2.3L ('83-'97) Cylinders #2 and #3 fouling plugs

[Silas Mc]

1990 Ford Ranger 2.3 5spd. I have lots of exhaust popping and sometimes the engine will POP POP POP and die when you open the throttle. I took the plugs out and #2 and #3 appear to be fouling. I've read from someone in the forum that 1&4 injectors are grounded together and 2&3 are grounded together from the ECM. My thought is the ecm driver for these injectors isnt quite right. What else would cause these cylinders to run rich? My compression is great in all, 15% difference in total.

 

[scotts90ranger]

The only other thing relating to timing is the crank sensor (well and the ignition module, both of which are usually all or nothing), I don't remember the difference on how it uses the two vanes on the balancer but if the divider between the two is broken it wouldn't work right...

 

[Mechrick]

Is the pop noise backfiring?

If so, backfires are *almost* always an ignition concern.

 

[Silas Mc]

Is the pop noise backfiring?

If so, backfires are *almost* always an ignition concern.

Possibly. Either those plugs are not burning hot enough or mistimed. Or the injectors are staying open way too long and fuel is going into the exhaust.

 

[Silas Mc]

The only other thing relating to timing is the crank sensor (well and the ignition module, both of which are usually all or nothing), I don't remember the difference on how it uses the two vanes on the balancer but if the divider between the two is broken it wouldn't work right...

I think you're right. Injectors 2 & 3 are grounded together and both cylinders share the secondary coil on the coil pack. So, the ignition module could be partially faulty (somehow), or the crank sensor is for some reason sending off time signals. I will check the crank sensor, but whatever part it is, they are not cheap!

 

[Mechrick]

Crank sensor is common to all cylinders. Probably not that. DO check the tone ring on the crankshaft for missing/broken teeth.

 

[Silas Mc]

Just removed the balancer. The tone ring thingy had a loose rivet, so it has a slight wobble. But I think the bigger issue is the loose tone ring actually scratched the crank sensor up and dug into some of the plastic.

 

[scotts90ranger]

Yeah, that won't help, do what you can to center it. There's some cheaper crank sensors that just don't come with the connector and require some splicing of the 3 wires which likely isn't that big of a deal since the connector doesn't fit under the rear timing cover anyway...

Still, is it a early '90 with MAP or a later '90 with MAF sensor? that changes some troubleshooting...

 

[Silas Mc]

Yeah, that won't help, do what you can to center it. There's some cheaper crank sensors that just don't come with the connector and require some splicing of the 3 wires which likely isn't that big of a deal since the connector doesn't fit under the rear timing cover anyway...

Still, is it a early '90 with MAP or a later '90 with MAF sensor? that changes some troubleshooting...

Mine is later with the MAF sensor. Would that matter considering it's only cylinders 2 and 3?

 

[scotts90ranger]

Not really, mainly on the popping part, intake backfires are usually from running lean from my experience, MAF systems are WAY more picky on vacuum leaks than MAP systems but usually they just run bad not backfire and such...

 

[Silas Mc]

Not really, mainly on the popping part, intake backfires are usually from running lean from my experience, MAF systems are WAY more picky on vacuum leaks than MAP systems but usually they just run bad not backfire and such...

Good to know. I tested the vacuum and it sits at 17in/Hg so luckily no leaks. I'll give an update once I have a new sensor, finger crossed that's the issue.

 

[Silas Mc]

I put a new sensor in and that solved all my issues. My truck runs really well now.