Rough Running - Ignition Coil out?

[KPW]

Thanks for the tips, Young1.



To wrap things up here, the car is back together and running smooth once again. Some things I noticed during this process:

• Next time I'll make sure I drain more coolant than I think I need to. I followed a nice write-up that suggested draining the coolant using the hoses that connect to the plenum/throttle body. I still needed to pull some more to get down below the injector housing level - found out the hard way and spent a bunch of extra time cleaning up coolant. Definitely worth a little more effort at the beginning to avoid cleanup later.
• Old plenum gaskets completely fell apart on the way out. Possible that the last person to be in here added some adhesive...lots of cautious time spent cleaning off the surfaces with a scraper. I applied some silicone spray to the top surface of the new gaskets prior to installation - hoping next time I'm in here it will at least be easier to remove the gaskets, if not enable re-use.
• The valley was gross! Clearing out the drain was much overdue. I did find a plenum screw I had dropped (and a MAP sensor bracket screw someone before me had dropped).
• Solenoid contacts shined up nice with the die grinder stone, and were needed (I'm at 40k miles or so). I have to imagine the starter sitting in a little bit of the valley "soup" wasn't helping either. Feeling more confident in avoiding "no starts" moving forward.
• While the service manual is handy - this forum is just as useful. We're lucky to have access to such a community.

I will say it's nice to have a successful plenum pull under my belt. Nice boost of confidence to understand the effort required, so that the next time it doesn't seem so daunting.

[Paul Workman]

Originally Posted by KPW

Thanks for the tips, Young1.



To wrap things up here, the car is back together and running smooth once again. Some things I noticed during this process:

• Next time I'll make sure I drain more coolant than I think I need to. I followed a nice write-up that suggested draining the coolant using the hoses that connect to the plenum/throttle body. I still needed to pull some more to get down below the injector housing level - found out the hard way and spent a bunch of extra time cleaning up coolant. Definitely worth a little more effort at the beginning to avoid cleanup later.
• Old plenum gaskets completely fell apart on the way out. Possible that the last person to be in here added some adhesive...lots of cautious time spent cleaning off the surfaces with a scraper. I applied some silicone spray to the top surface of the new gaskets prior to installation - hoping next time I'm in here it will at least be easier to remove the gaskets, if not enable re-use.
• The valley was gross! Clearing out the drain was much overdue. I did find a plenum screw I had dropped (and a MAP sensor bracket screw someone before me had dropped).
• Solenoid contacts shined up nice with the die grinder stone, and were needed (I'm at 40k miles or so). I have to imagine the starter sitting in a little bit of the valley "soup" wasn't helping either. Feeling more confident in avoiding "no starts" moving forward.
• While the service manual is handy - this forum is just as useful. We're lucky to have access to such a community.

I will say it's nice to have a successful plenum pull under my belt. Nice boost of confidence to understand the effort required, so that the next time it doesn't seem so daunting.

As Jerry said: Thanks 4 the follow up! And, I too recommend spraying one side of the plenum gasket w/ silicone spray. The plenum side is clean except for the area circling the coolant port - the plenum side and gasket get some 3M gasket adhesive to keep the gasket stable around the coolant port (past experience with leaking there fixed w/ the 3M adhesive, I found).

And, FYI, installing the gasket as you did (w/ the silicone on ONE side), I have been able to removed the plenum one or two more times w/o having to replace the gasket(s). (But, I keep some of Jerry's gaskets on hand, "just in case"!)

And, kudos on the info on the condition of the stater solenoid contacts and mileage! Your experience falls right in line with a few others I have noted in my maintenance log - that is servicing likely required every 40k miles (give or take). I experienced a intermittent NO START as result of those contacts (and the bridge ring connecting the contacts) at just over 40k miles, and now (counting you) reports from 4 others experiencing either some sort of NO START or intermittent starting issues @ ~ 40k miles.

NOTE: I opted to remove my Secondary Port Throttles (SPTs) and plugged the coolant passage leading to the throttle body. As result, there is no need to drain coolant to pull the plenum - just another nice perk resulting from either plugging, or as Marc Haibeck recommends, bypassing the coolant thru the throttle body via a tube running under the plenum. (Marc's method better facilitates removal of air from the system when also jacking the passenger side up to bring the air bubbles to the reservoir tank.)

A plenum pull is "A RITE OF PASSAGE"! Welcome to the BROTHERHOOD OF THE BEAST!!

[XfireZ51]

Side Question. U say u are using yellow top BOSCH injectors on a 91 IH? Are these Bosch III injectors?