car:
1994 Honda Civic EX 134,XXX miles automatic transmission. No CEL even after stalling.

Detailed description of Symptoms:
The car stutters with sudden acceleration. The RPMS drop very low flutter close to stalling, if I let up on the gas, it tends to stabilize, but I've had it completely stall on me even after letting up. The more sudden I accelerate, the worse the symptoms are.
You can smell un-burnt fuel when the car stalls.
Yesterday I replaced the NGK spark plugs with BOSCH Platinum spark plugs, the stuttering is gone. I can push on the gas as quickly as I want, I cannot get it to stall.

History:
Before I owned the car, my father did, he informed me that multiple components in the starter had been replaced before finally they replaced the entire starter. When I got the car, it did fine for a while, but it would start taking longer and longer to start. Eventually it wouldn’t start at all. It seems to do worse when low on gas, but I’m NOT SURE. It would and has always cranked, but it wouldn’t start. I replaced the spark plugs, and the engine fired up, no problem.
Fast forward a few months, I’ve been doing multiple maintenance operations on the car, I’ve found that the TPS is bad. The car would downshift incorrectly at the wrong speeds, and spontaneously jump gears. I unplugged the TPS and the shifting smoothed out. However, I have yet to install a new TPS. Could a bad TPS cause spark plugs to go bad? Right now I’m leaving the TPS unplugged, so there IS a CEL for that, but only that. When I reconnect the TPS the CEL goes away.

Elimination of Suspects:
To my knowledge all potential combustion problems will fall into three main categories:
1. Fuel System (Pump, Regulator, Filter)
2. Electrical (Plugs, Rotor, Sensors, ECU)
3. Airflow (Intake/Exhaust/Vacuum Restrictions)

My logic: By eliminating even one of these categories, I can effectively cut off dozens of individual tests and have a better chance of making a successful repair.

From my own research the following are a few of the top suspects:
Catalytic Converter, Head Gasket, Fuel Pump/Fuel Pressure Relay, Vacuum Leak, Grounding Issue, Distributor Cap, Wiring Short, Idle Air Control, Ignition Coil, Ignition Timing, Wrong Spark Plug Type, Rotor.

 

Last ignition tune up? Fix your TPS.

 

Fixing TPS is first on my to do list. That and buying new NGK plugs for the car. I hear bad things about BOSCH in hondas.
Ignition tune up, that would just be a regular tune up, right?

I've visually inspected the rotor and distributor cap, they look good, but I haven't replaced them. They look pretty new to be honest. Spark plug wires are new

 

How do you know the TPS is bad?

 

Car would shift erratically at lower speeds. When coasting down from 20 mph in particular, the car would suddenly shift down prematurely, the result was a sudden jerk. At times it would shift down, and then up. Again this all happened fairly regularly (several times a day) and was quite annoying. The car was always in gear, but it didn't seem to know which gear to go into. When I unplugged the TPS, the symptoms completely dissipated. I've been driving for several days, trying to reproduce what it used to do.

I'm not very experienced with fixing cars. But I'm 100% sure that the strange shifting issues were completely resolved by disabling the TPS.

For more info, see this post:
https://honda-tech.com/forums/showth...7#post49210057