1988 3.2 trouble with #2
 

Working through the list of causes to a rough running motor.

I use car for auto-cross. stock motor with chip.

2012: First indication of a problem started after tracing it to cylinder #2 not firing. Plug was dirty, spark checked out and ended up replacing the injector, problem solved. I thought.

2013: Rough running, idle and low RPM rough running returned. At event once again loOKing at #2, and pulled wire no real change in idle. At higher rpm power seemed OK. Although I have to admit hard to tell above 5k rpm.

1. Spark checked out, all cylinders.
2 Checked rotor and Cap, OK
3. Fuel pressure confirmed on the numbers.
4. Injectors 1-3 checked for electrical resistance, in range
5. Plugs pulled 1-3 pulled. 1 and 3 dry, #2 wet.
6. Injector electrical input. to injectors, checked ohm meter, OK.
7. Leak down on # 2, compared to #1 both under 6% (see note)
8. Pulled head temp plug, idle went up ~ 2k, ran better than @ 800 idle
9. After bringing car up to temp, checked head temps. In this check #2 running cooler by 120 degrees Vs #1 and # 3.

Next steps ( Open to Suggestions )
1. Reconfirm leak down test ( 1 st attempt, second just to confirm it)
2. If the leak down indicates a bad cylinder then planning repair.
3. If leak down confirms compression is OK then.

#2 injector, pulling valve covers and checking clearances, Other suggestions.

Updated. Just finished last night

1.Checked timing again, confimed
2. Re-checked leakdown, # 2 under 4%.
2.Replaced # 2 plug with used bench stock.
3. Confirmed it was firing.


Ran up to temp and seemed to run better, idle improved to my ear
Scanned exhaust man. temps again and # 2 back in range +/- 30

Conclusion at this point was could have been a bad plug,,,

Next step is to adjust valves, with oil change
Replace plugs...
Hope this solves the issue...
Thanks Dave B for the help....

1.Checked timing again, confimed
2. Re-checked leakdown, # 2 under 4%.
2.Replaced # 2 plug with used bench stock.
3. Confirmed it was firing.


Ran up to temp and seemed to run better, idle improved to my ear
Scanned exhaust man. temps again and # 2 back in range +/- 30

Conclusion at this point was could have been a bad plug,,,

Next step is to adjust valves, with oil change
Replace plugs...
Hope this solves the issue...
Thanks Dave B for the help....

I see leak down is good did you do a compression test?

Bad valve guide on #2? Wet & fouled plug is often caused by a leaky valve guide.

common on 3.2, the lower intake gasket gets sucked in, creating an air leak that kills the cylinder function at idle and low rpm. hard to diagnose by spraying stuff at the area because it's deep below the surface of the fan shroud. if you have compression, injector function, spark, and valve clearance, it's a possibility.

Thanks, never would have considered that...Appreciate the post..

you could also swap injectors between 1 & 2 and see if anything changes. hard to check electric injectors to see if they're actually spraying. kind of a pain, but easier than pulling the intake.

Kevins post seems to be possible. R&R'd plugs, after bench replacement on # 2 seemed to solve firing issue. The plugs got a few runs during the club auto x yesterday and car was running much better. First DE in a few weeks and will check # 2 again to see if it is getting fouled.

I did not do a compression test (CT), just leak down, I do plan to complete a leakdown and CT after the DE.

Thanks for the posts.