Intermittent cylinders dropping

[sdb999]

87' 22re 5spd. Good compression and normally rock solid reliable. It has started to have "spells". It will be running fine then drop 1 or 2 cylinders, then just as mysteriously they will come back and it will run fine. These spells have happened on the trail crawling in 4wd low first gear and on the street cruising in third or fourth. They can last for a few minutes or an hour or two, of course duration is inversely proportional to distance from tools and paved roads. I have replaced the plug wires and the plugs are fresh. Haven't been able to narrow down to specific cylinder(s) just yet.

Last thing I touched was removal of top half of intake manifold to re route wires that po had routed incorrectly. Pretty much touched every connector including injectors on that side of engine. I cleaned intake track and t-body at the same time.

Going to explore tomorrow and looking for any ideas better than mine.
I'll start around the intake wiring as this never happened before that work. Fuel and spark connections first and hope I can replicate. After that I'd be down to throwing parts at it. Wow this got long, sorry.
Any thoughts and ideas greatly appreciated.
Thanks, S.

 

[flyinhawaiian01]

Long good! Short and no info, bad!!!!

I'm thinking its the connectors to the injectors, only because you removed the top side stuff lately, and it sounds like it ran fine before that.

Its a pain to get to the wiring while the intake is still on, but if you can jiggle the wires for the injectors around when its running on 2 cylinders, see if it changes it. Free and you don't have to pull anything apart just yet.

If its spark, you could just pull wires to see which cylinder(s) are misfiring. And running that long without spark, you should be able to just pull the plugs and see which ones are wet. If you have an IR thermometer, just read the temps on each cylinder after about 5 or 10 minutes of it misfiring. Should be colder right at the plugs that aren't running.

 

[mikesmith140]

I had a similar issue. I tried all the easy to get to stuff, plugs, wires, distributer, coil ... finally pulled the air induction to get to the fuel injectors and discovered one injector connector with a broken snap connector. It was secure most of the time but was occasionally pulling back far enough to cause that cylinder to stop firing. I fixed the connector and checked the other 3, now it's all good.

Mike

 

[sdb999]

Standard Reproduce, Eliminate, Isolate, methodology.
Was able to reproduce stumbling idle (wire wiggle method) that was consistently the dropping of cylinders 2 AND 4 together...never individually. By the sound of my girlish yelps each time I got shocked spark was solid so eliminate that. That isolates it to fuel and the most likely shared component between 2 and 4 was a pair of wires, Blue and White. Blue it was! Factory splice literally fell apart as I unwrapped it.

I'll repair all factory splices in this section of the harness now that it's open and replace all the injector connectors too. Your right Mike, crumbling as I removed them.

Thanks guys, if anyone knows a good source for injector leeds let me know.
S.

 

[sdb999]

Quick pic of factory splice that had failed. Wrapped in electrical tape they look like diy repairs, and fail in a similar manner. In this case two Blue into one.

 

[flyinhawaiian01]

By the sound of my girlish yelps each time I got shocked spark was solid so eliminate that.

LOL!!!! That's funny! Only because most of us here know that sound and feel all too well!

You can find the EV1 connectors with pigtails for replacing the old connectors on ebay and amazon, here's one for 8 of them:

Set of 8 EV1 Fuel Injector Connector Plug Clip Pigtail Quick Disconnect New | eBay

Its actually cheaper for 8 on ebay than it is for 4 on amazon. I'm sure if you search, you can find it even cheaper for just 4 of them.

And just an fyi, there are two banks of injector pulses from the ecu, which is why #'s 2 and 4 go out at the same time. Seems it may not be the connectors at the injectors themselves, but the splice where the wires go. I'd trace them from the connectors back, you should see the wires spliced into the main harness going back to the ecu somewhere along that line. Stock wires were crimped with a copper sleeve then taped up with yellow or orange electrical(?) tape. When you find the connections, go ahead and cut them out completely, strip back fresh wire, and either solder a new connection, or at the very least, use a good quality butt connector and heat shrink the whole thing tight.

If that doesn't solve the issue, and you've replaced the EV1 connectors already, then it may be a bank on the injector's relay pack going out. You'll need to check all those connections to the pack too. Brake cleaner in the connector itself will clean it relatively well, then add some new dielectric grease to each pin.